Reduction of drift error of a network analyser in small antenna measurement

The radiation resistances of electrically small antennas are precisely measured on the basis of the Wheeler cap method, reducing drift error, which is due to thermal fluctuation of components of a network analyser, by using a double-stub tuner. For the first time in antenna measurements, quantitative consideration of the reduction of the drift error for the network analyser is conducted. Also, time fluctuation of the drift error is characterised with a vector diagram to find an effective method for the drift error reduction. As a result, the measurement precision of the antenna with a very large input reactance (more than 180Ω in its absolute value) is considerably improved using the stub tuner