A Compact Coupling-Fed Patch Antenna With Quasi-Elliptic Filtering Response

A novel compact coupling-fed antenna with a quasi-elliptic filtering response for 5G-N78 band applications is developed. The proposed antenna achieves excellent filtering performance with a simple configuration. Specifically, the traditional open-ended feedline is replaced with a short-circuited SIR feedline, which generates a radiation null below the passband and introduces a pole in the operational band. Furthermore, two slim parasitic strips are modified from horizontal coupling to vertical coupling to improve selectivity/suppression above the passband and reduce the antenna size simultaneously. The driven patch is also modified to a slim rectangular patch to further reduce the antenna size. All these arrangements result in a compact filtenna with a quasi-elliptic response. To verify the performance, a prototype is fabricated and its performance was evaluated. This antenna exhibits a compact size of 0.39λ
₀
× 0.36λ
₀
× 0.08λ
₀
. The operation band is from 3.16 to 3.84 GHz (19.43%). The peak gain achieves 8.55 dBi. The efficiency is up to 94.87%, and the suppression is higher than 19.24 dB.