Resonant mode limitations with the Wheeler method of radiation efficiency measurement

The measurement of the radiation efficiency of electrically small antennas or those containing dissipative loading is not straightforward. Various methods for doing it have been presented in the literature but some are more practicable than others. An interesting approach known as Wheeler´s method (1947) is outlined and some results obtained when using it are presented. Of particular significance is the presence of resonant modes which adversely affect the measurements. The method is suitable for the indoor testing of small antennas and offers scope for further development