THE INTEGRAL EQUATION FOR THE CURRENT IN A THICK TUBULAR ANTENNA
HARVARD UNIV CAMBRIDGE MA CAMBRIDGE
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The conventional integral equation for the current in a cylindrical antenna is not correct for a tubular antenna when driven by an emf maintained in a narrow circumferential region along its outside surface. The basic electromagnetic theory of the doubly-connected region represented by such an antenna is reviewed. It is shown that the scalar potential and the normal derivative of the vector potential must be discontinuous across the air cylinder within the tube and that this discontinuity contributes an additional term to the integral equation. This term is negligible for electrically thin antennas but of major importance in determining the current and admittance for antennas that are electrically thick.