Design of Compact MultiChannel Diplexer Using Defected Microstrip Structure

In this paper, two compact quadchannel and sixchannel diplexer are designed and fabricated using defected microstrip structure (DMS). This structure is designed for the desired frequency based on the literature reviews. The proposed configuration is composed of a conventional Tjunction divider with two pairs of open bended stubs and dual/triband filters. In designing dual band filters, a loop resonator loaded with two steppedimpedance resonator and defected microstrip structure. In addition, by adding a pair of open stubs, triband responses easily achieved without increasing the circuit size. The operating mechanism in resonance frequencies by surface current density is obtained. As a result, the multichannel diplexer occupies a compact size of 0.13λg by 0.13λg. The measured results are fully in agreement with the simulated predictions indicating that an isolation between channels is more than 29 dB.