Ku-Band Transmitarrays With Improved Feed Mechanism

Combining the advantages of lens antenna and array techniques, transmitarrays have been widespreadly concerned in recent years. In the first part of this paper, a wideband four-layer transmitarray operating at 13 GHz fed by a horn with a focus-to-diameter ratio (F/D) of unity is proposed. The employed elements composed of dual-resonance double hexagonal rings are closely arranged in the honeycomb lattice. The simulated results show that the transmitarray can achieve a 53.34% peak aperture efficiency and a 19.23% bandwidth for 1 dB gain drop, respectively. The factors with strong influences on the measured results are analyzed. In the second part, an improved feed mechanism, which is aimed at reducing the transmitarray profile, is discussed in detail. The conjugate field matching technology is utilized to realize an ideal compensation. The small-scale antenna array, which has a nearly identical aperture size to the feed horn applied in the first design, can effectively excite the transmitarray with a profile reduction of 64.5%. These prototypes confirm the feasibility of designing a wideband transmitarray and a low-profile array-fed transmitarray.