Design of a wide stop-band LPF using microstrip/CPW composite structure

A novel low-pass filter (LPF) with harmonic-suppressed, sharp-rejection slop, wide and deep stop-band attenuation properties is proposed, which is composed of coplanar waveguide (CPW) short-circuited stubs and microstrip shunt open-end stubs as series and shunt components in the pass-band. Based on this composite microstrip/CPW structure, the low-pass filter with excellent electrical performances is simulated and optimized by the momentum of method (MoM). The obtained frequency responses show that the harmonics are not only suppressed effectively, for most attenuation is more than 40 dB from 4 GHz to 16 GHz, but the transition response exhibiting sharp slop varieties from -3 dB to -70 dB, corresponding to frequency range from 3.8 GHz to 4.5 GHz. The insertion loss in the passband is less than 1.0 dB.