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Abstract
A numerical solution to an integral equation is developed (via the moment method) for the current induced on an axially-directed antenna in the presence of an infinitely long, perfectly conducting tube where the antenna can be either inside or outside the tube. The special case of a cylindrical antenna residing coaxially within the conducting tube is treated as is the more general off-axis case. The salient properties of the part of the integral equation kernel due to the presence of the infinite tube are highlighted since this term contains an infinite series of Sommerfeld-type integrals with complicated integrands. Attention is given to the efficient numerical evaluation of this term in light of the various singularities which exist on the path along which the integral is evaluated. Techniques which accelerate the convergence of the series are presented for the case where the antenna is very near the tube's surface. Data for the current induced on the antenna are presented for various cases where the antenna is inside or outside the tube.