Novel techniques of avoiding dips of radiation efficiency measured by improved Wheeler method

Novel techniques to exclude the dips in the estimated efficiency for the improved Wheeler method are proposed and examined: one is statistic approach for the magnitude of the reflection coefficients; the other uses the cross-ratio for four points along the circle on the reflection coefficient plane. These techniques are still valid to extract the reflection coefficient of the antenna with the resistor at the cavity resonance because they are useful for the circle off the origin on the reflection coefficient plane. Although the results for monopole antennas near a wave absorber and so on are not shown in this paper, due to the space limitation, however the two techniques can work well to remove the effects of the cavity resonance from the estimated efficiency.