A novel compact J ‐admittance inverter‐coupled microstrip bandpass filter using arrowhead‐shape as defected ground structure

This letter reports a new design of compact end‐coupled microstrip bandpass filter with two arrowhead slots as defected ground structure (DGS) in the ground plane [Boutejdar etal., IEEE AP‐SSymp (2005); Ahn, IEEE Trans Microwave Theory Tech 27 (1979), 44–50; Won etal., IEEE Trans Microwave Theory Tech 49 (2001), 86–93]. These slots replaced two λ/ 2 ‐microstrip resonators. Both feeds are indirectly coupled with the resonator on top layer by means of a J 12 ‐admittance inverter (gap g ). This method gives an advantage of size reduction over the conventional design by more than 50%, this structure allows for a convenient method to control the center‐frequency and high suppression of harmonics. From 6 to 14 GHz, the investigated DGS‐BPF has a rejection level better than 20 dB. According to design and measurement results, a good agreement between simulated and measured results is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 34–38, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24817