A microstrip LPF with attenuation poles by using coupled lines and a chip-capacitor

A microstrip LPF with sharp attenuation and broad stopband by using coupled lines and a chip-capacitor is proposed and investigated in this paper. Firstly, the circuit analysis is performed by transmission line model of coupled lines. As a result, the proposed filter has three attenuation poles at a stopband. Then, cascaded LPF is cross examined with the simulated and measured results. Well agreement was seen from this outcome. In addition, the measured result shows that fabricated LPF has low insertion loss, sharp attenuation slope at cutoff frequency and wide-band rejection characteristic.