Figure 2 shows the models of rectangular waveguides with the capacitive window or the inductive window inside and the equivalent lumped element circuits.
Through a q length of transmission line from the aperture to the capacitive window or inductive window, the equivalent source and source impedance are given by
For the case of capacitive window shown in Figure 2(a), [Z.sub.w] = [Z.sub.c]; for the case of inductive window shown in Figure 2(b), [Z.sub.w] = [Z.sub.j].
Figure 3 and Figure 4 show the shielding effectiveness of the enclosure with a capacitive window and an inductive window, respectively.
Figure 5 shows the shielding effectiveness of an empty enclosure and enclosures with a capacitive window or an inductive window when [d.sub.c]/b = [d.sub.i]/a = 1/2 with the method of TLM.
It can be seen in the Figure 8 that for the enclosure with a inductive window, the resonant frequency is getting higher when q is getting larger.
The present method can also be used in the condition in which the enclosure has both capacitive and inductive windows. Figure 12 shows the equivalent circuit mode of the enclosure with an inductive window and an capacitive window.
The capacitive window lowers the resonance frequency while the inductive window enhances the resonance frequency, and the inductive window has a greater effect on the value of shielding effectiveness and resonance frequency.
In this paper, capacitive windows and inductive windows in the enclosure are considered as lumped elements, and their effects on shielding effectiveness are presented with the method of TLM.
The equivalent impedance of the inductive windows is given by
The Effects of Capacitive Windows and Inductive Windows