Dual-Layer Transmitarray Antenna With High Transmission Efficiency

In contrast to traditional multilayer transmitarray designs, a novel dual-layer transmitarray antenna, consisting of two metallic layers printed on opposite sides of a single dielectric substrate, is proposed to achieve high transmission efficiency. First, it is theoretically derived that a dual-layer element, using the circular polarization conversion approach, can achieve a high transmission magnitude and a full transmission phase coverage. Next, a split-ring element has been designed as an example to demonstrate the theoretical analysis, where a full 360
^o
transmission phase range with better than -1.0 dB transmission magnitude has been obtained. To experimentally validate the proposed concept and design, a circular transmitarray prototype is designed, simulated, fabricated, and tested at Ka-band. The diameter of the circular aperture is 405 mm (27λ), and the thickness of the transmission surface is 3.18 mm (0.2λ). The measured peak gain of the designed transmitarray is 36.1 dBic at 19.4 GHz with the aperture efficiency of 60.2%, while the measured 1 dB gain bandwidth is 9.5% (19.0-20.9 GHz).