RETRACTED: Novel method for skirt response improvement of open‐stub low‐pass filter

A direct circuit replacement method using interdigital low‐pass structure directly replaced all open stubs of odd‐order open‐stub low‐pass filter to achieve sharp skirt response. The characteristics of the interdigital structure are analyzed by lumped element equivalent circuits and investigated by full‐wave electromagnetic simulator, IE3D. These simulated results were then applied as a guideline for the replacement. Two open‐stub low‐pass filters were designed by this method to enhance the skirt response near 3‐dB cutoff frequency. The measured results show very good improvement on skirt response and the rejection level in stop band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2434–2438, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22764