Research On Characteristic Mode Analysis Method Based On Thin Dielectric Shee

Thin dielectric coated conductor structures have been widely used in practical engineering.With the rapid development of military modernization,aerospace technology and Naval Technology dominated by ships,naval aircraft and shipborne weapons are constantly updated and improved.In order to realize the stealth and avoid radar monitoring,most of the fighters,missiles and ships will be coated with a layer of microwave absorbing coating on the surface to reduce the radar cross section(RCS)of the target.Moreover,the precision circuit boards can be regarded as the combination of dielectric and thin dielectric coated conductors.The characteristic mode(CM)method has not attracted extensive attention since it was proposed,and it has not been applied in electromagnetics engineering until nearly 20 years.The thin dielectric sheet approximation-based CM analysis method is studied in this thesis,and the main contributions can be listed below:In the first part,the characteristic mode formulas for thin dielectric coated conductors are proposed,in which the thin coatings are divided into two cases: lossless one and lossy one.Firstly,the CM formulas for lossless dielectric coated conductors are studied.On this basis,the CM formulas for the lossy case are deduced.When the coated dielectric is lossy,the operator corresponding to loss needs to be separated from the weight operator in the integral equation.Finally,the combined field integral equation(CFIE)is proposed for the mixed model of thin dielectric sheets and thin dielectric coated conductors.The corresponding CM formulas are proposed as well by introducing the theory of generalized CM and considering the type of the impedance operators.In the second part,the calculation accuracy of the second kind of integral equation is improved for both the models mentioned above.In addition,the accuracy of the corresponding modal solution is also improved.The main reasons for the error of the second kind of integration equation are analyzed and the basic rules for selecting test basis functions are clarified.Both the accuracy of the magnetic field integral equation(MFIE)and the corresponding modal solution are improved obviously by replacing the original test functions(RWG basis function)with the n×BC basis functions for the models studied in the first part.