Effects of Wheeler cap loss on wideband antenna efficiency measurement results

Recently, Wheeler cap method was extended to measure wideband antennas. This paper presents an investigation on the effects of the loss of wheeler cap on antenna efficiency measurement results. Two caps/cavities (one large and one small) are employed for this study and numerical simulation is also conducted to aid the analysis. Both the experimental and numerical results show the loss due to the imperfection of the cavity can cause a serious problem for obtaining an accurate result. How to eliminate the effects of the cavity loss and improve the measurement accuracy for the wheeler extended method is an issue to be resolved.