Small Footprint Multilayered Millimeter-Wave Antennas and Feeding Networks for Multi-Dimensional Scanning and High-Density Integrated Systems

This paper overviews the state-of-the-art of substrate integrated waveguide (SIW) techniques in the design and realization of innovative low-cost, low-profile and low-loss (L3) millimeter-wave antenna elements, feeding networks and arrays for various wireless applications. Novel classes of multilayered antenna structures and systems are proposed and studied to exploit the vertical dimension of planar structures to overcome certain limita-tions in standard two-dimensional (2-D) topologies. The developed structures are based on two techniques, namely multi-layer stacked structures and E-plane corners. Differ-ent E-plane structures realised with SIW waveguide are presented, thereby demonstrating the potential of the proposed techniques as in multi-polarization antenna feeding. An array of 128 elements shows low SLL and height gain with just 200g of the total weight. Two versions of 2-D scanning multi-beam are presented, which effectively combine frequency scanning with beam forming networks. Adding the benefits of wide band performance to the multilayer structure, two bi-layer structures are investigated. Different stacked antennas and arrays are demonstrated to optimise the targeted antenna performances in the smallest footprint possible. These structures meet the requirement for developing inexpensive compact millimeter-wave antennas and antenna systems. Different structures and architectures are theoretically and experimentally studied and discussed for specific space- and ground-based appli-cations. Practical issues such as high-density integration and high-volume manufacturability are also addressed

Mixer-Duplexer-Antenna Leaky-Wave System Based on Periodic Space-Time Modulation

We present a mixer-duplexer-antenna leaky-wave system based on periodic space-time modulation. This system operates as a full transceiver, where the upconversion and downconversion mixing operations are accomplished via space-time transitions, the duplexing operation is induced by the nonreciprocal nature of the structure, and the radiation operation is provided by the leaky-wave nature of the wave. A rigorous electromagnetic solution is derived for the dispersion relation and field distributions. The system is implemented in the form of a spatio-temporally modulated microstrip leaky-wave structure incorporating an array of sub-wavelengthly spaced varactors modulated by a harmonic wave. In addition to the overall mixer-duplexer-antenna operation, frequency beam scanning at fixed input frequency is demonstrated as one of the interesting features of the system. A prototype is realized and demonstrated by full-wave and experimental results

Towards an Advanced Automotive Radar Front-end Based on Gap Waveguide Technology

This thesis presents the early works on dual circularly polarized array antenna based on gap waveguide, also microstrip-to-waveguide transitions for integration of automotive radar front-end. Being the most widely used radar antenna, PCB antenna suffers from dielectric loss and design flexibility. Next generation automotive radars demand sophisticated antenna systems with high efficiency, which makes waveguide antenna become a better candidate. Over the last few years, gap waveguide has shown advantages for implementation of complicated antenna systems. Ridge gap waveguides have been widely used in passive gap waveguide components design including slot arrays. In this regard, two transitions between ridge gap waveguides and microstrip lines are presented for the integration with gap waveguide antennas. The transitions are verified in both passive and active configuration. Another work on packaging techniques is presented for integration with inverted microstrip gap waveguide antennas.Systems utilizing individual linear polarization (LP) that lack polarimetric capabilities are not capable of measuring the full scattering matrix, thus losing information about the scenery. To develop a more advanced radar system with better detectability, dual circularly polarized gap waveguide slot arrays for polarimetric radar sensing are investigated. An 8 78 planar array using double grooved circular waveguide polarizer is presented. The polarizers are compact in size and have excellent polarization properties. Multi-layer design of the array antenna benefits from the gap waveguide technology and features better performance. The works presented in this thesis laid the foundation of future works regarding integration of the radar front end. More works on prototyping radar systems using gap waveguide technology will be presented in future publications

An Overview of Recent Development of the Gap-Waveguide Technology for mmWave and Sub-THz Applications

The millimeter-wave (mmWave) and sub-terahertz (sub-THz) bands have received much attention in recent years for wireless communication and high-resolution imaging radar applications. The objective of this paper is to provide an overview of recent developments in the design and technical implementation of GW-based antenna systems and components. This paper begins by comparing the GW-transmission line to other widely used transmission lines for the mmWave and sub-THz bands. Furthermore, the basic operating principle and possible implementation technique of the GW-technology are briefly discussed. In addition, various antennas and passive components have been developed based on the GW-technology. Despite its advantages in controlling electromagnetic wave propagation, it is also widely used for the packaging of electronic components such as transceivers and power amplifiers. This article also provided an overview of the current manufacturing technologies that are commonly used for the fabrication of GW-components. Finally, the practical applications and industry interest in GW technology developments for mmWave and sub-THz applications have been scrutinized.Funding Agencies|European Union - Marie Sklodowska-Curie [766231WAVECOMBEH2020-MSCA-ITN-2017]</p

In-Band Co-Polarization Scattering Beam Scanning of Antenna Array Based on 1-Bit Reconfigurable Load Impedance

Controlling the in-band co-polarization scattering of the antenna while maintaining its radiation performance is crucial for the low observable platform. Thus, this paper studies the in-band co-polarization scattering beam scanning of antenna arrays. Firstly, the regulation method of antenna scattering is analyzed theoretically, concluding that the amplitude and phase of the antenna's scattering field can be regulated by changing the load impedance. Subsequently, PIN diodes are implemented to control the load impedance of the antenna. Consequently, the scattering of the antenna, ensuring that the antenna's scattering meets the condition of equal amplitude and a phase difference of 180{\deg} when the PIN diode switches, thereby realizing scattering beam scanning. Moreover, by introducing an additional pre-phase, the inherent symmetric dual-beam issue observed in traditional 1-bit reconfigurable structures is overcome, achieving single-beam scanning of the scattering. Finally, a 1{\times}16 linear antenna array is designed and fabricated, which operates at 6 GHz with radiation gain of 16.3 dBi. The scattering beams of the designed array can point to arbitrary angles within 45{\deg}, significantly reducing the in-band co-polarization backward radar cross section. The measured results align well with the simulated ones

Dual Frequency Electronically Controlled Radiation Beam Reconfigurable slotted Antenna for Detection of a Stationary or Nonstationary Target

A dual-frequency and radiation pattern reconfigurable microstrip patch antenna for detecting a stationary as well as a non-stationary target is described. Six angular patches, that collectively form a circular shape, are used. All the six patches radiate one by one after a fixed interval of time and their feed controlling is done by six PIN diodes. The switching of PIN diodes is controlled by an embedded biasing network. This antenna provides radiation beam scanning characteristics. It gives the main lobe scanning at every 60o&nbsp;clockwise (or anticlockwise) continuously by applying a signal to patches one by one.&nbsp;The purpose of introducing the slot is to get the radiation pattern in the desired direction since by changing the length, width, and position of the slot, the direction of the radiation pattern can be controlled.&nbsp;The slotted antenna operates in a C band with two frequencies 4.21 GHz and 4.82 GHz and provides a radiation pattern,&nbsp;90o&nbsp;apart from each other. The scanning rate of 0.6 deg/ms is obtained; however, the scanning rate can be changed with the help of ATMEGA 2560 microcontroller. This compact Microstrip patch antenna can be widely used for short-range applications i.e. ground surveillance radar, missile control, mobile battlefield surveillance for military and many other applications in a modern wireless communication system. The designed antenna along with the switching application will be able to track the stationary as well as a non-stationary target

Cassini Titan Radar Mapper

The Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission, scheduled for launch in 1995. The individual modes of Cassini Radar Mapper will allow topographic mapping and surface imaging at few hundred meters resolution. The requirements that lay behind the design are briefly discussed, and the configuration and capability of the instrument are described. The present limited knowledge of Titan's surface and the measurement requirements imposed on the radar instrument are addressed. Also discussed are the Cassini mission and the projected orbits, which imposed another set of design constraints that led to the multitude of modes and to an unconventional antenna configuration. The antenna configuration and the different radar modes are described

Advanced automotive radar front-end based on gapwaveguide technology

The pursuit of higher levels of autonomous driving necessitates the utilization of advanced radar sensors that possess improved environmental perception capabilities. Consequently, next-generation automotive radars require sophisticated antenna systems with high efficiency, thereby making waveguide antennas a more viable choice. In this context, it has been observed that gapwaveguides exhibit superior performance in comparison to traditional waveguides, particularly in terms of assembly reliability, when employed in the development of multi-layer waveguide antennas. Within the scope of this thesis, the primary objective is to comprehensively explore the design of front-ends for cutting-edge automotive radar sensors by leveraging the potential of gapwaveguide technology. The initial aspect of this thesis involves an exploration of integration techniques capable of achieving high performance in waveguide-based RF front-ends. In particular, the thesis introduces novel vertical gapwaveguide-to-microstrip transitions that facilitate the integration of RF front-ends featuring multi-layer configurations. Furthermore, this thesis introduces radar transceivers equipped with built-in waveguide-to-microstrip transitions, known as launcher-in-package, along with an imaging radar antenna featuring customized interconnections explicitly designed utilizing gapwaveguide technology to interface with the transceivers.Secondly, in light of the utilization of radar sensors incorporating orthogonal dual polarizations on the transmitting and/or receiving ends, an opportunity arises to acquire polarimetric information from the surrounding environment, thereby representing a promising advancement in the realm of autonomous driving. This thesis presents novel antenna designs based on gapwaveguide technology for polarimetric radar sensors. An 8$\times$8 planar array utilizing double grooved circular waveguide polarizers is introduced, specifically designed for fixed beam, high gain polarimetric sensing applications. In addition, this thesis presents a polarimetric radar sensor that utilizes a MIMO configuration featuring single-CP transmitting antennas and dual-CP receiving antennas. The antenna design incorporates series-fed septum polarizers, which offer low-profile characteristics.In summary, this thesis undertakes a comprehensive investigation into the designs of advanced automotive radar front-ends utilizing gapwaveguide technology. The study explores the advancements in terms of integration techniques and polarimetric capability, demonstrating the potential of gapwaveguide technology for the practical implementation of waveguide-based RF front-ends. The utilization of such front-ends can significantly enhance the capabilities of autonomous driving systems