Design and analysis of ultrathin X‐band frequency selective surface structure for gain enhancement of hybrid antenna

Abstract

A wideband ultrathin frequency selective surface (FSS) structure is designed and developed for the complete X-band. The design employs a metallic tetra-arrow (two bidirectional arrows placed diagonally) and a circular split structure (metallic) in the top side and bottom side of RT duroid 5880LZ low-loss substrate respectively. The proposed design has novel contribution in terms of significant reduction in electrical thickness (0.007λ0 which is corresponding to lowest operating frequency, 8.3 GHz) and wider transmission (S21) bandwidth (measured: S21 ≤ − 10 dB, 8.15-13.2 GHz, 47.3%), covering entire X-band due to cumulative loading of surface mount chip resistors in the top layer. The principle of operation of the proposed FSS further can be justified with its equivalent transmission line circuit model, which is based on microwave filter (band-stop and band-pass) topology for anticipating the desired characteristics. The FSS structure is further integrated with dielectric resonator (DR)-slot hybrid antenna for enhancing the gain (measured: peak gain of 4.5 dBi without FSS and 7.8 dBi with FSS) of the antenna. The proposed FSS structure is fabricated and measured performance has very similar responses as simulated ones.