Reference Calibration Methods for Small Circular Loop Antenna in Low-Frequency Band

In this paper, we propose two reference calibration methods (RCMs) for small circular loop antennas. Generally, the standard field method is widely employed in loop antenna calibration at many national metrology institutes and calibration laboratories. In this method, a thermocouple is employed as a current sensor on an antenna element of a transmitting loop antenna to calculate the magnetic field strength at an antenna under calibration. This method has certain disadvantages: The standard transmitting antenna is complicated, cumbersome, and fragile. On the other hand, a calibration method is necessary to be reasonably traceable to the standard of the magnetic antenna factor. Our proposed methods can establish and keep traceability to it. We also compare the two proposed RCMs and show that they are efficient in calibrating the loop antennas.