Luneberg lens antenna with multiple gimbaled RF feeds

A Luneberg lens has a plurality of feeds arranged to send and receive signals to and from a plurality of satellites. The lens is spherical and is fixedly supported on a support mount. Also supported on this mount are a plurality of arcuate positioner tracks which form arcs parallel to the surface of the lens. Each of the feeds is mounted on a separate one of these tracks. The tracks are supported on the mount for separate pivotal motion along separate paths equidistant from the surface of the lens about a "y" axis relative to the lens. A motor is coupled to the drive of each of the tracks to pivotally drive its associated track in response to control signals. The feeds are mounted on the tracks for motion in paths about an "x" axis relative to the lens, such paths being equidistant from the surface of such lens. A motor drives each of the feeds in response to control signals along separate paths parallel to the lens surface. The feeds thus can be separately positioned about the lens surface along mutually orthogonal paths in response to control signals over a wide range. This facilitates continuous communication as the direction of a satellite from the site changes by utilizing two satellites simultaneously so that when one goes out of sight, the other can be used to continue communications.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to antennas utilizing Luneberg lens in conjunction
 with a plurality of feeds for communicating with satellites and more
 particularly to a device for separately positioning each of the feeds
 relative to the lens.
 2. Description of the Related Art
 The use of a Luneberg lens in conjunction with multiple feeds for
 communicating with satellites is well known in the art. Luneberg lenses
 which have an arcuate surface and are either spherical or cylindrical to
 provide wide angle scanning. With a point source located on the surface of
 the lens the lens transforms the spherical wave into a plane wave with the
 propagating vector aligned along the diameter of the lens passing through
 the feed point.
 The use of a Luneberg lens has the advantage of providing a wide field of
 view. In addition, a single such lens can be utilized with a plurality of
 feeds, each arranged relative to the lens to simultaneously provide
 communication with a satellite at a different angle from the
 communications site. Thus, when one satellite disappears from view, the
 other can be utilized to continue communications.
 The use of a Luneberg lens with a plurality of feeds for use in a radar
 system is described in U.S. Pat. No. 4,531,129 issued Jul. 23, 1985 to
 Bonebright, et al. In this system, a single axis of movement for a
 plurality of feeds is described. There is no suggestion of motion of these
 feeds about a second axis. This limits the tracking ability of the feeds.
 In addition, in Bonebright, the Luneberg lens is rotated which requires an
 additional drive system.
 SUMMARY OF THE INVENTION
 The system of the present invention uses a Luneberg lens having a plurality
 of feeds each for simultaneously communicating with a separate satellite
 at a different orientation relative to the communications site. The lens
 is fixedly mounted on a support mount. Also mounted on the support mount
 are a plurality of similar arcuate tracks which run parallel to the
 surface of the lens. A separate feed is mounted on each of such tracks for
 positioning on its associated track along an "X" axis relative to the
 lens. A motor is provided to drive each of the feeds along its track to
 any position therealong in response to control signals. The tracks are
 mounted for pivotal motion movement along a "y" axis relative to the lens
 and are each separately driven by a motor in response to control signals
 to any position along this axis.
 The feeds thus can each be separately positioned to a location along
 mutually orthogonal paths to track a separate satellite in response to
 control signals. Communication with separate satellites can be achieved
 simultaneously so that when one satellite goes out of sight, communication
 is not interrupted but continued through another satellite.
 It is therefore an object of this invention to provide an improved
 satellite communications system.
 It is a further object of this invention to enable the continuous
 communication through satellites by employing a Luneberg lens having a
 plurality of feeds which are separately positionable about "x" and "y"
 axes relative to the lens.
 Other objects of the invention will become apparent in view of the
 following description taken in connection with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION
 Referring now to the Figures, a preferred embodiment of the invention is
 illustrated.
 Spherical Luneberg lens 11 is fabricated of a dielectrically non
 homogeneous material with the dielectric constant varying from 2 at its
 center to 1 at the RF feed interface along its surface. The lens is
 fixedly supported on support mount 15 by means of posts 14 which are
 fixedly attached to support arms 15 of the mount. The lens could also be
 held in place by a post or other support from underneath to minimize
 signal blockage, if so required. RF feeds 12 and 13 operate to receive or
 transmit either linearly or circularly polarized signals focussed from the
 lens, these signals being amplified and converted to an intermediate
 frequency(IF)) by techniques well known in the art. Additional RF feeds
 can be employed, this depending on the application involved. The two feeds
 12 and 13 are mounted in mutually orthogonal relationship on tracks 16 and
 respectively. The feeds are supported for motion along their associated
 tracks by means of wheels 23 which engage the tracks and are capable of
 rolling therealong. Feed 12 is driven along track 16 by means of motor 18
 in response to a control signal while feed 13 is driven by means of motor
 21 in response to a separate control signal along its associated track 19.
 The two feeds are thus positioned as may be required along a curved "X"
 path opposite the surface of the Luneberg lens.
 The two feeds are separately positioned along a curved "Y" path (normal to
 the "X" path) by means of motors 17 and 20 which are each driven in
 response to a separate control signal.
 Motor 17 rotatably drives pulley wheel 24 which in turn drives pulley line
 25. Line 25 drives shaft 26 which is rotatably mounted on post 14 and
 fixedly attached to sleeve 27 which is also mounted for rotation on post
 14. The opposite end of track 16 is fixedly attached to sleeve 29 which is
 mounted for rotation on post 14. The track 16 is fixedly attached to shaft
 26 and rotates therewith. Thus, the motor drives track 16 vertically(along
 a "Y" axis) about lens 11 in response to a control signal fed to the
 motor. Track 19 is similarly driven by motor 20 which drives pulley wheel
 30 and through line 31 drives shaft 32 which is fixedly attached to one
 end of the track and mounted for rotation on post 14. The opposite end of
 track 19 is rotatably supported on post 14. Thus, each of the tracks can
 be independently driven vertically and horizontally( along "X" and "Y"
 axes) in response to control signals.
 The feeds thus can be separately positioned for communication with
 different satellites or other sites along different axes "Z" running from
 the center of the lens "O" such that continuous communication can be
 maintained when one of the satellites disappears from line of sight. The
 antenna system of the invention can also be utilized in conjunction with
 additional tracks and feeds for additional satellite communications
 utilizing a single Luneberg lens. This antenna system could also be used
 in conjunction with a radar system.
 While the invention has been described and illustrated in detail, this is
 intended by way of illustration and example only, the scope of the
 invention being limited by the terms of the following claims.