New triple-mode ring resonator bandpass filter with source-load coupling

Summary form only given, as follows. A new triple-mode resonator is implemented by three coupled rings. The rings are connected to a ground via through short high-impedance sections, providing inductive coupling among the resonant modes. The rings are also realized by stepped-impedance equivalence for size reduction. With source-load coupling, two extra zeros can be created on both sides of the passband. Two filters are fabricated and measured for validation. The measured results show good agreement with the simulation.