Dual-Polarized Slot-Coupled Microstrip Antenna Array With Stable Active Element Pattern

A dual-polarized slot-coupled microstrip antenna array with stable active element pattern is investigated. The antenna element of the array is a slot-coupled microstrip antenna with a reflector. The effect of the ground size on the radiation pattern of the antenna element is analyzed based on the electric field and current distributions. The method of adding copper pillars around the antenna element is proposed to mitigate the influence of the ground plane. A prototype of ${1} \times {3}$ microstrip antenna array is fabricated and measured. Its measured impedance bandwidth for $\mathrm{VSWR} < {2}$ is 520 MHz (1.69–2.21 GHz). Within the operating band, the performances of low mutual coupling, low cross polarization, and stable active element pattern are achieved.

I. Introduction

Dual-polarized antenna is widely used in modern radar and wireless communication systems. Dual-polarization could provide more information by collecting two copolarized and two cross-polarized scattering data, avoid the requirement of precise alignment, enhance the system capability by providing two independent channels, and address the issue of multipath fading [1]–[3]. Moreover, antenna array with high gain, beam-forming, and beam-steering characteristics is often required to further improve the system performance. Thus, dual-polarized antenna array has been studied extensively.