Electric- and magnetic-field strengths in the Fresnel zone of a microradiator formed by an electric and a magnetic dipole

The propagation of electric and magnetic fields and of the Poynting vector in the near zone (Fresnel zone) of an electric dipole, a loop, and a dipole-loop pair is considered. The dimensions of all radiators are much smaller than the radiation wavelength. It is shown that the ideas of the field distribution (polar diagram) in the far zone cannot be applied to the properties of the field in the Fresnel zone. The radiated-power fraction that is absorbed by an object whose electrodynamic properties are close to those of biological media is found at a distance from the radiator to the absorbing object on the order of several millimeters. (c) 2005 Pleiades Publishing, Inc.