Planar Absorptive Balanced Filtering Power Dividers With Arbitrary Transmission Zeros

This paper presents, for the first time, the design and realization of absorptive balanced filtering power dividers (BFPD) featuring customizable transmission zeros. By replacing the conventional \lambda / 4 transmission line with a novel low-pass filtering unit (LPFU), precise control over the transmission zero frequency is achieved. Meanwhile, the power-dividing ratio of the proposed BFPDs is governed by the admittance ratio of the LPFU, leading to excellent amplitude balance bandwidth characteristics. A novel absorptive network is further introduced and integrated into the balanced ports, enabling effective DM signal transmission, cross-mode conversion suppression, and CM noise absorption in all states. To validate the proposed design, two 2-GHz absorptive BFPDs were designed and measured, with each one featuring transmission zeros at 3.0 GHz and 4.0 GHz, respectively. The measured 15-dB DM matching, isolation, and 15-dB CM reflection loss, isolation, and insertion loss bandwidths for the two BFPDs are superior to 462 MHz and 1290 MHz, respectively.