A DBR Microstrip Duplexer Based on Improved Microstrip Cross-Shaped Resonators

A DBR microstrip duplexer based on improved microstrip cross-shaped resonators is proposed in this paper. Firstly, a high-precision UWB equivalent circuit parameter extraction method based on admittance matrix is proposed by modeling and researching the microstrip cross-shaped resonator. Then, the conventional microstrip cross-shaped resonator is improved to a concave-microstrip cross-shaped resonator and a convex-microstrip cross-shaped resonator to eliminate the parasitic capacitance produced by the center junction structure, and the DBR filter based on the improved microstrip cross-shaped resonator was developed. Finally, based on this, a high-performance DBR microstrip duplexer operating in the Ku-band is designed. The 3 dB relative bandwidth of the lower channel (at 14 GHz) and the upper channel (at 16.5 GHz) is 7.3% and 6.4%, respectively. The insertion loss in the passband is less than 2.2 dB and 2 dB, respectively, and the return loss is better than 14 dB and 12 dB;Stop-band suppression is higher than 50dB; the isolation is up to 60dB.