Compact bandpass filter using open-loop resonators with capacitive loading

A novel compact microstrip bandpass filter, based on open-loop resonators with capacitive loading, is presented in this paper. The new filter has the advantages of compact size together with sharp rejection. Compared with the conventional filters using square open-loop resonator, the proposed filter has a size reduction of 45%. A demonstration filter was designed, fabricated, and measured. Theoretical and experimental results are presented and show good agreement. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 83–84, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22035