Communications: radio wave antennas – Antennas – With means for moving directive antenna for scanning,...
Reexamination Certificate
1999-05-07
2001-03-06
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With means for moving directive antenna for scanning,...
C343S765000, C343S839000, C343S882000
Reexamination Certificate
active
06198452
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to radio frequency (RF) antennas, and particularly to a positioner or gimbal assembly for an antenna mounted to a platform subject to submarine motion such as a ship, submarine, or the like.
Millimeter-wave RF antennas intended for use aboard ships or submarines, or on similarly moving platforms face extraordinarily severe operating requirements and constraints including limited allowable swept volume, complete hemispherical coverage under significant platform dynamics, very strong/rigid gimbal structure and high radio frequency (RF) performance (e.g., effective isotropic radiated power (EIRP) and gain-to-noise-temperature-ration (G/T)). Because of the severe attenuation of practical, millimeter-wave, high-power transmission line technologies, the need for higher EIRP performance from relatively small diameter apertures has driven placement of the antenna's millimeter-wave RF power amplifier unit as close to the feed input port as possible. The size and weight of such devices, together with the desire for multi-frequency band operation, have led to a strong desire for a positioner that has the ability to accommodate relatively heavy loads on its axis. Thus, the necessity of intersecting gimbal axis driven by the need for minimum swept volume forces normal, 3-axis gimbal configurations using orthogonal axis into geometrical arrangements which significantly decrease the effective antenna aperture in order to withstand the imposed loading requirements.
Accordingly, a goal of the present invention is to provide a positioner for a compact millimeter-wave RF antenna mounted on a rapidly moving platform which provides accurate pointing of a narrow beam radio frequency (RF) radiating assembly to provide complete hemispherical coverage within a confined volume (i.e., a minimum swept volume).
SUMMARY OF THE INVENTION
The present invention is directed to a novel positioner (or gimbal assembly) for compact RF antennas suitable for mounting to platforms subject to submarine motion. The positioner provides accurate pointing of a narrow beam radio frequency (RF) radiating assembly [hereinafter antenna assembly] to provide complete hemispherical coverage under significant platform dynamics. The positioner is comprised of a first axis assembly supporting the antenna assembly, which is configured to rotate the antenna assembly about a first axis. A second axis assembly supports the first axis and antenna assemblies and is configured to rotate the antenna assembly about a second axis. A third axis assembly supports the antenna assembly and first and second axis assemblies, and is configured to rotate the antenna assembly about a third axis. The axis assemblies are arranged so the first, second and third axis are non-orthogonal and intersect at the approximate geometric center of the antenna assembly allowing continuous and independent rotation of the antenna assembly about each axis within a confined volume. This allows the diameter of the radiating aperture (i.e., the antenna's reflector) to be maximized for a given minimum swept area.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.
REFERENCES:
patent: 4251819 (1981-02-01), Vickland
patent: 4516128 (1985-05-01), Watanabe et al.
patent: 4598297 (1986-07-01), Hawkins
patent: 4994816 (1991-02-01), Kondo
patent: 5419521 (1995-05-01), Matthews
patent: 5945961 (1999-08-01), Price et al.
Beheler Carl M.
Grona William H.
Eppele Kyle
Jensen Nathan O.
O'Shaughnessy J. P.
Phan Tho
Rockwell Collins, Inc.
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