Admittance of Coaxially Driven Infinite Monopole

The apparent admittance of a coaxially driven infinite monopole is reexamined. Systematic procedures are found to derive the higher-order terms. The first-order terms for both the exact admittance Ya∞ and the approximate admittance YTEM∞ are shown to vanish. The slope of (Ya∞ - YTEM∞) with respect to (b/a-1) is therefore zero as b/a→1. This information is important to bridge the heretofore little understood region between (i) the exactly known limiting value for b/a=1 and (ii) the values for b/a>1 which can be calculated numerically.