A compact conductor-backed CPW-based dual bandpass filter for satellite S-band and C-band

Abstract An efficient and compact dual bandpass filter having single narrow rejection band between S-band and C-band using CPW arrangement is proposed. The half wavelength square resonator is used in ground surface to eliminate certain frequency bands. The transmission zero of rejection band is restricted by modifying the dimension of the resonator. The CPW-based DB-BPF is simulated and tested with its equivalent prototype. This work emphasizes DB-BPF with square resonator coupling constructed on CPW process. An innovative integration of circular resonator incorporated with inter-digital line coupling in the top surface of the substrate and square resonator at the bottom surface of the substrate produces wide band and narrow stop band, respectively. The DB-BPF has remarkable bandwidth from 2 to 3.8 GHz and 4.3 to 7.8 GHz as S-band and C-band, respectively. Hence, the overall bandwidth of the filter is 5.3 GHz (1.8 GHz and 3.5 GHz). The filter performances are evaluated and analyzed through the factors like S-parameters, Q-factor and group delay. The overall dimension of DB-BPF is achieved to be (39 × 4.5 × 1.6) mm3, which is very much compact in dimension. The filter characteristics show the return loss of − 35.2 dB and insertion loss of − 1.2 dB which are validated by measured results.