Compact and Broadband Elliptical Microstrip Antenna with Low Cross-polarization

Abstract

A compact and broadband elliptical microstrip antenna (MSA) is designed using multilayer stacked patches with direct coupling. Two dumbbell shaped patches are printed underneath an air suspended FR-4 substrate layer. These patches are stacked on the top of an elliptical MSA, which is designed on the bottom layer, and fit in the same area as occupied by elliptical patch. The dumbbell shaped patches are excited through electromagnetic and direct coupling, which is enabled by connecting two symmetric shorting posts between ellipse and dumbbell shaped patches. The antenna geometry is enclosed in a metallic cavity enclosure to enhance gain and to reduce back radiation. The designed elliptical MSA is a low-cost antenna with compact size of 0.85 λ × 0.6 λ × 0.15 λ. It provides 43% BW (1.621 to 2.51 GHz) with peak gain of 9 dBi and front to back ratio (FBR) of more than 16 dB over BW. The cross polarization (X-pol) is less than 20 dB from 1.7 to 2.51 GHz. The designed antenna can be used for IoT devices utilizing 2G, 3G,4G-LTE, Wi-Fi and 5G applications. © 2023 IEEE.