Aperture-Stacked Patch Antenna Array With Front-to-Back Ratio Enhancement for Radar Application at 28 GHz

Abstract

In this study, we propose a new aperture slot design for a 32-element microstrip patch antenna array operating at 28 GHz. To improve the performance of the antenna array, circular aperture slots have been integrated and thoroughly analyzed. The optimized structure consists of a lower substrate in Rogers RT3003 with a thickness of 0.5 mm and a loss tangent of 0.001, and an upper substrate in dielectric foam with a thickness of 0.254 mm and a dielectric constant of 1. A cost-effective way of increasing the front-to-back ratio is to install a reflector, which is a stacked aperture structure printed on a thin dielectric layer (0.254 mm) with a dielectric constant of 4.4 and a loss tangent of 0.025. Implementing these techniques in the 32-element antenna array resulted in a wide impedance bandwidth <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\vert \mathrm{S}11\vert &lt;-10\ \text{dB})$</tex> of 11% around the 28 GHz center frequency, with a matching of less than −55 dB. In addition, the proposed reflector improves the front-to-back ratio by over 20 dB, and the structure achieves an impressive gain of around 22 dB.