Fringing field of finite parallel-plate capacitors

The effect of finite plate width on the fringing field of a parallel-plate capacitor is determined, and an exact expression is derived for the total capacitance by applying conformal transformation to a finite parallel-plate configuration. With small values of the plate-width/plate-separation ratio, finiteness of plate width is shown to have a predominant effect on the correction factor for capacitance as well as on the fringing field. The analysis is extended to shielded parallel plates and expressions are derived for capacitance and field distribution as functions of shield separation, plate width and plate separation. The effect of shielding on capacitance and fringing field is determined.