3-D-Printed Metal-Only Transmit-Reflect-Array Antenna for Bidirectional Communication

This letter presents a metal-only, high-gain, dual-band transmit-reflect-array (TRA) using a bi-layer cross-slot unit cell. These cross-slots engraved on the metal sheet provide a bandpass response at the desired frequency. Different thicknesses of the cross-slot unit cells have been manipulated to simultaneously obtain the reflection and transmission phase characteristics at $f_{1}$ (28 GHz) and $f_{2}$ (38 GHz), respectively. These unit cells are further arranged on a circular aperture to constructively reflect(transmit) the incident wave at $f_{1}$($f_{2}$). An engineered $K_{a}$-band linearly polarized horn antenna has been used as the feeding source of the TRA. The measured peak gain, maximum aperture efficiency, and 3 dB gain bandwidth of the TRA in reflectarray mode are 27.7 dBi, 44.4%, and 37%, and in transmitarray mode it is 27 dBi, 30.9%, and 4.5%. Moreover, the proposed TRA also exhibits excellent polarization purity. The horn antenna is fabricated using conventional micromachining, and the TRA layers are fabricated using metal three-dimensional printing.