Double-ring 3rd order bandpass filter with half-wavelength coupled-line integration / Nurzuraihan Jamaludin

This paper proposes the cascaded of two-ring resonator topology. The response of this ring resonator is a 3rd order bandpass response, resulted the extra poles that comes from the cascaded-rings. There was an improvement in size and shape of the design of a ring resonator from the previous topology of a microwave ring resonator with quarter wavelength coupled-line integration. The proposed ring resonator is consisted of two cascaded circular rings where the half-wavelength coupled-line is integrated at the center of the two ring resonator. The response of the 3rd order bandpass filter can be controlled by varying the values of several parameters such as the gap of the coupling. The proposed concept is demonstrated at the operating frequency of 2.4GHz. The substrate used in this simulation is FR4 with the following characteristics: sr = 5.4 and h = 1.6mm. To show its feasibility, the measurement result is presented.