A rectangular slot Yagi DGS microstrip filter with sharp rolloff and wide suppression band
AbstractA compact microwave lowpass filter based on defected ground structure (DGS), consisting of Yagi slot DGS resonators etched on the metallic ground plane of a microstrip line, is studied in this paper. The proposed lowpass filter was analyzed by parameter sweeping and optimal parameters were selected to design a prototype demonstrator filter. Measurements show the developed lowpass filter exhibits a 3dB cuto frequency of 3.07 GHz with a sharp transition between the passband and the stopband, low insertion loss of less than 0.6 dB in the passband and an in-band group delay of 0.4 ns. Moreover, an ultra-wide suppression band from 3.68 to over 20 GHz with a suppression level generally better than 20 dB is also observed from measurements.