Analysis of a Wire Antenna in the Presence of Sphere

An integro-differential equation is formulated for the problem of a thin-wire antenna in the presence of a sphere, and this equation is solved by the method of moments. The analysis is valid for an arbitrarily oriented and positioned wire relative to the sphere which may be either a perfect conductor or may be any simple homogeneous material. Input admittance of the wire antenna near a conducting sphere is determined from computed wire current and is corroborated by measured values of admittance. Also presented are calculated radiation patterns for the antenna/sphere structure.