Switchable compact widestopband bandstop filter to wideband bandpass filter

In this paper, a switchable compact microstrip band-stop filter (BSF) to bandpass filter (BPF) using spiral resonator is reported. In BSF, spiral resonator has open ends as against to the shorted ends of the BPF. This concept is used to design the filter switchable so that in a single layout, the two filters - BSF and BPF - can be achieved. PIN diode is used for switching operation. Also a mathematical two-port system approach is used to derive the response of the proposed filter consisting of spiral resonator. To validate the proposed filter design, a switchable BSF to BPF is designed and fabricated on the substrate RT/Duroid 6010.2 having dielectric constant and thickness of 10.2 and 0.635 mm respectively. Simulation and experimental results are in good agreement.