Design of a 5.8 GHz narrow band-pass filter with second harmonic suppression using the open stubs

In this article, λg/2 open stub bandpass filters with flexible narrow bandwidth on duroid substrate are presented. This filters show flexible bandwidth with variation of the position of the open stubs using the external quality factor, Qe without changing the impedance value at microwave range. On the other hand, by replacing the series quarter-wavelength connecting-lines with the equivalent T-shaped line, a compact stub bandpass filter with second harmonic suppression can be obtained. This filter shows the insertion loss of 1.2 dB and the return loss of 21.9 dB at the center frequency of 5.8 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1763–1766, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23492