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• 9:00
  Omnidirectional Millimeter-Wave Propagation Characteristics of Corridor Environments Based on Measurements at 28, 38, 71 and 82 GHz
  Juyul Lee, Kyung-Won Kim, Jae-Joon Park, Myung-Don Kim and Heon Kook Kwon (ETRI, Korea (South))
  
  This paper investigates measurement-based omni-directional millimeter-wave propagation characteristics for an indoor corridor environment. The omnidirectional characteristics were obtained with actual omnidirectional antenna measurements both at TX and RX, and not by synthesizing directional antenna measurements. With wideband sounding at 28, 38, 71 and 82 GHz, we analyzed path loss, shadow fading, excess loss and delay spread characteristics. In the path loss and the excess loss analyses, evident differences between the LOS and the NLOS were observed due to the waveguide effects. In the excess loss and the delay spread analyses, gaps were observed between the relative lower mmWave frequencies (28 and 38 GHz) and the upper frequencies (71 and 82 GHz).
• 9:20
  An Introduction to Dimensionality Reduction for Propagation Measurements
  Alejandro Ramírez-Arroyo and Luz Garcia (University of Granada, Spain)
  Antonio Alex-Amor (Universidad CEU San Pablo, Spain)
  Juan Valenzuela-Valdés (Universidad de Granada, Spain)
  
  This paper presents the dimensionality reduction of a propagation channel dataset created through a measurement campaign. The scenario knowledge is essential for the signal processing prior to the transmission and the application of these techniques allows a quick scenario differentiation. The measurement campaign, which has been performed in the SWAT research group's facilities at the University of Granada, includes propagation channels from three different scenarios: anechoic, reverberation and indoor. t-SNE, a Machine Learning technique that performs a non-linear dimensionality reduction, has been applied to the propagation channels. The results show the separability of the three scenarios in a low-dimensional space for an optimal election of the t-SNE hyperparameters. The most relevant hyperparameters in the performance of the technique are the distance metric and the perplexity.
• 9:40
  RMS Delay Spread Model for 60 GHz Band for Offices and Conference Rooms
  Monika Drozdowska (The Polytechnic University of Valencia, Spain)
  Amar Al-Jzari and Sana Salous (Durham University, United Kingdom (Great Britain))
  Narcis Cardona (The Polytechnic University of Valencia, Spain)
  
  The performance of indoor wireless systems depends on the deployment scenario, so proper parameterization and planning of the local area network (LAN) are crucial, in particular in the millimeter wave band which suffers from blockage. Two of the key performance indicators for wireless LANs are the packet delay and the end-to-end latency, which are related to the amount of redundancy added at the PHY and MAC layers, aimed to compensate the dispersive effect of the radio channel, usually represented by the root mean square delay spread (RMS-DS). This paper proposes a model that helps to predict RMS-DS in 60 GHz band based on room's geometry and compares the results with the ITU model. The work is based on measurements and results previously presented in the literature, especially focuses on offices and conference rooms.
• 10:00
  A Low Cost Dual-Branch Q-Band 39.4 GHz I/Q Satellite Beacon Receiver for Atmospheric Propagation Studies
  Patrick Eggers and Igor Syrytsin (Aalborg University, Denmark)
  Johannus Kristmundsson (Fiskaaling P/F, Faroe Islands)
  
  A satellite beacon receiver is designed for research and educational purposes. To provide data to investigate possible weather induced scattering processes, a complex valued dual branch architecture is chosen, operating in the Q-band. The construction is based on mostly readily available components and instruments at Aalborg University radio laboratory. The paper describes the beacon receiver and its features.
• 10:20
  Multi-Band Outdoor-To-Indoor Propagation Measurements Using a Drone
  Franco Fuschini, Marina Barbiroli, Enrico M. Vitucci and Vittorio Degli-Esposti (University of Bologna, Italy)
  
  Outdoor-to-indoor propagation path-loss measurements have been carried out at 27 and 38 GHz, two of the frequencies allocated for 5G networks, for two different buildings: an office glass, steel and concrete building and a brick-wall residential house. The outdoor station has been mounted on a drone in order to have more placement flexibility and reach the desired height above ground without the use of a crane truck. Overall outdoor-to-indoor loss seems to depend primarily on the window surface and on the construction material. While loss is higher at 38GHz with respect to 27 GHz for the office building, brick-walls of the residential house appear to be less frequency selective.

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• 11:00
  SDR-Based Communication Sniffing for Determining the Proliferation of ITS-G5
  Golsa Ghiaasi (Silicon Austria Lab, Austria)
  Thomas Blazek and Fjolla Ademaj (Silicon Austria Labs GmbH, Austria)
  Julian Karoliny (Silicon Austria Labs GmbH & Johannes Kepler University, Linz, Austria)
  Stefan Marksteiner, Markus Wolf and Peter Priller (AVL List GmbH, Austria)
  Hans-Peter Bernhard (Johannes Kepler University Linz, Austria)
  
  This paper describes the measurement setup for the proliferation of the vehicular communication systems in operating cars. The setup builds on a communication sniffer which detects cooperative awareness messages broadcast from ETSI ITS-G5 systems, decodes them and records the public information in these messages. The experimental characterization of the setup in an outdoor scenario is presented in order to verify the sniffer's performance with respect to transmit power and communication range. The setup is deployed for measurements on a busy road with slow moving traffic in the center of the city of Linz, Austria. The number of active users as well as their transmit power, duration of the transmission and packet length have been recorded.
• 11:20
  Statistical Modelling of Short-Range Interference Paths
  Richard Rudd (Plum Consulting Ltd, United Kingdom (Great Britain))
  
  There is a frequent requirement in spectrum sharing studies (e.g. in relation to frequency assignment for 5G systems) to assess the basic transmission loss on short (typically less than 1 km) outdoor paths in a variety of environments. In most sharing studies, it is required that the results of the modelling are generic (i.e. no site specific inputs to the model are necessary) and are presented in statistical terms (typically path loss not exceeded for a given probability). A useful model must also be suitable for computer implementation, often within a Monte Carlo framework. Many existing models are deterministic in the sense that they apply to specific geometries or environments which makes it impossible to apply such models in the general case where statistics covering all path geometries are required. This paper proposes a new, unambiguous, method for the prediction of the statistics of basic transmission loss in such cases.
• 11:40
  Multibeam Leaky-Wave Antenna for Mm-Wave Wide-Angular-Range AoA Estimation
  Julien Sarrazin and Guido Valerio (Sorbonne Université, France)
  
  The design of a periodic leaky-wave antenna for angle-of-arrival (AoA) estimation is presented. Thanks to multiple radiating space harmonics, a multibeam operation is achieved in order to scan a large angular range with a limited fractional frequency bandwidth. The matching and radiation efficiency issues raised by the large spatial period involved with multibeam operation is addressed by using a dedicated unitcell to control both the leakage constant and the Bloch impedance. Simulations confirm that a MUSIC processing enables the system to perform AoA estimation without ambiguity among the multiple beams. This allows for AoA estimation over the 180°-angular range with a bandwidth of only 3.7% at 27 GHz.
• 12:00
  A Reference Model for Channel Sounder Performance Evaluation, Validation and Comparison
  
  Sven Wittig (Fraunhofer Heinrich Hertz Institute, Germany)
  Michael Peter (Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Germany)
  Wilhelm Keusgen (Technische Universität Berlin, Germany)
  
  In this paper, we propose a detailed generic reference plane model for performance evaluation and system validation of radio channel sounders. It allows to abstractly describe a broad variety of channel sounder implementations and architectures in a common framework, thus facilitating systematic evaluations and comparisons. To illustrate the utility of the concept, we present the mapping of two practical channel sounder realizations - one time domain and one frequency domain - to the model, along with selected performance metrics defined on its reference planes. For the two presented channel sounders, we give measurement examples for these metrics.
• 12:20
  Challenges for 5G and Beyond
  Jelena Senic, Anmol Bhardwaj, Camillo Gentile, Derek Caudill and David Lai (NIST, USA)
  Damir Senic (ANSYS, USA)
  Sung Yun Jun (National Institute of Standards and Technology, USA)
  Jack Chuang and Jian Wang (NIST, USA)
  Anuraag Bodi (National Institute of Standards and Technology, USA)
  Raied Caromi (National Institute of Standard and Technology, USA)
  Nada Golmie (NIST, USA)
  
  In this paper, we discuss some challenges for 5G-and-beyond communications systems based on our measurements conducted with millimeter-wave (mmWave) channel sounders. One study analyzes path loss at 28 GHz vs. 83 GHz and in line-of-sight conditions vs. non-line-of-sight conditions and finds it to depend much more heavily on the latter than the former. A significant factor of path loss is penetration loss; in fact, another study focuses on obstructions that are typical in wireless environments: building walls, human bodies, and trees. Finally, in addition to investigating how power is distributed over distance through path loss, we also investigate how power is distributed over delay and angle per distance, otherwise referred to as channel dispersion. In particular, we discuss the importance of diffuse multipath to the total received power at mmWave and the foregone conclusion of wide-sense stationarity, which we show will often not apply to mmWave small-scale fading.

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• 16:40
  SbD-Based Propagation Contouring Through 1-Bit Dual-Polarization Reconfigurable Intelligent Surfaces
  Giacomo Oliveri (University of Trento & ELEDIA Research Center, Italy)
  Andrea Massa (University of Trento, Italy)
  
  The possibility to achieve advanced beam contouring capabilities with single-bit dual-polarization reconfigurable intelligent surfaces (RISs) is addressed in this contribution with reference to their application in the Smart Electromagnetic Environment (SEE) framework. The discrete multi-scale RIS reconfiguration problem is firstly recast in terms of a phase-only inverse source one. The RIS discrete descriptors are then optimized through a customized System-by-Design (SbD) strategy. Preliminary numerical results are presented to illustrate the wave manipulation capabilities and efficiency enabled by the proposed strategy.
• 17:00
  Array Antenna Power Pattern Analysis Through Quantum Computing
  Luca Tosi and Nicola Anselmi (ELEDIA Research Center, Italy)
  Alessandro Polo (ELEDIA Research Center, University of Trento, Italy)
  Paolo Rocca (University of Trento & ELEDIA Research Center, Italy)
  
  The analysis of the power pattern generated from a uniform linear array is here carried in the Quantum Computing (QC) framework. The formulation and the analysis method based on the quantum Fourier transform (QFT) algorithm and the values observable at the output of the quantum computation are presented. A preliminary proof-of-concept result is reported and analyzed to point out the peculiarities and the advantages of the proposed method.
• 17:20
  Design of an Amplitude-Tapered Corporate-Feed Slot Array Antenna with Reduced Side-Lobe Level for Silicon Micromachining
  Armin Karimi and Joachim Oberhammer (KTH Royal Institute of Technology, Sweden)
  
  This work proposes a novel unbalanced corporate-feed network antenna design with amplitude tapering of the radiated power to get a reduced sidelobe level. The phase imbalance of the asymmetric power dividers is compensated by integrated delay lines which maintain the aperture efficiency. The 10 dB beamwidth is reduced by 8.5% in E-plane and 10.2% in H-plane after the phase compensation. A 16×16 and a 32×32 array antenna have been designed for 230-290 GHz, i.e., a 23% fractional bandwidth. The 16×16 and 32×32 antenna's realized gain is between 29.4-32.1 dBi and 34.6-37.6 dBi, with sidelobe levels better than 21.2 dB and 20.5 dB, respectively. The design is optimized for being implemented by silicon micromachining. To the best of the author's knowledge, this is the first amplitude tapered corporate feed slot array antenna with delay lines for phase compensation that has been proposed in this frequency range with this wide operational bandwidth.
• 17:40
  On the Design of HAPs High Throughput and Flexible 5G Communication Payloads
  Miguel Salas-Natera and Gonzalo Lázaro (Universidad Politécnica de Madrid, Spain)
  Antonio Abad (C/Anabel Segura 11 - Edificio Albatros 4 floor & Hispasat, Spain)
  Ramón Martínez (Universidad Politécnica de Madrid, Spain)
  
  This work presents a technical analysis and a proposal of the payload architecture including a 5G antenna design. The analysis covers the comparison with terrestrial networks and satellites, and the frequency bands and service area limitation versus available power and payload technology onboard actual High-Altitude Platforms (HAP). For this, a review of the HAP system capacity and payload requirements is done. Furthermore, the definition of the payload architecture is based on actual and mature state of the art of the technologies and the antenna aperture has dual-band and dual-circular polarization operation capacity.
• 18:00
  Enhanced Data Throughput Using 26 GHz Band Beam-Steered Antenna for 5G Systems
  Muhammad S Rabbani and James Churm (University of Birmingham, United Kingdom (Great Britain))
  Sohail Payami (University of Surrey, United Kingdom (Great Britain))
  Mohsen Khalily (University of Surrey & 5G Innovation Centre, Institute for Communication Systems (ICS), United Kingdom (Great Britain))
  Pei Xiao and Rahim Tafazolli (University of Surrey, United Kingdom (Great Britain))
  Tian Hong Loh (UK, National Physical Laboratory, United Kingdom (Great Britain))
  James Kelly (Queen Mary University of London, United Kingdom (Great Britain))
  Alexandros Feresidis (University of Birmingham, United Kingdom (Great Britain))
  
  A high gain (20 dBi) Leaky-Wave Antenna (LWA) is presented at 26 GHz with beam steering capabilities (44°) for high data throughput in millimeter-wave (mm-wave) 5G systems. A tunable phase shifting High Impedance Surface (HIS) exhibiting low loss (<0.1 dB), is employed for the antenna's beam steering. A Piezo-Electric Actuator (PEA) is employed to electromechanically tune the HIS. The employed PEA exhibited fast (milliseconds) and continuous displacement variation of up to 500 μm. The LWA has been demonstrated by deploying it within a 5G testbed operating within the 26GHz band. It was observed that the channel performance can significantly be improved utilizing the beam steering capability of the antenna in the case when the line-of-sight (LOS) is blocked by an obstacle.

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• 15:00
  Nondestructive Material Measurements
  Michael J Havrilla (Air Force Institute of Technology, USA)
  
  Nondestructive measurements are often employed for characterizing electromagnetic materials, especially in non-laboratory environments. Nondestructive techniques are fairly well established for simple media (i.e., materials that are linear, isotropic, homogeneous and time-invariant). However, the past decade or two has seen considerable interest in materials that are non-linear, non-isotropic (e.g., hyperbolic and bianisotropic media), spatially varying & dispersive (e.g., wire media), time varying (e.g., spacetime metamaterials) and non-reciprocal (e.g., topological insulators). What types of nondestructive techniques can be utilized for these materials? What new theory must be developed and what new measurement devices need to be invoked? What are the future challenges of nondestructive material characterization? How has 3D printing shifted the paradigm of the meaning of nondestructive evaluation? This talk will provide an overview of modern nondestructive material measurement techniques and will address the many questions and challenges one encounters when dealing with nondestructive evaluation of contemporary materials.
• 15:40
  Current Research Aspects in the Automotive Antenna Measurement Chamber VISTA at the TU Ilmenau
  Christian Bornkessel (Technische Universität Ilmenau, Germany)
  
  The Thuringian Center of Innovation in Mobility (ThIMo) under the roof of the Technische Universität Ilmenau operates an automotive antenna measurement chamber VISTA, equipped with a multi-probe measurement system covering the frequency range from 70 MHz … 6 GHz including the sub-6-frequencies for 5G mobile radio. In this talk, several current application-oriented research topics are presented and illustrated with examples. These research topics include: Fast car antenna measurements in the installed state with various boundary conditions beneath the car. Extension to antenna measurements installed on other electrically large objects like locomotives. Emulation of LTE and V2X links as well as automotive radar in virtual environment. Characterization of small cell antennas with regard to their RF exposure to humans by using a hybrid measurement-numerical method.

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• 15:00
  On the Modelling, Design and Characterization of Pulsed Photo-Conducting THz Front Ends
  Andrea Neto (TNO, The Netherlands)
  
  The power available from Photoconductive Antennas (PCA) by exploiting pulsed Optical-to-THz up/down conversions was so far only sufficient for localized spectroscopy. This has been a bottle neck for the wider use of these type of sources in sensing. However, recently reproducible m-watt power sources in the THz spectrum have been demonstrated by the THz Sensing Group. This talk will address some of the difficulties that hindered the progress for many years. The most important were likely associated to wide band modelling of short Electromagnetic pulses in complex active passive environments. Also the difficulties in manufacturing and interpretation of the measurements will be addressed.
• 15:40
  Microwave and Millimeter-Wave Imaging in Real Time
  Natalia Nikolova (McMaster University, Canada)
  
  Real-time microwave and millimeter-wave imaging methods are the workhorse in applications ranging from synthetic aperture radar, which operates with far-field data, to nondestructive testing and medical imaging, which employ near-field measurements. Research in this field is intensifying due to the rapid expansion of the wireless technologies beyond communications and into imaging and sensing. This expansion is fuelled by the advances of on-chip millimeter-wave to sub-THz electronics and the envisioned integration of communication and sensing in the future (beyond-5G) wireless networks and devices. This paper is an attempt to explain, categorize, compare and contrast the real-time imaging methods and algorithms within a common mathematical framework so that this interdisciplinary subject is rendered more comprehensible and accessible to the wider research community.

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• 9:00
  Production Measurement of 5G Millimeter Wave Plane Wave Generators
  Francesco Scattone (Microwave Vision Group (MVG), Italy)
  Darko Sekuljica (MVG, Italy)
  Andrea Giacomini and Francesco Saccardi (Microwave Vision Italy, Italy)
  Ruben Tena Sanchez (Microwave Vision Group (MVG), Italy)
  Alessandro Scannavini (Microwave Vision Italy, Italy)
  Kim Rutkowski (Microwave Vision Group, Satimo Industries, France)
  Evgueni Kaverine (MVG Industries, France)
  Shoaib Anwar (Microwave Vision Group, Satimo Industries, France)
  Nicolas Gross (MVG Industries, France)
  Per Iversen (Orbit/FR, USA)
  Lars Foged (Microwave Vision Italy, Italy)
  
  A Plane Wave Generator (PWG) is an array of elements with suitable complex excitation that approximates a plane wave condition at close distance within a Quite Zone (QZ). The StarWave system has been designed to enable transmit and receive testing of 5G devices in dual polarization, within a 380 mm diameter QZ. The testing is performed using up to seven individual PWG's generating plane wave conditions from different directions. Each PWG undergoes a production testing to verify the amplitude and phase dispersion of the array elements by the feeding network. As several individual PWG are required, each with many array elements, the production testing becomes time consuming and impractical. In this paper we report and experimentally validate a fast production testing procedure that allow to verify amplitude and phase conformance and to determine the QZ performance of a PWG from a quick Planar Near Field (PNF) scan of the aperture.
• 9:20
  A Novel CATR Design with Diamond-Shape Reflector for 5G/6G OTA Measurement
  Rong-Chung Liu (Yuan Ze University & WavePro, Taiwan)
  Chung-Huan Li (WavePro Inc., Taiwan)
  
  A novel compact antenna test range (CATR) design is presented in this study. Conventionally, the edges of the reflector are parallel to the chamber walls. Instead, a diamond-shape reflector (DSR) is proposed in this design. The reflector is rotated for 45 degrees, so the corners of DSR point to the walls (patent pending). This design suppresses the scattering from the absorbers on the walls, which improves quiet-zone (QZ) performance accordingly. This is important for some applications, such as angle-of-arrival (AoA), which are sensitive to clutters. In addition, the chamber size can be more compact as the new design allows shorter distance between the reflector and the walls. The design has been realized and validated with QZ measurement.
• 9:40
  Potential of Edge-Soldering in Millimeter-Wave Antenna Design
  Katerina Galitskaya, Mikko K. Leino and Jari Van Wonterghem (Radientum Oy, Finland)
  
  A dual-polarized, cavity-based antenna array with implemented edge-soldered transition technique is presented for 5G millimeter-wave applications. The working band of the proposed antenna is 26.5-29GHz. Full structure consists of two PCBs soldered together to achieve end-fire radiation pattern. A 4x1 array prototype supporting single polarization has been manufactured and measured. The measured reflection coefficient over the band is -12 dB, and with uniform amplitude distribution, a maximum gain of nearly 10 dBi is measured. The measured array exhibits a scanning potential up to 30 deg. The measured results have good agreement with the simulations.
• 10:00
  Measurements of IP3 and P1dB for Spectrum Monitoring with Software Defined Radios
  Mike McNulty (Colorado School of Mines, USA)
  Dazeh Gu and Daniel Kuester (NIST, USA)
  Payam Nayeri (Colorado School of Mines, USA)
  
  This paper discusses methodology for characterizing basic power linearity parameters of software-defined radios. First, we introduce a highly automated testbed for 1-dB compression point (P1dB) and thirdorder input intercept point (IIP3). With this system, we have observed some surprising deviations from the expected slope of 3 dB/dB in the power response of the third order intermodulation distortion (IMD3). In response to this, we developed a measurement technique based on linear regression that accounts for the actual slope. A methodology study considers this technique in comparison with existing techniques for IIP3 measurements of spectrum monitoring receivers. In consideration for the increase in IM3 model complexity, we also propose an alternative parameter to simplify the quantitative evaluation of spectral regrowth near the receiver noise floor. We argue that this equivalence point provides a designer with more valuable information than an IIP3 point for spectrum monitoring applications.
• 10:20
  An Investigation into the Effects of Spatial Correlation Error on 5G MIMO OTA Testing Using Single-Probe Anechoic Chamber Method
  Qiwei Zhang (University of Chinese Academy of Sciences, China)
  Tian Hong Loh (UK, National Physical Laboratory, United Kingdom (Great Britain))
  Zhibei Huang (University of Chinese Academy of Sciences, China)
  Fei Qin (Chinese Academy of Sciences, China)
  
  Multiple-input-multiple-output over-the-air testing evaluates the multi-antenna wireless systems' performance in a controlled laboratory environment by emulating realistic real-world fading channel conditions. Spatial correlation is the key metric to character the accuracy of MIMO OTA testing system. Along with the evolution into 5G era, the MIMO OTA measurement setup complexity increase as well, especially for accurate implementation of three-dimensional channel model. Furthermore, extension of the two-dimensional multi-probe anechoic chamber (MPAC) method into full spherical three-dimensional MPAC is impractical due to cost consideration and setup complexity. In this paper, we present the use of a cost-effective single-probe anechoic chamber (SPAC) method for MIMO OTA testing and demonstrate that better spatial correlation accuracy can be achieved over implementation of the 3D spatial channel model as compared with MPAC. The development of such method can significantly reduce implementation cost to support wireless device R\&D process. Both the theoretical derivation and simulation results are validated.

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• 11:00
  Developing a MIMO Test Methodology Using Dynamic Channel Models and Link Adaptation
  Michael D. Foegelle (ETS-Lindgren, USA)
  Thorsten Hertel (Keysight Technologies, USA)
  Pekka Kyösti (Keysight Technologies & University of Oulu, Finland)
  Jukka Kyröläinen (Keysight Technologies Finland oy, Finland)
  Doug Reed (Spirent Communications, USA)
  
  Industry standards for over-the-air testing of LTE MIMO devices have used multi-probe anechoic chamber based systems to evaluate device performance in a spatially static environment. The spatial distribution of clusters in the chosen channel models are fixed, and the only geometric variation relative to the device under test is accomplished by physically rotating the device in the generated test environment. For 5G FR1 testing, the CTIA MIMO OTA working group is developing a test plan based on the use of dynamic channel models that vary the spatial configuration as a function of time, and allowing the communication tester base station emulator to perform link adaptation, allowing the device to choose the best MIMO or SISO diversity mode and data rate for a given channel condition. This paper will discuss the design considerations associated with developing this new channel model and the related test system requirements.
• 11:20
  All-Optical Fiber Link Antenna Measurement System Using an Industrial Robot System
  Satoru Kurokawa (National Institute of Advanced Industrial Science and Technology, Japan)
  
  Our developed system consists of an optical fiber link microwave transmitting system, an antenna-coupled-electrode electric-field sensor system for 28 GHz-band as a microwave receiving system, and a 6-axis vertically articulated robot with an arm length of 1 m. Our developed optical fiber link microwave transmitting system can transmit the microwave from 23 GHz to 33 GHz with more than -20 dBm output level. Our developed electric-field sensor can receive the microwave from 27 GHz to 30 GHz. In this paper, we show a measured near field radiation pattern for the WR-28 standard gain horn antenna using the system.
• 11:40
  Investigation on Simplified Test Environment of OTA In-Band Blocking for 5G Millimeter-Wave Radio Base Stations
  Hans Andersson, Stefan Nilsson, Jonas Fridén, Sam Agneessens, Joakim Lysell, Anders Fransson, Arya Khan-Amidy, Jacob Mannerstråle, Noor Choudhury, Bo Xu and Queenie Zhang (Ericsson AB, Sweden)
  Over-the-air testing enables realistic verification of radio base stations with antenna panels. To conform with the requirements, most over-the-air measurements for uplink of 5G radio base stations are performed in fully anechoic chambers. In this work, the comparison between using the fully anechoic chamber and the reverberation chamber for in-band blocking testing is conducted on a 5G millimeter-wave radio unit. The use of the reverberation chamber can reduce the time and cost of the tests. Good agreement can be observed between the results obtained from the anechoic chamber and the reverberation chamber for the in-band blocking testing.
• 12:00
  MIMO mmWave Over-The-Air Testbed Calibration Using Symmetries and Experimental Verification
  Koen Buisman (University of Surrey, United Kingdom (Great Britain) & Chalmers University of Technology, Sweden)
  Thomas Eriksson (Chalmers University of Technology, Sweden)
  
  Calibration and validation of mm-wave transceiver arrays with respect to phase and amplitude of all elements is an essential part of production testing. Also afterwards during operation it may be necessary to update calibration coefficients. Here we present an algorithm based on channel symmetries, derive mathematically its expression, experimentally verify its results with respect to amplitude in a mm-wave testbed and compare the results to an extract model.
• 12:20
  Definition of Far Field Measurement Distance for 5G mmW Antenna Arrays: Application on N x M Patch Arrays
  Walid El Hajj and Tsitoha Andriamiharivolamena (Intel Corporation, France)
  Juan Antonio Del Real (Intel Corporation SAS & CCG WCS WTCC WRF Lab, France)
  Nawfal Asrih (Intel Corporation, France)
  
  The purpose of this paper is to define a mathematical formulation for patch arrays Far Field (FF) distance allowing to calculate the FF distance from the array size (N x M), the operation frequency and substrate permittivity. It illustrates how the theoretical FF distance based on the antenna dimension and wavelength overestimate the practical FF distance by 5 times.

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• 16:40
  Design of a Rotman Lens Operating in the Full K/KA Band Using Ridge Waveguide Technology
  Fábio Martinho Cardoso (Iscte - Instituto Universitário de Lisboa)
  Sergio Matos (ISCTE-IUL / Instituto de Telecommunicações, Portugal)
  Jorge R. Costa (Instituto de Telecomunicações / ISCTE-IUL, Portugal)
  Carlos A. Fernandes (Instituto de Telecomunicacoes, Instituto Superior Tecnico, Portugal)
  Joao M. Felicio (Instituto de Telecomunicações, Portugal)
  Nelson Fonseca (European Space Agency, The Netherlands)
  
  Several services associated with Satellite on the move and 5G applications are populating the K and Ka frequency bands. Beam forming networks are crucial components for achieving the necessary beam flexibility and agility of these systems. Rotman lens is being widely investigate as cost-effective solution for overcoming the main limitations of other types of beam forming networks, namely bandwidth, losses, and size. One of the main design challenges is obtaining broadband transitions for the array and beam ports. In this work we used a standard K/KA double ridge (WRD180) for interfacing with the Rotman Lens. The main motivation for this choice is the wide bandwidth (K/KA band) and the avoidance of dielectric losses associated with microstrip implementations. We present a design capable of fully exploring the ridge waveguide bandwidth with wide beam scanning, outperforming previous works. The presented design consists of a 13x7 Rotman Lens with a scanning range of ±50 degrees operating between 17.3 and 40 GHz, validated through full-wave simulations.
• 17:00
  Synthesis of Sparse Large Arrays via Sequential Convex Optimizations
  Christos Monochristou (University of Rennes 1, France)
  Shang Xiang (Lund University, Sweden)
  Mark Holm (Huawei Technologies (Sweden) AB, Sweden)
  Ronan Sauleau (University of Rennes 1, France)
  Mauro Ettorre (University of Rennes 1 & UMR CNRS 6164, France)
  
  In this work a synthesis technique for designing sparse phased arrays of large size is presented. The procedure is based on an iterative convex optimization algorithm, also known as compressive sensing, which is straightforward to implement and efficient in terms of computational cost. It is capable of producing a layout with a significant reduction of active elements for predefined performance. Due to its effectiveness, it can also be employed for the optimization of large arrays. The capabilities and versatility of the algorithm are illustrated by different case studies. In particular, the possibility to reduce by 45% the number of elements in a large array is shown in details.
• 17:20
  Efficient Design of H-Plane SIW Horn Antenna Array at mmWaves
  Cleofás Segura-Gómez (University of Granada, Spain)
  Angel Palomares-Caballero (Universidad de Granada, Spain)
  Pablo Padilla (University of Granada, Spain)
  
  This paper presents an efficient design of an SIW horn antenna array for upper part of the Ka-band. The array is formed by a corporate network in substrate integrated waveguide (SIW) technology which feeds eight SIW horn. Impedance matching between each SIW horn and the free space is carried out by using a SIW-to-air transition that efficiently matches with the rest of the antenna elements. The array feed is based on an end launch connector over grounded coplanar-waveguide (GCPW) technology that makes an efficient transition to SIW. The corporate network has two-by-two electromagnetic (EM) field splitting levels through the use of H-plane T-splitters and waveguide bends. Thus, an in-phase and equal power symmetrical array structure is achieved from 34 GHz to 41 GHz (18.6% of bandwidth). The simulated results present a high stable gain of 14 dBi in the H-plane along the whole frequency range.
• 17:40
  Penrose Tiling Subarrays for Large-Scanning and Energy-Saving Phased Array
  Francesco Dicandia (IDS - Ingegneria dei Sistemi SpA, Italy)
  Simone Genovesi (University of Pisa, Italy)
  
  A novel partitioning scheme based on Penrose tessellation subarrays has been proposed for phased array design. More in detail, the radiating elements of a phased array arranged on a regular and periodic lattice are grouped into irregularly-shaped tiles by exploiting the features offered by the aperiodic Penrose tessellation. The preliminary results reveal that the novel array architecture ensures a remarkale reduction of the Transmit/Receive modules without compromising the performance in terms of scan angle and peak side lobe level.
• 18:00
  Array Antenna Fault Diagnosis via near Field Amplitude-Only Data
  Roberta Palmeri (IREA-CNR, Napoli, Italy)
  Giada Maria Battaglia (Università Mediterranea di Reggio Calabria, Italy)
  Andrea Francesco Morabito (University Mediterranea of Reggio Calabria, Italy)
  Tommaso Isernia (University of Reggio Calabria, Italy)
  
  The paper deals with the diagnostics of realistic array antennas by exploiting phaseless measurements. Provided the number of faults is not small with respect to the overall number of elements, the proposed approach allows performing the diagnostics whatever the kind of radiating elements even if the measurement surface is located in the near-field zone. Despite the high non-linearity induced by the adoption of phaseless measurements, the underlying optimization problem can be cast as a Convex Programming one taking decisive advantage of the Compressive Sensing theory. Examples concerning 1-D array diagnostics are given for both cases of ON-OFF and phase faults.

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• 15:00
  A Holy Grail Quest: The Concept of Stored Electromagnetic Energy
  Guy Vandenbosch (Katholieke Universiteit Leuven (KU Leuven), Belgium)
  
  In this talk the quest for the "final" expressions for the energy stored in a radiator is overviewed. First, the several forms of power and energy that have been defined and used in electromagnetics over the last 100 years are briefly summarized, and their most important characteristics are discussed. In a first step, frequency domain is considered. Starting from two power balance equations, a field based reactive energy is formally defined and compared to the numerous "definitions" already available in literature. Then the concept of recoverable energy is introduced. The differences with reactive energy are pointed out. Moving to time domain, it is possible to write unifying expressions generalizing the concept of reactive energy. It is shown that recoverable energy is just a special case for a specific current evolving in time. Illustrative examples are given where these energies can be used to solve practical problems. The paper clearly illustrates that the concept of stored electromagnetic energy is still not well-understood when a radiator is involved.
• 15:40
  Recent Developments in the Design and Realization of Advanced Electromagnetic Surfaces
  Sean V Hum (University of Toronto, Canada)
  
  Advanced electromagnetic surfaces (AESs) comprise a spectrum of artificially engineered surfaces for manipulating the temporal and/or spatial dispersion of electromagnetic waves, and include structures such as reflectarrays, transmitarrays, frequency selective surfaces, polarizers, and most recently, metasurfaces / metagratings. The design of such surfaces can be separated into two steps: a macroscopic step, where the surface parameters required to achieve particular manipulations of the incident field are determined; and a microscopic step, where the geometric structure of the underlying unit cells or meta-atoms is determined to realize those properties. This talk will review recent developments in systematic design techniques for both steps. In particular, synthesis methods will be described for carrying out the macroscopic step, particularly for spatially-dispersive AESs used to implement specific radiation patterns. Subsequently, a variety of techniques for solving the inverse design problem associated with the microscopic step will be presented, with emphasis on recently developed techniques based on machine learning. A selection of AES designs developed based on the proposed techniques will be presented, including experimental demonstrators of several metasurfaces.

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• 15:00
  Propagation and Channel Modelling for Smart Railways
  Ke Guan (Beijing Jiaotong University, China)
  
  In the vision of smart railways, a seamless high-data-rate and dependable wireless connectivity both for communication and sensing will be required. It is of primary importance to generate realistic channel data in order to do properly all the application layer end-to-end tests for all the relevant use cases that will be enabled by these wireless systems in railways. In this talk, we identify the major challenges and present the state-of-the-art solutions towards realistic channels of smart railways, especially for high frequencies, such as the millimeter-wave and THz bands. Moreover, future research trends are pointed out towards a thorough understanding of the propagation and wireless channel characteristics to support the design and evaluation of future smart railway wireless sytems.
• 15:40
  Stratified Media, Spectral Domain, Square Roots and Sommerfeld Integrals
  Juan R Mosig (Ecole Polytechnique Federale de Lausanne, Switzerland)
  
  The study of stratified media, defined as layered configurations of material substrates, is of paramount relevance in many scientific and technological areas like Acoustics, Geophysics and Lightning. In Electromagnetics, the first treatment of these problems is due to Arnold Sommerfeld who, more than one century ago, solved the most basic of all stratified media geometries, i.e. the two semi-infinite media problem. In doing so, Sommerfeld developed the fundamentals of a mathematical method, which is now known as the spectral domain approach (SDA). After many decades of latency, the analysis of stratified media using SDA knew a strong regain of interest, due to the introduction of printed technologies (microstrip and striplines) and the development in the 70s of the first planar antennas. Nowadays, SDA is used in many other areas of Electromagnetics, like Ground Penetrating Radar, satellite-based Remote Sensing and Optics&Photonics. This tutorial will review the stratified media problem and its formulation through the so-called Sommerfeld Integrals. Some tricky points, like complex square roots definitions, the relevance of a ground plane at infinity and the existence of a Sommerfeld pole (and hence of a surface wave) will be discussed. Numerical techniques will be briefly discussed and used to illustrate some recent discussions in the literature about the behavior of electromagnetic fields as a function of radial distances and of elevation angles (radiation patterns).
  

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• 9:00
  Sub-Terahertz Path-Loss Characteristics in an Urban Microcell Environment for 6G
  Minoru Inomata, Wataru Yamada, Nobuaki Kuno and Motoharu Sasaki (NTT, Japan)
  
  The establishment of 6G networks is being actively pursued worldwide. 6G will require extremely high-speed and high-capacity communications exceeding 100 Gbps, and one solution is to utilize new frequency bands above 100 GHz. However, specific new radio- interface technologies and service frequency bands have not been determined yet, because propagation characteristics above 100 GHz in various environments have not been studied sufficiently. In consideration of exploiting new frequency bands for 6G, path-loss characteristics from the microwave to sub-terahertz bands in an urban microcell environment were investigated. Also, the dominant paths that affect the path-loss characteristics were clarified on the basis of the measured power angular profiles.
• 9:20
  Simulating the Radar Cross Section of a Bare Tree: From Megahertz to Terahertz
  Oliver Csernyava and Katsuyuki Haneda (Aalto University, Finland)
  An approach to estimate a radar cross-section (RCS) of a tree through numerical simulations is studied. This paper covers bare trees with a trunk and branches and without leaves. Recent advancements in three-dimensional (3D) modeling of trees and electromagnetic solvers allow simulation of field scattering from a whole tree. There are open issues in performing the simulations: 1) obtaining 3D models of tree trunks and branches, especially whether they have to be multi-layered or not; 2) knowing dielectric parameters of tree trunks and branches, especially for higher frequencies than 10 GHz; 3) using a right field solver depending on the electrical size of a tree. We propose suitable 3D models of tree trunks and branches, show our present knowledge of dielectric parameters of living trees, and finally demonstrate impacts of branches in addition to a trunk on the estimated RCS through numerical simulations at 1000 MHz to 0.1 THz.
• 9:40
  Analysis of Residential Sub-THz Deployments from Accurate Radio Simulations and Planning Techniques
  Laurent Maviel, Yoann Corre and Grégory Gougeon (SIRADEL, France)
  Djamel Amar (Siradel, France)
  
  High-capacity bandwidth makes sub-THz spectrum a key element of beyond-5G or 6G networks. However wireless communications at frequencies such as in W-band, D-band or above do suffer from strong constraints at the physical layer, they may be greatly beneficial for adequately chosen ultra-broadband applications and network topologies. Multi-hop backhauling and Fixed Wireless Access (FWA) networks are both candidates that we decided to assess as a combination. The physical-layer performance is estimated from LiDAR-based ray-tracing predictions and by considering a sub-THz polar-QAM modulation. The site placement is optimized by an automated heuristic method. Finally, analysis of a case study in a North American residential area demonstrates that a FWA design at 150 GHz is challenging due to propagation, but feasible. The comparison between a coverage-constrained sub-THz design and a capacity-constrained 5G design shows interesting complementarity.
• 10:00
  On the Phase-Compensated Long-Range VNA-Based Channel Sounder for Sub-6GHz, mmWave and Sub-THz Frequency Bands
  Yejian Lyu (Aalborg University, Denmark)
  Allan Mbugua (Huawei Technologies Duesseldorf GmbH, Munich Research Center, Germany)
  Kim Olesen (Aalborg University, Denmark)
  Pekka Kyösti (Keysight Technologies & University of Oulu, Finland)
  Wei Fan (Aalborg University, Denmark)
  
  This paper presents an overview of the vector network analyzer (VNA)-based phase-compensated channel sounder at sub-6 GHz, mmWave and sub-Terahertz (sub-THz) bands. The optical cable solution can enable long-range channel measurements for all these three bands, since it can effectively minimize the cable loss. The phase compensation architecture and principle are also discussed in this paper. The phase compensation scheme could stabilize the phase change introduced by optical fiber of the channel sounder to enable accurate phase measurement, which is essential for application in multichannel/ antenna measurements. We summarized the performance of the designed channel sounder under two types of cable effect condition, namely thermal changes and mechanical stress. Under these two cable conditions, the phase compensated channel sounders are validated in back-to-back measurements. The compensated phases demonstrate the robustness and effectiveness of these channel sounder for the frequency bands of 1-30 GHz, and 220-330 GHz.
• 10:20
  Verification of THz Channel Sounder and Delay Estimation with Over-The-Air Multipath Artifact
  Diego Dupleich (Technische Universität Ilmenau, Germany)
  Sebastian Semper (Ilmenau University of Technology, Germany)
  Mohanad Dawood Al-Dabbagh (Physikalisch-Technische Bundesanstalt (PTB), Germany)
  Alexander Ebert (Technische Universität Ilmenau, Germany)
  Thomas Kleine-Ostmann (Physikalisch-Technische Bundesanstalt, Germany)
  Reiner S. Thomä (Ilmenau University of Technology, Germany)
  
  In the present paper we introduce the empirical results of measurements with an over-the-air based propagation artifact for verification and validation of sub-THz and THz channel sounders and parameter estimation algorithms. This experiment produces a fixed number of multipath components with traceable propagation properties in the different domains that can be used to test resolution and performance. Because of the inherent characteristics of the measurement hardware, we have introduced an adaptation on a parametric high resolution estimation algorithm to account the imperfections of the channel sounder. The results have shown to account for a relative good performance of the sounder and the tested parametric and non-parametric estimation algorithms.

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• 11:00
  Indoor Material Transmission Measurements Between 2 GHz and 170 GHz for 6G Wireless Communication Systems
  Mohamed Abdelbasset Aliouane (Telecom Paris, Ecole Polytechnique de Paris & Orange Labs, France)
  Jean-Marc Conrat (Orange Labs, France)
  Jean-Christophe Cousin (Telecom ParisTech, France)
  Xavier Begaud (LTCI, Télécom Paris, Institut Polytechnique de Paris, France)
  
  The sixth-generation wireless communication research activities were launched worldwide. A tendency of some researchers to use the sub-terahertz frequency band for 6G is noticed. This frequency band is selected as a candidate for 6G due to its remarkable wide unused frequency bandwidth. In this paper, typical indoor environment material transmission measurements from 2 GHz to 170 GHz are presented. These measurements aim to further understand and compare wave-material interaction for above and below 100 GHz frequencies by providing a continuous measurement up to 170 GHz of 16 different materials e.g. glass, plasterboard, concrete, and wooden materials. The measurement system is based on a vector network analyzer, with frequency extension modules for frequencies above 50 GHz.
• 11:20
  Initial Results on D Band Channel Measurements in LOS and NLOS Office Corridor Environment
  Joonas Kokkoniemi, Veikko Hovinen, Klaus Nevala and Markku Juntti (University of Oulu, Finland)
  
  A need for measurement data for frequencies above 100 GHz has increased. In this paper, we present the measurement system for millimeter wave frequencies (30-300 GHz). It is based on Keysight PNA-X vector network analyser with frequency extenders mounted on custom built 3-axis rotation stages (both the transmitter and receiver sides). We present some initial results from measurements conducted in an office corridor. Both line-of-sight (LOS) and non-LOS (NLOS) cases are included in the measurement set-ups. The results show that in all cases the channels are sparse with clear clusters from large reflecting surfaces, such as walls and floors. The measured power levels are rather strong indicating relatively low reflection losses. While the channels were sparse, there were still typically relatively large numbers of distinguishable paths. The numbers of observable paths as well as the delay spread of the channel increase with increasing beamwidth.
• 11:40
  Comparison of Indoor Channel Characteristics for Sub-THz Bands from 125 GHz to 300 GHz
  Marina Lotti (University of Bologna, Italy & CEA Leti, France)
  Mathieu Caillet (CEA-LETI, France)
  Raffaele D'Errico (CEA, LETI & Université Grenoble-Alpes, France)
  
  This work presents an empirical indoor sub-THz channel characterization. The frequency aspect is studied through measurement campaigns conducted for different frequency ranges: 125-155 GHz, 235-265 GHz and 270-300 GHz, allowing to compare the channel of the D-band range with the channel above 200 GHz. Two different laboratory scenarios are taken into account. A double steering of the antennas at the transmitting and receiving side allows to perform a double angular characterization. The multipath components detection results are provided and path loss and delay spread models are reported. Finally, a clustering of the detected paths is also presented.
• 12:00
  Propagation Measurements Comparing Indoor and Outdoor Hotspot Coverage at 28, 58, and 143 GHz
  Christina Larsson (Ericsson Research & Ericsson AB, Sweden)
  Bengt-Erik Olsson (Ericsson AB, Sweden)
  Sinh Nguyen and Martin Johansson (Ericsson Research, Sweden)
  
  In this paper, we compare radio propagation channel characteristics of the 28, 60 and 140 GHz bands in one indoor and one outdoor hotspot scenario. The paper concludes that the excess loss, i.e., the loss in addition to the free-space path loss, is very similar for 28, 60 and 140 GHz as long as the measurements are conducted in open areas or where only one or two reflections are needed to get coverage. In areas requiring multiple reflections or wall penetration to achieve coverage, the excess loss increases for the higher frequencies.
• 12:20
  Investigation of Eavesdropping Opportunities in a Meeting Room Scenario for THz Communications
  Christoph Herold, Tobias Doeker, Johannes M. Eckhardt and Thomas Kürner (Technische Universität Braunschweig, Germany)
  
  Due to the large available bandwidth, wireless communications in the THz range are foreseen to provide high data-rate transmissions. Compared to transmissions at lower frequency ranges, wireless communications in the THz range are inherently more robust against eavesdropping attacks due to their propagation characteristics such as a high free space path loss. It does not connote, however, that eavesdropping is not possible. In this paper, ray-optical methods and confirming channel sounder measurements at 300 GHz are used to show that even common, ordinary features such as door frames or a TV screen in the selected meeting room scenario can have a significant influence on the wave propagation at 300 GHz. Thus, such objects can provide opportunities for eavesdropping signals even at unexpected locations outside of the main lope of the antenna diagram and behind the transmitter and cannot be neglected.

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• 16:40
  Dual-Band Metal Frame Blockage Reduction for 5G Mm-Wave Arrays in Mobile Phones
  Rocio Rodriguez-Cano, Kun Zhao, Shuai Zhang and Gert Pedersen (Aalborg University, Denmark)
  
  This paper proposes a solution that allows reducing the obstruction from the mobile phone frame to electromagnetic waves in two bands of the mm-wave spectrum. This response is obtained by etching longitudinal corrugations of two different lengths in the metal frame. The corrugations are inspired on the hard surfaces principle, which supports the propagation of electromagnetic waves on metal. The proposed structure is matched to a 50-Ohm source in the following bands: 25.4-27.7 GHz, 28.7-29.9 GHz, and 36.4-40.3 GHz. The realized gain of the mm-wave array with the corrugated frame is higher than the one of the array in free space in the majority of the operating bandwidth. The proposed solution can increase the gain of the array with a normal frame up to 10 dB.
• 17:00
  A 28 GHz Beam Steerable Elliptic Microstrip Array Antenna for 5G Applications
  Amir Mohsen Ahmadi Najafabadi, Firas Abdul Ghani and Ibrahim Tekin (Sabanci University, Turkey)
  
  This paper discusses the design, fabrication, and measurement of a two layer, 2X10 elliptic, microstrip series fed antenna array operating at 28 GHz 5G and mm-wave user equipment. A branch line coupler (BLC) was used as a feeding network which generates three beams. The peak gain value of each beam was 13 dBi at 28 GHz. The gain value was above 10 dBi within a beam coverage of 45 to 45 degrees, and the peak gain value for the 26.5 GHz to 29.5 GHz band was above 10 dBi. The impedance bandwidth of the proposed design was below -10 dB in the 26.5 GHz to 29.5 GHz band. The dimensions of the 2 X 10 antenna array with coupler were 80 x 40 x 0.203 mm3 on Rogers RO4003 substrate. This design is suitable for 5G mobile user applications due to low cost and compactness.
• 17:20
  A Dual-Polarized Dual-Band Flat-Top Pattern 5G mm-Wave Array Antenna
  Johan Wettergren and Xinxin Yang (Qamcom Research and Technology, Sweden)
  Per N Landin (Ericsson AB, Sweden)
  
  A nine-element antenna array is presented. It has a flat-top radiation pattern and is matched for use in both the 24.25-29.5 GHz and the 37-40 GHz frequency bands for 5G mm-wave systems. The application of this antenna is for use in over-the-air test systems for mm-wave base stations.
• 17:40
  Surface Current Optimization of Dipole Antenna Close to Ground Plane for 5G Mobile Applications
  Jin Zhang (Aalborg University, Denmark)
  Resti Montoya Moreno (Huawei Technologies Finland, Finland)
  Ville Viikari (Aalto University & School of Electrical Engineering, Finland)
  
  When a dipole is placed close to a ground plane, the induced currents on the ground plane are opposite to dipole currents making the entity a poor radiator. This paper presents a dipole antenna design at the ground distance of only 0.5 mm (0.04\(math\lambda_0) at 25 GHz). The dipole-ground interaction is tuned with reactive loading so that induced currents on the ground and those on the dipole arms contribute additively in the far field. Thus, the radiation efficiency is significantly improved when the total current reaches the peak. The value of the components are obtained through a quick circuit optimization and can be easily converted to a discrete form. This method is verified in the simulations with both the lumped and discrete elements. The results show that the proposed antenna has reached a good radiation efficiency, realized gain, and impedance matching at 25 GHz.
• 018:00
  Millimeter-Wave Quasi-Optical Feeds for Linear Array Antennas in Gap Waveguide Technology
  Artem Vilenskiy and Yingqi Zhang (Chalmers University of Technology, Sweden)
  Esmé Galesloot and A. B. (Bart) Smolders (Eindhoven University of Technology, The Netherlands)
  Marianna Ivashina (Chalmers University of Technology, Sweden)
  
  A realization of the quasi-optical (QO) feed concept for linear millimeter-wave (sub-)array antennas is demonstrated in gap waveguide technology. The proposed feed architecture employs an input transition from a ridge gap waveguide (RGW) to a groove gap waveguide (GGW), a radial (H-plane sectoral) GGW section, and a transition to an output RGW array. A design decomposition approach is presented to reduce simulation complexity. Several 20-element QO feed implementations are investigated at W-band demonstrating a 20% relative bandwidth (85-105 GHz), 0.5 dB insertion loss, and a capability of an amplitude taper control within the 10-20 dB range.

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• 15:00
  Chip-To-Chip THz Communications - in Pursuit of Ultra High Throughput, Super Low Latency, High Reliability, and Minimal Energy Consumption
  Alenka Zajic (Georgia Institute of Technology, USA)
  
  Reliable, high-speed connectivity with low energy consumption and latency is a fundamental need in data centers. The use of wires and optical links in current data centers precludes adaptive scalability and suffers drawbacks in terms of assembly cost, airflow blockage, maintenance, and lengthy service time. It has been envisioned that future data center interconnects would alleviate the aforestated problems and introduce a higher data rate and low-latency communication. In this talk, we will discuss various opportunities, challenges, and current experimental trials in an effort to accomplish this in future data centers with the use of wireless Terahertz (THz) technology. We will show how these performance objectives can be achieved by affording data rates of up to 1.5 Tera-bits-per-second (Tbps) at a low power consumption of about 2.75 pJ/b (Energy-per-bit value), latency of 4.78 ns and good signal fidelity that ensures a Bit-Error-Rate (BER) of 10−12.
• 15:40
  Numerical Weather Prediction Models for the Simulation of Propagation Impairments on Earth-Satellite Communications.
  Danielle Vanhoenacker-Janvier (Université catholique de Louvain, Belgium)
  
  The C to Ku frequency bands currently in use are becoming more and more crowded, whereas there is still a need for new services. Increasing the frequency to Q/V band increases the degradation due to the troposphere: not only rain, but also clouds, gases and turbulence are affecting the propagation. Radiowave propagation models for geostationary satellites links are available worldwide in ITU-R Recommendations. In the absence of Earth-LEO propagation measurements, however, only statistical models are available for non-GEO links and they were not validated against measurements. Numerical Weather Prediction models produce meteorological parameters that can be used to simulate the degradation of the GEO and non-GEO earth-space links. The talk will illustrate the results already obtained, their validation with existing GEO measurements and finally underline the potential of this method but also its limitations.

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• 16:40
  Information Processing at the Deep Physical Layer Level
  Marco Donald Migliore (University of Cassino, Italy)
  
  Recently it has been proposed the introduction of an additional layer placed below the Physical Layer of the OSI model, called the "Deep Physical Layer" (DPL), to analyze the communication process at the electromagnetic field level. While the transmission process at the Physical Layer level is focused on bits, information at the DPL level is modeled in terms of distinguishable configurations of the electromagnetic field. In this approach, the numerous solutions proposed for 6G, which include intelligent modifications of the propagation environment, can be seen as "data processing" at the DPL level able to preserve information lost in previous generations of cellular systems.
• 17:00
  Smart EM Environments: Current Trends and Future Perspectives
  Arianna Benoni (ELEDIA Research Center, Italy)
  Giacomo Oliveri and Paolo Rocca (University of Trento & ELEDIA Research Center, Italy)
  Marco Salucci and Francesco Zardi (ELEDIA Research Center, Italy)
  Andrea Massa (University of Trento, Italy)
  
  The smart electromagnetic environment (SEE) is a rapidly evolving paradigm aiming at revolutionizing the design of next-generation mobile communication systems. It is founded on the main idea that the propagation scenario should be no more regarded as an impairment to the overall system performance, but rather as a powerful additional degree-of-freedom (DoF) for tailoring the complex EM propagation phenomena towards an enhanced quality-of-service (QoS). Current trends and future perspectives of such an emerging framework are discussed to provide an overview of the most recent advancements in this field as well as to identify open challenges and promising future tracks of research.
• 17:20
  Smart Electromagnetic Environments Enabled by Metasurfaces 3.0
  Mirko Barbuto (Niccolò Cusano University, Italy)
  Zahra Hamzavi-Zarghani (RomaTre University, Italy)
  Michela Longhi (University of Rome "Tor Vergata", Italy)
  Alessio Monti (Niccolò Cusano University, Italy)
  Davide Ramaccia (RomaTre University, Italy)
  Stefano Vellucci (Roma Tre University, Italy)
  Alessandro Toscano (University Roma Tre (IT), Italy)
  Filiberto Bilotti (University Roma Tre, Italy)
  
  The concept of smart electromagnetic environments has been proposed in the last years as an effective strategy to overcome the detrimental effects of the propagation scenario on the efficiency and robustness of communication systems. Specifically, a smart electromagnetic environment is a complex and properly designed environment able to maximize the efficiency and capacity of one or more communication channels. The environmental engineering has been made possible thanks to the new degrees of freedom introduced by metasurfaces, which allow generalized field transformations and play an active role in achieving unprecedented system performances. In this contribution, we present and discuss some recent applications of metasurfaces in the antenna frame and contextualize them in the scenario of next-generation wireless systems. We show their potentialities in overcoming some undesired effects introduced by conventional environments in wireless communications and discuss their crucial role
  towards the practical implementation of a smart electromagnetic environment.
• 17:40
  A Summary of Actual Maximum Approach Studies on EMF Compliance of 5G Radio Base Stations
  Bo Xu, Davide Colombi, Paramananda Joshi, Fatemeh Ghasemifard, David Anguiano Sanjurjo, Carla Di Paola and Christer Törnevik (Ericsson AB, Sweden)
  
  For radio base stations enabling massive multiple-input multiple-output (MIMO) and beamforming technologies, using the highest possible power and gain values for all beams result in a very unrealistic assessment of radio frequency (RF) electromagnetic field (EMF) exposure. A more accurate approach, namely the actual maximum approach, has been developed in the past few years and recommended by international RF EMF exposure assessment standards and regulatory bodies. In this paper, we summarize the recent EMF research studies on this approach, including statistical modeling studies, measurement campaigns, and related applications, such as the usage of time-averaged power monitoring and control features.
• 18:00
  The Measurement-Based Intelligent Reflecting Surfaces Path Loss Model
  Qibo Qin (China)
  Zhimeng Zhong (Huawei Technologies Co., Ltd., China)
  Xinyu Gao (Huawei Technologies Co. Ltd., China)
  Jianyao Zhao and Chao Li (Huawei Technologies Co., Ltd., China)
  LI Fan (Shanghai Huawei Technologies CO., Ltd, China)
  Zhiyuan Jiang (Shanghai University, China)
  
  IRS can control the reflection of electromagnetic wave, so the deployment of IRS can adjust the channel conditions to enhance the coverage and throughput in the 5G evolution networks. Since the IRS is only capable of passively reflecting the received signals, its path-loss modelling method is different from existing two-hop communication networks, such as repeater, or relay. In this paper, the path-loss model for IRS in real urban scenario is proposed. Based on the theoretical analysis, the novel measurement methodology is proposed that the path-loss channel measurement campaign can be divided into separate measurement and cascade measurement, so that the measurement efficiency is dramatically improved under the constraint of modelling accuracy. The measurement data at 3.7GHz verifies the accuracy of the proposed IRS path-loss model with the RMSE as 2.33dB. The work investigated in this paper could be the foundation for IRS-based network link budge calculation and system level evaluation.

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• 15:00
  Antenna-On-Display for Near, Mid-And Long-Range Wireless Applications
  Wonbin Hong (Pohang University of Science and Technology (POSTECH), Korea (South))
  
  Electronic devices equipped with high-resolutions display panels with the capability of high-speed, low-latency wireless communication are becoming increasingly popular. State-of-the-art wireless generations such as 5G, ultra-wideband (UWB), Wi-Fi 6 will rely on the implementation of efficient and intelligent radio antennas. However, the evolution of display panels such as foldable, stretchable, breezeless and largescreen displays have triggered the need to reevaluate antenna design strategies and methodologies. Classical antenna theory professes the radiation efficiency of an antenna to be proportional to the effective antenna volume. Given the fact that conventional antennas have been designed and implemented as independent components, antenna radiation and performance suffers as the antenna real estate is further decreased amid the increased portion of display panels within a device. This eventually leads to performance degradation of wireless devices which use the latest display panel technologies. This talk introduces the original concept of incorporating a transparent, optically invisible antenna circuitry within the display panel. Denoted as an Antenna-on-Display (AoD), this approach demonstrates that electromagnetic fields can be generated and controlled within the view area of the display. This concept is applied and demonstrated across a variety of different wireless standards such as GPS, Wi-Fi and millimeter-wave 5G and 6G.
• 15:40
  Industrial Design of Active Antenna Arrays
  Matthias Geissler (IMST, Germany)
  
  From a theoretical and conceptional point of view, active array technology can be the basis for powerful and flexible antenna solutions for many applications. However, when it comes to the industrial realization, there is always a danger of ending up with a very complex system, suffering from e.g. high material costs, a complex assembly process and/or a heavy weight. Therefore, the industrial design process of active arrays starts with a careful selection of the material baseline in combination with an application specific tailoring of the antenna to the functionality needed. The design process applied is very much based on efficient 3D EM modelling of the whole system including all details of the antenna and the integration scenario. By using a modular approach, one can combine high design and tailoring flexibility with affordable production costs. The presentation gives insight into today's industrial design process and shows several examples of active array antennas realized e.g. in aluminum, plastic molding, organic substrate and LTCC. Based on latter systematic design process, the active array technology can provide very powerful industrial solutions at medium complexity and acceptable costs.

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• 9:00
  High Gain and Fixed Broadside Radiation at 140GHz Band by a Leaky Wave Slotted Waveguide
  Seyed Ali Razavi (Graduate University of Advanced Technology, Kerman, Iran)
  Ashraf Uz Zaman (Chalmers University of Technology, Sweden)
  
  In this paper a new topology for high gain antenna aperture with fixed broadside radiation is presented for 140GHz band. In the proposed structure, two symmetrical sets of leaky wave radiating slots are placed back to back on the broad wall of a metal parallel plate waveguide. A Corrugated surface is also applied in the feeding waveguide in order to deal with the grating lobe problem. The designed aperture provides proper fixed broadside radiation with 27.8-30.2dBi directivity over 142-148GHz frequency band. The aperture efficiency of more than 60% up to about 80% is also obtained over the most of desired band.
• 9:20
  Dielectric Image Line Rod Antenna Array with Integrated Power Divider at W-Band
  Henning Tesmer (TU Darmstadt, Germany); Daniel Stumpf (Technical University of Darmstadt, Germany)
  Ersin Polat (Technische Universität Darmstadt, Germany)
  Dongwei Wang (Technical University of Darmstadt, Germany)
  Rolf Jakoby (Institute for Microwave Engineering and Photonics, Technische Universität Darmstadt, Germany)
  
  This paper presents a dielectric image line antenna array at W-band. The array consists of four dielectric image line rod antennas, fed by an image line multimode-interference power divider, which divides power without the use of y-branches. The whole array, including the power divider, is machined from one piece of low permittivity Rexolite, which is mounted on a ground plane. Gain is up to 21 dBi and the bandwidth is 15 GHz, from 93 GHz to 108 GHz with a nearly frequency-independent pattern. The image line topology proves to be an attractive alternative to fully dielectric arrays, since integration with conventional circuitry and increased gain is possible.
• 9:40
  Stub-Loaded Sub-Terahertz Wideband Antenna Design and Measurement
  Dongjin Jung (Samsung Electronics, Korea (South) & Skyworks Solutions, USA)
  Chan Ju Park, Jung Woo Seo, Taek Sun Kwon and Jun Gi Jung (Samsung Electronics, 34 Seongchon-gil, Seoul Korea, Korea (South))
  Sang Hyuk Wi (Samsung Research, Samsung Electronics, Korea (South))
  Ilju Na and Sunghyun Choi (Samsung Electronics, Korea (South))
  
  This paper presents a wideband dual-fed/dual-polarized sub-terahertz (THz) array antenna design and D-band measurement system setup. The designed array is 4x1 linear array operating from 136 to 148 GHz. The array is fed by vertically constructed corporate feeding network, and it is fabricated through printed circuit board (PCB) using modified semi-additive process (mSAP). For wideband impedance matching of the antenna element, stub-loaded proximity coupled stacked patch antenna is introduced. By employing two or more open/short stubs on vertical via transition of the proximity coupled line, wideband input impedance matching is achieved, and these stubs can be easily integrated into the antenna element without increasing the element size. A customized probe station is also built to enable probing from the bottom side of the probe station. The maximum gain is measured as 9.1 dBi in the proposed D-band measurement system.
• 10:00
  Synthesis and Characterization of a Focused-Beam Transmitarray Antenna at 300 GHz
  Francesco Foglia Manzillo (CEA-LETI, France)
  Orestis Koutsos (IETR & CEA Leti, France)
  Benjamin Fuchs (University of Rennes 1 - IETR, France)
  Ronan Sauleau (University of Rennes 1, France)
  Antonio Clemente (CEA-LETI Minatec, France)
  
  This paper presents the synthesis, design and characterization of a centrosymmetric transmitarray antenna operating at 300 GHz. A broadside pencil beam with reduced sidelobe levels is obtained by fixing the illumination (i.e. feed and focal distance) and using a phase-only array synthesis procedure. The optimal aperture phase distribution is determined by means of an iterative convex optimization algorithm using semidefinite relaxation. Based on this distribution, a 400-element transmitarray comprising eight different unit cells is designed at 300 GHz, fabricated using low-cost printed circuit board technology and characterized. The measured results provide a first experimental validation of the synthesis approach.
• 10:20
  Cavity-Backed Broadband Microstrip Antenna Array for Photonic Beam Steering at W Band
  Jérôme Taillieu (Université de Rennes 1, France)
  Ronan Sauleau (University of Rennes 1, France)
  Mehdi Alouini (Institut de Physique de Rennes - Université Rennes 1 -CNRS, France)
  David González-Ovejero (Centre National de la Recherche Scientifique - CNRS, France)
  
  We present here the design of a broadband antenna array for photonic beam-steering at W-band. The array unit-cell consists of two stacked microstrip patches that are cavity backed, and fed by aperturecoupling using an hourglass slot. The unit-cell shows a simulated impedance bandwidth of 37% for SWR<2 from 77 GHz to 112 GHz, thus covering most of the W band. The feeding network is designed using a low-loss Substrate Integrated Waveguide (SIW) and respects nearly the same bandwidth as the unit cell for a total SWR<2. Therefore, the structure is well-suited for fabrication by PCB technology. The final array is composed of 4 sub-arrays of 2×8 unit cells and exhibits a broadside directivity of 26 dBi. Each sub-array is expected to be fed by a Uni-Traveling-Carrier (UTC) photodiode, which enables power combining to overcome the low emitted power at mm-waves and also the use of optical phase shifters in the antenna architecture to achieve a +/-5° beam steering with reasonable grating lobes.

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• 11:00
  On the Demonstration of Dynamic Beam-Steering with a Scanning Lens Phased Array at W-Band
  Sjoerd Bosma, Nick van Rooijen, Maria Alonso-delPino, Marco Spirito and Nuria LLombart (Delft University of Technology, The Netherlands)
  
  We report on progress towards a sparse 4x1 scanning lens phased array at W-band (75-110 GHz) capable of beam steering a directive (>30 dBi) beam towards 15deg with sidelobe levels below -10dB. The lens array relies on a combination of mechanical and electrical phase-shifting to steer the beams. These concepts have been demonstrated separately, but we are working towards the first demonstration of the concept with mechanical and electrical phase shifting. The lens feed achieves high aperture efficiency illumination of the lenses by suppressing the spurious TM0-mode over a wide bandwidth with annular corrugations in a groundplane. We have fabricated a 4x1 W-band array prototype. Preliminary measurements of a single lens are in good agreement with simulations. We present preliminary measurements from a W-band electrical phase-shifting setup using low-frequency IQ-mixers that will allow 20deg scanning of the array. More measurement results from the array will be presented at the conference.
• 11:20
  Core-Shell Leaky-Wave Lens Antenna for 150GHz Fly's Eye Communication Systems
  Nick van Rooijen, Maria Alonso-delPino, Marco Spirito and Nuria LLombart (Delft University of Technology, The Netherlands)
  
  This work introduces a new core-shell lens antenna based on low-cost plastic materials and a leaky-wave in-packaged antenna at 150GHz. The lens antenna is made of an electrically small core lens made of a dense material to enhance the radiation from the in-packaged antenna, plus an electrically large shell lens made of a low loss dielectric material. The proposed lens antenna presents good quality patterns with aperture efficiencies above 80% over a bandwidth of 20%. A single layer feeding network using a coplanar waveguide line for connection to a 150GHz chipset is also discussed. Good impedance matching is achieved over a bandwidth of 25%.
• 11:40
  Design Aspects of 3D Printing for Gradient Index Lenses
  Dmitry E Zelenchuk (Queen's University of Belfast, United Kingdom (Great Britain))
  Irina Munina (St. Petesburg Electrotechnical University LETI, Russia)
  Igor Grigoriev (St. Petersburg Electrotechnical University LETI, Russia)
  
  Various aspects of implementing a gradient refractive index distribution using 3D printing are considered. These approaches are applied to two types of lens design: cylindrical Luneburg lens and thick flat lens. Based on simulated and measured results the main constraints for the lens design using additive manufacturing are defined.
• 12:00
  Stacked Geodesic Lenses for Radar Applications in the W-Band
  Germán León (Universidad de Oviedo, Spain)
  Omar Orgeira (KTH Royal Institute of Technology, Spain)
  Nelson Fonseca (European Space Agency, The Netherlands)
  Oscar Quevedo-Teruel (KTH Royal Institute of Technology, Sweden)
  
  New radar architectures employ multiple transmitters and receivers to enhance their performance, combining wide and narrow beams to improve the spatial resolution. In this contribution, two antenna system configurations based on stacked geodesic lenses are compared. These lenses are fully-metallic parallel plate waveguides that present very low transmission losses in the millimetre-wave band. Narrow beams are generated by a 15-port Luneburg-Rinehart lens with a scanning span of 100º and 23.4 dB gain at 77 GHz. For wide beams, two alternatives are proposed. One alternative is a 3-port defocused lens antenna with a scanning angle of 100º and 14.5 dBi gain. The second proposal is a 12-port Luneburg-Rinehart lens fed with 1-to-4 power dividers forming a 3-port antenna with a scanning span of 91 and 16.2 dBi gain.
• 12:20
  Transmit Lens Arrays for Broadband THz Power Distribution and Beam Steering
  Maria Alonso-delPino and Sjoerd Bosma (Delft University of Technology, The Netherlands)
  Cecile Jung-Kubiak (NASA-JPL, Caltech, USA); Juan Bueno (Delft University of Technology, The Netherlands)
  Goutam Chattopadhyay (NASA-JPL/Caltech, USA); Nuria LLombart (Delft University of Technology, The Netherlands)
  
  This paper presents a novel quasi-optical power distribution technique based on a transmit lens array that allows achieving an efficient multi-pixel LO power distribution for submillimeter-wave instruments. This method can distribute the power from one antenna to a multi-pixel lens array in a hexagonal configuration with a power coupling efficiency of nearly 60%. To maximize this coupling, we synthesize a tophat radiation pattern using multi-mode leaky-wave feeds that feed silicon elliptical lenses. Moreover, the proposed transmit array architecture could be operated in a coherent mode for applications requiring beam steering of highly directive beams. We will present a prototype based on a transmit array of 7 pixels at 450-650 GHz with preliminary measurements showing a good agreement with simulations.

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• 9:00
  Intelligent Design of Metamaterials via Machine Learning Techniques
  Che Liu and Tie Jun Cui (Southeast University, China)
  
  Digital coding representation of metamaterials makes it possible to realize intelligent designs of metamaterials using machine learning algorithms. Recently, there have been some works that have successfully designed the S-parameters of coding metamaterials with the machine learning techniques. However, wide-band reflection phases are much more difficult to design because of the periodicity of phase representation. Here, a machine learning method is proposed to automatically design anisotropic digital coding metamaterials with desired wide-band reflection phase responses (8-12GHz) under both TE and TM polarizations. Meanwhile, a deep learning method is presented to predict the phase curves in real time, in which the phase curves are creatively represented by their sine and cosine curves. A binaryparticle-swarm optimization method is then introduced, cooperating with the deep learning prediction module to design the coding metamaterials in seconds, and the testing results show a state-of-art fitness of anisotropic wide-band phase responses.
• 9:20
  Recent Advances in Artificial Neural Networks for EM Parameterized Modeling and Optimization
  Li Ma (Tianjin University, China)
  Jianan Zhang (Southeast University, China)
  Shuxia Yan (Tianjin Polytechnic University, China)
  Qijun Zhang (Carleton University, Canada)
  
  This paper reviews the recent advances in artificial neural networks (ANN) for electromagnetic (EM) parameterized modeling and optimization. As an advanced ANN-based EM parameterized modeling and optimization technique, the neuro-transfer function (neuro-TF) is discussed further in this paper. The trained neuro-TF parameterized models can be further used for EM design optimization with repetitive geometrical variations.
• 9:40
  Simulation-Based Machine Learning Training for Brain Anomalies Localization at Microwaves
  Valeria Mariano, Mario Roberto Casu and Francesca Vipiana (Politecnico di Torino, Italy)
  
  Machine learning enters the world of medical application and, in this paper, it joins microwave imaging technique for brain stroke classification. One of the main challenges in this application is the need of a large amount of data for the machine learning algorithm training that can be performed via measurements or simulations. In this work, we propose to make the algorithm training via simulations based on a linear integral operator that reduces by three orders of magnitude the data generation time with respect to standard full-wave simulations. This method is used here to train the multilayer perceptron algorithm. The data-set is organized in nine classes, related to the presence, the type and the position of the stroke within the brain. We verified that the algorithm metrics (accuracy, recall and precision) reach values close to 1 for each class.
• 10:00
  Accelerating Electromagnetic Inverse-Design Using Deep Learning
  Ronald P Jenkins and Sawyer D Campbell (The Pennsylvania State University, USA)
  Pingjuan Werner and Douglas H Werner (Pennsylvania State University, USA)
  
  One of the primary ways that deep learning has been applied to electromagnetics in recent years is for accelerating inverse design. We present one such method for designing metasurface supercells which are robust to structural erosion and dilation, a typical variety of nanofabrication error. A pair of deep neural networks are trained to high accuracy to predict diffraction efficiencies from a supercell mask, and then evaluated exhaustively to find tolerance bounds for freeform supercell designs.
• 10:20
  Programmable Metasurface Intelligent Beamforming
  Shangyang Li, Zhuoyang Liu, Yan Wang and Feng Xu (Fudan University, China)
  
  This paper proposes an intelligent beamforming architecture to predict the mapping relationship between codes and three-dimensional patterns. First, the two-dimensional intelligent beamforming (IB) framework is proposed. Then, the one-dimensional intelligent beamforming to realize the fast calculation of P-C and C-P is presented. The IB includes: 1) Substrate integrate waveguide programmable metasurface and automatic measuring systems design, 2) fast prediction from codes to patterns, 3) real-time prediction from patterns to codes, and intelligent beamforming architecture. Finally, the proposed IB is validated by the measured results.

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• 11:10
  A Deep Learning Architecture for Augmented Shape Reconstruction via Microwave Imaging
  Álvaro Yago Ruiz (CNR, National Research Council, Italy)
  Marija Nikolic Stevanovic (School of Eletrical Engineering, University of Belgrade, Serbia)
  Marta Cavagnaro (Sapienza University of Rome, Italy)
  Lorenzo Crocco (CNR - National Research Council of Italy, Italy)
  
  In this paper, an innovative microwave imaging approach that combines deep learning techniques and qualitative inversion methods is presented. In particular, the proposed approach is meant for imaging piece-wise homogeneous targets and aims at providing an augmented morphological reconstruction, which not only retrieves the shape of the targets, but also the spatial variations of the permittivity values. Such an information is not displayed by qualitative inversion methods; however it is efficiently encoded in the gradient of the unknown contrast.
  In particular in this paper, a physics-assisted deep learning technique, where domain knowledge is given in the inputs of a U-Net architecture, is developed. The domain knowledge is provided by the qualitative image of the unknown targets obtained using the orthogonality sampling method, thus allowing the architecture to provide, once trained, a fully automated and real-time prediction. An initial assessment for the approach with synthetic data is provided.
• 11:30
  AI-Assisted Global Optimization for Solving Inverse Scattering Problems
  Marco Salucci (ELEDIA Research Center, Italy)
  Lorenzo Poli (ELEDIA Research Center, University of Trento, Italy)
  Paolo Rocca (University of Trento & ELEDIA Research Center, Italy)
  
  The solution of inverse scattering (IS) problems supported by artificial intelligence (AI) is addressed. An innovative solution strategy based on the System-by-Design (SbD) paradigm is proposed for the computationally-efficient exploitation of a global optimization strategy for minimizing the data mismatch cost function. Towards this end, a suitable selection, customization, and interconnection of SbD functional blocks is adopted. Moreover, the computationally-unaffordable repeated evaluation of each trial solution during the optimization is bypassed thanks to the exploitation of a digital twin (DT) based on the learning-by-examples (LBE) paradigm. An illustrative numerical example is shown to prove the
  effectiveness and computational efficiency of the proposed solution strategy when dealing with 2D free-space microwave imaging (MI) scenarios.
• 11:50
  Ensemble Learning for 5G Flying Base Station Path Loss Modelling
  Sotirios Sotiroudis (Aristotle University of Thessaloniki, Greece)
  Georgia E. Athanasiadou and George Tsoulos (University of Peloponnese, Greece)
  Sotirios Goudos (Aristotle University of Thessaloniki, Greece)
  Christos Christodoulou (The University of New Mexico, USA)
  
  The usage of unmanned aerial vehicles (UAVs) as flying base stations (FBSs) for expanding coverage and assisting the terrestrial cellular networks constitutes a promising technology for 5G and beyond. The wide range of a flying base station's movement may stretch the boundaries of path loss at the receiver's site and induce the occurrence of extreme values. Thus, using machine learning techniques may help in accurate path loss modeling for this case. In this paper, we use a combination of the techniques of ensemble learning and oversampling to provide a satisfactory path loss model for FBSs.
• 12:10
  Evolved Multiobjective Low Side-Lobe Taper for Beam Steerable Arrays
  Sudipta Das (National Institute of Technology Sikkim)
  Ritu Rimjhim (National Institute of Technology Sikkim, India)
  Durbadal Mandal and Rajib Kar (National Institute of Technology, Durgapur, India)
  
  Antennas and arrays are indispensable elements of wireless communication systems. The directional characteristics is one of the most attractive features of antenna arrays. This article takes up a case of array pattern synthesis, and adopts two contemporary and highly competitive Evolutionary Algorithms, named Nondominated Sorting Genetic Algorithm III (NSGA III), and Double Niched Evolution Strategy for solving Multimodal Multiobjective Problems (DN-MMOES). The results show the effectiveness of Evolutionary Algorithms for such problems.
• 12:30
  A Hybrid Machine Learning-Based Model for Indoor Propagation
  Aristeidis Seretis and Costas D Sarris (University of Toronto, Canada)
  
  A common limitation among many applications involving machine learning techniques is the availability of training data. In propagation modeling scenarios, measurement campaigns are usually undertaken for network planning decisions. However, this can be a challenging task, especially in electrically large environments. In these cases, simulation data generated by physics-based methods, such as ray tracing, can replace or augment the measured data. This paper provides a case study in a typical office environment, where both measured and simulated data are used to separately train two machine learning models. A hybrid model combines the predictions of these two models, to predict the signal levels at any location in the environment. In cases where the volume of measured data is insufficient, the hybrid model is shown to improve the accuracy of the overall predictions. It is also shown that a small number of measurements can improve the accuracy of a solver-trained model.

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