Design and Characterization of the Fully Metallic Gap Waveguide-Based Frequency Selective Radome for Millimeter Wave Fixed Beam Array Antenna

Abstract

This paper presents a bandpass frequency selective surface (FSS) radome based on fully metallic gap waveguide (GW) technology. The element of the proposed FSS radome consists of a conventional cross-dipole slot etched on metallic plates and positioned over a groove GW cavity. A design with a single GW cavity layer was initially produced which was later optimised for performance, to comprise a dual GW cavity layer, while considering both functionality and manufacturability. It is shown that the proposed FSS element offers a stable and wide bandpass (from 26-30 GHz) performance in the broadside direction for both transverse electric (TE) and transverse magnetic (TM) polarizations. For oblique angle of incidence, the suggested FSS element works up to 30 • with a reduction in usable bandpass bandwidth performance to 26-28 GHz for both TE and TM polarizations. A 20 × 20-element GW-FSS array prototype has been fabricated and measured, which was integrated with a fixed beam array antenna to further validate its functionality as a filtering radome. The findings show an excellent agreement between simulations and measurements. Hence, the proposed GW-FSS represents a great opportunity to develop a all-metallic FSS with low insertion loss, sharp-roll-off filtering, wideband performance and inexpensive fabrication cost.

Miniaturization of a Fully Metallic Bandpass Frequency Selective Surface for Millimeter-Wave Band Applications

“…By positioning the proposed FSS in close proximity to the transmitting antenna, it is possible to mitigate this edge effect for the proposed FSS radome used in this study. In terms of practical deployment, the second scenario, in which the polarizer is positioned close to the transmitting antenna, is also preferable because it reduces the antenna system's overall profile [11], [16]. However, when the proposed FSS radome is positioned close to the transmitting antenna, the waves impacting the FSS will become less planar.…”

“…Recently, there has been a growing interest in developing fully metallic FSSs with low-loss performance [4], [8], [9], [10], [11]. However, two significant problems must be overcome for a totally metallic FSS to be used in the mmWave and the terahertz (THz) bands.…”

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

“…In addition, multi-layer GGW-based filters may be implemented utilizing the direct coupled approach to reduce the size of the filters [117], [118]. In addition, a GW-based bandpass frequency selective surface filtering radome has been demonstrated in [119]. The user of the GW in the FSS radome design has greatly enhanced the filtering response of the FSS, especially at the rejection band.…”

Low-Loss All-Metallic Gap Waveguide-Based Bandpass FSS Radome for Broadside mmWave Applications

“…In fact, the proposed structure is insensitive to polarisation due to the cross-dipole slot and the symmetrical design of the unit cell structure. It is worth noting that, the detailed design procedure of the proposed GW-FSS is presented in [12].…”