Quasi-Optical Multi-Beam Antenna Technologies for B5G and 6G mmWave and THz Networks: A Review

Multi-beam antennas are critical components in future terrestrial and non-terrestrial wireless communications networks. The multiple beams produced by these antennas will enable dynamic interconnection of various terrestrial, airborne and space-borne network nodes. As the operating frequency increases to the high millimeter wave (mmWave) and terahertz (THz) bands for beyond 5G (B5G) and sixth-generation (6G) systems, quasi-optical techniques are expected to become dominant in the design of high gain multi-beam antennas. This paper presents a timely overview of the mainstream quasi-optical techniques employed in current and future multi-beam antennas. Their operating principles and design techniques along with those of various quasi-optical beamformers are presented. These include both conventional and advanced lens and reflector based configurations to realize high gain multiple beams at low cost and in small form factors. New research challenges and industry trends in the field, such as planar lenses based on transformation optics and metasurface-based transmitarrays, are discussed to foster further innovations in the microwave and antenna research community

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Low-Cost Integrated Waveguide Antenna Front-End Solutions for Fifth Generation Cellular Systems and Beyond

RÉSUMÉ : À ondes millimétriques (ou simplement mm - ondes) réseaux d'antennes avec un seul polarisation linéaire (LP ) , double polarisation linéaire ( DLP ) et double polarisation circulaire ( DCP) caractéristiques sont largement utilisés pour de nombreuses applications , il y compris la communication de données sans fil , capteurs radar , passive imagerie , la récupération d'énergie et les systèmes de radiocommunication cognitifs . Parmi les différents types de structure d'alimentation , guide d'ondes présente un excellent candidat pour mettre en oeuvre des réseaux d'alimentation à faible perte et gain élevé réseaux d'antennes sur la plage de fréquence à ondes millimétriques . Ces antennes à base de guide d'ondes - ont été présentant d'excellentes caractéristiques de rayonnement , mais ils ne sont pas faciles à intégrer avec des composants actifs . A la fréquence à ondes millimétriques , SIW ( substrat de guide d'ondes intégré ) est un candidat exceptionnel émergents à mettre en oeuvre une faible perte et des réseaux d'alimentation à faible coût. Antenne SIW - alimenté est capable de produire l'efficacité de rayonnement à haute et le comportement d'impédance à large bande . Dans cette thèse , la technologie de transmission alimentation SIW est choisi pour mettre en oeuvre des réseaux électriques et de phase de distribution pour réaliser une grande efficacité antenne extrémités avant. Les principales contributions scientifiques et techniques peuvent être résumées en deux parties .Dans la première partie , des solutions pour les ouvertures rayonnantes efficacement ont été proposés tels que gain élevé réseaux d'antennes LP , DLP réseaux d'antennes et DCP réseaux d'antennes . Le choix de l'élément rayonnant avec d'excellentes caractéristiques de rayonnement est vital dans la réalisation de gain élevé réseau d'antennes et réseaux phasés, électroniquement orientables . Dans la deuxième partie , de nouvelles techniques ont été proposées pour diriger le faisceau fixe dans des directions multiples en élévation et azimut en utilisant le réseau de décalage de phase passive.----------ABSTRACT Millimeter-wave (or simply mm-wave) antenna arrays with single linear polarization (LP), dual linear polarization (DLP) and dual circular polarization (DCP) characteristics are widely being used for numerous applications including wireless data communication, radar sensors, passive imaging, energy harvesting and cognitive radio systems. Among different types of feeding structure, waveguide presents an excellent candidate to implement low-loss feeding networks and high-gain antenna arrays over mm-wave frequency range. Those waveguide-based antennas have been exhibiting excellent radiation characteristics, but they are not easy to integrate with active components. At mm-wave frequency, SIW (substrate integrated waveguide) is an emerging outstanding candidate to implement low loss and low cost feeding networks. SIW-fed antenna is able to yield high radiation efficiency and broadband impedance behavior. In this thesis, SIW feeding transmission technology is chosen to implement power and phase distributing networks for realizing high efficiency antenna front ends. The main scientific and technical contributions can be summarized into two parts. In the first part, solutions for efficiently radiating apertures have been proposed such as high gain LP antenna arrays, DLP antenna arrays and DCP antenna arrays. The radiating element choice with excellent radiation characteristics is vital in realising high gain antenna array and electronically steerable phased arrays. In the second part, new techniques have been proposed to steer the fixed beam into multiple directions in elevation and azimuth utilizing passive phase shifting network. At 60 GHz frequency, dielectric rod antenna is selected for linearly polarized radiation and cavity backed metallic circular patch antenna is selected to obtain circular polarization radiation. Single rod antenna element is experimentally characterized to validate the proposed concept. In the next stage, high gain antenna array with 45o linear polarization utilizing rod antenna radiating element is demonstrated and feeding implemented in three dimensional (3-D) architecture is integrated along with the 4 x 4 antenna array. The data handling capability of single polarization antenna array is increased up to two fold by integrating two orthogonal polarized antenna arrays with an aperture area of one single polarized array

Novel Antennas for mm-Wave and Microwave Systems

The emergence of high-performance antennas based modern manufacturing technology and novel additive processing is becoming a hot topic. Specifically, the substrate integrated waveguide (SIW) has demonstrated its impact in miniaturization, planarization, and low-cost manufacturing of transmission lines, while 3D printing technology has enabled the creation of customized, high-performance antennas. The research into SIW and 3D printed antennas are emergence for the advancement of wireless communication systems. In this thesis, novel millimeter-wave and microwave antennas based on modern and newly emerged additive manufacturing are investigated. First of all, in terms of novel antenna designs based on traditional manufacturing, several SIW-based planar directional antennas are presented in achieving high gain, miniaturization, easy integration and design simplification. They are i) SIW H-plane horn antenna with gradient air slots, ii) SIW H-plane horn antenna with an embedded air cavity; iii) SIW H-plane horn antenna loaded with linear dipole directors. Then, in terms of novel antenna designs based on 3D printing technologies, a variety antenna structures were proposed and studied. They are i) Fused deposition modelling (FDM) printed E-plane horn for gain enhancement; ii) Liquid crystal display (LCD) printed horn antennas for size reduction; iii) LCD printed horn antenna for beam-steering; iv) LCD printed rod antenna with modified permittivity for high gain; v) LCD printed dielectric lens for high directivity. All antenna designs including the concepts and design process presented are theoretically analyzed and introduced. They are fabricated and measured. The main contribution includes the novel antenna designs in both modern and additive manufacturing technologies for superior radiation performance and various design purposes

Agile intelligent antenna system for industry 4.0 and beyond

The next-generation industrial paradigms such as Industry 4.0 and beyond require ultra-high reliability, extremely low latency, high throughput, and fine-grain spatial differentiation for wireless communication, sensing, and control systems. Traditional industrial wired networks suffer from impediments such as expensive installation and maintenance costs, wear and tear, reduced flexibility, and restricted mobility in dynamic industrial environments. Moreover, the conventional sub-6 GHz industrial, scientific, and medical (ISM) wireless bands such as 2.4 and 5 GHz are not able to fully meet the requirements of high bandwidth, high data rate, and low latency for emerging industrial wireless applications. To overcome the aforementioned challenges, the utilization of the 60 GHz millimeter-wave (mmWave) license-free ISM band, spanning from 57–71 GHz, is being considered as a potential solution for advancing next-generation industrial wireless communication and sensing applications, as well as for future technologies of beyond fifth-generation (5G) and sixth-generation (6G). This spectrum offers a large bandwidth of 14 GHz and experiences low spectral congestion. However, its effectiveness is hindered by significant path loss and high signal attenuation caused by oxygen absorption, posing additional challenges to design wideband, high-gain, compact, and cost-effective antenna solutions. This thesis encompasses three antenna design solutions offering high-performance metrics, aimed at next-generation mmWave industrial wireless applications and 6G technologies. The first antenna design is a compact and wideband 64-element planar microstrip array based on a hybrid corporate-series network. The array has the size of 2 cm × 3.5 cm × 0.025 cm and offers -10 dB impedance bandwidth over the entire 57–71 GHz, 1 dB gain bandwidth of 13 GHz from 57–70 GHz, low side lobe levels, and above 70% radiation efficiency in the whole band of interest. The inherent phase shift across the operating frequency in the series-fed antenna elements is leveraged to achieve frequency beamscanning over a scan range of 40° with less than 1 dB scan loss. The second antenna design is a compact, low-cost, high-gain, and planar 16-element linear array using the corporate feed technique. This design provides squintless high directional beamstowards the broadside over 7 GHz of bandwidth (57–64 GHz), and 1 dB gain -bandwidth of more than 3 GHz. This makes it a suitable candidate for industrial fixed wireless access communication scenarios that require large bandwidth and multi-gigabit data rate, such as highdefinition video signal transfer. An antenna with a broad 1 dB gain bandwidth can find various applications across different sectors. Primarily, such an antenna could be utilized in wireless communication systems where reliable and high-speed data transmission is essential. spans across mobile communication networks, enhancing signal strength and coverage for improved data throughput, and seamless connectivity for IIoT applications, enabling efficient data exchange in various settings such as critical industrial automation scenarios. Additionally, in radar systems, a broad 1 dB gain bandwidth antenna could improve target detection and tracking accuracy, enhancing situational awareness in surveillance applications. Overall, the broad frequency coverage provided by the 1 dB gain bandwidth antenna makes it versatile for a wide range of applications requiring robust and reliable wireless communication capabilities. The third proposed antenna solution is the hallmark of this thesis. A fully programmable electronically beamsteerable dynamic metasurface antenna (DMA) is designed and tested for the first time at 60 GHz band, thereby marking a significant milestone in advanced mmWave beamforming metasurface antennas. The 16-element linear DMA is based on novel digital complementary electric inductive capacitive (CELC) metamaterial elements whose radiation states can be dynamically controlled through a high-speed field programmable gate array (FPGA). The smart DMA can synthesize narrow beams, wide beams as well as multiple beams from a single aperture by generating different digital coding combinations. The proposed DMA is a low-cost and low-power smart beamforming antenna applicable to a diverse range of mmWave communication, sensing, and imaging avenues for smart wireless industries and 6G networks with agile beam-switching having a delay of less than 5 ns. The proposed DMA boasts striking features, including compact size, meticulously designed PCB, and software control via binary coding from a high-speed FPGA. Operating within the high-frequency mmWave ISM band, it encompasses a diverse range of license-free mmWave applications. The designed DMA achieves key performance metrics, boasting a bandwidth exceeding 2.16 GHz around 60 GHz, a high gain of above 9 dBi for most beamforming codes, and a radiation efficiency surpassing 60%. Additionally, it offers a versatile beam synthesis capability, enabling the generation of narrow pencil beams, wide beams, and multiple beams from a single DMA aperture. The proposed antenna solutions were fabricated, and tested through an in-house designed measurement setup which is elucidated in this thesis. Eventually, the striking futuristic applications of mmWave antennas, and their associated open research challenges are highlighted

Performance Improvement of Dense Dielectric Patch Antenna using Partially Reflective Surfaces

Recently, millimeter-wave (MMW) band is being considered as the spectrum for future wireless communication systems. Several advantages are achieved by utilizing the millimeter-wave range, including high gain with large available bandwidth, compact size, and high security. Nevertheless, attenuation loss may restrict wireless communication systems’ transmission range. Meanwhile, printed antenna technology has gained the attention of antenna designers’ due to its low profile and ease of fabrication. High-gain antennas are very desirable as a critical part of MMW systems. Designing millimeter wave antennas with high gain characteristics would be a significant advantage due to their high sensitivity to atmospheric absorption losses. Moreover, planar configurations are required in many applications, such as for wireless communication. The main goal of this thesis is to design and propose state of the art designs of Fabry Pérot Cavity antenna (FPCA) designs with several types of superstrates to achieve high gain, wide bandwidth, and high efficiency to satisfy the requirements of today’s advanced wireless communication systems. A dense dielectric patch (DD) antenna is used as the main radiator and designed to operate at 28 GHz. The thesis presents several contributions related to the design and analysis of FPC antennas using several types of superstrates. The first research theme of this thesis has two parts. The first part presents a holey dielectric superstrate applied over a 2×2 dense dielectric square patch antenna array to enhance the gain, improve the bandwidth and efficiency, as well as to reduce the side lobe levels (SLLs). A dense dielectric patch replaces the metallic patch and is used as a radiated element. The measured results show a high gain of 16 dBi, with radiation efficiency of about 93 %, wide bandwidth of 15.3 %, and a reduced SLL. The second part focusses on a partially reflective surface (PRS) unit cell composed of two thin perforated dielectric slabs. The effect of the thicknesses of the unit cell dielectric slabs is discussed in detail. An array of the proposed PRS unit cell is applied over a dense dielectric square patch antenna array to broaden the bandwidth and to enhance the gain as well. The measured results exhibit a 3 dB gain bandwidth of 27 % with a high gain of 16.8 dBi. The second research theme presents an effective method to design a tapered superstrate of an FPC antenna with a DD patch element. This type of superstrate is designed to correct the phase above the superstrate to be almost uniform. The proposed single-layer perforated tapered superstrate is constructed by tapering the relative permittivity to be high in the center of the superstrate slab and then decrease gradually as it moves towards the edges. This tapered relative permittivity is then applied over a single DD patch antenna. The proposed antenna exhibits good performance in terms of the antenna gain and bandwidth. The antenna gain becomes flat and as high as 17.6 dBi. The antenna bandwidth is about 16 %, and the side lobe level of the antenna is very promising. A third theme presents the implementation and design of a high gain dense dielectric patch antenna integrated with a frequency-selective surface (FSS) superstrate. A 7×7-unit cell is used to build the superstrate layer, and applied above the high DD patch antenna. A modified unit cell is proposed to generate a positive reflection phase with high reflection magnitude within the frequency design in order to broaden the antenna bandwidth. A bandwidth of 15.3 % with a high gain of 16 dBi is obtained. Finally, a high gain linearly polarized (LP) substrate integrated waveguide (SIW) cavity antenna based on a high-order mode is implemented, fabricated, and tested. A TE440 mode is excited at 28 GHz. In this design, 4×4 slots are cut into the top metal of the cavity, where each slot is placed above each standing wave peak. These slot cuts contributed to a high gain of 16.4 dBi and radiation efficiency of about 96 %. The LP SIW cavity antenna was then integrated with a linear-to-circular polarization converter developed as a high gain circularly polarized (CP) SIW cavity antenna with high gain and high radiation efficiency of 16 dBi and 96 %, respectively

A Modular and Scalable Architecture for Millimeter-Wave Beam-forming Antenna Systems

As the demand for higher data rates increases, wireless technologies (e.g., satellite communications, fifth Generation (5G) wireless communications, and automotive radars) are migrating toward millimeter-wave (mm-W) frequencies (30-300 GHz) to utilize the numerous unused spectra available over this frequency band. For truly ubiquitous coverage over the globe, high throughput Ka-band satellite communication (SATCOM) offers the most optimal and a unique solution for providing world-wide information and sensing. Of particular interest is the development of land, or close-to-land, mobile systems for high data rate communications with continuous coverage for on-the-move commercial platforms, including cars, airplanes, ships, and trains. A modular and scalable phased-array antenna (PAA) architecture wherein the entire phased-array system is made of identical sub-array modules (building blocks) is the most promising approach to develop cost effective and flexible systems for mass market applications. Obviously, such architecture depends on the availability of a high-performance antenna element, antenna subarray modules, and beam-forming circuits. These are the main topics investigated in this PhD thesis. Two approaches were extensively studied in this PhD research to develop intelligent steerable antenna array modules as building blocks for large-scale Ka-band SATCOM applications. The first approach targeted the development of a working prototype for a wide-angle beam-steering Ka-band active PAA (APAA). In this approach, two APAA architectures were proposed, designed, fabricated, and measured to validate the proposed concepts. Both approaches exhibit wide beam-steering angles and fast beam-forming capabilities with full control on amplitude and phase of each antenna element by utilizing an intelligent beam-forming circuit that was developed at CIARS (Centre for Intelligent Antenna and Radio Systems). The first architecture comprises a novel single-fed CP antenna element integrated with the intelligent beam-forming circuit, to construct a wide beam-steering and low-cost CP-APAA. A 4×16 CP-APAA was designed and fabricated using low-cost printed circuit board (PCB) technology and it was tested over the frequency range (29.5-30 GHz) over an angular range of 0o-±40o. The second architecture utilized a highly integrated and wide band dually-polarized antenna element as a core component for the realization of a high-performance, compact, and polarization-agile Ka-band APAA module. The proposed antenna module was used to construct a proof-of-concept 16×16 modular APAA to radiate a high polarization purity pattern over a wide beam-steering angles ≥70o. The second proposed approach investigated two novel wideband and passive steerable antenna concepts as attractive low-cost alternatives suitable for a wide range of emerging mm-W communication systems. Such antenna systems are made of passive components, antennas, phase shifters, and passive feeding networks to reduce the power consumption, cost, and complexity of conventional active electronically steered arrays. In order to build such systems, a high-performance antenna and passive phase shifter (invented at CIARS) were integrated to eliminate the necessity for costly variable gain amplifiers (VGAs). The first proposed concept is a novel CP passive PAA comprised of the proposed single-fed CP antenna integrated with the CIARS phase shifter. The novel high-performance passive phase shifter was controlled by a low-profile and low-power consumption novel magnetic actuator to overcome the limitation of state-of-the-art passive phased arrays. The proposed CP passive PAA was designed, fabricated and tested at Ka-band (29.5-30.5 GHz) over an angular range of 0o-±38o. The second concept proposed here is a novel reconfigurable reflectarray antenna (RAA) element with a true-time-delay functionality. Its reconfigurability is realized by utilizing the proposed phase shifter integrated with an aperture-coupled microstrip patch antenna (ACMPA) to receive and re-radiate the electromagnetic energy efficiently. The proposed RAA element was designed and tested at Ka-band (27.5-30 GHz)

Design and Measurement of a Millimeter-wave 2D Beam Switching Planar Antenna Array

A millimeter-wave 2-D beam switching microstrip patch antenna array excited by a 4x4 substrate integrated waveguide (SIW) Modified Butler Matrix is designed and experimentally evaluated in this thesis. A novel architecture is introduced for the Butler Matrix feed network to give designers a choice for phase shifter location to pursue a smaller circuit area. In addition, it enables the designer to control the BM phased outputs for achieving a set of desired 2-D beam directions, e.g., ϕ0=45°, 135°, 225°, and 315° at θ0=45°, with a passive beam switching network for a given array geometry. Full-wave simulation results show when the so designed 4x4 Butler Matrix feeds a 2x2 planar patch antenna array, 4-quadrant beam switching is achieved. To meet the goal of providing a low cost small footprint solution, the presented Modified Butler Matrix features straight SIW phase shifter using periodic apertures. The Modified Butler Matrix is fabricated on a single layer Rogers RO4350B substrate, achieving a circuit area of 222.5 mm2, which is a 54% improvement over previously published 60 GHz results. The fully-integrated antenna array system is created by development of a new SIW to planar patch antenna transition structure which maintains a total antenna frontend area of 333 mm2, just 42% of the area of the next closest SIW 2-D beam switching publication at 60 GHz. For verification of beam switching via over the air (OTA) measurements at 60 GHz, a benchtop anechoic chamber with proper transmitter and receiver antenna positioners is designed and fabricated using in-house maker laboratory resources. 2-D beam steering is proved in the intended 4 quadrants of radiation space at ϕ0=50°, 140°, 220°, and 300° and θ0=30±5° demonstrating meeting the design specifications with a very good margin. As well, for each switched beam the gain of antenna array was measured to be between 4.8 to 6 dBi at 60 GHz which is within 1dB deviation from the simulated results