LAUSR

In this paper, a novel double-layer transmitarray antenna operating in X-band with high efficiency is presented. Different from the traditional transmitarray element design, the proposed transmitarray element uses a compound substrate which is composed of two horizontally arranged different dielectric substrate materials. By etching metal square loop and patch on both sides of the compound substrate, two resonance modes can be realized. Then, much enlarged transmission phase cover can be realized. The proposed element provides 360° transmission phase shifts with better than -2.3 dB transmission magnitudes, when the length $L_{2}$ of the element varies from 5.95 mm to 9.05 mm. To experimentally validate this novel design, a $13\times 13$ -element transmitarray is designed, fabricated and tested. The measured peak gain of the transmitarray is 20.77 dBi at 10 GHz, with its aperture efficiency of 55%. This compound structure can also provide an additional degree of freedom in broadening the transmission phase shift range.