Ridge Waveguide Coupled Stripline Resonator Filters and Multiplexers

Strip line resonator bandpass filters with evanescent-mode coupling sections by ridge waveguides are introduced in this paper. Such filters have very compact cross sections, which makes them suitable choices for some integrated systems having cross section constraints. Low temperature co-fired ceramic (LTCC) technology can be employed to build such filters for PCB systems. It is also possible to manufacture them in air-filled metallic structures. Two filter design examples by mode matching method (MMM) are given in this paper. Stepped impedance line resonators are used in one example to improve the spurious. The presented filters can also be applied for multiplexer applications using stripline junctions. One diplexer design example for LTCC application is presented to show the feasibility