Dual-band stepped-impedance resonant filter with dual-band admittance inverter

In this paper, stepped impedance resonator with dual-band admittance inverter is proposed to design the dual-band microstrip filter to operate at (2.4, 5.2) GHz and at (0.9, 2.3) GHz respectively. The proposed dual-band microstrip filter consists of SIRs in shunt cascaded by dual-band inverter. The half-wavelength stepped-impedance resonator is constructed to simultaneously excite the dual resonances at those specified frequencies. The dual-band admittance inverter employed is comprised by two open stubs and one transmission line to make the contribution of the performance of the J-admittance. The study has indicated that the proposed structure and method can achieve the design goals of dual-band filter. Experimental filters are fabricated and measured to confirm the design.