Accession Number : AD0782229

Title :   Physical Limitations on Interference Reduction by Antenna Pattern Shaping.

Descriptive Note : Technical note,

Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Personal Author(s) : Mayhan,Joseph T. ; Ricardi,Leon J.

Report Date : 19 JUN 1974

Pagination or Media Count : 42

Abstract : The note addresses the problem of nulling out an interfering noise source by appropriately modifying the antenna radiation pattern. It considers two complementary, one-dimensional antenna structures, i.e., a circumferentially symmetric line source of length a, and an axially independent cylindrical antenna of radius rho sub o. The authors consider first the case of N discrete noise sources and compute the loss in antenna directivity (and subsequent loss in signal/noise ratio) when the radiation pattern is modified so as to place a null at each angular position of the interfering noise source. The results indicate that if all noise sources are outside the main beam, the loss in directivity is negligible. When one or more noise sources are in the main beam, the antenna directivity can be reduced appreciably. It is shown that when uniformly distributed noise is superimposed over the discrete noise, the same antenna pattern maximizes the signal/noise ratio for those practical cases when the discrete noise source power is significantly greater than the uniformly distributed noise source. (Author)

Descriptors :   *RADIO INTERFERENCE, REDUCTION, ANTENNA RADIATION PATTERNS, SHAPE, COMMUNICATION AND RADIO SYSTEMS

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE