Applications of probe-compensated near-field measurements

The fundamental theoretical aspects of near-field measurements are examined. The Lorentz reciprocity theorem is the basis for the calculation of the output of any reciprocal receiving antenna. The theorem is applied to relate the output of a probe receiving antenna to the mode amplitudes in the modal expansion of any fields which are incident upon it. By recording the electrical output of the probe as it moves over some predetermined surface in the near field of a test antenna, the mode amplitudes in the expansion of the field radiated by the antenna can be calculated. The two-dimensional complex vector far-field pattern of the test antenna can be determined on the basis of these mode amplitudes. Attention is given to the planar measurement surface, the cylindrical measurement surface, the spherical surface, aspects of probe characterization, measurement systems and procedures, and approaches of data reduction.