ABSTRACT
There are many transmission lines located in an electronic system. If the system is well shielded, the internal transmission lines may not be affected by the external excitation; however, all systems must have imperfections in the shielding. The apertures are needed for such various reasons as input and output connection, ventilation panels, etc. An external electromagnetic (EM) source produces an incident field that penetrates through the aperture into the system interior, where it couples to the Transmission Line (TL). Their effect is to induce currents and voltages on the line and in the load impedances at the ends. Generally, the behavior of the induced responses can be evaluated using EM scattering theory and coupling theory. However, in many cases of practical interest, fast network BLT equation that provides approximation is sufficient. To provide some advice for EMC design of equipments and systems, it is necessary to compute the induced load responses of transmission line inside a rectangular cavity with a rectangular aperture by an incident EM field and analyze the influence of the transmission line currents on the shielding effectiveness.
