Parametric study of side-coupled ring resonator dualband bandpass filter

Parametric study of a dual-bandpass filter based on a one-wavelength side-coupled dual-mode ring resonator is presented. The change in response of the filter based on the variation of the impedance of its lines is analyzed. The results show that the dualband resonance frequencies and their separation depend simultaneously on the ring line impedance, and the even- and odd-mode impedances of the coupled lines of the filter. Such understanding provides useful information on how to tune the impedances to obtain the desired characteristics of the dualband response of the filter. Examples are given based on a dualband response resonating at 4 GHz and 6 GHz.