Dual-band Capacitive-coupled Ring Resonator with Second and Third Order Harmonic Rejection

This paper presents a capacitive-coupled dual-band ring resonator. A pair of resonators is coupled at the edges to create capacitive coupling, with two identically sized slots diagonally cut into the outer loop's edge. These notches assist in coupling two degenerate modes. Further, two capacitors are incorporated to ensure out-of-band rejection. The proposed ring-resonator is simulated using Advanced Design System. The simulation results indicate that the proposed dual-band ring resonator covers the frequency range from 1.52 GHz to 2.01 GHz and from 2.31 to 2.83 GHz. Further, more than 25 dB suppression of second and third order harmonics has been obtained for the designed prototype. Proposed design can find its extensive application in WiMax and WiFi.