A resistor-loaded microstrip line resonator with a punched hole structure for ultra-wide-stopband bandpass filters

Summary form only given, as follows. A novel microstrip line resonator is proposed for ultra-wide-stopband microwave bandpass filters. It consists of a stepped-impedance resonator (SIR) with thin-film resistors for absorbing higher-order resonance power. A fabricated 2-stage microstrip bandpass filter at fo = 2.0 GHz has realized a spurious response level −29 dB up to 25 fo, which seems to be one of the best wide-stopband performance among ever-reported ones in the category of microwave microstrip line filters.