Measurement of S-parameters of balun and its application to determination of complex antenna factor

A method to measure the S-parameters of a transformer-type balun is investigated. The two baluns to be measured are regarded as error equivalent circuits in the TRL calibration of a network analyzer. The required conditions for this method are shown, and the errors due to the conditions are estimated. The complex antenna factor (CAF) of a dipole antenna with the balun is determined form the S-parameters measured by the TRL method, and compared with the result obtained by the three-antenna method