Miniature DBR with series capacitive loading

A new miniature Dual Behavior Resonator (DBR) topology with capacitors placed in series between the feed lines and the stubs is demonstrated. Design equations are derived. For a proof-of-concept, a first-order prototype with a 1-GHz working frequency and 70% size reduction is realized, measured and compared to a classical DBR. The design method is simpler and more accurate compared to a miniaturized DBR with capacitors connected at the end of the stubs. Hence, the agreement between simulation and measurement results is better than previously published results of a miniature DBR using capacitors at the end of the stubs. Results also point out a quality factor improvement of 12%.