A compact bandpass filter using open‐loop and C‐SCMRC resonators with harmonic suppression

A novel compact open‐loop resonator bandpass filter is proposed to suppress the spurious passband using a compensated spiral compact microstrip resonant cell (C‐SCMRC). Due to the inherently compact and stopband characteristics of the C‐SCMRC, the proposed filters shows a better spurious‐rejection performance than the only open‐loop resonator filter. The proposed bandpass filter improves the rejection level of 20 dB from 2.8 to 5 GHz. Furthermore, 40‐dB suppression improvement and better than 57‐dB rejection level at the 2 nd ‐harmonic passband from 3.3 to 3.85 GHz are achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 906–909, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21514