A compact ultra-wide stopband, low insertion loss, and sharp cutoff low-pass filter

A novel compact microstrip low‐pass filter (LPF) with ultra‐wide stopband, low insertion loss, and sharp cutoff is introduced in this letter. The LPF is composed of a stepped‐impedance hairpin resonator, a square split‐ring resonator, defected ground structure (DGS), and a pair of coupled DGSs with compensated microstrip lines. Measured results show that the 10‐dB stopband is up to 19.62 GHz, passband loss is below 0.5 dB, and the selectivity of the filter is more than 180 dB/GHz, but its occupied area is only 20 × 35 mm2. It can be widely used for higher harmonics suppression for wideband microwave applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 568–570, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24976