A filtering patch antenna with reflectionless in a wide frequency range

Abstract

AbstractA filtering antenna consists of a reflective filtering antenna (RFA) and a bandstop filter (BSF) is presented. Due to the L‐shaped feeding structure, slots etching on the radiator and the ground plane, the RFA obtains good impendence matching, stable in‐band gain, as well as four reflective radiation nulls, and that contribute an operating band of 19% and good frequency selectivity to the proposed filtering antenna. The RFA and BSF are cascaded directly, and the compact BSF is terminated by a resistor to absorb the stopband energy of the RFA, bringing good reflectionless characteristics in a wide frequency range to the proposed filtering antenna. The proposed filtering antenna has a 2‐dB gain bandwidth of 22% (1.78–2.22 GHz), in‐band gain of about 6.81 dBi, radiation suppression levels of higher than 23.4 and 21.4 dB for the lower and upper stopbands, respectively. Within 1.0–3.0 GHz, |S11| ≤ −12 dB, implying slight effect of reflected wave on the devices connected to the proposed filtering antenna.