The Impedance of the Guyed Quarter Wave Monopole

Measurements to determine the effect of metallic guy wires on the input impedance of a quarter wave monopole over a ground screen are described. Impedance data from several existing AM broadcast towers has shown great variation from the theoretical value for a monopole over an ideal ground. Experimental results show that in the commonly used configuration, the guy wires have a significant effect that is not easily predicted by present techniques. In addition, it is shown that taking the "base capacitance" into account greatly improves theoretical results obtained with moment methods.