Balanced‐to‐Single‐Ended Out‐of‐Phase Filtering Power Divider With Continuously Tunable Center Frequency and Bandwidth Using Compact Patch Resonators

ABSTRACT This paper presents a novel compact balanced‐to‐single‐ended out‐of‐phase filtering power divide with continuously tunable center frequency and bandwidth. By introducing a T‐shaped slot on the isosceles right triangle patch resonator to perturb the TM 10 mode and exploring varactors‐loaded stubs, a new tunable miniaturized patch resonator is created. The proposed filter comprised three new tunable patch resonators connected by back‐to‐back varactors to adjust bandwidth in between. By studying the electric field distribution of the odd mode TM 10 and grounded isolation resistors, the wished out‐of‐phase output signal and good port‐to‐port isolation can be generated. Based on such a simple structure, a balanced‐to‐single‐ended out‐of‐phase filtering power with tunable bandwidth is designed and realized with a center frequency tuning range covering from 1.60 to 1.95 GHz (19.7%) and 3‐dB bandwidth tuning range covering from 265 to 328 MHz at 1.90 GHz.