A simplified expression for the self/mutual impedance between coplanar and parallel surface monopoles

A simplified expression that is valid both for the self-and mutual impedances between two coplanar and parallel piecewise sinusoidal (PWS) surface monopoles is presented. In contrast to the currently existing two-dimensional integral form, the present expression involves only a one-dimensional integral. Further, the integrand remains regular even for the case of self-impedance and does not involve any special functions such as the exponential integral. It is in a form suitable for efficient implementation on a computer. The expressions are valid when the two surface monopoles are of the same size. Comparison is made with literature to demonstrate the validity of the expression.