Square patch resonator bandstop filter

Rectangular patch resonator is analyzed, and dual-mode and multi-mode bandstop filters using square loop resonator are proposed. Compared with traditional dual-mode filter with single operation band, the new design takes fully advantage of the dominant mode and its degenerate mode, even higher order mode to implement operation band, respectively, and tri-band bandstop filters are developed by using DGS. It is shown that with simple and compact structures, dual-mode and tri-band bandstop filters are realized, and the design is demonstrated by measurement. The new filters are expected to find applications in future wireless communication systems.