Stub-loaded resonator-fed filtering patch antenna with improved bandwidth

A method of designing a patch antenna with wideband and filtering characteristics is proposed in this paper. Different from traditional aperture-coupled patch antenna, a stub loaded resonator (SLR) is employed as the feed. This coupled SLR-patch produces three reflection zeros (dual-mode from the SLR and one from the patch) and therefore a wider bandwidth. Due to the resonant property of the SLR, the antenna exhibits a filtering performance and good out-of-band rejection. This integration approach eliminates the 50 Ohm interfaces between the traditionally cascaded filter and antenna. This contributes to a more compact and simplified RF frontend. Methods to control the modes of the SLR are investigated. The simulation and measurement results agree well with each other, showing an excellent performance in terms of bandwidth, frequency selectivity and radiation patterns.