Gain and Bandwidth Enhancement of Superstrate Loaded 2×2 Circular- Array Antenna for X-Band and RADAR Applications

Abstract

This article demonstrates the fabrication and measurements of a corporate offset-fed 2×2 array electromagnetically coupled patch (EMCP) circular antenna based on the Fabry-Perot cavity principle. A single-element antenna has a low gain of 6.28 dBi; it is enhanced to 13.45 dBi by loading the array with a superstrate. The antenna parameters—10 dB fractional bandwidth (FBW) and gain—are improved by an air gap with four stacked circular patches and four stubs in the proposed design. The peak gain of a 2×2 array without a superstrate was 8.88 dBi at 8.19 GHz, which was enhanced to 13.82 dBi at 9.55 GHz by parasitic loading and a superstrate. The FBW of the proposed array antenna was enhanced by arranging four stubs between the four circles in the superstrate structure. The − 10dB FBW without stubs was 24.82% (7.62–9.73 GHz), and with stubs it became 38.47% (7.73–11.0 GHz). Adjustment of the height of the substrate at 2.0 mm not only improves the gain and bandwidth but also supports enhancing the unidirectional radiation patterns. The array was prototyped and measured to validate the simulated reflection coefficients and radiation characteristics, which found excellent agreement with each other. Therefore, the designed array is most suitable for launchers in transitions, radio wave detection and ranging (RADAR), military, satellite, X-band communications, and microwave laboratory applications.