Microstrip Lowpass Filters with Reduced Size and Improved Stopband Characteristics

Zhewang MA  Kaneo NOMIYAMA  Yoshio KOBAYASHI  

IEICE TRANSACTIONS on Electronics   Vol.E88-C    No.1    pp.62-67
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.1.62
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Trends of Microwave and Millimeter-Wave Passive Circuit Components and Technologies for Improvement of Characteristics)
lowpass filters,  microstrip lines,  open stubs,  stepped-impedance,  transmission zeros,  

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Novel microstrip lowpass filters are developed with reduced size and significantly improved stopband characteristics. After introducing quarter-wavelength open stubs, we get one or two transmission zeros in the stopband. By folding the high impedance microstrip lines, we reduce the size of the filter. Three-pole and five-pole lowpass filters are designed, and their measured frequency responses agree well with theoretical predictions.