Coupling Analysis And Computation Of Rectangular Cavity With Apertures Based On Electromagnetic Topology Method

With the fast development of the electric information technology, the electricsystems themselves and the electromagnetic environment have become more andmore complex. Nowadays, the electromagnetic coupling of complicated electric sys-tems has become an interesting and hot issue in the area of electromagnetic com-patibility. In this thesis, coupling analysis and computation of a rectangular cavitywith apertures are studied based on the electromagnetic topology method. Themain results are included as follows.1. A new transmission line coupling model is deduced from Maxwell’s equa-tions. It is a kind of coupling model with respect to the scattered voltages andcurrents. Using analytical method, the equivalence among this new coupling model,the Agrawal, Taylor and Rachidi coupling models for solving feld-to-line couplingproblems is proved.2. A method of the transfer functions is proposed to compute aperture couplingof a rectangular cavity. On the assumption that aperture equivalent currents areknown, expressions of the internal transfer functions are generated by the methodof the dyadic Green’s functions, the method of the scalar wave functions and thatof the potential functions, respectively. The equivalence among these three kinds ofexpressions is proved. We still use the method of the potential functions to obtainexpressions of the external transfer functions for obtaining the scattered electromag-netic feld outside the cavity with apertures. In order to determine the equivalentcurrents on the aperture, the equivalent magnetic dipole method is developed forthin aperture, while the triangular and pulse functions method is developed for thickaperture. Consequently, the transfer formulation between the external and internalfeld is obtained. Numerical comparisons are given to demonstrate the validity ofthe method of transfer functions.3. For aperture coupling problems of a single layer rectangular shielding cavityand a two-wire transmission line inside it, the terminal responses are estimated bytwo methods. One is the Agrawal coupling model method of the aperture to trans-mission line coupling based on the transfer functions. Another is the network BLT equation method of the aperture to transmission line coupling based on transmissionline topological networks. Numerical examples are given to demonstrate the valid-ity of the Agrawal coupling model method and that of the network BLT equationmethod.4. For aperture coupling problems of a double layer rectangular shielding cavityand a two-wire transmission line inside the inner cavity, two methods are proposedto compute the terminal responses including the methods of EMT1and EMT2,based on the transmission line topological network. EMT1involves the network BLTequation, the internal coupling feld inside the inner cavity and the Agrawal couplingmodel to compute the terminal responses of the line in the inner cavity. EMT2usesone network BLT equation to calculate the response voltages at one point in theouter cavity and another network BLT equation to compute the terminal responsesof the line inside the inner cavity. Simulation results based on these two methodsare in close agreement.5. Electromagnetic interaction of an empty multiaperture rectangular cavityand that of a muliaperture rectangular cavity and a two-wire transmission line in-side it are investigated. The linear superposition method based on the transferfunctions and the multistep iterative algorithm based on electromagnetic topologyare proposed.