A compact microstrip diplexer based on dual closed loop stepped impedance resonator (DCLSIR) is proposed. The proposed microstrip diplexer is composed of the combination of two DCLSIR bandpass filters (BPFs), which are designed for X-band application. For the demonstration, a dual-channel diplexer has been designed and fabricated using microstrip and printed circuit board (PCB) technologies, respectively. The fabricated diplexer operating at 8.3/10 GHz for X-band application has compact size (15.17 mm x 2.69 mm). The measured results are in good agreement with the full-wave simulation results. Good isolation between two channels is achieved.
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