A novel compact microstrip dual-band bandpass filter based on transversal filter structure and centrally loaded resonator with independent control of passbands

A novel compact microstrip dual-band bandpass filter based on transversal structure and centrally capacitive load is proposed. Take full advantage of the full-wavelength resonator and centrally capacitive load, two filter passbands can be designed independently whilst the transmission zero of transversal filtering is kept; and spurious at lower frequency is eliminated simultaneously. A dual-band prototype filter operated at 1.6 GHz and 2 GHz was designed and tested to validate its performance. The proposed filter prototype achieves 1.3 dB, 0.98 dB low insertion losses and 17 dB, 25 dB good matching at both lower and higher frequency passbands with half size of the conventional filter.