Filtering dual-patch antenna with flat gain response using F-shaped feeding structure

A novel wideband filtering dual-patch antenna with a flat gain response is presented in this letter. This filtering antenna mainly consists of two parts: two patches and an F-shaped feeding structure. The upper and lower patches are fed by two different horizontally placed narrow strips from the F-shaped structure. Two patch modes are simultaneously excited within the passband, yielding a 29.3% bandwidth with a very flat gain response and a stable radiation pattern. Furthermore, a pair of radiation nulls are generated symmetrically at the two sides of the passband owing to the mutual coupling between two patches. As a result, a filtering antenna without any extra filtering circuit is obtained which achieves a realized gain of 10 dBi within the passband and an out-of-band suppression level of 15 dB in the lower stopband and 20 dB in the upper stopband. Compared to the traditional patch antennas, this proposed filtering antenna demonstrates a very flat gain response, a sharp passband skirt, and a good selectivity, which is well designed and very suitable for high band cellular communication (2.0-2.7 GHz).