Impedance Method for a Shielded Standard Loop Antenna

A new measurement method for magnetic antenna factor, called the impedance method, is applied to the calibration of a shielded standard loop antenna. Generally, the magnetic antenna factor is defined in the far-field condition. However, it is difficult to realize the far-field condition when the electromagnetic wave is generated by electrically small antennas in a frequency range below 30 MHz. Although some methods have been proposed earlier, they present difficulties. It is possible to obtain the magnetic antenna factor of an electrically small loop antenna from Faraday's law and the input impedance of the antenna. In this paper, a comparison is made between a numerical simulation and experimental results. It shows that the impedance method is simple and efficient for calibrating a standard loop antenna