Admittance of thin, coaxially-driven infinite monopole antennas

Abstract

The apparent admittance of an infinite monopole antenna, driven by a coaxial line of inner radius "a" and outer radius "b" , is determined for the limit of small values of a/b , where kb « 1 Previous analytical work has determined the apparent admittance for the limit a/b → 1. These two results bracket and demonstrate the validity of earlier numerical work which determined the apparent admittance for 0 < a/b < 1 . The determination of the apparent admittance for a/b → 0 requires the asymptotic solution of an integral equation. In the derivation of the asymptotic solution to the original integral equation, a new and very curious integral equation results. This new integral equation is examined analytically and finally is solved numerically.