Co-Design of a New Filtering Impedance Transformer Based on a Single Patch Resonator

In this paper, a new impedance transformer with filtering characteristic is presented based on the patch resonators, which can realize the transformation from 50 Ω to 100 Ω with high frequency selectivity. At the beginning, the involved TM
10
mode is analyzed and an impedance transformer is designed at a single frequency point. To achieve the dual-mode bandpass performance, the patch resonator loaded with several shorting pins is adopted. In this way, the dual-mode filtering response can be realized by the newly introduced TM
00
mode and the fundamental TM
10
mode. Furthermore, the resonating frequency of TM
10
mode can be controlled independently, leading to a flexibility in realizing different bandwidth. To verify the design concept, a filtering impedance transformer working at 4.0 GHz is designed and simulated. Final results theoretically demonstrate that the designed circuit has a good capability to transform the impedance from 50 Ω to 100 Ω with good filtering response.