Study And Manufacturing Of OMT Duplexers

Rapid development of communication industry has been closely linked with our life, the concept of “frequency reuse” is payed more and more attention in high capacity microwave communication, whose purpose is to make the increasingly crowded spectrum resources fully utilized. Filter and OMT(ortho-mode transducer) are key components that combine and divide frequency signal in microwave system, which are widely used in kinds of communication, radar, electronic warfare system, etc. Study on filter and duplexer is relatively deeper, which has got quite a lot of research results, but research on OMT is not so particularly rich. This paper mainly discusses and studies the design of compact ortho-mode transducer and waveguide duplexer.Firstly, the research significance and trends of OMT, filter, duplexer was elaborated. The basic theory of OMT was introduced and the common waveguide T junction in microwave design was analysed, whose equivalent circuit model and closed-form expressions are helpful for the design of the whole OMT. Then the same frequency and different frequency OMTs were simulated and analysed, whose structure was novel, dimension was ideal. At last the OMTs of two frequency band were manufactured and tested, whose results were good.Secondly, basic theory of filters and duplexers were introduced, including the Chebyshev response theory, frequency transforming of lowpass to bandpass, coupling coefficient of filters, and T juctions in duplexers.They were all theory bedding for following design of waveguide duplexer specificially.Finally, according to the existing theory, the target were estimated and calculated with MATLAB, the receiving and transmiting channel filters, the E plane T junction and whole waveguide duplexer were simulated in HFSS software. They were manufactured and tested too, whose results met the requirements of indicators.So the design methods was verified that they were effective and accurate.