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Phased arrays, commonly used in IEEE 802.11ad and 5G radios, are capable of focusing radio frequency signals in a specific direction or a spatial region. Beamforming achieves such directional or spatial concentration of signals and enables phased array-based radios to achieve high data rates. Designing beams for millimeter wave and terahertz communication using massive phased arrays, however, is challenging due to hardware constraints and the wide bandwidth in these systems. For example, beams which are optimal at the center frequency may perform poor in wideband communication systems where the radio frequencies differ substantially from the center frequency. The poor performance in such systems is due to differences in the optimal beamformers corresponding to distinct radio frequencies within the wide bandwidth. Such a mismatch leads to a misfocus effect in near-field systems and the beam squint effect in far-field systems. In this paper, we investigate the misfocus effect and propose InFocus, a low complexity technique to construct beams that are well suited for massive wideband phased arrays. The beams are constructed using a carefully designed frequency modulated waveform in the spatial dimension. InFocus mitigates beam misfocus and beam squint when applied to near-field and far-field systems.

This paper presents a monolithically integrated E-band amplifier multiplier chain (AMC) developed in 130 nm SiGe BiCMOS process. This E-band AMC is composed of a 25 GHz 1:1 power divider, two 25 GHz driver amplifiers (DA 1,2 ), a 75 GHz passive frequency tripler, and a 75 GHz power amplifier (PA). By applying a bypass tuning capacitor based power enhancing technique in the single-ended DA and PA, the output power and power-added-efficiency (PAE) of the AMC have been effectively improved. Benefiting from the proposed passive tripler core with second harmonic suppression function, and the impedance matching network with frequency selection characteristics, the AMC presents better harmonic suppression performance compared with the conventional topology. The bias circuits with temperature compensation are applied to the DA and PA to ensure the performance of the AMC when the temperature changes. The AMC has a measured output power exceeding 0 dBm in the entire E-band frequency range with a peak output power of 10.9 dBm at 77 GHz, and exhibits a record PAE of 8.25 %. Within the 3 dB operating frequency range from 69 to 87 GHz, the rejection of fundamental and second harmonics are better than 33.5 dB. The AMC can work properly between -40 °C and 125 °C with the proposed temperature compensation bias circuits.

The deployment of the Millimeter-Wave (mm-Wave) band in 5G and beyond wireless communications networks is one of the emerging fields owing to its potential of providing extensive bandwidth. Frequency Hopping (FH) has a high potential for use in wireless networks due to its key advantages of spreading the interference over wide bandwidth and of providing diversity gain in counteracting frequency-selective fading. Furthermore, Fast Frequency Hopping (FFH) intrinsically amalgamated with directional Beamforming (BF) may overcome the impairments because of the path-loss of mm-Wave communications. Thus, we propose FFH assisted base-band precoding aided BF for mitigating the mm-wave channel impairments imposed by both fading as well as path loss, whilst relying on a minimal range of radio frequency chains. The mathematical analysis and simulation results demonstrate that hybrid precoded FFH is indeed a promising high-capacity technique of attaining both time- and frequency-domain diversity gains for the mm-Wave communications.

The integration of sub-6-GHz and millimeter-wave (mm-wave) bands has become an important issue for future fifth generation (5G) wireless communications owing to their large frequency ratios. This paper proposes a compact-size dual-function antenna operating at 3.5 GHz and the mm-wave band (28 GHz) for 5G mobile applications using a frequency reconfigurability technique. The proposed antenna comprises a microstrip patch linked with a meandered radiating structure through a radio frequency PIN diode to achieve frequency reconfigurability between the two bands. A significant size reduction up to 15.3 $\text {mm} \times 7.2\,\,\text {mm} \times 0.508$ mm for the proposed antenna was achieved using a meandered line structure and truncated ground plane. To enhance the functionality, $8 \times 8$ multiple-input multiple-output (MIMO) with possible long- and short-edge antenna placement configurations were demonstrated. The system exhibited satisfactory MIMO characteristics with wide decoupling −10 dB bandwidths of 7.4% and 4.8% at the low- and high-frequency bands, respectively, without utilizing any external decoupling structure. The simulated results were validated using fabricated prototypes, and good agreement was observed. Additionally, a safety analysis based on the specific absorption rate and power density at the prescribed frequency bands was conducted using a realistic human model, and the results were found to be in accordance with the safety guidelines. Owing to the integration of sub-6-GHz and mm-wave bands in a single compact structure with a large frequency ratio and good MIMO performance, the proposed antenna system is suitable for future 5G mobile handheld devices.

The millimeter-wave (mm-wave) band is expected to be the optimal solution for future wireless communication systems as it provides a wide bandwidth, which enhancing data transmission rate. Therefore, high-directive antennas, principal elements for mm-wave wireless communications, are used at the mm-wave band as they can overcome the negative effect of high path losses. A transmit-array antenna (TA) operates at the mm-wave band (around 28 GHz) with high aperture efficiency, high gain, wide bandwidth, and low-profile TA surface has been designed. Basically, the aperture efficiency of the TA depends on the unit cell (UC) characteristics, and feed antenna radiation pattern. Therefore, the UC elements designed based on capacitive differential feeding and true time delay techniques, as a result the designed UC has a wide bandwidth with a stable broadside radiation pattern, high cross-polarization discrimination and a full phase range (0–360°) and a maximum element loss of 0.5 dB. Moreover, the designed UC rotates the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal direction with high efficiency, a polarization conversion ratio higher than 0.9 is achieved within the operating frequency band. The used techniques to design the proposed UC have a significant effect on TA antenna performance, in terms of gain and bandwidth. The TA antenna surface and the feeding antenna have been designed and fabricated. The maximum gain is 31.15 dBi. The 1 dB gain bandwidth is 12.7% while the 3 dB gain bandwidth is 21% around 28 GHz. The aperture efficiency is better than 50% and the cross-polarization level is less than −37 dB, on the frequency range from 25 to 31.5 GHz.

Accurate prediction of the large-scale channel fading is fundamental to planning and optimization in 5G millimeter-wave cellular networks. The current prediction methods, which are either too computationally expensive or inaccurate, are unsuitable for city-scale cell planning and optimization. This paper presents FadeNet, a convolutional neural-network enabled alternative for predicting large-scale fading with high computation speed and accuracy. By using carefully designed input features and neural-network architecture to capture topographical information, FadeNet accurately predicts the large-scale fading from a base station to each location in its coverage area. Evaluations on realistic data, derived from millimeter-wave cells across multiple cities, suggest that FadeNet can achieve a prediction accuracy of 5.6 decibels in root mean square error. In addition, by leveraging the parallel processing capabilities of a graphics processing unit, FadeNet can reduce the prediction time by $40X-1000X$ in comparison to industry prevalent methods like ray-tracing. Generalizations of FadeNet, that can handle variable topographies and base station heights, and its use for optimal cell site selection are also explored.

A dual-band quad-polarized transmitarray (TA) is designed in a common aperture operating at 25.9/39.8 GHz. Using narrow strip patches as cells, the 25.9 GHz cells are arranged in the ±45° direction, and the 39.8 GHz cells are arranged in the 0/90° direction in the formed square gap of the 25.9 GHz cells to realize a compact design with four polarization directions. In each band of 25.9/39.8 GHz, the proposed TA is dual-polarization designed. Measurements show that the expected beams can be achieved, and their 3 dB gain bandwidth covers almost all of the 5G bands n258 (24.25–27.5 GHz) and n260 (37–440 GHz). This TA has potential application value in 5G construction.

This paper presents a compact dual-band and dual-polarized millimeter-wave patch antenna array with satisfactory performance on element mutual coupling and beam scanning capabilities. Using capacitive feed technique and stacked configuration with extra parasitic strips, the proposed antenna array is able to achieve a wide operating bandwidth in both the low- and high-bands. In order to reduce the array’s footprint, and to enhance the beam scanning performance in both bands, the element spacing is shrunk to less than 0.36 wavelength at 26 GHz. To improve the isolation between array elements due to their small spacings, two effective decoupling approaches are adopted, which result in a 6-dB isolation enhancement. The overall size of the proposed antenna array is only 18.2 mm $\times4.1$ mm $\times1.07$ mm, which is smaller than some industrial mm-Wave antenna modules released recently. Our simulation shows that the antenna array can fully cover the 5G NR bands of n258~n261 simultaneously. The four-element array provides ±60° and ±45° beam scanning performance in the low- and high-bands, respectively. The experimental data of reflection coefficient, mutual coupling, and radiation patterns confirm with the simulated results, rendering the proposed array to be a good candidate for 5G mm-Wave communications.

In fifth generation (5G) cellular networks, a single base station equipped with multiple antennas can determine the user position within centimeters, by processing the wireless millimeter-wave channel estimate. A fake base station serving a victim user can also obtain the user location. In order to protect the user privacy, we propose a technique to prevent localization. We design a user transmit beamformer, so that the angles of departure of each channel path are hidden to the base station, thus preventing localization. We also optimize the allocated power, in order to maximize the achievable rate. The proposed solution is compared with both the capacity-achieving beamforming (without location privacy) and the zero-forcing beamforming, which still provides location privacy, at the cost of a lower rate.

A design criterion for a compact 3D printed high gain corrugated plate antenns that has high aperture efficiency and wide bandwidth is presented in this paper. The proposed design criterion is validated numerically and experimentally by fabricating 3D printed and Aluminium prototypes for X-band and Ka-band applications. The proposed antenna structure consists of two layers, where the electromagnetic energy (EM) is launched into a cavity that exists between both layers and the EM energy is coupled to the surface of the second layer. The second layer is the radiating structure which consists of three slots surrounded by a rectangular cavity and periodic corrugations that significantly improve the gain of the antennas. The 3D printed prototypes of the proposed antennas are fabricated and tested to validate the proposed design criterion, and their performance is compared to the Aluminium metallic counterparts. Using 3D printing technology, to fabricate the proposed antennas offer low cost and low weight alternatives to the Aluminium metallic prototypes. The measured results of the fabricated prototypes show high gain, high aperture efficiency, low side lobe level, and low cross polarization performance over a wide bandwidth.

A four-element compact wide-band optically transparent MIMO antenna with a full ground plane is proposed. The four elements transparent MIMO system has a compact size of 24 × 20 mm2 with the undivided ground plane as most of the real-time systems demand a common reference. The complete antenna system achieves around 85% transparency due to a combination of AgHT-8 and Plexiglas which forms the transparent conductive patch/ground and substrate, respectively. The antenna geometry leads dual-band operation ranging from 24.10 - 27.18 GHz (Impedance bandwidth = 12%) and 33 - 44.13 GHz (Impedance bandwidth =28.86$ %) targeting the mm-wave 5G applications. The 4-element antenna system achieves isolation between inter-elements >16 dB and maximum gain value of greater than 3 dBi with more than 75% efficiency. The proposed transparent MIMO antenna is evaluated in terms of diversity gain (DG), envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG) where decent MIMO performance with isolation more than >16 dB between the adjacent and other elements is achieved. Transparent MIMO antenna achieves directional patterns for the operating band with the value of DG >9, ECC

International audience; We present a photonically-excited antenna array at E-band for scanning by beam switching in wireless links. First, we discuss the proposed technique applied to photonic-enabled (sub)millimeter-wave transmitters. Next, we present the proposed solution; it consists of two sub-arrays of stacked patches as primary feeds of a Polytetrafluoroethylene (PTFE) lens, with one photodiode feeding each sub-array. To validate the assembly, the return loss and radiation patterns have been measured for one of the sub-arrays excited with a coplanar probe. In turn, the lens illuminated by one of the sub-arrays yields a directivity of 27 dBi. The radiation patterns measured for the transmitter module (including the lens) are in very good agreement with full-wave simulations, and they show that excitation of one of either sub-arrays allows beam switching between 2.7 with a beam crossover at 3 dB. Finally, we have tested the transmitter in a 0.6 m wireless link. Depending on the position of the detector and on which subarray is excited, we have accomplished 5 Gbps transmission for on-off-keying modulation and direct detection (BER = 1E11). The system constitutes an initial proof of photonic-assisted beam switching for mm-wave transmitters enabling broadband operation with a directive and switchable beam. IEEE

The development of novel high-gradient accelerating structures operating at THz frequencies is critical for future free-electron lasers and TeV scale linear colliders. To reach high energies with reasonable length requires high accelerating gradients of ~100 MV/m. The main limitation to reaching these high-energy gradients is the vacuum RF breakdown phenomenon, which disrupts normal accelerator operations. For stable operations and to understand the breakdown microscopic dynamics, a new device capable of detecting the breakdown occurrences is required. In this paper, we provide the design of a pulse length monitor based on an analog to digital converter for fast signal digitization without the need to use high-speed digitizers to be used in a commercial mm-wave heterodyne spectrometer.

International audience; This paper aims to compare the performance of HBT-based and MOSFET-based mm-Wave SPDT switches in a single BiCMOS technology. To the best of authors' knowledge, a direct comparison of this function in the same integrated process has never been reported before. Measurement results on two 50-GHz integrated SPDTs reveal that the HBT-based SPDT switch yields 1.7 dB of insertion loss and 14 dB of isolation in its central frequency, with a bandwidth covering the 30-80 GHz frequency range when considering a return loss greater than 10 dB. On the other hand, the MOSFET-based SPDT switch yields 2.1 dB of insertion loss and 12 dB of isolation at center frequency and a bandwidth covering the 33-80 GHz frequency range.

Lower efficiencies of power amplifiers and increased path loss at higher frequencies are two reasons why utilizing millimeter-wave frequencies for future wireless communications systems is challenging. In this paper, two distinct antenna systems are presented which address this challenge by using high antenna gain. This allows lower transmit power levels, compared to conventional phased array antennas, while still providing high effective isotropic radiated power.

This paper investigates design considerations and challenges of integrating on-chip antennas in nanoscale CMOS technology at millimeter-wave (mm-wave) to achieve a compact front-end receiver for 5G communication systems. Solutions to overcome these challenges are offered and realized in digital 28-nm CMOS. A monolithic on-chip antenna is designed and optimized in the presence of rigorous metal density rules and other back-end-of-the-line (BEoL) challenges of the nanoscale technology. The proposed antenna structure further exploits ground metallization on a PCB board acting as a reflector to increase its radiation efficiency and power gain by 37.3% and 9.8 dB, respectively, while decreasing the silicon area up to 30% compared to the previous works. The antenna is directly matched to a two-stage low noise amplifier (LNA) in a synergetic way as to give rise to an active integrated antenna (AIA) in order to avoid additional matching or interconnect losses. The LNA is followed by a double-balanced folded Gilbert cell mixer, which produces a lower intermediate frequency (IF) such that no probing is required for measurements. The measured total gain of the AIA is 14 dBi. Its total core area is 0.83 mm2 while the total chip area, including the pad frame, is 1.55 \times 0.85 mm2. Science Foundation Ireland

WOS: 000470838000028 Physical layer security (PLS) has emerged as a new concept and powerful alternative that can complement and may even replace encryption-based approaches, which entail many hurdles and practical problems for future wireless systems. The basic idea of PLS is to exploit the characteristics of the wireless channel and its impairments including noise, fading, interference, dispersion, diversity, etc. in order to ensure the ability of the intended user to successfully perform data decoding while preventing eavesdroppers from doing so. Thus, the main design goal of PLS is to increase the performance difference between the link of the legitimate receiver and that of the eavesdropper by using well-designed transmission schemes. In this survey, we propose a conceptual, generic, and expandable framework for classifying the existing PLS techniques against wireless passive eavesdropping. In this flexible framework, the security techniques that we comprehensively review in this treatise are divided into two primary approaches: signal-to-interference-plus-noise ratio-based approach and complexity-based approach. The first approach is classified into three major categories: first, secrecy channel codes-based schemes; second, security techniques based on channel adaptation; third, schemes based on injecting interfering artificial (noise/jamming) signals along with the transmitted information signals. The second approach (complexity-based), which is associated with the mechanisms of extracting secret sequences from the shared channel, is classified into two main categories based on which layer the secret sequence obtained by channel quantization is applied on. The techniques belonging to each one of these categories arc divided and classified into three main signal domains: time, frequency and space. For each one of these domains, several examples are given and illustrated along with the review of the state-of-the-art security advances in each domain. Moreover, the advantages and disadvantages of each approach alongside the lessons learned from existing research works are stated and discussed. The recent applications of PLS techniques to different emerging communication systems such as visible light communication, body area network, power line communication, Internet of Things, smart grid, mm-Wave, cognitive radio, vehicular ad-hoc network, unmanned aerial vehicle, ultra-wideband, device-to-device, radio-frequency identification, index modulation, and 5G non-orthogonal multiple access based-systems, are also reviewed and discussed. The paper is concluded with recommendations and future research directions for designing robust, efficient and strong security methods for current and future wireless systems. Scientific and Technological Research Council of Turkey (TUBITAK) [114E244] This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant 114E244. (Corresponding author: Jehad M. Hamamreh.)

A realistic performance assessment of any wireless communication system requires the use of a fading channel model that reflects its main characteristics. The traditional Rayleigh and Nakagami-m models have been (and still are) the basis of most theoretical research on wireless technologies today, even for emerging technologies, such as millimeter-wave communications (mm-Wave). In this article, we show that the fluctuating multiple-ray (FMR) and κ-μ shadowed models had a better fit (i.e., lowest mean square error statistical test) to field measurements in outdoor environments at 28 GHz than the conventional channel models. Therefore, these generalized models are feasible alternatives that can be used as a benchmark when evaluating communication performance in mm-Wave scenarios.

A microstrip-fed air-substrate-integrated waveguide (ASIW) slot array with high efficiency and low cost is presented. The design cuts out the substrate material within SIW, replaces the vias with metallic sidewalls, and uses a simple microstrip line-waveguide transition to feed the slot array. Radiating slots are cut on a 5-mil brass-plate, which covers the top of the substrate cutout to resemble a hollow waveguide structure. This implementation provides a simple and efficient antenna array solution for millimeter-wave (mm-wave) applications. Meanwhile, the fabrication is compatible with the standard printed circuit board (PCB) manufacturing process. To demonstrate the concept, a 4-element ASIW slot array working at the n257 band for 5G communications was designed using low-cost Rogers 4350B and FR4 substrate materials. Our simulation result shows 18% more efficiency than a conventional SIW slot array using the same substrate. The fabricated prototype shows |S11| < −15 dB over 27–29 GHz and a peak realized gain of 10.1 dBi at 28.6 GHz. The design procedure, prototyping process, and design analysis are discussed in the paper.

This letter presents a 38/60 GHz dual-frequency band 3-stage transformer-based inductor-peaked differential rectifier in a 40 nm CMOS technology. The rectifier is used in a wirelessly powered receiver in a monolithic IoT transponder. Its sensitivity is a bottleneck for the transponder’s range. With the dual-frequency operating function, the wirelessly powered distance could be optimized based on the selected frequency band. In this letter, a new vertical integration transformer with a compact size is proposed and implemented to achieve stage-cascading, inductor peaking, and dual-frequency matching functions simultaneously. In addition, bulk-drain-connected transistors further improve the rectifier’s efficiency and sensitivity. In this combination, the 3-stage transformer-based inductor-peaked rectifier improves sensitivity at 38 GHz and 60 GHz frequency bands. The 1-V sensitivity is -6 dBm at the 38 40 GHz frequency band and -5 dBm at 57 64 GHz frequency band. This mm-wave dual-band rectifier achieves the peak 1-V sensitivity of -7.8 dBm at 40 GHz.

Thanks to the large bandwidth availability, millimeter and sub-millimeter wave systems are getting more attractive to be used in a wide range of applications, such as high-resolution radar or high-speed communications. In this contribution, a new lens antenna in-package solution is presented for the H-band (220320 GHz), including a wideband quartz-cavity leaky-wave feed combined with an air-bridge chip interconnect technology, based on spray coating and laser lithography. This interconnection acts as a wideband, low-loss transition between the GaAs front-end and the quartz antenna, avoiding the use of expensive waveguide split-blocks. An antenna prototype including the interconnect has been manufactured and characterized, validating the full-wave simulated results for the integrated H-band leaky-wave with aperture efficiency higher than 74% over 34% bandwidth, and radiation efficiency higher than 70% over 37% of bandwidth.

This work presents a multichannel D-band receiver front-end for multiple-input–multiple-output frequency-modulated continuous-wave radar applications. The 120-GHz local oscillator (LO) signal is generated from an external 24-GHz source by an integrated frequency multiplier by five. We propose co-design of power-matched differential buffers with active splitters. Thank to the optimal impedance ratio, the power consumption of the LO distribution network could be minimized. To demonstrate the effectiveness of the discussed method, a chip with three receivers is implemented, where each receiver signal path comprises a mixer-first Gilbert cell which shows 12-dB conversion gain, 13-dB single-sideband (SSB) noise figure, and −5-dBm input-referred 1-dB compression point. A fourth channel is included for built-in self-test and the characterization of the LO distribution chain, providing a −2-dBm output signal over the 111–123-GHz frequency range. The circuit has a low-power consumption of 66-mW per RX channel, for a total power consumption of 198mW from the 1.8-V supply. The active area is 2.07mm2 implemented using a 0.13- ${{\mu }}\text{m}$ SiGe BiCMOS technology.

This paper presents a transmitter (TX) and a receiver (RX) with bowtie-antenna and silicon lens for gas spectroscopy at 222-270 GHz, which are fabricated in IHP’s $0.13~\mu \text{m}$ SiGe BiCMOS technology. The TX and RX use two integrated local oscillators for 222 – 256 GHz and 250 – 270 GHz, which are switched for dual-band operation. Due to its directivity of about 27 dBi, the single integrated bowtie-antenna with silicon lens enables an EIRP of about 25 dBm for the TX, and therefore a considerably higher EIRP for the 2-band TX compared to previously reported systems. The double sideband noise temperature of the RX is 20,000 K (18.5 dB noise figure) as measured by the Y-factor method. Absorption spectroscopy of gaseous methanol is used as a measure for the performance of the gas spectroscopy system with TX- and RX-modules.

Low relative permittivity plastic elliptical lenses in combination with integrated focal plane arrays are a promising solution to be used in the future mm- and sub-mm-wave systems. Their appeal lies in the availability of materials with moderate loss and lightweight, and the possibility to use cost-effective manufacturing techniques. However, the achievable scanning angular range is relatively small with low permittivity lenses. In this article, we explore the use of dielectric gratings with modulated height integrated in the lens material, with the aim of enlarging the steering angle. The dielectric gratings synthesize a tilted feed pattern, reducing the reflection loss and spillover when illuminating the lens off-focus. A quasi-analytic approach based on the Floquet mode analysis of the gratings is used to synthesize the grating profile. This method is combined with an analysis in reception of the lens antenna. A wideband prototype in $G$ -band (140-220 GHz) has been fabricated, achieving a field of view of ±25° with gain >30 dBi.

A compact triple band antenna by using etching slots technique in the radiation element is presented in this paper. The proposed antenna is designed to target three different frequencies: 7.5 GHz (military satellite communication), 9 GHz (radar applications) and 28 GHz (fifth generation applications). The fabricated prototype of the antenna has overall dimensions of 13x12.8x1.6 mm3. Measurements were carried out to validate the simulation results. The impedance bandwidths are 259 MHz (7.435-7.695 MHz), 355 MHz (8.86-9.221 MHz) and 2.67 GHz (26.79-29.433 GHz) with return loss less than -10 dB. Furthermore, the suggested antenna provides a gain of 3.96 dBi, 3.05 dBi and 5.86 dBi at 7.5 GHz, 9 GHz and 28 GHz respectively. Therefore, the results demonstrate that the proposed triple band antenna can be used for military satellite communication, radar applications and is a good candidate for the future 5G applications.

International audience; This work presents novel transmission line structures based on Meandered Slow-wave CoPlanar Waveguides (MS-CPWs), aiming to achieve high miniaturization. As a proof-of-concept, these two kinds of transmission lines were designed and fabricated in the AMS 0.35 mu m CMOS technology together with classical straight and meandered microstrip lines. Measurement results from 70 kHz to 100 GHz of the fabricated transmission lines are presented. At 80 GHz, all the considered transmission lines present similar quality factors, ranging between 10 and 14. On the other hand, at this frequency, one of the developed MS-CPW presents an effective dielectric constant of 88, while the meandered microstrip exhibits an equivalent effective dielectric constant of 51, thus leading to higher compactness for the MS-CPW.

In this paper, the authors present a broadband transition from the standard WR-10 rectangular waveguide (RW) to a groove gap waveguide (GGW) in the W-band. The transition structure is based on electromagnetic band gap (EBG) technology where two EBG units are used, which are responsible for the transition and forming the transmission line. Metal pins in the E-plane together with the back surface of the transmission line create a forbidden band, which prevents power leakage between the connecting parts. Small air gaps will not harm the transition performance according to the simulation, which means it has a better tolerance of manufacturing and assembly errors and, thus, has advantages for mm-wave contactless connections. A back-to-back transition prototype was designed, fabricated and measured. The length of the GGW is 39.6 mm. The measured |S11| is better than &minus, 13 dB and the measured |S21| is better than &minus, 0.6 dB over 76.4&ndash, 109.1 GHz, covering a bandwidth of 35.3%.

A 24-GHz direct-conversion transmitter is proposed for in-cabin radar applications. The proposed RF transmitter consists of an I/Q up-conversion mixer, an I/Q local (LO) oscillator generator, and a power amplifier. To improve the linearity of the I/Q up-conversion mixer, an inverter transconductor with third-order intermodulation (IM3) distortion cancellation is proposed. To improve the I/Q balancing performance of the I/Q LO generator, a poly-phase filter, including parasitic line inductance, is proposed. By employing a highly linear I/Q up-conversion mixer and a balanced I/Q LO generator, the 24-GHz direct-conversion transmitter achieves high linearity and I/Q balancing characteristics. It is fabricated in a 65-nm CMOS process and consumes 150 mW. It shows an OP1dB of 8.6 dBm, an LO leakage of &minus, 48 dBc, and an image rejection ratio of &minus, 49 dBc for the entire operating band from 24 GHz to 24.5 GHz.

Millimeter wave oscillators are of particular interest towards future communications and sensing as frequency multiplication of local oscillator signal is resulting in degraded performance. At high frequencies, the quality (Q) factor of the LC tank is degraded. Thus, a higher transconductance $(\mathrm{G}_{M})$ size is required to compensate the losses, thereby consuming high power. Numerous techniques have been adopted to reduce the power consumption of a cross-coupled LC voltage controlled oscillator (VCO) and to improve the negative resistance $(\mathrm{R}_{neg})$ associated to it. One of them utilizes inductors in the cross-coupled pair. In this paper, we examine the tradeoffs of this inductor to improve negative resistance above 100 GHz. For the analysis, the transistor model is being verified with the simplified small-signal equivalent model. Moreover, we have studied the inductor influence on the transition frequencies of the cross-coupled pair. The restrictions of this technique at high frequencies is investigated. To study the benefits of this technique, an oscillator core is designed and simulated using the 22nm FDSOI CMOS process. It exhibits a tuning range of 5.4% from 125.5 GHz to 132.5 GHz, and phase noise from -101.23 dBc/Hz to -102.0381 dBc/Hz at 10 MHz offset over the entire tuning range. The VCO consumes power of 17 mW. In simulations, an improvement in power consumption by 4.3 mW and phase noise by 1.5 dBc/Hz were achieved when compared to conventional LC Tank VCO.

This article provides an overview of the fifth generation of cellular communications (5G) and beyond. It presents the transmission techniques of current 5G communications and those expected of future developments, namely a brief study of non-orthogonal multiple access (NOMA) using the single carrier with frequency domain equalization (SC-FDE) block transmission technique, evidencing its added value in terms of spectral efficiency. An introduction to the sixth generation of cellular communications (6G) is also provided. The insertion of 5G and 6G within the Fourth Industrial Revolution framework (also known as Industry 4.0) is also dealt with. Consisting of a change in paradigm, when compared to previous generations, 5G supports a myriad of new services based on the Internet of things (IoT) and on vehicle-to-vehicle (V2V) communications, supporting technologies such as autonomous driving, smart cities, and remote surgery. The new services provided by 5G are supported by new techniques, such as millimeter waves (mm-wave), in addition to traditional microwave communication, and by massive multiple-input multiple-output (m-MIMO) technology. These techniques were not employed in the fourth generation of cellular communications (4G). While 5G plays an important role in the initial implementation of the Fourth Industrial Revolution, 6G will address a number of new services such as virtual reality (VR), augmented reality (AR), holographic services, the advanced Internet of things (IoT), AI-infused applications, wireless brain&ndash, computer interaction (BCI), and mobility at higher speeds. The current research on systems beyond 5G indicates that these applications shall be supported by new MIMO techniques and make use of terahertz (THz) bands.

This paper proposes a novel high-gain antenna element that can be used in antenna arrays that only require a limited scan range. Each high-gain antenna element uses a linear sub-array of highly-coupled open-ended waveguides. The active central element of this sub-array is directly fed, while the remaining passive waveguides are reactively loaded. The loads are implemented by short-circuits positioned at various distances from the radiating aperture. The short-circuit positions control the radiation pattern properties and the scattering parameters of the array. The proposed sub-array antenna element is optimized in the presence of the adjacent elements and provides a high gain and a flat-top main lobe. The horizontal distance between the sub-array centers is large in terms of wavelengths, which leads to limited scanning capabilities in the E-plane. However, along the vertical axis, the element spacing is around 0.6 wavelength at the central frequency that is beneficial to achieve a wider scan range in the H-plane. We show that the sub-array radiation pattern sufficiently filters the grating lobes which appear in the array factor along the E-plane. To demonstrate the performance of the proposed array configuration, an array operating at 28.0 GHz is designed. The designed array supports scan angles up to &plusmn, 7.5&deg, along the E-plane and &plusmn, 24.2&deg, along the H-plane

Millimeter-wave wireless networks of the new fifth generation (5G) have become a primary focus in the development of the information and telecommunication industries. It is expected that 5G wireless networks will increase the data rates and reduce network latencies by an order of magnitude, which will create new telecommunication services for all sectors of the economy. New electronic components such as 28 GHz (27.5 to 28.35 GHz) single-chip transmit radio frequency (RF) front-end monolithic microwave integrated circuits (MMICs) will be required for the performance and power consumption of millimeter-wave (mm-wave) 5G communication systems. This component includes a 6-bit digital phase shifter, a driver amplifier and a power amplifier. The output power P3dB and power-added efficiency (PAE) are 29 dBm and 19.2% at 28 GHz. The phase shifter root-mean-square (RMS) phase and gain errors are 3° and 0.6 dB at 28 GHz. The chip dimensions are 4.35 × 4.40 mm.

International audience; In this paper, an innovative millimeter-wave (mm-wave) through-load switch for in-situ reflectometers and on-wafer calibration is proposed. This two-port device can switch between two states: (i) a through connection or (ii) a 50 Ω load for both of its ports. The through-load switch is composed of a 3-dB directional coupler and two nMOS transistors controlled through a biasing voltage applied to their gate. Measurement results of a 120-GHz 3-dB directional coupler are provided up to 145 GHz together with EM simulations and circuit-level simulations up to 220 GHz of the through-load switch. A wide bandwidth is obtained, from 73 GHz to 179 GHz, with limited insertion loss of 2 dB.

This paper presents a wide-range and low phase noise mm-Wave Voltage Controlled Oscillator (VCO) based on the transconductance linearization technique. The proposed technique eliminates the deep triode region of the active part of the VCO, and lowers the noise introduced by the gm-cell. The switch sizes inside the switched capacitor bank of the VCO are optimized to minimize the resistance of the switches while keeping the wide tuning range. A new layout technique shortens the routing of the VCO outputs, and lowers the parasitic inductance and resistance of the VCO routing. The presented method prevents the reduction of the quality factor of the tank due to the long routing. The proposed VCO achieves a discrete frequency tuning range, of 14 GHz to 18 GHz, through a linear coarse and middle switched capacitor array, and offers superior phase noise performance compared to recent state-of-the-art VCO architectures. The design is implemented in a 45 nm CMOS process and occupies a layout area (including output buffers) of 0.14 mm2. The power consumption of the VCO core is 24 mW from the power supply of 0.8 V. The post-layout simulation result shows the VCO achieves the phase noise performances of &minus, 87.2 dBc/Hz and &minus, 113 dBc/Hz, at 100 kHz and 1 MHz offset frequencies from the carrier frequency of 14 GHz, respectively. In an 18 GHz carrier frequency, the results are &minus, 87.4 dBc/Hz and &minus, 110 dBc/Hz, accordingly.

Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (µWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughput.

Millimeter-wave (mm-wave) communications, as any other emerging technology, require suitable experimentation platforms that allow validation and field tests in both academic and industry research environments. Existing platforms formm-wave systems are based on Commercial-Off-The-Shelf(COTS) devices or expensive proprietary hardware platforms. In this paper we propose a mixed software-hardware testbedfor mm-wave experimentation using Software Defined Radio(SDR) devices. Specifically, we design and implement the hardware processing blocks required to decode the preamble of frames that follow the structure of IEEE 802.11ad compliant frames, working at a scaled-down bandwidth, along with their integration in X310 USRP devices using the RFNoC framework and 60GHz transceivers. The testbed is validated for different indoor channels with real-time Channel Impulse Response (CIR)measurements. The design exploits the maximum bandwidth for X310 devices while leaving enough FPGA logic space (≈60%),for further upgrades and extension of the system. FALSE pub

This paper presents an antenna array which is based on a novel sub-array architecture. Each sub-array is a linear array of open-ended waveguides. The central element of the sub-array is directly fed, while the other elements are short-circuited. The position of the short circuits along the waveguides controls the radiation pattern properties and scattering parameters evaluated at the active ports of the array. The proposed sub-array structure exhibits high-gain characteristics with a flat-top distribution and is used as a unit cell in a two-dimensional array. The distance between the subarray centers along the relevant main axis is large in terms of wavelengths, which leads to limited scanning capabilities, whereas the inter-element separation along the orthogonal plane is about half free-space wavelength at the central working frequency, this leading to a wide scan range. Using the presented approach, an array operating at 28.5 GHz was designed in such a way as to feature a maximal scanning angle of ±7.4° along the E-plane and ±27.45° along the H-plane. The specific sub-array pattern, which approximates a rectangular pulse distribution, allows to filter out the grating lobes along the E-plane.

The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is mainly driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks, which are expected to bring transformative changes to this premise. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. In particular, the present paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a comprehensive study of the 6G vision and outlining seven of its disruptive technologies, i.e., mmWave communications, terahertz communications, optical wireless communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss the associated requirements, key challenges, and open research problems. These discussions are thereafter used to open up the horizon for future research directions. publishedVersion

In this brief, designs of two millimeter wave (mmWave) reconfigurable multi band low noise amplifiers (LNA) are presented targeted for fifth generation (5G) communications. A reconfigurable tunable load based on electrical and magnetic tuning is proposed to cover three mmWave frequency bands for 5G, i.e., 24 GHz, 28 GHz and 39 GHz. Two LNA structures are designed and fabricated using 45nm CMOS SOI technology. The first toplogy (LNA1) is composed of a single input wideband matching circuit to cover frequency operations from 24 GHz to 40 GHz. On the other hand, second topology (LNA2) uses three separate narrowband match inputs, one for each frequency band, with combined output. Design methodology of passive and active devices is presented towards compact integration of LNAs for systems such as, phased arrays. Ground plane and its impact on the performance parameters is also discussed in this brief. Measurement results show a wideband noise figure (NF) ranging from 3.8 dB to 4.9 dB and gain of 8.5 dB to 12.5 dB for LNA1 at different bands. Similarly, LNA2 exhibits NF of 4.5 dB to 5.5 dB and gain of 9.5 dB to 15.5 dB across all bands. Total area (including pads) of LNA1 and LNA2 are 0.316 $mm^{2}$ and 0.695 $mm^{2}$ , respectively.

This paper presents a study of the D-band radio solutions, with beam-steering functionality, intended for use in the reconfigurable meshed networks. The regulation and radio network constraints defining the specifications of a D-band transceiver are reviewed. The architecture of the radio link is proposed and key enabling technologies needed to build the D-band transceiver with beam-steering functionality are presented.

InP-based HEMTs with composite GaInAs/InAs channels are recognized for their high frequency performance thanks to their superior carrier transport properties. On the other hand, the addition of an InP subchannel to a GaInAs channel can effectively suppress channel impact ionization, lower the output conductance, and improve noise properties. Although the literature provides a number of reports about both separate approaches, we merge both strategies in the present study and report the first GaInAs/InAs/InP composite channel HEMTs. The influence of the InAs inset location is studied through DC, RF and noise characterization. Devices with the InAs inset located further from the top AlInAs barrier exhibit an improved minimum noise figure NFMIN due to a reduced gate leakage current. The NFMIN improvement is accompanied by a slight degradation in both the output characteristics and cutoff frequencies resulting from the increased average gate-to-2DEG separation. Our results indicate that the combination of an InAs inset and an InP subchannel opens promising HEMT design avenues for broadband low-noise applications.

With the growing attention at 60 GHz ISM band on millimeter-wave therapy for diseases treatment of sedative, anti-inflammatory actions or immune system stimulation, growing demand for new biomedical monitoring and treating systems with more bandwidth, high data rates and low power creates new challenges for 60 GHz body area network. Most smart wireless sensors wireless sensing operates on battery, which limits their life-time. To overcome this limitation, a system of radio-triggered batteryless monolithic wireless sensor based on mm-wave wireless power transfer technique is introduced in this work. From the system power budget analysis, it could support 10 bits communication within 10 cm, which would be sufficient for mm-wave wireless sensing application. Furthermore, it is identified that the receiver is power limited. Based on the system evaluation, an injection locked oscillator based self-mixing receiver is presented. In this architecture, the IJLO based LO scheme is used to save receiver power consumption. The sensitivity of the receiver is improved by applying the IJLO into the self-mixing architecture. This single chip receiver is implemented in a 65 nm CMOS technology. The DC power consumption of this receiver is only 16.4 mA from 1 V power supply. This power consumption is lower than other mm-wave receivers, which is an important step towards fully integrated monolithic sensor nodes.

A directional two-element mm-wave dipole antenna array with reconfigurable patterns is presented in this paper. An substrate integrated waveguide (SIW) 90° coupler is used to realize reconfigurable patterns of the antenna array. The two dipole elements are parallel in space, and there is a distance of λ0/4 (λ0 is the wavelength of the free space) between them. When the two inputs of the 90° coupler are excited, respectively, two completely opposite radiation patterns are able to be achieved. In order to further enhance the directivity of the proposed antenna, two groups of novel zero-index metamaterials and three metallic strips are introduced. As a consequence, a 0.7-1.2 dBi gain enhancement and reduced back lobe are obtained within the working frequencies. The measured amplitudes of S11 and S22 are below -10 dB from 45.5 to 49.5 GHz, and the measured gain is all great than 5 dBi within this band.

© 2013 IEEE. A wideband and high gain cavity-backed 4 × 4 patch antenna array is proposed in this paper. Each patch antenna element of the array is enclosed by a rectangular cavity and differentially-fed by the slot underneath. By optimizing the geometry of the radiating patch and the cavity, a very uniform E-field distribution at the antenna aperture is achieved, leading to the high array aperture efficiency and thus the gain. Taking advantages of the higher-order substrate integrated cavity excitation, the elements of the array are efficiently fed with the same amplitude and phase in a simplified feeding mechanism instead of the conventional bulky and lossy power-splitter-based feeding network. Measured results show the antenna bandwidth is from 56 to 63.1-GHz (16.1%) with the peak gain reaching 21.4 dBi. The radiation patterns of the array are very stable over the entire frequency band and the cross-polarizations are as low as -30 dB. These good characteristics demonstrate that the proposed array can be a good candidate for the future 60-GHz communication system applications.

This paper presents a Dual-sideband Optical Carrier Suppression (DSB-OCS) technique which is used to generate an optical millimeter-wave (mm-wave) signal in radio over fiber (RoF) systems. The proposed system employs a Dual-Electrode Mach-Zehnder Modulator (DE-MZM) and a carrier of 40 GHz mm-wave for data transmission through the RoF systems. Characteristics determining the performance of the system, among which are the modulation index, phase imbalance and dispersion parameters, are included. The performance evaluations of the system show that the mm-wave signal output power follows MZM’s transfer function when the modulation index is raised. Moreover, the generated optical mm-wave signal power is affected by phase imbalance and optical splitting ratio. It is observed that the optical fiber dispersion influences the DSB-OCS system by decreasing the amplitude of the mm-wave and the signal-to-noise ratio (SNR).

Future generation mobile communications running on mm-wave frequencies will require great robustness against frequency selective channels. In this paper, we evaluate the transmission performance of 4.9 Gb/s wavelet-coded orthogonal frequency division multiplexing (OFDM) signals on a 10 km fiber plus 58 m wireless radio-over-fiber link using a mm-wave radio frequency carrier. The results show that a 2 × 128 wavelet-coded OFDM system achieves a bit-error rate of 1e-4 with nearly 2.5 dB less signal-to-noise ratio than a convolutional coded OFDM system with equivalent spectral efficiency for 8 GHz-wide signals with 512 subcarriers on a carrier frequency of 86 GHz. Our findings confirm the Tzannes’ theory that wavelet coding enables high diversity gains with a low complexity receiver and, most notably, without compromising the system's spectral efficiency.

The aim of this paper is to introduce the use of sparse multistatic arrays to reduce the number of elements in novel portable and muti-view millimiter-wave scanners. Thus, the complexity of these novel scanners is significantly reduced. Furthermore, sparsity is expected to enable embedding a conventional optical camera sensor inside the aperture of the scanner allowing a reduction of the scanner size. This camera sensor is used to build a complementary 3-D optical model as well as to estimate the millimeter-wave scanner position so that the imaging merging techniques can be applied. The approach is validated for concealed weapon detection by means of simulation as well as measurements, in which the scanner aperture is emulated by raster scan, showing a performance comparable to the case of dense arrays.

This paper presents a 60 GHz band transformer-based inductor peaked differential rectifier in a 40 nm CMOS technology. The rectifier is used as a wireless power receiver in a monolithic wireless powered IoT transponder. A new transformer-based inductor peaked differential topology is proposed and implemented to improve the sensitivity. In this method, the input transformer performs voltage boosting function, inductor peaking function, and impedance transfer function simultaneously within a compact die size. The proposed rectifier topology achieves an excellent peak sensitivity of -12 dBm at 64 GHz for 1 V output voltage. The overall sensitivity over the entire operational range of 58-64 GHz is below - 5 dBm.

[ES] Esta tesis aborda temas de especial interés en el diseño de antenas en la banda de milimétricas. Hui en dia, implementar components passius per a operar en la banda de mil·limètriques i assegurar el contacte i l'alineament metàl·lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guies d'ones metàl·liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl·lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnología Gap Waveguide (GW) resulta adecuada ya que no requiere de contactos metálicos. En los últimos años han surgido las agrupaciones de antenas basadas en la tecnología Gap Waveguide y son un candidato prometedor para satisfacer algunas de las necesidades mencionadas. La tecnología GW ha demostrado ser atractiva para dispositivos de milimétricas porque permite redes de distribución completamente metálicas de una manera más simple que las guías de onda convencionales. Por tanto, estas redes tienen muy bajas pérdidas pero además son simples de fabricar. Esto es posible gracias a la capacidad de las GW de confinar de forma segura la propagación de ondas electromagnéticas por medio de una estructura que no requiere de contacto. Durante la última década, se han hecho avances importantes en la tecnología GW y en la literatura se pueden encontrar un buen número de antenas basadas en GW. Esta tesis va un paso más allá en la contribución de este tipo de antenas. Aquí, no solo se presentan antenas con polarización lineal, como suelen ser las desarrolladas hasta ahora, sino también con polarización dual, circular y duales en banda. Estas aportaciones son especialmente atractivas dentro del campo de las comunicaciones por satélite en movimiento (SATCOM on-the-move). Además, se han explorado nuevas redes de distribución que permiten antenas planas más compactas, más ligeras., [CA] Esta tesi aborda temes d'especial interés en el disseny d'antenes en la banda de mil.limètriques. Hui en dia, implementar components passius per a operar en longituds d'onda tan xicotetes (de l'orde de mil.límetres) i assegurar el contacte i l'alineament metàl-lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guia d'ones metàl.liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl.lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnologia Gap Waveguide (GW) resulta adequada ja que no requerix de contactes metàl.lics. En els últims anys han sorgit les agrupacions d'antena basades en la tecnologia Gap Waveguide i són un candidat prometedor per a satisfer algunes de les necessitats mencionades. La tecnologia GW ha demostrat ser atractiva per a dispositius de banda d'ones mil-limètriques perquè permet xarxes de distribució completament metàl-liques d'una manera més simple que les guies d'onda convencionals. Per tant estes xarxes tenen baixes pèrdues peró, a més, són simples de fabricar. Açò és possible gràcies a la capacitat de les GW de confinar de forma segura la propagació d'ones electromagnètiques per mitjà d'una estructura que no requerix de contacte. Durant l'última dècada, s'han fet avanços importants en la tecnologia GW i en la literatura es poden trobar un bon nombre d'antenes basades en GW. Esta tesi va un pas més enllà en la contribució d'este tipus d'antenes. Ací, no sols es presenten antenes amb polarització lineal com solen ser les desenrotllades fins ara, sinó també antenes amb polarització dual, circular i inclús antenes duals en banda. Estes aportacions són especialment atractives dins del camp de les comunicacions per satèl.lit en moviment (SATCOM on-the-move). A més també s'han explorat noves xarxes de distribució que permeten obtindre antenes planes més compactes, més lleugeres., [EN] This thesis deals with topics of special interest regarding the design of antennas at the mm-wave band. Today, implementing passive components that operate in the mm-wave band and to ensure the appropriate metallic contact is challenging. Commonly, conventional planar transmission lines and hollow metallic waveguides are the usual solutions but they present high losses or they do not ensure a good metallic contact. So, new concepts must be explored. Gap Waveguides (GWs), result suitably since they do not require metallic contact for shielding. Antenna arrays in Gap Waveguide Technology (GW) emerges as one promising candidate to naturally meet some of the mentioned needs. GW technology has demonstrated to be effective for mm-wave band devices because it enables full-metal distribution networks in a much simpler way than conventional waveguides. Very low distribution losses can be achieved preserving at the same time the assembly simplicity of multilayer microstrip feeding networks. This unique feature is a consequence of gap waveguides ability to safely confine the electromagnetic wave propagation through a contactless structure. During the last decade, there have been important advances in GW technology and a good number of gap waveguide-based arrays can be found in the literature. This thesis goes a step further in the contribution to mm-wave gap waveguide antennas. Here, antennas with linear polarization as well as circular or dual polarization are proposed. Dual band antennas has also been explored. These contributions have been carried out with a focus on satellite communications on-the-move. In addition, new distribution networks have also been explored to obtain more compact, low-profile and lighter antennas.

This paper presents a study of the D-band radio solutions, with beam-steering functionality, intended for use in the reconfigurable meshed network. The regulation and radio network constraints defining the specifications of a D-Band transceiver are reviewed. The architecture of the radio link is proposed and key enabling technologies needed to build the D-band transceiver are presented. The proposed solutions can be used for plenty of different radio connections, since they can provide a capacity level up to 100 Gbps over 160 meter and, at reduced capacity, hop lengths exceeding 1 km.