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

Automotive RADAR Planar Antenna Optimization Based on Conformal Transformation Optics

A novel approach to mitigate diffraction effects from finite ground planes in antenna design is presented. The method is based on the conformal transformation optics. A computational framework has been developed to optimize the shape of the ground plane since it has a great impact on the beam ripple and width of the radiation pattern of an antenna. Due to the limited thickness of the outer wall of slotted waveguide antennas, it is not possible to shape this outer wall, which acts as the ground plane of the antenna. Conformal transformation optics presents a solution to virtually add a deformation without needing to change the physical shape of the ground plane. Although conformal transformation optics can also be applied to transverse-magnetic waves, large fluctuations in the dielectric constant with respect to the wavelength cannot be supported in practice. In order to mitigate this problem, we have proposed a rescaling of the dielectric constant. Furthermore, we derive the connection between conformal transformation optics and transverse electromagnetic modes, which serve as a tool for joint optimization of the radiation pattern together with the conformal transformation. This method is then used to optimize the radiation pattern of a slot antenna and evaluated for increasing curvature within the conformal transformation.Numerical computations have shown promising results, i.e. a reduction of the farfield ripple from 1.92 dB to 0.64 dB at a half-power beam-width of 112\ub0 at 77 GHz. This is a promising result for designing automotive radars with a wide field of view, especially, for advanced driver-assistance systems used in the corner radars. This will contribute to further improving safety on the roads