Simulated near-field gain of dielectric-coated circular loop antennas operated in liquid and in HF band

To evaluate specific absorption rate (SAR) in HF band using reference antenna method, dielectric-coated and shielded loop antenna operated in the liquid can be used. It is found that the electric and magnetic field intensity in the near-field region of the reference antenna behave like corresponding far-field if the near-field gain have a plateau as a function of the distance from the antenna. To simulate the perimeter of the loop with a plateau in its near-field gain using Richmond´s method of moments, the dielectric property of the cylindrically dielectric shell should be well given by using Lichtenecker´s logarithmic mixture law if the dielectric shell is made of heat-shrinkable tube.