A compact LPF with broad stopband characteristics using hairpin structure and chip-capacitor

A compact microstrip lowpass filter is proposed in this paper. The LPF consists of hairpin type inductor lines as quasi-lumped elements, coupled lines and a chip-capacitor. Firstly, using the equivalent circuit, the transmission zero frequencies are investigated. As a results, the proposed filter has two attenuation poles at a stopband. Then, cascaded LPF is cross examined with the simulated and experimental results. The measured results show that the experimental LPF has sharp attenuation slope at the cut-off frequency and wide rejection characteristics.