A Mesh-Type Shared-Aperture Dual-Band Circularly Polarized Transmit- Reflect-Array Antenna

Abstract

This article proposes a dual-band bidirectional circularly polarized transmit-reflect-array (TRA) antenna, which consists of an oblique 45° feed horn and a shared-aperture TRA. The TRA is an optically transparent mesh-type structure consisting of 14 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times14$ </tex-math></inline-formula> three-dimensional (3-D) cross-shaped elements. The cross-shaped element assembled from two orthogonal vertical layers is independent of polarization and can adjust the phase of reflected and transmitted waves. Due to the polarization and frequency independence of the element, the TRA is able to convert the linearly polarized waves radiated by the feed horn into circularly polarized reflected and transmitted waves in the lower and higher frequency bands, respectively. The measurement results show that in the reflection band, the TRA antenna has a maximum gain of 21.3 dBi at 6.2 GHz (corresponding to an aperture efficiency of 32.1%) and a 3 dB axial ratio (AR) bandwidth of 11.2% (5.9–6.6 GHz). In the transmission band, the TRA antenna has a maximum gain of 23.1 dBi at 8 GHz (corresponding to an aperture efficiency of 29.1%) and a 3 dB AR bandwidth of 16.0% (7.5–8.8 GHz). The proposed TRA antenna has potential applications in dual-band, circularly polarized, and bidirectional communications.