Accession Number : ADP007430

Title :   Focal Arc Pattern Measurements,

Corporate Author : ROME LAB HANSCOM AFB MA

Personal Author(s) : Franchi, Peter R. ; Tobin, Harvey

Report Date : FEB 1992

Pagination or Media Count : 11

Abstract : Problems exist with the measurement of large aperture antennas due to the far field requirement. This paper discusses a new method to measure a phased array at about 1/10 the normal far field. The basic idea involves focusing the test array, at probe, antenna a distance R away from the aperture, and then, measuring an antenna pattern by moving the probe antenna on a constant focal arc given by R cos(Theta). This arc minimizes phase aberrations due to defocusing error. To minimize the amplitude errors, the pattern of the probe antenna is carefully matched in order to compensate for the 1/R variation induced amplitude error. The application of this technique will enable arrays to be measured in anechoic chambers, allowing convenient classified testing, while avoiding the effects of weather, and will reduce the risks inherent in the high power testing on transmit. The results of a computer simulation is presented that characterizes the validity and limitations of the technique.

Descriptors :   *ANTENNAS, *ANTENNA ARRAYS, AMPLITUDE, ANECHOIC CHAMBERS, ANTENNAS, APERTURES, ARRAYS, CHAMBERS, COMPUTERS, CONSTANTS, ERRORS, FAR FIELD, FOCUSING, HIGH POWER, LIMITATIONS, MEASUREMENT, PAPER, PATTERNS, PHASE, PHASED ARRAYS, POWER, PROBES, REQUIREMENTS, RISK, SIMULATION, TEST AND EVALUATION, VARIATIONS, WEATHER, MEASUREMENT, COMPUTERIZED SIMULATION.

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE