A Dual-Ported, Dual Polarized Spherical Near-Field Probe

Authors: J. R. Jones

Publication: AMTA 1983

Copyright Owner: NSI-MI Technologies

Spherical near-field testing of antennas requires the acquisition of a great volume of data. In general, to compute the far-field of the antenna under test in any direction requires the acquisition of data at sample intervals related to the size of the antenna under test over a spherical sampling surface completely enclosing the antenna under test. This data must also be sampled as a function of probe orientation. Even for the simplest possible case, two probe orientations (or two probes) must be used.

Acquisition of this much data takes a long time. The requirement that data be acquired as a function of probe orientation is particularly troublesome, since acquiring data for even two probe orientations doubles the time required for data acquisition. In 1979, F. H. Larsen' demonstrated the feasibility of using a dual- polarized, dual-ported spherical near-field probe. Such a probe makes possible the acquisition of spherical near-field data for two probe orientations in a single scan. The development of a broadband, dual-ported, dual-polarized antenna which could be used as a spherical near-field probe was the goal of the efforts reported herein.