Accession Number : ADD013681

Title :   Apparatus for Scanning and Measuring the Near-Field Radiation of an Antenna.

Descriptive Note : Patent, filed 6 Nov 85, patented 3 Nov 87,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Poirier, J L ; Yaghjian, Arthur D

Report Date : 03 Nov 1987

Pagination or Media Count : 9

Abstract : Apparatus for measuring the near-field radiation of an antenna such that its far-field radiation characteristics can be determined. The invention utilizes the principle of the Foucault pendulum. It uses a bob attached to a long pendulum arm that is free to rotate. Rotation of the earth causes an apparent rotation of the swing plane of the pendulum with a period of T=24/sin(latitude). By attaching a field sensing probe to the pendulum bob and mounting the antenna under the Foucault pendulum, the entire antenna aperture can be scanned without moving the antenna. The motion of the probe covers part of an external sphere centered at the pivot point of the pendulum and having a radius equal to the length of the pendulum. Appropriate transformation of the measured near-field data gives the far-field radiation pattern.

Descriptors :   *ANTENNA APERTURES, *FAR FIELD, *NEAR FIELD, *PATENTS, *RADIATION, *RADIATION PATTERNS, DETECTION, EARTH(PLANET), EXTERNAL, MOTION, PENDULUMS, PIVOTS, PROBES, ROTATION, SPHERES

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE