Symmetries, Images, and Dielectrics

The physical symmetries in a geometry description can be used to reduce the number of variables required for a given resolution model. Because of the physical and voltage symmetries of the geometry description, there is no need to include the extra equation to guarantee charge neutrality. The modeling procedure using images for the stripline and microstripline transmission lines is useful in that it produces numbers for the characteristic impedance and the line end fringing capacitance and allows us to model junctions of dissimilar lines. Any of the stripline or microstripline models (both without and with a dielectric) described in this chapter, especially the very high resolution of the two-dimensional cross-sectional calculation, can be used to examine the charge profile on the line(s). For a given material system and a given allowed cross-sectional area of the line, the power loss can be minimized by minimizing current bunching.