A Novel Compact Stepped-Impedance Resonator Lowpass Filter

A novel stepped-impedance resonator (SIR) and its simplified equivalent circuit are proposed in this paper. The frequency responses of the SIR with different sizes are analyzed by the full-wave electromagnetic (EM) simulator. A novel low-pass filter (LPF) with two transmission zeros is designed and fabricated based on the SIR. The measured 3 dB cutoff frequency fc is 7.2 GHz with 0.3 dB ripple level in the pass-band. The rejection bandwidth of the insertion loss more than 15 dB is 9 GHz. The experimental results show good agreement with simulated ones, which validates the effectiveness of the SIR equivalent circuit and the feasibility of the novel SIR LPF.