Optimum sampling of the near field for the prediction of antenna patterns
Abstract
A method is presented for the determination of the maximum modal spectral bandlimits for cylindrical and spherical wave functions in the radiated field. This development is based on the Dyadic Green's function of free space expressed in the corresponding vector wave functions. An expression is obtained for the wave expansion coefficients for an arbitrary source. An upper limit depending on the maximum radial extent of the source is derived for these coefficients for sources which are square integrable with respect to spacial distributions. The resulting expression for the contribution of each field harmonic to the radiated field is found to be broad banded very close to the source surface. With radial distance from the source, free space attenuates the higher modes so the maximum spectrum becomes bandlimited. The bandlimits are found to approach ka in the radiative fields, particularly for very large antennas.
 Publication:

Ph.D. Thesis
 Pub Date:
 December 1974
 Bibcode:
 1974PhDT........17O
 Keywords:

 Antenna Radiation Patterns;
 Near Fields;
 Fourier Transformation;
 Green'S Functions;
 Harmonics;
 Wave Functions;
 Communications and Radar