Novel Low-Pass Microwave Filter Based on Rectangular Ring DGS

Due to the frequency response periodicity of distributed transmission line, microstrip band-pass filter usually produces parasitic pass-band and outputs harmonics away from the center frequency of main pass-band. Based on the study of rectangular ring defected ground structure, a 5-order microstrip LPF(low-pass filter) was designed using the single-pole band-stop and slow-wave characteristics of the rectangular ring DGS(Defected Ground Structure) and SISS(Step-Impedance Shunt Stub) structure. Compared with traditional LPF, this LPF presents the advantages of compact size, low insertion loss, broad stop-band and high steep. It also validates the requirements of miniaturization and high performance for filters.