Low Cost Frequency Doubler Using a Modified Dual-Mode Hybrid Ring Coupler

This paper presents a low cost frequency doubler with high performance. A modified dual-mode hybrid ring coupler is employed in the doubler design. The operation principle of the ring coupler is analyzed. A 12-/24 GHz doubler is designed and fabricated based on the proposed coupler. Measurement results show the doubler achieves low conversion loss of less than 9 dB, and fundamental/third-harmonic rejection of more than 28 dBc, within the input frequency range of 11 to 12 GHz.