Accession Number:

AD0600480

Title:

GENERALIZED COHERENCE THEORY.

Descriptive Note:

Scientific rept. no. 3,

Corporate Author:

HUGHES AIRCRAFT CO CULVER CITY CALIF

Personal Author(s):

Report Date:

1964-03-01

Pagination or Media Count:

94.0

Abstract:

Current coherence theory applies primarily to ergodic fields generated by uncontrolled sources. In communications, radar, etc., controlled sources predominate since they are essential to the operation of such systems. Coherence concepts must therefore be extended to include nonstationary, controlled sources. The theory developed in this report applies to any type of process of source. It is shown that the coherence properties of electromagnetic waves bear a direct relationship to their information carrying capacity. Thus a maximum information transfer can only be accomplished by means of a coherent field. The coherence function is defined as a space-andtime averaged correlation function between field strengths at two points in a 4-dimensional spacetime domain. The field is defined as coherent when the coherence function is a periodic function of an increment in the space-time coordinates. The field is defined as incoherent when the coherence function is zero. If the coherence function satisfies neither of these conditions, the field is partially coherent. A number of examples are worked out of the coherence properties of monochromatic and polychromatic waves emitted by either point sources or extended objects. The effect of aperture limitation on the coherence properties of the image of the above sources is also investigated. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE