Research On Millimeter Wave Broadband High Isolation Quadrature Mode Coupler

With the development of modern communication technologies,frequency resources are becoming more and more crowded,and frequency reuse has become the hot research direction in communication fields.Orthomode transducer as the core of the double polarization system,can directly synthesis and separation the microwave communication to double polarization signal,solve the problem of frequency reuse,and realisze the use of double frequency resources.At present,the research results of OMT appear to be lacking in comparison with other microwave devices.In this paper,the design of millimeter wave broadband high isolation orthogonal mode coupler is analyzed and studied.First,this paper introduces the research background of orthomode transducer and the research status of various structure OMT at home and abroad,and through the waveguide structure of electromagnetic wave transmission forms and the anallysis of the impedance transformation theory,these have the intimate relationship to the high performance of the OMT.Then,through the analysis and the research of the affecting factors to every performance of OMT,and based on the influence of the orthomode transducer structure on high order mode,the symmetric basic structure of OMT is designed in this paper.In this paper,the transmission electromagnetic field distribution of various components of broadband OMT is modeled and simulated,and the model selection and parameter derivation of the components of symmetric broadband OMT are designed and analyzed.And then,based on the broadband orthomode transducer design process,with the aid of the electromagnetic simulation software HFSS,through calculation and simulation,and designed a V band broadband orthogonal mode coupler of the double ridge structure,and physical processing and testing,the measured results showed that the insertion loss less than 0.5 dB,return loss is better than 15 dB,isolation reached 45 dB.Finally,based on the analyzed of the turnstile structure,through calculation and simulation,and designed a W band broadband orthomode transducer,and it has carried on the physical processing and testing,the measured results showed that the insertion loss less than 0.6 dB,return loss is better than 15 dB,isolation reached 52dB,the final result meet the design index,this a series of engineering practicability of the broadband OMT was verified.