Radiation efficiency measurement method for electrically small antennas using radio wave scatterers

The radiation frequency of a small built-in antenna in portable radio equipment could not be measured accurately because of the nearby electric parts and the human body. A description is given of a measurement method taking account of these influences. The authors devise a modified version of the random field measurement (RFM), which is based on the assumption that the cumulative probability of reception should be the same for both the unknown and the reference antennas. This method has an advantage of being able to measure the radiation efficiency including the effects of the human body. Experimental results using the indoor RFM are presented and some inherent problems with this measurement scheme are discussed. An alternate method of using radio wave scatterers surrounding the transmitting antenna is proposed to improve the accuracy of the measurement.<>