Performance Enhancement of Array Antennas using Metasurface Superstrates

Abstract

This work presents a novel design of a high gain circularly polarized (CP) crossed‐bowtie shaped antenna with cloverleaf arms which exhibits a wideband impedance match as well as 3dB axial ratio bandwidths. The designed wideband antenna is realized by employing a low‐cost phase shifting mechanism that uses a Metasurface (MTS) superstrate which is placed above the radiating surface of the antenna. A design chart is developed for the determination of the required phase variation based on the distance between MTS and the antenna radiator. Next, the concept of MTS placement above the antennas is extended to the cases of 3x3 and 5x5 cloverleaf‐shaped bowtie antenna arrays, with the goal of improving the gain and sidelobe levels (SLLs). The study includes a systematic analysis of the variation in gain and SLL of CP antenna arrays as we change the number of elements of the superstrate.