Study on Two Compact CPW-FED Bandpass Filters Using Dual-Mode Patch Resonator

Two compact CPW-fed band-pass filters using dual-mode resonator are proposed and studied - one resonator with two unequal corner-cut elements located at two diagonal corners of a conventional micro-strip patch and the other with unequal crossed slots at the center of a conventional micro-strip patch. In this paper, adjusting the length of corner-cut element and the crossed slot are mainly studied. By use of HFSS, the simulation results are given and analyzed. The simulation results show that the pass-band of the filter(a) may be adjusted over the bandwidth range from 4.9% to 16%, and the pass-band of the filter(b) may be adjusted over the bandwidth range from 5.4% to 8.2%, and filter(b) with cross-slot has smaller size than filter(a) with corner-cut to meet the same application demand. According to the simulation results, to design a filter which works at 1.65 GHz, the configuration of filter(b) is adopted owning to smaller size. finally, filter(b) with len1=20.2mm and len2=20.4mm is fabricated and measured, which has a minimum insertion loss of 2.48 dB in its pass-band.