Design of a Double-Layer Transmitarray Element Featuring a Single Degree of Freedom

This paper presents a design for a pair of complementary transmitarray elements operating in the Ku-band, which utilize a single degree of freedom. Both elements feature a double-layer metallic structure printed on both sides of a single dielectric substrate. At the center frequency of 15 GHz, Element 1 provides a phase coverage of 338° with an insertion loss of less than 2.5 dB, while Element 2 covers 109°, complementing Element 1 to achieve a full 360° phase coverage with an insertion loss below 0.9 dB. The phase adjustment for both elements is accomplished by tuning only a single geometric variable. To validate the proposed element design, an 11×11 square-faceted transmit array was fabricated and simulated. The results indicate that the antenna achieves a peak aperture efficiency of 46.9% and a 1-dB gain bandwidth of 10.5% (14.14-15.72 GHz). Compared to existing transmit array elements, the proposed double-layer design offers high efficiency and broad bandwidth while significantly optimizing design complexity, cost, and thickness.