Electromagnetic Fields in the Searchlight Beam of Aperture Antennas With the Aperture of a Round Shape

On the basis of the solution of the vector external problem of electrodynamics about the radiating of continuous plane aperture antennas, the amplitudes of the electric and magnetic field strength vectors are calculated depending on the longitudinal and transverse coordinates of the observation points in the near and intermediate zones of the antenna. It is shown that the searchlight beam near the antennas is formed with the aperture dimensions not less than 1 … 1,5 wavelengths In the case of a constant amplitude and phase distribution of the field sources in a circular aperture, the length of the searchlight beam region at the half-power level of the field at the midpoint of the aperture substantially exceeds the distance of the near zone, and at a level of -10 dB almost reaches a distance of half the distance of the far zone.