Switchable absorptive bandstop to bandpass filter using dual-mode ring resonator

In this paper, a new switchable absorptive bandstop to bandpass filter using dual mode ring resonator is presented. This switchable filter provides two modes of operation which is absorptive bandstop and bandpass response. The first part of this paper presents a theoretical analysis of the absorptive bandstop dual mode ring resonator based on two low-Q lossy resonators topology. The operating frequency of the absorptive bandstop filter is 2.4 GHz with S
₁₁
> -10dB and S
₂₁
> -30dB. The absorptive bandstop response can be achieved by controlling the K-inverter and perturbing stub. The second part of this paper presents an investigation and the design of the switchable absorptive bandstop to bandpass filter in EM simulation. Varactor diodes are used to control the K-inverter and a PIN diode is used as the ON and OFF switch of the additional length of perturbing stub. A bandpass response can be achieved by controlling the voltage from 1 V to 10 V of the varactor diodes. The bandpass response can be enhanced to dual-mode bandpass response by adding additional length to the perturbing stub. The parametric studies together with the EM simulation of the new switchable absorptive bandstop to the bandpass dual mode ring resonator filter is presented in this paper.