Measuring the impedance of balanced antennas by an S-parameter method

The input impedance of a balanced antenna is conventionally measured by using a balun that forces opposite currents in each part of the radiator. In this paper, balanced antennas are viewed as two-ports, the S-parameters of which are determined by standard network-analyzer techniques. Simple formulas then lead to the differential input impedance. The method is illustrated by measurements on a dipole antenna, which are compared to the results for monopoles over a ground plane.