A Study Of Dielectric And Microstrip Structure Based On The Method Of Moments

Nowadays, as the rapid developments of the communications industry, New requirements for equipments are put forward to be further miniaturized, more portability and more efficient, microstrip structure has been widely used for having these characteristics, and has been widely applied in aviation, aerospace and communications sector, therefore the study of microstrip structure becomes even more important, analyzing the characteristics of electromagnetic scattering and radiation for microstrip structure becomes a noticeable topic.In the study of microstrip structure, the commonly used methods include the Finite-Difference Time-Domain(FDTD) method and the Method of Moments(MOM). The Finite-Difference Time-Domain is simple in programing and fine in commonality, it can calculate response of the whole frequency band at once, but in order to achieve precision requirement, the mesh must be generated small enough in the vertical direction of the thin layered media when using this method, which will lead to the increasing amount of calculations. When using the method of moments in the analysis, the Spectral-Domain Immittance(SDI) method and the spatial Method of Moments are used extensively, we can use the Spectral-Domain Immittance method to deduce the spectral domain Green’s function of layered medium with arbitrary metal strips, use the spatial Method of Moments based on the Mixed Potential Integral Equation to deduce the spatial domain Green’s functions. In actual program, it will involve Somerfield Integral(SI), this integral has the characteristics of high oscillation and slow attenuation, which can be handled with the Discrete Complex Image Method(DCIM).Microstrip structure is analyzed by the Moment of Method based on surface integral equation in this paper. First start with the basic principle of the Method of Moments, analyze the structure of perfect conductor, pure medium and coated conducting bodies step by step, use real-space Green’s function based on integral equation method to obtain the integral equations for different types of scatterers, make a detail deduction in formulas to calculate the far field distribution for large scattered objects of any shape. Based on the results above, analyze the microstrip structure model, using the surfaceintegral equation method similarly, change the way of feeding, calculated the radiation characteristic of microstrip structure. Considering that there is no ideal absorbing boundary in Method of Moment, then model without wave reflection is very important to the calculation of antenna feed port. Modeling wave ports by using the equivalence principle of aperture coupling and Mode Matching Method(MMM), assuming that the lateral of wave ports connected with infinite long coaxial line to simulate the state of no reflection, to get radiation characteristics or S parameters for both antennas and filters of microstrip structure. Finally, discuss the other two methods briefly, they are open circuit method and pattern matching method, which are used to solve the problem of the impedance matching in microstrip structure.Compared with the spatial Method of Moments, the method in this paper is easier to process, don’t need to deduce analytical expression of spatial green’s function particularly, and don’t involve the processing of Somerfield Integral, but achieve high precision.