A Generalized Method for Gain Bandwidth Enhancement of Transmitarray Antennas Considering Oblique Incidences

This paper introduces a generalized phase compensation method to enhance gain, 1-dB gain bandwidth of transmitarrays considering oblique incidences. This method is based on studying the transmission phase of each element in the holistic framework of a transmitarray, where all oblique incidences to each element are included. As a result, the actual transmission phase of every element at different spatial positions involving oblique incidence effects can be obtained, which is leveraged to improve the performance of transmitarrays. The proposed method is especially efficient for transmitarrays with discrete phase states. For proof of the concept, dielectric lenses with a 2-bit phase quantization are configured to demonstrate performance enhancement. The simulated results show that the gain enhancement of 1.67 dB, 3.41 dB, and 4.5 dB at 26 GHz can be achieved when the focal length-to-diameter ratio (F/D) is 0.37, 0.24, and 0.14, respectively, which are experimentally verified by the measured results.