A High-Gain, Broadband Filtering Antenna With High Sideband Suppression in Sub-6-GHz Band

A low-cost, broadband filtering antenna is designed for high gain and high sideband suppression (SBS). The antenna is designed with a metallic fed patch and two electromagnetically coupled patches. A pair of longitudinally tapered and Γ-shaped slots is etched in a metallic fed patch to generate radiation nulls in the lower and upper frequency bands. Partial metallic walls are used to improve the antenna impedance matching. Its performance is investigated with systematic design evolution. The antenna prototype is fabricated to validate the results. The designed antenna provides 50% bandwidth for |S₁₁| ≤ −10 dB with a peak gain of 9.4 dBi, null depth, and SBS of more than 27 and 18.7 dB, respectively, in both bands. Cross-polarization (X-pol) and front-to-back ratio (FBR) of the filtering antenna are more than 20 and 18 dB, respectively, with an antenna size of 0.9λ × 0.57λ × 0.11λ at 2.05 GHz. The proposed filtenna is a good candidate for 5G and base station applications in sub-6-GHz frequency band.