An Accurate Representation of the Complete Electromagnetic Field in the Vicinity of a Base-Driven Cylindrical Monopole

An accurate numerical representation of the electromagnetic field in the near zone of a cylindrical monopole oriented perpendicular to a highly conducting ground screen and driven at its base is needed for use in calibrating field strength measuring equipment. The fields H¿(p,z), Ep(p,z), and Ez(p,z) are given by different integrals. The integrands are formed by multiplying the current distribution Iz(z) by certain derivations of K(p, z ¿ z´) = e-jßR/R taken by hand, where ß is the radian wavenumber and begin{equation*}R = sqrt{(z - z^prime)^2 + p^2}.end{equation*}. Alternatively, the integrands may be constructed by multiplying K(p,z - z´) by certain derivatives of Iz(z). The current Iz(z) is obtained by solving an integral equation with feedpoint correction employing a linear zoning technique. Generally speaking for a tubular monopole, the current may be obtained to any desired accuracy, and, of course, it is bounded at the driving point. The integrands are then formed, and the resulting integral expressions for the fields are evaluated using a digital computer. By this means it is felt that accurate numerical values of the fields H¿(p,z), Ep(p,z), and Ez(p,z) in the vicinity of the monopole are found, excluding observation points near the feedpoint and end of the radiator. A brief discussion of the methodology employed in programming the Chang theory is presented.