Analysis And Design Of Microwave Passive Devices

Microwave and millimeter wave passive devices are important components of the microwave and millimeter wave systems.Improving the electrical index of the passive device,improving the design precision,shortening the design cycle,reducing its volume,weight and cost,is a big trend,or the pursuit of the goal.Therefore,it is necessary to study fast and accurate method of analysis and design.In this paper,some discontinuities in the waveguide structure are analyzed by the full wave analysis method,and a variety of microwave passive devices are designed and optimized in combination with the optimal design theory of a variety of microwave passive devices.A variety of microwave passive devices,such as transverse iris bandpass filter,low pass filter,longitudinal metal isis bandpass filter,waveguide cavity filter,evanescent mode waveguide filter,diplexer or multiplexer,impedance transformer and coupler,are designed.The calculation datas of the program and the simulation data of commercial software are given,and so the contrast chart of the experimental datas.In the design of these microwave passive devices,a general design method and a new precise optimization method are also proposed for some types of devices.Finally,the physical size error of the microwave filter is analyzed,which has a certain reference value for practical engineering application.The research achievements obtained in this paper can be divided into three main aspects:(1)the full wave analysis method is used to analyze the waveguide step,the transverse metal iris,the E-plane metal iris,the waveguide T junction,the curved waveguide and the ridge waveguide,and obtain the respective generalized scattering matrix(GSM):A)The classical mode matching method(MMM)is used to match the transverse electric field and magnetic field at the discontinuity of the waveguide,such as the transverse iris,resonant iris,capacitive iris,inductive iris,and the ET and HT of rectangular waveguides,are analyzed in detail,then the generalized scattering matrix of the general structure is given.B)The matching of the discontinuous complex power conservation(CCPT)is used to replace the matching of the transverse magnetic field,and the field analysis of the E surface metal insert with any metal strip structure is carried out by this method.C)the transcendental equation of the cut-off wave number of the TM and TE modes of the ridge waveguide is obtained by the transverse resonance method,and the equation is solved by a dichotomous method.Then the discontinuity of the rectangular waveguide to the ridge waveguide is analyzed by the matching of the transverse and transverse magnetic fields.D)In the analysis of rectangular curved waveguide,the electromagnetic field expansion of the whole arc section is difficult to obtain,so the hermholtz equation of the arc section is converted to the eigenvalue problem first,and then the generalized scattering matrix of the whole discontinuity can be obtained by combining the pattern matching method.The narrow band waveguide bandpass filter can be designed based on the traditional inverter model.However,in the design of broadband waveguide bandpass filter,there are often problems such as poor return loss and serious center frequency shift.The bandpass filter with distributed impedance inverter model can achieve wider bandwidth and good return loss.In addition,the M matrix of the cross coupled filter is obtained by using the comprehensive theory of the cross-coupled filter.Combined with the fast analysis and optimization method,various microwave passive devices have been optimized.A)An improved micro population genetic algorithm is used to optimize the design of ideal impedance converter and rectangular waveguide impedance converter.The optimized design method can get a better initial value and obtain the physical size of the rectangular waveguide impedance converter faster.B)In the design of bandpass filters for transverse metal iris,a general design method is proposed.The physical size of the narrowband filter obtained by this method does not need to be further optimized.Several transverse metal insert filters are designed,and the relationship between filter parameters and physical dimensions in practical design is discussed.C)The optimization design of longitudinal metal insert filter is studied,and narrow band and wideband bandpass filters are designed.D)The waveguide cavity filter with a regular structure is optimized and a cross coupling filter of four cavity waveguide cavity is designed.Using this structure,a dual band wideband filter with six cavity waveguide cavity is designed.When designing the cross coupled filter,the coupling matrix of the cross coupled filter is obtained through the theory of cross coupled filter.By using the effective elements and full wave analysis in the matrix,the initial size of different coupling cavities can be obtained and optimized.E)Ridge evanescent mode waveguide band-pass filter and band-pass filter are designed.F)The rectangular waveguide band-pass filter with right angle is designed.G)A general optimization design method for diplexer and a multiplexer is proposed,and a variety of diplexers and five channels multiplexer are designed.(3)The optimum value of microwave filter is often deviation from the size produced in practical application.Therefore,the error analysis of the physical size of the E plane metal iris filter is presented.Though the analysis is mainly numerical,it can be used for reference in designing,processing and debugging transverse metal iris and longitudinal metal iris filter.In addition,the bending angle of waveguide inductive iris is analyzed.Through analysis,the physical optimization value of this kind of filter can be obtained by using this method.Generally,the angle size at the corner of the iris can not need taken into considerationIn this dissertation,a large number of full wave analysis methods for microwave passive device are compared with the simulation of HFSS,as well as the measured data.The results show that the simulation data and the measured data are in good agreement.