Spherical near-to-near, near-to-far- and far-to-near-field transforms: Calculated versus measured radiation distributions in the spherical waveguide

The complete phase/amplitude radiation pattern was measured at three radial distances and where and corresponded to measurements of the radiating near-field region and corresponded to a measurement of the far-field region of the antenna. The usual spherical near-field transformation was applied to the measured data sets to transform numerically between the spherical surfaces at and . Comparison between measured data and numerically transformed data demonstrates the equivalence of the measured radiation patterns corresponding to the three distances and illustrates the concept of the spherical waveguide.