A broadband bandpass filter with a notch-band using step-impedance resonator and embedded slots

This paper proposes a new broadband microstrip bandpass filter based on a step-impedance resonator (SIR) and embedded slot structure for a notch-band and improved upper stopband performances. A comprehensive treatment of a slotted resonator with both ends of interdigital coupled lines and an embedded slot feed is described. The proposed filter has a notch-band and a wider upper stopband, resulting from the slotted feed line and resonator characteristics. The simulated and experimental results show a narrow notch-band and superior stopband performances of better than 10 dB for a frequency range up to 25 GHz.