ABSTRACT. This paper reports an overview on the on-going research activity aimed at the exploitation of 3D-printing technologies to the development of dual-band and dual-polarization components for SatCom antenna feed chains. In particular, architectures optimized for 3D-printing are discussed, and the results of a preliminary study on the application of perforations along the internal channels is reported.

ABSTRACT. This report presents a recently developed fabrication method combining fused deposition modelling with Field’s metal for the manufacturing of complex metal structures. First, a dielectric mold is printed using standard 3D printing methods. The mold is designed with hollow cavities, which form the desired shape of the structure’s metal parts. Next, molten Field’s metal is injected inside, filling the cavities and adopting their architecture. Field’s metal has a low melting point of 65 degrees Celsius, which can realistically be lower than the temperature where heat deformation in numerous thermoplastic materials occurs. This method can produce metamaterial resonators with high quality factors. Numerical methods are used to model the response of the metamaterial and further investigate the resonance.

ABSTRACT. New possibilities in antenna and microwave manufacturing are opening up through the exploitation of additive manufacturing (AM) 3D printing techniques. Despite being used primarily for the fabrication of dielectric structures, with the right filament, these procedures could also be able to print conductive parts, giving birth to true fully-3D-printed radiating elements. However, to take full advantage of these thermoplastic materials, a rigorous electromagnetic characterization needs to be performed. Based on this, the dielectric properties of one of the most common plastic 3D printable materials are investigated, and, in addition, the electric conductivity of one of the most promising conductive filaments (Electrifi) is experimentally evaluated in a wide frequency range (0.5-7.5 GHz) and then validated in the design of different fully-3D-printable patch antennas

ABSTRACT. A 3D printed antenna embedded in a 3D printed ring for 5G millimeter wave applications is proposed. Two additive manufacturing (AM) methods have been combined in a single machine to develop the structure. Fused filament fabrication (FFF) was used to make the substrate of the antenna and supporting ring while direct write with conductive paste was used to create the antenna radiator. Polylactic acid (PLA) plastic was used in the development of the dielectric layers while the metallic patch of the radiator was created using silver paste. Reflection coefficient and radiation pattern of the ring antenna were tested in free space and worn on a hand phantom. The hand phantom was developed using pork sausages placed inside a thin glove. The design and simulations were carried out in CST Microwave StudioTM. Measured results show consistency with the simulated results. The antenna operates satisfactorily at the proposed 5G millimeter wave communication band. This work aims to demonstrate a concept of millimeter wave 3D printed ring antennas and the development and use of sausage-based hand phantoms for antenna measurements.

ABSTRACT. With increasing levels of vehicle automation, the requirements for the sensors that are used for environment perception are rising at least as steadily. In automotive radars, the capability to perceive polarimetric information inspired some recent work to exploit this aspect in order to improve perception of static and dynamic surroundings. Such utilization requires a well-calibrated radar system. This paper demonstrates how to achieve the necessary stability in the scattering information of an automotive multiple input multiple output (MIMO) millimeterwave radar. The parameters of a fully polarimetric calibration are derived based on pole and dihedral target measurements in an automated test facility. Furthermore, the impact on the polarimetric quantities estimation due to mounting the radar behind a radome is analyzed.

ABSTRACT. The requirements dictated by Sixth Generation (6G) to support Vehicle-to-Everything (V2X) communications together with the propagation drawbacks at high frequencies impose the use of highly directive beams. Conventional Beam Management (BM) approaches based on an exhaustive beam search are characterized by high training times and frequent link interruptions. To overcome these issues side information coming from sensors at both vehicular UE, e.g., Global Position System (GPS), and Base Station (BS), e.g., radar, side are integrated in the BM procedures. This paper shows pros and cons of the two approaches and propose a joint radar- and GPS-aided BM procedure that allows to reduce training time in typical urban scenario.

ABSTRACT. Abstract--- The principal element of interest concerning the use of Synthetic Aperture Radar (SAR) technology in the automotive scenario is the possibility to synthesize an arbitrarily long array by exploiting the natural motion of the ego-vehicle, and therefore achieve much finer spatial resolution and improved detection capabilities without increasing hardware requirements in terms of number of physical antennas. In this paper, we discuss the application of SAR imaging in the automotive context under a theoretical and experimental perspective. Experimental results are shown based on open road campaign data acquired using an 8-channel Radar at 77 GHz, considering the cases of side-looking SAR, forward SAR, and SAR imaging of moving targets. Results corroborate the idea that SAR imaging could be successfully and systematically used in the near future for high-resolution mapping of the urban environment.

ABSTRACT. Vehicle-to-Everything (V2X) is an emergent technology for enhancing traffic efficiency, road safety, and autonomous driving. Vehicles interconnected with their prevalent wireless environment are prone to various security threats that might affect traffic and life safety immensely. Jamming attacks, a legacy and dated problem, still persists much to the havoc of V2X communications. The following paper proposes a framework for jammer detection adapted to the V2X communications scenario. generalized Dynamic Bayesian network is used to learn the V2X signal environment in a statistical manner. Subsequently, a Modified Markov Jump Particle filter (M-MJPF) is used for signal predictions where the innovations in the observed signal versus the predicted signal enable our framework to detect the jammer. Simulation results highlight the efficacy and accuracy of our approach in V2X jammer detection.

ABSTRACT. In this paper, we provide an overview of the stereolithography (SLA) manufacturing process applied to the design of microwave filter components. For that purpose, a spherical cavity that operates with the overmode TE101 has been used in order to design filters oriented for additive manufacturing. The characteristics of such mode (high Q-factor and size) makes it an interesting choice for filters manufactured with 3-D printers. For validation purposes, two doublet prototypes with different configurations and mechanical structures have been manufactured with an SLA 3-D printer, metallized and measured. Results show various discrepancies between the two prototype: with measurements matching perfectly the simulations for one, while a certain frequency shift is present for the other prototypes.

ABSTRACT. Screen printing of a Frequency Selective Surface (FSS) on a plasterboard block to curtail the drop of wireless signals within indoor settings is described in this paper. The proposed low-cost FSS solution operates at a central frequency of 2 GHz and covers some of the existing mobile phone frequency bands. An array of square loop elements is used for this application. The array structure was printed with the help of a screen-printing setup on a plasterboard using dycotech silver paste. Simulated transmission responses compared well with measurements. The FSS was simulated using CST Microwave StudioTM. Screen printing allows the direct printing of FSS on the uneven and porous surfaces of plasterboards with the details necessary for various microwave and mm-wave applications and provides the necessary conductivity for filtering. The intended application is the production of plasterboard FSS as a building material with embedded RF properties.

ABSTRACT. This article presents different high-frequency topologies implemented with fused filament fabrication (FFF) 3D-printing, using low-loss dielectric filaments and a low-cost 3D-printer. The proposed structures are three different graded index lenses, two dielectric leaky-wave antennas and a dielectric anisotropic polarizer. Good results are obtained in simulations and measurements in terms of bandwidth and radiation patterns, which shows that is possible to implement these structures even in millimeter wave bands, making it a cost-effective solution.

ABSTRACT. In the field of microwave engineering, additive manufacturing technologies enable the rapid prototyping of cost-effective and light-weight components and the simple realization of otherwise impractical topologies. In this work, a technique for the creation of passive microwave components based on 3D printing of plastic material is discussed. A number of devices are presented, including a microstrip-to-waveguide transition, a dielectric sensor, and two microwave filters. Each of these components highlights the aspects that additive manufacturing can bring to their respective applications.

ABSTRACT. The problem of evaluating the shielding effectiveness of a metallic circular disk with finite conductivity and finite thickness against a circular current loop coaxial with the disk is addressed. First the metallic disk is modeled through a new boundary condition which correctly takes into account the thickness of the disk and then the problem is reduced to only one set of dual integral equations which are solved in an exact form by expanding the spectral unknowns in a series of Bessel functions. The proposed formulation is compared with the one based on the Mitzner boundary conditions, showing its accuracy and the capability of reducing the computation time and with the one based on the thin-screen boundary conditions, showing that the latter can lead to erroneous results for sufficiently large thickness-to-skin-depth ratios.

ABSTRACT. The plane wave diffraction by a slit in a material screen is analyzed using the Wiener-Hopf technique together with generalized boundary conditions (GBC). Exact and high-frequency asymptotic solutions are obtained. The scattered field is evaluated asymptotically based on the saddle point method and a far field expression is derived. Numerical examples on the far field intensity are presented and the scattering characteristics of the slit are discussed.

ABSTRACT. Carbon-based materials are being increasingly used in electromagnetic shielding applications substituting traditional materials such as metals. One of these materials is graphene, which is the first 2-D material created having very high surface conductivity in the RF-microwave region. In addition to extensive experimental works, many models have been also proposed to simulate graphene in the context of numerical methods. In this work, we develop a Method of Auxiliary Sources (MAS) approach to perform full-wave analysis of a cylindrical medium covered by a graphene layer. When the conventional MAS approach is followed, numerical difficulties arise when simulating graphene as a material layer due to its extremely small effective thickness, and its very high surface conductivity. To this end, a modified version of MAS is proposed where graphene is simulated as an Impedance Matrix Boundary Condition (IMBC). Numerical experiments verify the effectiveness of the MAS with IMBC the results of which showcase excellent agreement with those obtained by the Finite Element Method (FEM).

ABSTRACT. In this work the wakefield of a charged particle traveling through a plane conducting ring is evaluated. The problem is formulated in the spectral domain as integral equations of Fredholm type, solved by Galerkin method employing entire domain functions factorizing the correct edge behavior of the unknown induced current. As a result, high accuracy and numerical stability are achieved, allowing the calculation of parameters relevant to accelerator physics, such as longitudinal impedance and wakefield.

ABSTRACT. The problem of the scattering of an E-polarized plane wave from 2D open-ended S-shaped cavities is rigorously solved by the Method of Analytical Regularization. The obtained solution is used for full-wave analysis of backscattering. The special focus is on studies of resonance phenomena observed in the spectral dependence of the Radar Cross Section. They are explained as excitation of the complex natural oscillations in S-shaped cavities.

ABSTRACT. A single snapshot MUSIC based algorithm is proposed on the framework of ADAS radar processing. It is known that MUSIC is a spectral estimation method that allows to surpass the classical Rayleigh resolution limits. However, the computational cost is much higher than the one required by classical FFT processing, especially if a smoothing procedure has to be employed, as for the single snapshot case. To reduce the numerical complexity here we exploit a Toeplitz data arrangement and split the pseudospectrum formation in two steps. The first one consists of one-dimensional processing whose results are employed as proxy for the multidimensional estimation problem. It is shown that this strategy greatly reduces the cost for building the multidimensional pseudospectrum. Here, for the sake of simplicity, we limit to address the range/angle target estimation.

ABSTRACT. A packaged transmitarray (TA) antenna operating at 77 GHz is designed. The proposed configuration is based on a standard Quad Flat No-lead package (QFN) technology. The electromagnetic field radiated by a feed placed in the QFN is focused by the transmittarray antenna placed on the package cover. An analytical model is used to estimate the basic parameters of the proposed transmit-array like gain, directivity, and spillover efficiency. The final design has then been optimized through full-wave simulations. Simulated gain is 18 dBi at 77 GHz while the half-power beamwidth is 22°. The proposed configuration is a good candidate for automotive highly integrated mid-gain applications

ABSTRACT. W-Band radar systems have the advantages of smaller footprint, improved range resolution, and lower atmospheric attenuation. However, these high frequency systems can suffer range limitations due to the substandard power handling of their smaller components. This paper presents the front end modification of a 80 GHz for improved range performance.. A high frequency power amplifier integrated circuit is ribbon bonded directly to the radar to amplify the transmitted signal. Calculations based on simulations of radar components predict a two-fold increase in the maximum detectable range. This work demonstrates the enhancement of mm-wave radar, the feasibility of after-market adjustment, and the production of low-cost improvements.

ABSTRACT. Investigation on ultra-wide band slot-sinuous antenna for in band monostatic radar cross section behaviour are performed. The possibility of using opening ellipses on the metallic patch of the slot-sinuous antenna are presented with the intent of reducing structural radar cross section on the overall frequency band. Simulated results for in-band RCS for modified slot-sinuous antenna and slot-sinuous are presented discussed. The proposed solution result as a good candidate to be further investigated on a multi-objective optimization context for in band RCS reduction.

ABSTRACT. High interest in millimeter-wave and sub-TeraHz bands has been rising in the recent years due to the enormous amount of under-utilized bandwidth that lies in this part of the electromagnetic spectrum. The significant advantages offered by the propagation characteristics in terms of frequency re-usability and large channel bandwidths, make (sub)millimeter-wave suitable for the very high data rates required by enhanced Mobile BroadBand (>10 Gpbs peak throughput and 10 Mbps/m2) both for the 5G and beyond 5G Radio Access Network and the Backhaul.

The millimeter-wave bands can be suitably used for the access networks to increase the throughput to the User Equipment and the backhaul/front-haul of the base stations as well as envisioning new applications and services for what will be beyond 5G.

At the same time the use of millimeter-wave bands, thanks to very compact antenna size that makes products “blend” in the environment, allows the densification of the cells in dense urban scenarios.

Envisioned “beyond 5G” communication architecture scenario

5G and “5G beyond” key requirements driving evolution of mobile access and wireless x-haul to millimeter-wave ranges

Analysis of the most important requirements of 5G and “beyond 5G” to drive the trends and technology at (sub-) millimeter-wave bands for wireless high data rate communications:

Application scenarios and potential bands for 5G and “beyond 5G” new spectrum above 90 GHz and innovative ways to use it technology challenges and research directions Millimeter-wave access

Since the beginning, large antenna arrays have been exploited for radar applications in order to achieve very high spatial resolution, beamforming and null steering. This trend has been recently introduced to communication systems too, in order to provide highly-directive beams as a means to both reduce interference and increase the overall capacity, allowing spectral reuse through spatial diversity. Nowadays the big challenge is not only related to the maximization of the overall system performance – which has been proven to be very effective when considering full-phased/full-digital architectures – but is mainly focused on the economic side: the real goal is to keep cost and energy consumption sufficiently low to obtain affordable products. In this invited talk it will be presented an overview of some techniques that can be adopted to design highly integrated, energy- and cost-efficient front-ends for millimeter-wave wireless systems (mm-Waves), which – having instantaneous bandwidths of hundreds of MHz to GHz – are seen as promising technology for meeting the exploding capacity requirements of 5G (and beyond) communication networks.

Millimeter-wave and Sub-TeraHz backhaul

Research activities in the E-Band (71 to 86 GHz) and D-Band (130 to 175 GHz) for outdoor backhaul applications

Standardization status Technology overview (semiconductor trends) MMIC, Antenna, Engineering solutions Propagation model from field trials results Research activities in the Sub-TeraHz bands above 175 GHz.

ABSTRACT. This work presents the development of two 2-FETstacked cells at 26 GHz in the WIN Semiconductors 150 nm power GaN/SiC technology. Two different compact layouts, based on the same circuit scheme, are designed targeting similar performance in the FR2 5G frequency band. One version favoring distance between components, to relieve electromagnetic cross-talk, and the other favoring instead symmetry. The cells have been conceived as basic building blocks for the development of high-power 5G amplifiers, rather than as stand-alone amplifiers, hence including only input matching and stabilization networks. Based on large-signal simulations on the optimum load, the cells are expected to deliver around 34 dBm with an efficiency higher than 35% at 26 GHz, and a linear gain of 10 dB. The output power performance is maintained from 24.5 GHz to 27.5 GHz, where the saturated efficiency is above 30% for both cells. The small-signal experimental characterization results are in very good agreement with the simulations, proving the effectiveness of the electromagnetic simulation setup adopted for all the passive structures, despite the challenges posed by the compact layouts.

ABSTRACT. A CMOS negative impedance converter (NIC) circuit with cross-coupled topology is designed to generate negative resistance/capacitance/inductance in the frequency range between 100 MHz and 3 GHz. The proposed NIC circuit is able to cancel parasitic gate-source capacitances of NMOS transistors which are the core elements of this type topology. The negative impedance conversion capability of the circuit is shown analytically. It is also verified in AWR Design Environment using BSIM3 and BiCMOS transistor models comparatively. The circuit is tested with the loads 50Ω resistance, 5 pF capacitance and 10 nH inductance. The results show that the performance of proposed NIC circuit is satisfactory and close to its theoretical values.

ABSTRACT. This study is aimed at investigating the performance of an advanced GaN HEMT technology for millimeter-wave applications. Both DC and frequency-dependent measurements are performed on multifinger on-wafer devices with different gate widths at different ambient temperatures for foreseeing GaN technology capability when applications require challenging frequency operation.

ABSTRACT. This work discusses the design and the expected results of two stacked-cells implemented in a 0.15μm gate-length Gallium Nitride (GaN) Monolithic Microwave Integrated Circuit (MMIC) technology for K-band power applications. Both cells are based on the same overall active periphery but one exploits a self-bias (SeB) approach for the common gate device, whereas the other is biased on a more traditional independent bias routing (SaB). Moreover, with respect to the traditional approach, in both cells the common source device is split in two in order to reduce the parasitic contribution and also to obtain a more compact and easy to implement overall stacked cell. The main goal of this paper is to provide a fair comparison between SeB and SaB stacked cells, by highlighting pros and cons of both approaches in terms of linear and nonlinear performances.

ABSTRACT. We present a comprehensive review of the recent advancements in directivity enhancement and feeding network reduction techniques. The presented techniques focus on providing a low-cost solution while maintaining high radiation efficiency. The solutions also provide physical insight to further explain the structures radiation mechanism. The provided solutions counter many challenges faced in designing mm-Wave antennas.

ABSTRACT. Unique Hexagram shaped microstrip patch antenna variants are reported here which provide multiple bands in the useful frequencies ranging from WiMAX, WLAN, 5 GHz U-NII, C-band, X-band, Ku-band, K-band and Ka-band. These unique hexagram-shaped patches yield at least six resonances with a UWB at X, Ku (5-15.2 GHz) and Ka (22-26.5GHz) bands. Reactive loading provided better impedance matching over the wide frequency range. The frequencies obtained from the fabricated prototype agree very closely with the simulated ones. Several higher order modes were found to be excited in the antennas due to the uniqueness of the geometrical structure. These antennas aim to replace multiple antennas which are required for frequency hopping techniques as well as energy harvesting applications. Additionally, they may also be used in UAVs replacing multiple antennas integrated for different communication standards. It is noted from a chronological study of reported multiband antennas that the antenna presented here is showing significant betterment w.r.t. design simplicity, compactness and bandwidth improvement performances.

ABSTRACT. This manuscript presents a set of Substrate Integrated Waveguide components realized through thin-film technology and suitable for E-band applications. The non-standard choice of alumina as dielectric material leads to superior performance and increases the operational frequency of such devices, usually limited by fabrication tolerances. The intrinsic fragility of the ceramic substrate is mitigated through ad-hoc design rules which limit the via-hole density while the higher dielectric constant allows a small die size, with clear advantages in stiffness and handling robustness. Three components have been designed, manufactured and tested: a straight interconnection, a matched load, and a three-pole in-line band pass filter. All the devices show interesting performance across the 70-80 GHz spectrum portion.

ABSTRACT. A 25 GHz SFCW radar is modified for operation in 9K7 LTCC. The LTCC fabrication method is outlined and adjustments which improve manufacturing and performance are described. Meshed ground planes and extra layers of metallization are used to reduce board deformities that arise due to metal loading. Solid regions are placed under RF transmission lines to maintain proper transmission. Matching structures for complex port impedances are simulated and measured in order to address the increase in the dielectric constant. Obstacles arising in the design of transmission structures for LTCC dielectrics are discussed.

ABSTRACT. this contribution presents a corporate-fed microstrip patch antenna array EM simulation performed in Keysight ADS RFPro for millimeter-wave automotive radar applications. The 4×4 antenna array design is envisioned for operation in the long-range radar (LRR) band of 76-77 GHz. ADS RFPro enables automatic expert setting EM simulations leading to efficient use of computational resources and reduced simulation times. Finite Element Method (FEM) solver is used for simulation of the antenna array. Scalability of design and simulation using RFPro is also demonstrated.

Riccardo Giacometti – Graduated in Electrical Engineering from University of Florence, Italy, in 1992 he joins Hewlett Packard in Santa Rosa (CA)as an Application Engineer and successively as Product Manager for the EEsof EDA division of HP. In 2004 he moves to France to become EMEA Market Development Manager for Agilent EEsof EDA and then for the Signal Sources Division of Agilent Technologies. Since 2011 he’s an EDA Application Engineer at Keysight Technologies and more recently manager of the EMEAI Solutions Engineering team.

ABSTRACT. In this paper, a novel “Real Frequency Line Segment Technique” based numerical procedure is introduced to assess the gain-bandwidth limitations of the given source and load impedances, which in turn results in the ultimate RF-power intake/delivering performance of the amplifier. During the numerical performance assessments process, a robust tool called “Virtual Gain Optimization” is presented. Finally, a new definition called “Power-Performance-Product” is introduced to measure the quality of an active device. Examples are presented to assess the gain-bandwidth limitations of the given source and load pull impedances for the 45W-GaN power transistor of Wolfspeed “CG2H40045” over 0.8 -3.8 GHz bandwidth.

ABSTRACT. Source degenerated HEMTs are used to achieve good noise matching and better input return loss without degrading the noise figure and reducing the stability. This work presents an MMIC design for the frequency band of 8 – 11 GHz by using HEMTs with source degeneration in 0.15 μm GaN on SiC technology. All design work is done in the Advanced Design System. The LNA delivers more than 6.9 dB gain with better than 8.5 dB and 9.5 dB input and output return losses, respectively. In addition, the gain ripple is around 2.7 dB. The noise figure of the amplifier is achieved below 1.1 dB with P1dB of 17.2 dBm and %12.7 drain efficiency within the operating bandwidth at the bias conditions of 9 V/20 mA.

ABSTRACT. Cascode HEMTs exhibit better stability and broad bandwidths performance as compared with common source HEMTs. This paper presents the design of a single stage broadband low noise amplifier based upon 0.15 um GaN HEMT technology in the frequency range of 8 – 12 GHz. Cascode HEMT with inductive source degeneration is utilized. All the design work is done using PathWave Advanced Design System. The LNA provides 9.5 to 10.6 dB with input return loss better than 10 dB and output return loss better than 8 dB in the whole band. The noise figure of the amplifier is below 1.9 dB. The linearity parameters P1dB and OIP3 are greater than equal to 16 dBm and 28 dBm respectively within operating bandwidth. The noise figure of the amplifier is fairly constant over 30 mA to 60 mA bias currents and 9 V – 18 V operating bias voltage. This is a unique finding which is being reported for the first time to the best of authors’ knowledge.

ABSTRACT. A printed hexagonal antenna with double reconfigurable notched bands was presented and performed for modern wireless communication systems. The dismissed bands were obtained by etching a complementary split ring resonator (CSRR) on the original antenna layout. By placing two varactors diode on the resonator the discarded bands become easily controllable and tunable by varying the DC voltage of the varactors. Two wide continuous tuning ranges of 0.5 GHz and 1.1 GHz were achieved. The simulated and measured results show a good agreement.

ABSTRACT. This paper proposes an antenna array with a feeding network to obtain low sidelobe levels. The design procedure for a feeding network that uses Dolph-Tschebyscheff distributed coefficients is presented in this paper. The Dolph-Tschebyscheff coefficients have been calculated to get a -20 dB sidelobe level. The shunt-connected series feeding network has been designed according to coefficients. By adding delay lines to the output of the feeding network, the radiation pattern of the antenna has been directed to the desired angle. It is observed that the sidelobe level has been reduced to -15 dB. The proposed feeding network can help to reduce the sidelobe level of linear antenna arrays.

ABSTRACT. This paper deals with the fabrication of different types of resonant networks and with analysis of their resonant modes. As a reference serves a standard structure of the well-known Birdcage resonator, supplemented by three resonators with the same geometry, but different resonance modes. The modes of the resonators were analysed in order to provide a universal comparison, applicable also to the original birdcage resonators. The described resonators were modelled and analysed using FEM simulation and fabricated using copper tape and lumped capacitors. Their parameters – impedance and distribution of the leg currents were evaluated. Two of three introduced resonators can be used to create a homogeneous magnetic field.