An investigation of near-field radiatin patterns measured with large antennas

The plane-wave spectrum concept is used to derive an expression for the radiation pattern of an antenna in a two-dimensional system and an investigation is made of the effect of the aperture size of the measuring antenna on the pattern obtained. It is shown that measured sidelobe levels either above or below the far-field values may be obtained. Measurements of near-field antenna radiation patterns are carried out in a parallel-plate pattern range, and the predicted effects of measuring antennas of finite size on the beamwidth and sidelobe levels of the measured patterns are confirmed experimentally.