Dual Band Bandpass Filter With Sharp Passband Resonances Using Dual-Mode SIRs

Bandpass filter with square loop shaped uniform impedance resonator and L-shaped stepped impedance resonators is proposed here. By using dual mode loop resonators and 2 stepped impedance resonators in the structure, the passbands are controlled in the expected range. The parameters are adjusted in the proposed structure so as to get optimum resonances without any ripples in the passband. The lengths of the low-Z and high-Z sections of SIRs are so chosen that the resonant frequencies do not alter from the band of interests. Dual bands are realized due to dual coupling paths present as loop resonators, in the structure. This dual segment loop resonator helps in achieving second order mode bandpass filter. The proposed filter occupies 48x48x1.6mm footprint.