Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Reexamination Certificate
1998-08-04
2001-02-06
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
C342S368000, C342S377000, C342S417000, C342S420000, C342S422000, C342S423000, C342S442000
Reexamination Certificate
active
06184830
ABSTRACT:
BACKGROUND OF THE INVENTION
In the past, interferometric direction finding arrays used elements with identical spatial orientation in order to avoid the difficulties associated with polarimetrics. Normally such arrays must have elements with identical orientation since the polarimetric sense of the impinging signal affects the received phase.
This invention allows such arrays to have elements with orientations based on other criteria, such as fitting the elements into an existing space or conforming to surface.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, an algorithmic technique is described which allows antenna arrays that are used for interferometric direction finding to have elements with arbitrary orientation. This technique allows the phase errors associated with non-identical element orientation to be estimated, without explicit knowledge of either the polarimetrics of the array elements or the polarimetrics of the source. It relies upon the fact that there exists a single complex number (herein referred to as &zgr;) which describes the polarimetric interaction, and that this number can be estimated and then utilized to remove the phase component due to polarimetric interaction. It is the recognition of the existence of this number and the fact that it can be calculated which forms the basis of this aspect of the invention.
This invention makes it feasible to incorporate direction finding arrays into articles that could benefit from such arrays, but because of size or shape constraints, were not able to do so. Examples of such articles are cellular and satellite telephone equipment, aircraft and vehicular collision avoidance systems, radars and radar warning systems, guided missiles and homing devices, law enforcement personnel locators, and satellite systems.
REFERENCES:
patent: 5541608 (1996-07-01), Murphy et al.
patent: 5608411 (1997-03-01), Rose
Collins David W.
Gregory Bernarr E.
Lenzen, Jr. Glenn H.
Raytheon Company
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