Contactless Method to Estimate Antenna Efficiency in a Reverberation Chamber

Measuring the efficiency of electrically small antennas (ESAs) and integrated antennas (IAs) is challenging, since for ESAs, the probe may significantly affect the results and for IAs, establishing a connection with the IA is in many cases not possible. Therefore, a contactless method to estimate the efficiency of ESAs and IAs is necessary. This article proposes a novel method to estimate antenna efficiency contactlessly using a reverberation chamber (RC): the contactless efficiency method (CEM). In the CEM, we combine the two-antenna method (TAM) with the contactless characterization method (CCM), to estimate the ${S}$ -parameters contactlessly. To validate the results, the CEM measurements are compared to the measurements of the widely used TAM and for both methods, an uncertainty analysis is performed. Results show a good agreement in the 95% confidence interval between the CEM and the existing connectorized method for both the total antenna efficiency and the radiation antenna efficiency. The uncertainty of the CEM with a 95% confidence level is below 6% for the whole 0.55-1.05-GHz frequency band.