Novel tunable bandstop filter using E-shaped dual mode resonator

This paper reports analysis and design of novel tunable bandstop filter utilizing E-shaped dual mode resonator. The basic bandstop filter using E- shaped dual mode resonator is modified to a tunable bandstop filter with two discrete frequency states of 5 and 6 GHz having same fractional bandwidth of 5%. The centre frequency control is achieved by modifying the open stub inverter length using PIN diode. Bandwidth control is obtained by choosing appropriate value of resonator width, spacing between the resonator and the main line and controlling the normalized reactance slope parameter of a resonator. Simulation results of the tunable bandstop filter with and without biasing circuit using Micro-Stripes Software are reported. The simulated results show good agreement between the performance characteristics under forward and reverse bias conditions.