Fast Analysis Of Wideband Electromagnetic Characteristics Of Antennas And Arrays

With the development of information technology and the demand of the national defense,the research on electromagnetic radiation and scattering characteristics is attracting more and more attention.Wideband characteristics analysis is often required in electromagnetic scattering and radiation.The method of moments(MoM)is one of accurate numerical methods and has been widely applied to analyze the electromagnetic problems.The MoM is a frequency-domain technique.The impedance matrix has to be repeatedly computed at each frequency when it is applied to compute wideband properties.Thus,it is very time consuming.Moreover,the impedance matrix is a dense one,which leads to large memory requirement.In this thesis,the frequency-independent reaction for MoM(FIR-MoM)is used to efficiently analyze the wideband radiation characteristics of the wire antenna and Yagi-Uda antenna.Numerical results show that the FIR-MoM can greatly improve the computing efficiency and can reduce the memory requirement,which makes the analysis of the large complex targets more efficient.The accurate sub-entire-domain(ASED)basis function and the characteristic basis function(CBF)method are two physically meaning basis functions with less unknowns comparing with the conventional MoM.The accuracy comparison between them has not been studied.In this thesis,the accuracy comparison between them is conducted by analyzing scattering by finite periodic structures.Simulation results show that the relative error of the results obtained by using the CBF basis function method is less than that of the results obtained by using the ASED basis function method.It is concluded that the accuracy of the CBF basis function method is higher than that of the ASED basis function method.The work in the thesis provides a theoretical basis for the efficient wideband analysis of large arrays and finite periodic structures.