The Use of the Lorentz Reciprocity Theorem to Prove Equality of the Open-Circuit Voltages of a Receiving Dipole and a Monopole

A common error is made by antenna engineers in the calculation of the load current in monopole (and slot) receiving antennas. The mistake is to assume that the open circuit voltage at the terminals of the monopole is precisely one-half the open-circuit voltage of the equivalent dipole. It is shown in this paper by physical reasoning, as well as analytical argument, that the open-circuit voltages of both structures are identical. It is particularly important in dealing with receiving antennas over a ground plane not to neglect the image source that effectively doubles the field acting on the receiving configuration.