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The paper deals with vectorial and phasorial characterization of electric and magnetic fields in Fresnel zone for a short dipole antenna. As known, in Fresnel zone, these fields have a special behaviour, so that they result in a reactive energy component which flows coming back to the source. This cross-field phenomenon is characteristic to waveguides, reflection and Fresnel zone of radiating systems . The accurate description of the vectors/phasors evolution in the near field zone is very important for calculating both the Poynting vector and the characteristic impedances in this area; also, it is of great importance for studying the interaction between electromagnetic field and substance . The electromagnetic field of an alternating dipole is involved in macroscopic applications (impulse radiation, electromagnetic shielding in Fresnel zone) as well as in molecular theory (polarization and magnetization). On the other hand, the paper may be help for the development of the theory concerning fields of impulse radiating antennas. If spectral analysis used, all the conclusions of the paper may be extended to pulse propagation because each spectral component will propagate according to the same rules . So, the paper should be considered as the first stage of complex theoretical and experimental research, in order to obtain an accurate characterization of electromagnetic radiation in Fresnel zone. |
