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A compact microstrip interdigital stepped‐impedance band‐pass filter with enhanced stop band
Author(s) -
Crute John R.,
Davis Lionel E.
Publication year - 2002
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.10455
Subject(s) - passband , center frequency , band pass filter , microstrip , band stop filter , resonator , stopband , microwave , acoustics , electronic engineering , bandwidth (computing) , electrical engineering , engineering , filter (signal processing) , physics , materials science , low pass filter , telecommunications
Microstrip bandpass filters are widely used in a variety of microwave subsystems to select a desired band of frequencies. However, common filter topologies with uniform impedance resonators exhibit poor stop‐band performance. This is due to the occurrence of harmonic passbands at multiples of the fundamental passband frequency. This study describes the design of a compact interdigital microstrip filter, using short‐circuit stepped‐impedance resonators (SCSIRs) to enhance the harmonic stop‐band response. Measurements on an experimental filter, with a design center frequency of 2442 MHz and 3‐dB bandwidth of 611 MHz (25%), show an increase in the first harmonic passband frequency to 8809 MHz. At three times the fundamental passband center frequency (7326 MHz), stop‐band attenuation is better than −35 dB. The results demonstrate the usefulness of SCSIRs for improving the stop‐band performance of interdigital bandpass filters, with only a small increase in overall size. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 336–340, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10455