1983 Technical Papers

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

Author: J. R. Jones
Publication: AMTA 1983
Copyright Owner: NSI-MIa 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.

Gain Comparison Measurements in Spherical Near-Field Scanning

Authors: Doren W. Hess, John R. Jones
Publication: AMTA 1983
Copyright Owner: NSI-MI Technologies

A set of near-field measurements has been performed by combining the methods of non-probe-corrected spherical near-field scanning and gain standard substitution. In this paper we describe the technique used and report on the results obtained for a particular 24 inch 13 GHz paraboloidal dish. We demonstrate that the gain comparison measurement used with spherical near-field scanning gives results in excellent agreement with gain comparison used with compact range measurement. Lastly we demonstrate a novel utilization of near-field scanning which permits a gain comparison measurement with a single spherical scan.

New Positioners for Antenna Measurements

Author: Pedro E. Amador
Publication: AMTA 1983
Copyright Owner: NSI-MI Technologies

The antenna measurement environment has changed substantially in the past few years. Designers are working with higher frequencies than were practical before and new techniques require both phase and amplitude data for design optimization. This has created new demands for positioner designs. This paper describes how modern mechanical design tools together with modern components were used to develop a now generation positioner for antenna measurement.