Multi-Mode Bandstop Filter Using Defected Equilateral Triangular Patch Resonator

Abstract

Microstrip multi-band bandstop filters using multi-mode equilateral triangular patch resonator are developed, and the rules of resonant frequency and patch defection dimension are obtained by calculation. With fractal patch defection and a higher substrate permittivity, the dominant mode TM_1,0,–1, and the higher order modes TM_1,1,–2 and TM_2,–2,0 are fully applied to the multi-band implementation, and filter performances are greatly improved compared with the case without defection. The designed filters have advantages of simple topology, compact size, good frequency selectivity and multi-band operation, and all these features are very popular for wireless communication systems.