A combined aperture-coupled membrane microstrip patch antenna array

A novel lightweight L-band combined aperture-coupled microstrip antenna has been proposed for synthetic aperture radar (SAR) applications. The proposed antenna element is composed of only two membranes. This design innovatively integrates the coupling aperture with the radiating patch, significantly reducing the number of required dielectric layers to achieve a simplified and lightweight structure. The feed line is placed on the front side to facilitate integration with the transmit/receive (T/R) module. Simulation results demonstrate that the antenna element exhibits excellent radiation pattern performance and bandwidth. A $4\times 4$ passive antenna array utilising polyimide as the dielectric material was fabricated and measured to validate its performance. This array employs a 4-stage Wilkinson power divider network. Measurements show that S_1,1 is below −15 dB in the frequency range from 1.15 to 1.49 GHz, with a maximum efficiency of 72.87%. Additionally, an $8\times 4$ phased array antenna was fabricated and tested. This array demonstrated stable radiation pattern performance over an azimuthal scan range of $\pm 25°$ and an elevation scan of $\pm 15°$. This design offers a new option for antenna modules in spaceborne SAR applications.