Substrate-integrated waveguide (SIW) technology represents an emerging and very promising candidate for the development of circuits and components operating in the microwave and millimetre-wave region. SIW structures are generally fabricated by using two rows of conducting cylinders or slots embedded in a dielectric substrate that connects two parallel metal plates, and permit the implementation of classical rectangular waveguide components in planar form, along with printed circuitry, active devices and antennas. This study aims to provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components.

Review of substrate-integrated waveguide circuits and antennas

With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Multibeam Antenna Technologies for 5G Wireless Communications

Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Gain enhancement methods for printed circuit antennas

Foundations For Microwave Engineering

Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.

Method and apparatus for coupling an antenna to a device

Significant advances in the development of millimeter-wave and terahertz (30-10 000 GHz) technologies have been made to cope with the increasing interest in this still not fully explored electromagnetic spectrum. The nature of electromagnetic waves over this frequency range is well suited for the development of high-resolution imaging applications, molecular-sensitive spectroscopic devices, and ultrabroadband wireless communications. In this paper, millimeter-wave and terahertz antenna technologies are overviewed including the conventional and nonconventional planar/nonplanar antenna structures based on different platforms. As a promising technological platform, substrate-integrated circuits (SICs) attract more and more attention. Various substrate-integrated waveguide (SIW) schemes and other synthesized guide techniques have been widely employed in the design of antennas and arrays. Different types of substrate-integrated antennas and beamforming networks are discussed with respect to theoretical and experimental results in connection with electrical and mechanical performances.

Substrate-Integrated Millimeter-Wave and Terahertz Antenna Technology

A dielectric resonator antenna (DRA) array having an array feeding network and a parasitic patch array made up of individual antenna elements is provided with a dielectric lens made from a single piece of dielectric material in the form of a generally planar sheet. The sheet may be substantially coextensive with the DRA array so as to cover all of the antenna elements. The single piece of dielectric material has a plurality of dielectric portions defined by a plurality of holes through the sheet. Each dielectric portion may be positioned over one of the antenna elements. Adjacent dielectric portions are connected to each other along connecting edge portions thereof, and a single hole is defined through the sheet between connecting edge portions of a group of mutually adjacent dielectric portions.

Dielectric resonator antenna arrays

There are many applications such as local positioning systems (LPS) and wireless sensor networks that require high-directivity and compact-size or small footprint antennas. The classical Yagi-Uda antenna may be useful in meeting such demands, which however, becomes very large in size to achieve a high-gain performance due to a large number of directors as well as space required between those elements. In this paper, high-gain yet compact stacked multilayered Yagi antennas are proposed and demonstrated at 5.8 GHz for LPS applications. This structure makes use of vertically stacked Yagi-like parasitic director elements that allow easily obtaining a simulated gain of 12 dB. Two different antenna configurations are presented, one based on dipole geometry for single polarization, and the other on a circular patch to achieve dual polarization. The characteristics of these antennas with respect to various geometrical parameters are studied in order to obtain the desired performance. Measured results of the fabricated antenna prototypes are in good agreement with simulated results. The measured dipole Yagi antenna yields 11 dB gain over 14% bandwidth with a size of 80 × 80 × 29 mm3. Radiation patterns of the dual-polarized Yagi antenna are nearly identical to those of the single-polarized antenna, which has a size of 50 × 50 × 60 mm3, and also its two-port isolation is found to be as low as -25 dB over 4% bandwidth. The proposed antennas present an excellent candidate for compact and low-cost microwave and millimeter-wave integrated systems that require fixed or variable polarization capabilities and small surface footprint.

Vertically Multilayer-Stacked Yagi Antenna With Single and Dual Polarizations

A super-compact substrate integrated waveguide (SIW) directional coupler is proposed and demonstrated. This coupler consists of a simple cross-over of two SIW sections with two inductive metallic posts in a square junction, showing a cruciform. Attractive features including compact size and planar form make this coupler structure easily integrable in microwave and millimeter-wave planar circuits, especially in beam-forming networks. A 3-dB coupler operating at 24GHz is designed using HFSS, fabricated and measured. Characteristics of 15dB isolation and 90deg phase shift between the output and coupled ports are achieved over 18% bandwidth. Design considerations and simulated as well as measured results are presented and discussed.

Super-Compact Substrate Integrated Waveguide Cruciform Directional Coupler

For original paper see ibid., vol.17, no.5, p.757-9, (2007). For comment see ibid., p.374, (2008). Our proposed coupler was developed and designed on the basis of an idea similar to the H-plane crossed-waveguide hybrid. In our design, the standard metallic waveguide scheme was replaced by the substrate integrated waveguide (SIW) technology. This technology offers a number of advantages that can overcome several constraints with respect to the standard waveguide technique. A small inventory of coupler structures with the use of standard waveguide techniques was enumerated together with the existing SIW couplers. By properly choosing a dielectric constant and a sheet thickness, a directional coupler can be designed for a given frequency.

Tarek Djerafi

Papers

Substrate-Integrated Millimeter-Wave and Terahertz Antenna Technology

Dielectric resonator antenna arrays

Vertically Multilayer-Stacked Yagi Antenna With Single and Dual Polarizations

Super-Compact Substrate Integrated Waveguide Cruciform Directional Coupler

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