A Hybrid-Element Approach to Design Wideband ME-Dipole Transmitarray With Improved Aperture Efficiency

In this letter, a wideband efficiency-enhanced transmitarray is proposed using a variety of phasing elements based on the magneto-electric (ME) dipole structure. Several different ME-dipole geometries and excitation mechanisms are investigated to realize the receive-and-transmit type elements that have same multilayer configuration, wide common bandwidth, and stable transmission phase differences. A number of different phase adjustments can be provided within a wide bandwidth by the proposed elements. A 16×16 transmitarray antenna working from 21.5 to 33 GHz (42%, defined according to 3 dB variation in aperture efficiency) is designed, fabricated, and tested, which confirms a peak gain of 26.8 dBi and a peak aperture efficiency of 41%. Comparing to the original 1-bit ME-dipole transmitarray, where only two transmission phases can be used, the presented hybrid-element design demonstrates a pronounced improvement in aperture efficiency with nearly the same bandwidth and element thickness.