Filtenna With Enhanced Gain and High Sideband Suppression in Sub‐6 GHz Band

ABSTRACT

A high‐gain filtenna with excellent sideband suppression (SBS) characteristics is presented in this work. The proposed design integrates a bandpass filter, based on a stepped impedance stub resonator, into a pentagon‐shaped patch antenna operating at 3.7 GHz (3.56–3.85 GHz). By etching a pair of hexagonal rings and a square‐shaped slot in the ground plane, the surface current distribution changes. This generates radiation nulls in the lower and upper frequency bands. As a result, impedance matching and overall filtenna performance improve. The fabricated prototype demonstrates a wide impedance bandwidth for |S ₁₁ | ≤ −10 dB, a peak gain of 8.2 dBi, and sideband suppression levels exceeding 18.1 dB and 23.2 dB in the lower and upper bands, respectively. With a compact size of 0.495 λ  × 0.33 λ  × 0.0176 λ at lowest frequency of operation, the proposed filtenna offers a promising solution for 5G and base station applications in the sub‐6 GHz frequency band.