A band-stop RF switch using a dual-mode stepped-impedance microstrip ring resonator

This paper presents a bandstop RF switch using a dual-mode stepped-impedance ring resonator and two PIN diodes. Sharp band-rejection characteristic is realized by direct-feeding and adjustable bandwidth is achieved using stepped-impedance transmission line between two exited ports. Two PIN diodes are mounted after quarter-wavelength transmission lines of from each feeding point to turn the switch on and off and reduce the size of the ring resonator. To analyze the practical performance of the proposed switch in accordance with the perturbation and PIN diodes, the lossy transmission line equivalent circuit and even-odd mode analysis are studied. The calculated transmission characteristic of the proposed switch shows good agreement with the measurement. The fabricated switch exhibits off-state isolation of 43.3 dB within the range of 2.29-2.40 GHz and on-state insertion loss of 0.72 dB.