Efficient $2\times2$ Printed Circuit Band-Gap Cavity-Backed Slot Antenna

In this article, a novel structure is proposed for the realization of cavity section in the printed gap waveguide (PGW) technology. For the proof of the concept, a multilayer cavity-backed slot antenna element is designed and fabricated so that its performance can be compared to the devices in the literature made by printed circuit board (PCB) technology and also by metal parts using the CNC machine. The proposed structure benefits from the advantages of efficient, low cost, simplified fabrication process, lightweight, and high aperture efficiency compared to common cavity-backed antennas. To manage the available space, the feed is connected to the antenna cavity from the underneath using a coupling aperture. The proposed configuration simplifies the integration of accessory devices in antenna arrays, such as feed networks, phase shifters, and amplifiers. Also, the separation of feed network from the radiation slot section prevents any unwanted radiation. Using the mode analysis, four slots were implemented in the proposed cavity to achieve four equivalent magnetic surface currents with identical phase and magnitude. The antenna operating frequency is 16 GHz, the realized antenna radiation and aperture efficiencies are over 92% and 81.6%, respectively, and its achieved gain is 12 dBi.