Broadband high gain triple-layer transmitarray antenna

The goal of this paper is to present a design technique that optimizes the transmission phase distribution of triple-layer transmitarray antennas. It aims to reduce the effects of the lossy elements with low transmission coefficients on the antenna gain. A full transmission phase range of 360° is achieved using triple-layer spiral-dipole element with transmission magnitude equal to or better than -4.2 dB. A transmitarray antenna prototype has been designed, fabricated, and tested at X-band. The measured gain is 28.9 dB at 11.3 GHz. A broadband of 9% bandwidth for 1 dB gain is achieved.