Transportable rolling radar platform and system Number:7,183,989 from the United States Patent and Trademark Office (PTO) owispatent

Title: Transportable rolling radar platform and system

Abstract: A transportable platform for a rolling radar array system has a base whereupon a track for an array wheel is provided. A segment of the track can be folded for transportation and deployed when the rolling radar array system is to be in an operational mode. The transportable platform has several adjustable supports for stabilizing and leveling the foldable segment of the track upon which the array wheel revolves as well as the base. The transportable platform may include a hitching element and a pair of wheels for towing and transportation.

Patent Number: 7,183,989 Issued on 02/27/2007 to Tietjen

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Inventors:	Tietjen; Byron W. (Baldwinsville, NY)
Assignee:	Lockheed Martin Corporation (Bethesda, MD)
Appl. No.:	11/197,016
Filed:	August 4, 2005

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	11074495	Mar., 2005	7129901
	10334434	Apr., 2005	6882321
	10119576	Nov., 2004	6812904

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Current U.S. Class:	343/757 ; 343/766; 343/882
Current International Class:	H01Q 3/00 (20060101); H01Q 3/02 (20060101)
Field of Search:	343/757,758,761,766,882

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References Cited [Referenced By]

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	6646616		November 2003		Tietjen
	6753822		June 2004		Tietjen
	6812904		November 2004		Tietjen
	6850201		February 2005		Tietjen
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Foreign Patent Documents

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Other References

"Mechanically-Steered, Mobile Satellite-Tracking Antenna", NTIS Tech Notes, US Department of Commerce. Springfield, VA, US, May 1, 1990, pp. 394, 1-2, XP000137363, ISN: 0889-8464. cited by other . Cauchois et al., "Absolute Locallization with the Calibrated SYCLOP Sensor", pp. 1-14. cited by other . European Search Report dated Aug. 4, 2003 for related European Patent Application No. EP 03252428. cited by other . European Search Report dated Apr. 29, 2004 for related European Patent Application No. EP 03252280. cited by other.

Primary Examiner: Chen; Shih-Chao
Attorney, Agent or Firm: Plevy, Howard & Darcy, PC

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Parent Case Text

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RELATED APPLICATIONS

The present application is a continuation in part of U.S.patent application Ser. No. 11/074,495 filed on Mar. 8, 2005, issued as U.S. Pat. No. 7,134,901 which is a continuation in part of U.S. patent application Ser. No. 10/334,434, file on Dec. 31, 2002, issued as U.S. Pat. No. 6,882,321, on Apr. 19, 2005, which is a continuation in part of U.S. patent application Ser. No. 10/119,576, filed on Apr. 10, 2002, issued as U.S. Pat. No. 6,812,904, on Nov. 2, 2004, the subject matter of each of the foregoing applications incorporated herein by reference in their entireties.

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Claims

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What is claimed is:

1. A transportable platform for use in a rolling radar array system having an array mounted on a first side of a wheel, comprising: a base having a peripheral edge; a first circular track mounted on said base; a second circular track, concentric with said first circular track, having a first segment mounted on said base, and a second segment foldably mounted on said base for moving between a folded position and a deployed position, said second segment extending beyond said edge when in said deployed position.

2. The transportable platform of claim 1, wherein said second segment is hingedly mounted on said base.

3. The transportable platform of claim 1, further comprising a plurality of supports depending from said base and said second segment.

4. The transportable platform of claim 3, wherein at least one of said supports comprises: a longitudinal member; and a flat, load-bearing member attached to a first end of said longitudinal member.

5. The transportable platform of claim 4, wherein said longitudinal member has an adjustable height.

6. The transportable platform of claim 1, further comprising an IFF antenna mounted on said base.

7. The transportable platform of claim 1, wherein said platform further comprises means for folding and unfolding said foldable second segment of said second circular track.

8. The transportable platform of claim 7, wherein said means for folding and unfolding said foldable second segment of said second circular track is a hydraulic mechanism.

9. A radar antenna system, comprising: a radar array mounted on a first wheel, the first wheel having a circumferential portion shaped to engage a first circular track for revolving the radar array about the track, the first radar array having an axis normal to the first wheel, wherein the first wheel rotates about the axis as the radar array revolves around the track during operation; and a transportable platform comprising: a base having a peripheral edge; a second circular track mounted on said base; wherein said first circular track is concentric with said second circular track, and has a first segment mounted on said base, and a second segment foldably mounted on said base for moving between a folded position and a deployed position, said second segment extending beyond said edge when in said deployed position.

10. The radar system of claim 9, wherein said transportable platform further comprises a plurality of supports depending from said base and said foldable second segment.

11. The radar system of claim 10, wherein at least one of said supports comprises: a longitudinal member; and a flat, load-bearing member attached to a first end of said longitudinal member.

12. The radar system of claim 11, wherein said longitudinal member has an adjustable height.

13. The radar system of claim 9, further comprising an IFF antenna mounted on said base.

14. The radar system of claim 9, further comprising a sighting system for verifying the position of said foldable second segment, when said foldable second segment is deployed for operation.

15. The radar system of claim 14, wherein said sighting system is a laser sighting system.

16. A method for providing a transportable rolling radar system, said method comprising the steps of: providing a base having a peripheral edge; laying a first circular track on said base; laying a second circular track on said base, said second circular track being concentric with said first track, and having a first segment mounted on the base and having a second segment foldably mounted on said base for moving between a folded position and a deployed position, said second segment extending beyond said edge when in said deployed position; and mounting a radar array on a first wheel, the first wheel having a circumferential portion shaped to engage a first circular track for revolving the radar array about said second circular track, the first radar array having an axis normal to the first wheel, wherein the first wheel rotates about the axis as the radar array revolves around said circular track during operation.

17. The method of claim 16, said method further comprising the step of providing a mechanism for folding and unfolding said foldable second segment of second circular track.

18. The method of claim 17, wherein said mechanism is a hydraulic mechanism.

19. The method of claim 16, said method further comprising the step of providing a plurality of supports, said supports depending on said base and said foldable second segment.

20. The method of claim 19, wherein at least one of said supports comprises: a longitudinal member; and a flat, load-bearing member attached to a first end of said longitudinal member.

21. The method of claim 16, further comprising the step of providing a system for verifying location of said foldable second segment, when said foldable second segment is unfolded and said first wheel is rotating on said second circular track.

22. The method of claim 16, wherein said system for verifying position of said second segment of said track, when said segment is deployed, is a laser sighting system.

23. A method of using a transportable rolling radar system having an array mounted on a first side of a wheel, said method comprising the steps of: transporting a radar system to a desired location, said radar system comprising: a base having a peripheral edge; a first circular track mounted on said base; a second circular track, concentric with said first circular track, having a first segment mounted on said base, and a second segment foldably mounted on said base for moving between a folded position and a deployed position, said second segment extending beyond said edge when in said deployed position, while said second segment being in folded position during said step of transporting said radar system; moving said second segment to said deployed position; and operating said system such that said wheel rolls about said second circular track.

24. The method of claim 23 further comprising the step of using a plurality of supports to level said foldable segment and said base, at least one of said supports comprising: a longitudinal member; and a flat, load-bearing member attached to a first end of said longitudinal member.

25. The method of claim 23 further comprising the step of using a laser sighting system to verify a position of said second segment with respect to the position of said first segment.

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Description

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FIELD OF THE INVENTION

The present invention relates generally to radar array systems, and more particularly to a transportable platform for radar array systems.

BACKGROUND OF THE INVENTION

Arrays such as RF beam scanning amys and the like are often implemented using large rotating array platforms that revolve the array in the azimuth direction. For example, the platform may rotate so as to slew the array by a predetermined azimuth angle, or to scan the entire range of azimuth angles available to the antenna at a constant angular rate. Traditional approaches to implementing rotating radar array platforms involve the use of a variety of mechanical or electromechanical parts including sliprings for providing array power, and large load-bearing bearings to support the rotating platform. However, these components are subject to significant stress, resulting in mechanical fatigue and ultimately component failure. This of course impacts on the reliability of the platform and overall, on the revolving radar antenna system.

Sliprings are a limiting feature in revolving antenna designs. Commercially available sliprings have limited current transmission capability. This limits the power that can be supplied to a conventional radar array. Future radar arrays may require 1000 amps or more, and may not be adequately supported using sliprings.

Fluid cooling presents another limitation on conventional arrays. Coolant has conventionally been transmitted to radar arrays using rotary fluid joints, which have a tendency to leak.

An apparatus and method for providing a reliable rotating array that is not subject to such component fatigue is highly desired.

There is also a need for a transportable platform upon which a rolling radar system can be transported and deployed at a selected location with a rapid set-up time.

SUMMARY OF THE INVENTION

One aspect of the invention is a transportable platform for use in a rolling radar array system. The transportable platform includes a base having a peripheral edge. A first circular track is mounted on the base. A second circular track, which is concentric with the first circular track, is also mounted on the base. The second circular track has at least one segment rigidly mounted on the base, while at least one more segment is foldably mounted on the base. The foldable segment can move between a folded position and a deployed position. When the foldable segment of the track is deployed, it extends beyond the peripheral edge of the base. In an exemplary embodiment, the foldable segment is hingedly connected with the base.

The transportable platform may include supports depending from the base and the foldable segment of the second circular track. The support has at least one longitudinal member and a flat load-bearing member attached to the longitudinal member. The longitudinal member has an adjustable height.

The transportable radar array platform includes a mechanism to fold and unfold the foldable segment of the track. In an exemplary embodiment, a hydraulic mechanism is used. Other such mechanisms are well-known in the art.

The transportable radar platform may also include a sighting system, such as a laser sighting system, to verify the positioning of the foldable segment of the second circular track, when it is deployed.

The transportable may further include an independently rotating Identify Friend-or-Foe (IFF) antenna.

Another aspect of the invention is a radar antenna system which is transportable. The radar antenna system has a radar array mounted on a wheel. The wheel has a circumferential portion shaped to engage a circular track for revolving the radar array about the track. The radar array has an axis normal to the radar array. The wheel rotates about the axis as the radar array revolves around the circular track during operation. The system includes a transportable platform which has a base having a peripheral edge. A second circular track is mounted on the base. The first circular track, which is concentric with the second circular track, is also mounted on the base. The first circular track has at least one segment rigidly mounted on the base, while at least one more segment is foldably mounted on the base. The foldable segment can move between a folded position and a deployed position. When the foldable segment of the first track is deployed, it extends beyond the peripheral edge of the base.

The radar antenna system may have supports depending from the base and the foldable segment of the first circular track. The support may have at least one longitudinal member and a flat load-bearing member attached to the longitudinal member. The longitudinal member may have an adjustable height.

The radar system may include an independently rotating IFF mounted on the base.

Yet another aspect of the invention is a method for providing a transportable rolling radar system. A base with a peripheral edge is provided. A circular track is laid on the base. A second circular track is laid on the base, such that the second circular track is concentric with the first circular track. A segment of the second circular track is rigidly mounted on the base, while a second segment is foldably mounted on the base. The foldable segment can move between a folded position and a deployed position. When the foldable segment of the track is deployed, it extends beyond the peripheral edge of the base. A radar array is mounted on a wheel, which has a circumferential portion shaped to engage the second circular track for revolving the radar array about the second circular track. The radar array has an axis normal to the radar array. The wheel rotates about the axis as the radar array revolves around the circular track during operation.

The method may include a step of providing a mechanism for folding and unfolding the foldable second segment of the second circular track. In an exemplary embodiment, a hydraulic mechanism is provided. Other such mechanisms are well-known in the art.

The method may further include a step of providing supports, depending from the base and the foldable second segment of the second circular track. The support has at least one longitudinal member and a flat load-bearing member attached to the longitudinal member. The longitudinal member may have an adjustable height.

The method may include a step of providing a sighting system for verifying location of the foldable second segment of the second circular track, when the foldable segment is unfolded and the wheel is rotating on the second circular track. For example, a laser sighting system may be provided.

BRIEF DESCRIPTION OF THE FIGURES

Understanding of the present invention will be facilitated by consideration of the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which:

FIG. 1A is an isometric view of an exemplary radar system according to the present invention.

FIG. 1B shows the radar array of FIG. 1A, covered by a radome.

FIG. 2 is a side elevation view of the assembly shown in FIG. 1A.

FIG. 3 is a perspective view of a first exemplary azimuth drive mechanism for the radar system of FIG. 1A.

FIG. 4 is a side elevation view of the azimuth drive mechanism of FIG. 3.

FIG. 5 is a front elevation view of the azimuth drive brackets shown in FIG. 4.

FIG. 6 is a side elevation view of the azimuth drive brackets shown in FIG. 4.

FIG. 7 is a plan view of the azimuth drive mechanism of FIG. 3.

FIG. 8 is a side elevation view showing a variation of the azimuth drive bracket shown in FIG. 6.

FIG. 9 is a plan view of the drive mechanism shown in FIG. 8.

FIG. 10 is a side elevation view of a second azimuth drive mechanism.

FIG. 11 is a rear elevation view of the radar array shown in FIG. 10.

FIG. 12 is a plan view showing the motor-weight assembly of FIG. 11.

FIG. 13 is a side elevation view showing the motor-weight assembly of FIG. 11.

FIG. 14 is a side elevation view of a variation of the azimuth drive mechanism of FIG. 10.

FIG. 15 shows a detail of the drive mechanism of FIG. 14.

FIG. 16A is an isometric view of an array assembly having a bar code pattern on the axle.

FIG. 16B shows the bar code pattern of FIG. 16A "unwrapped," with zero degrees at the top and 360 degrees at the bottom.

FIG. 17 is a stretched view of the bar code of FIG. 16B, showing the precision attainable with each additional bit of data.

FIG. 18 is an isometric view of an array assembly having an optical encoding disk on the axle.

FIG. 19 is a front elevation view of the optical encoding disk of FIG. 18.

FIG. 20 is a side elevation view of a system including the optical encoding disk of FIG. 19, with an optical reading apparatus and a passive fiber optic link.

FIG. 21 is a front elevation view of the bracket assembly of FIG. 20.

FIG. 22 is an enlarged detail of FIG. 20.

FIG. 23 is a plan view of the assembly of FIG. 20.

FIG. 24 is a cutaway plan view of the optical reader of FIG. 23.

FIGS. 25A 25C show three methods to interface an optical fiber to a conical reflector.

FIG. 26 shows a simplified optical slipring including two conical reflector interfaces of the type shown in one of FIGS. 25A 25C

FIG. 27 is an enlarged view of an optical slipring having many fibers.

FIG. 28 is a simplified electrical-optical slipring that can be used in place of the optical slipring of FIG. 20.

FIG. 29 shows a variation of the system, including a central stationary optical reader for reading the optical encoding disk of FIG. 19.

FIG. 30 shows a another variation of the system, including a second central stationary optical reader for reading the axle mounted bar code of FIG. 16B.

FIG. 31 is an isometric view showing another variation of the system, including a third central stationary optical reader for reading the axle mounted bar code of FIG. 16B.

FIG. 32 is a side elevation view of the system of FIG. 31.

FIG. 33 shows a variation of the system, in which radar array is positioned at the base of a cone or frustum.

FIG. 34 shows a variation of the system, in which the radar array rotates about a track without a platform.

FIG. 35A is an isometric view of the system of FIG. 34. FIG. 35B is an isometric view of an alternative configuration for the system of FIG. 34.

FIG. 36 shows a first transport configuration in which the radar array and track of FIG. 34 are transported on two trailers.

FIG. 37 shows a second transport configuration in which the radar array and track of FIG. 34 are transported on one trailer.

FIG. 38 shows a system having a plurality of rolling axle arrays for multiple frequency operation on a single pair of tracks.

FIG. 39 shows a variation of the system of FIG. 38, in which the multiple arrays have respectively different tracks.

FIGS. 40A and 40B show motion of individual array elements during rotation of the array.

FIG. 41 shows how an array sweeps through an azimuthal angle while a target is in the field of view, forming a virtual aperture.

FIG. 42 is a block diagram of the signal processing for a rolling axle array system.

FIG. 43 shows a variation of a rolling array configuration that can increase the system scanning capabilities and the size of the virtual aperture for a given track radius by employing a three-dimensional array, for example.

FIG. 44 shows geometrical parameters used in motion compensation.

FIG. 45 is a diagram showing the aperture increase ratio as a function of the array tilt angle for various azimuth scan angles.

FIG. 46 is an oblique rear view of a rolling radar array assembly illustrating an electromagnetic drive mechanism according to another embodiment of the invention.

FIG. 47 is a more detailed illustration of an oblique rear view of the electromagnetic drive mechanism of FIG. 46.

FIG. 48 is a plan rear view showing the carriage weight assembly of FIG. 47.

FIG. 49 is a partial side view showing the propulsion principle of the electromagnetic drive mechanism of FIG. 47.

FIG. 50 is a cutaway side view showing a detail of the drive mechanism of FIG. 47.

FIG. 51 is a schematic illustration of a control loop for controlling operation of the electromagnetic drive circuitry of the present invention.

FIG. 52 illustrates a transportable rolling radar array system with segments of the track folded for transportation.

FIG. 53 illustrates a transportable rolling radar system, with segments of the track unfolded, in an operational configuration.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements found in typical array radar systems. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. The disclosure herein is directed to all such variations and modifications known to those skilled in the art.

FIGS. 1A, 1B and 2 show a first exemplary embodiment of a radar system 100 according to the present invention. FIGS. 1A and 2 show the array assembly 110 and platform 150. FIG. 1B also shows a radome 102 covering the assembly 110 and platform 150. The radar system 100 comprises an array assembly 110 and a platform 150. The array assembly 110 includes a radar array 112 mounted on a first circular wheel 114 having a first size S1. In addition to the array 112, the first wheel 114 may contain transmitters, receivers, processing and cooling mechanisms. The first wheel 114 has a circumferential portion adapted to engage a path 152 disposed on a platform 150 for revolving the radar array 112 about the platform. An axle 130 is coupled to the first wheel 114. The wheel 114 rotates about the axle 130 as the radar array 112 revolves around the platform 150 during operation. In a preferred embodiment of the invention, the radar array 112 rotates with the first wheel 114, as both the radar array 112 and the first wheel 114 revolve around the platform 150.

As used below, the terms "rotate" and "roll" refer to the rotation of the first wheel 114 and/or the radar array 112 about a roll Axis "A" (shown in FIG. 2) normal to the radar array, located at the center of the array. The term "revolve" is used below to refer to the "orbiting" motion in the tangential direction of the array assembly 110 about a central axis "B" of the platform 150 (shown in FIG. 1A).

The system 100 includes a means to support the array 112 in a tilted position, so that the axis "A" is maintained at a constant angle.A-inverted. with respect to the plane of the platform 150. In some embodiments, the radar system 100 also includes a second wheel 132 coupled to the axle 130. Preferably, if present, the second wheel 132 has a second size S2 different from the first size S1 (of the first wheel 114). For example, as shown in FIGS. 1A and 2, the second size S2 is smaller than the first size S1, and the second wheel 132 engages a second path 154 on the platform 150. The first and second paths 152 and 154 are concentric circles, so that the radar array 112 is tilted at a constant angle.A-inverted. between vertical and horizontal as it rotates around the axle 130. The first wheel has a flange 118, and the second wheel has a flange 134. The two flanges 118, 134 help maintain the array assembly 110 on the tracks 152, 154 without any fixture locking the assembly 110 in place. This configuration eliminates the need for very large support structures, such as the bearing mounted platform and bracket structures that supported conventional arrays. Without these large support structures, it is possible to eliminate the large load-bearing bearings that lay beneath the support structures. In other embodiments (not shown), instead of the second wheel 132, the end of the axle 130 opposite the radar array 112 can be supported by a universal joint or other means providing an alternative means for supporting the array in a tilted position.

In the exemplary embodiment of FIGS. 1A and 2, the first path 152 and second path 154 are conductive tracks. The circumferential portion of the first wheel 114 and the circumferential portion of the second wheel 132 are conductive. The tracks 152, 154 may be connected to power source 156 to provide power and ground to the radar array 110, similar to the technique used to provide power to an electrically powered train by way of conductive tracks. This mechanism allows the elimination of sliprings used to provide power to conventional radar arrays, which revolve around a platform without rotating around the axis normal to the array front face. The signals from the array can be transferred to by an infrared (IR) link, to improve isolation and eliminate crosstalk, so that sliprings are not required to transfer signals, either.

The exemplary system 100 includes a radar array 112 having just one face on it, but capable of covering 360.degree. of azimuth revolution. This configuration can support a very large and heavy array 112 that is very high powered. Sliding surface contacts are not required. The contact between the first wheel 114 and the first path (track) 152, and the contact between the second wheel 132 and the second path (track) 154 are both rolling surface contacts. In a rolling contact, the portions of the wheels 114 and 132 that contact the tracks 132 and 154, respectively, are momentarily at rest, so there is very little wear on the conductive wheels and tracks. This enhances the reliability of the system. In addition, the wheels 114 and tracks 132 can be made of suitably strong material, such as steel, to minimize wear and/or deformation.

FIGS. 1A and 2 also show a drive train 160 that causes the first wheel 114 to revolve around the platform 150. The drive mechanism 160 is described in greater detail below. A variety of drive mechanisms 160 may be used. All of these mechanisms fall into one of two categories: mechanisms that apply a force to push or pull the array assembly 110 in the tangential direction, and mechanisms that apply a moment to cause the array assembly to rotate about the central axis "A" of the array 112. Both systems are capable of providing the desired rolling action that allows the array assembly 110 to revolve around the platform 150 to provide the desired 360.degree. azimuth coverage.

The example in FIGS. 1A and 2 includes a drive mechanism 160 that pushes against the axle 130 in the tangential direction, causing the array assembly 110 to roll. Other pushing drive mechanisms (not shown) may be used to push against either the first wheel 114 or second wheel 132 in the tangential direction.

Various methods are contemplated for operating a radar system comprising the steps of: revolving a wheel 114 housing a radar array 112 around a platform 150 (wherein the radar array has a front face), and rotating the wheel about an axis "A" normal to the front face, so the wheel rotates as the wheel revolves. The method shown in FIGS. 1A and 2 includes revolving a radar array 112 around a platform 150, the radar array having a front face; and rotating the radar array about an axis "A" normal to the front face as the radar array revolves. Other variations are contemplated.

For example, the wheel 114 may rotate without rotating the radar array 112. The radar array 112 may rotate relative to wheel 114, while wheel 114 rolls around the first track 152 of the platform 150. If the rotation rate of the radar array 112 has the same magnitude and opposite sign from the rotation of the wheel 114, then the radar array 112 does not rotate relative to a stationary observer outside of the system 100. This simplifies the signal processing of the signals returned from the assembly, because it is not necessary to correct the signals to account for the different rotational angle of the array. Rotation of the radar array 112 relative to the wheel 114 may be achieved using a motor that applies a torque directly to the center of the array, or a motor that turns a roller contacting a circumference of the radar array or the inner surface of the circumference of the wheel 114.

Although the example shown in FIG. 1A includes only two wheels 114, 132 and two conductive paths 152, 154 on the platform 150, any desired number of wheels may be added to the axle 130, with a respective electrical contact on the circumferential surface of each wheel, and a corresponding conductive path located on the platform 150. The additional wheels (not shown) would be sized according to their radial distances from the center of the platform 150, so that all of the additional wheels can contact the additional conductive paths (not shown) at the same time that wheels 114 and 132 contact paths 152 and 154. The additional conductive paths may be used to provide additional current sources, to avoid exceeding a maximum desired current through any single electrical path. The additional conductive sources may also be used to provide power at multiple voltages.

FIG. 33 shows another variation of the system 700, including an array assembly in which radar array 112 is positioned at the base of a housing in the shape of a circular cone 715 or frustum 710. In the frustum array assembly configuration 710, the apex section of the cone 715 (shown in phantom) is omitted. The frustum or cone configurations allow the addition of any desired number of contacts 714 on the circumferential surface. Each contact 714 maintains an electrical connection with a corresponding conductive path 752 as the cone 715 or frustum 710 rolls around its own axis "A" and revolves around the axis "B" of platform 750. These configurations can allow a very even weight distribution across the platform 750. The cone 715 and frustum 710 configurations also inherently provide a means for supporting the array 112 in a tilted position.

Depending on the interior design of the cone 715 or frustum 710, the system 700 may or may not have an axle coupled to the radar array 112. The continuous housing of cone 715 or frustum 710 provides the capability to mount components of the radar antenna system 700 to the side walls of the cone or frustum in addition to, or instead of, mounting components to an axle. Further, the cone 715 or frustum 710 may have one or more interior baffles or annular webs (not shown) on which components may be mounted.

Each variation has advantages. Although the cone 715 provides extra room for more contacts 714, the frustum 710 allows other system components to occupy the center of platform 750 such as, for example, a roll angle sensing mechanism, described further below with reference to FIG. 29.

The rotating array has many advantages compared to conventional arrays. For example, maintenance can be made easier. If an array element must be repaired or replaced, the array can be wheeled to a position in which that element is easily accessed. Also, the rotating array has very few moving parts, enhancing reliability. The rolling array assembly 110 has much lower mass and moment of inertia than the rotating platform of conventional revolving radar systems, so the azimuth drive 160 of the rolling array should not require as powerful a motor as is used for conventional rotating platform mounted radars. Also, the azimuth drive assembly does not have to support the weight of the antenna (whereas prior art rotating platform azimuth drives did have to support the weight of both the array and its support). This should improve the reliability of the azimuth drive.

Azimuth Drive

Bullring Gear and Pinion Drive

FIGS. 3 7 show a first exemplary azimuth drive 160 for a rolling radar array assembly 110 of the type described above. Azimuth drive 160 is of the general type in which the array assembly 110 is pushed in the tangential direction. The exemplary drive 160 can either rotate the array assembly 110 with a constant angular velocity, or train the array to a specific desired azimuth position.

Drive 160 includes a rotatable bullring gear 170, including a rotatable ring portion 172 rotatably mounted to the platform 150 by way of a fixed ring portion 171. Bullring gear 170 has bearings 173 for substantially eliminating friction between the fixed portion 171 and the rotatable ring portion 172. A motor 181 having a pinion gear 180 drives the rotatable ring portion 172 of bullring gear 170 to rotate.

At least one bracket portion 162 is coupled to the rotatable ring portion 172. An exemplary support platform for mounting the bracket 162 is shown in FIG. 7. A drive bracket bearing support platform 167 is mounted on a portion of the movable ring portion 172. The at least one bracket portion 162 may include one bracket arm, or two bracket arms connected by a connecting portion 165. Other bracket configurations are also contemplated. The bracket portion 162 pushes in the tangential direction against the array assembly 110 that includes the radar array 112, causing the radar array to rotate about the axis "A" normal to the radar array (as shown in FIG. 4) and revolve about the platform 150 with a rolling motion.

The bracket portion 162 is arranged on at least one side of the axle 130 for pushing the axle in the tangential direction. Although the exemplary bracket portion 162 pushes against the axle 130, the bracket portion 162 can alternatively apply the force against other portions of the array assembly, such as one or both of the wheels 114, 132 or against the conical housing 715 or frustum-shaped housing 710 shown in FIG. 33.

As best shown in FIG. 5, there are preferably two bracket portions 162 with at least one roller 164 on each bracket portion 162. The rollers 164 allow the bracket portions 162 to apply force against the axle 130 with substantially no friction, thus allowing the array assembly 110 to roll freely around the platform 150. In the example, each bracket portion 162 has two rollers 164 mounted on bearings 166, contacting the axle 130 above and below the center of the axle 130. If only a single roller 164 is included on each bracket portion 162, then it may be desirable to position the roller at the same height as the center of the axle 130. In either of these configurations, the resultant force applied by the one or two rollers 164 is applied in the direction parallel to the platform 150 (e.g., horizontal for a horizontal platform). In the two roller configuration of FIG. 5, the vertical force components of the two rollers above and below the axle on each side are equal and opposite to each other, canceling each other out.

In some embodiments (not shown), there may be only a single bracket portion 162 for pushing the axle 130 in one direction. In some cases, this would require the array to rotate by more than 180 degrees to reach an azimuth angle that could be achieved by a turn of less than 180 degrees if two brackets 162 are provided.

As shown in FIGS. 4 and 6, the axle 130 is tilted away from horizontal, and each roller 164 is mounted so as to have an axis of rotation "C" parallel to an axis of rotation "A" of the axle. Also, the bracket portions 162 are preferably oriented in a direction parallel to a face of the radar array 112.

The bracket design of FIGS. 4 and 6 performs well when the center of mass CM of the array is near the brackets 162. However, if the point of application of the force by the brackets 162 on the axle 130 is further from the center of mass, it is possible that a large unbalanced moment would cause the second wheel 132 to lift out of the smaller track 154. Even if the unbalanced moment is not large enough to cause the wheels 114, 132 to lift out of the tracks 152, 154, the unbalanced moment is likely to cause uneven wear of the wheels 114, 132 and/or the tracks 152, 154. For a straight bracket 162 as shown in FIG. 4, the location of the bracket is limited by the availability of a bullring gear 170 of appropriate size to allow the bracket 162 to be mounted proximate to the center of mass CM.

FIGS. 8 and 9 show a variation of the azimuth drive of FIG. 3, wherein the bracket portions 262 are offset from the attachment point to the drive bracket bearing support platform 167. The bracket portions 262 are located at a radial distance from a center of the rotatable ring portion 172 greater than the radius of the rotatable ring portion. This allows the bracket rollers 164 to be positioned near the center of mass CM of the array assembly 110, regardless of the radius of the movable ring 172 of the bullring gear 170. As shown in the drawings, it is not necessary to provide elaborate fixtures to maintain the array assembly 110 on the platform 150.

Offsetting the brackets 262 to apply the force at the center of mass CM as shown in FIG. 8 avoids the application of an unbalanced moment to the array assembly 110. Applying the force at the center of mass CM leaves the wheels 114 and 132 safely on their respective tracks. Because any unbalanced moment is eliminated, there is no need to support or restrain the end of the axle 130 opposite the array 112. The opposite end of the axle 130 can float freely.

The system 100 has an azimuth position control mechanism. An azimuth position sensor 190 is provided. The azimuth position sensor 190 may be, for example, a tachometer or a synchro. A tachometer is a small generator normally used as a rotational speed sensing device. A synchro or selsyn is a rotating-transformer type of transducer. Its stator has three 120.degree.-angle disposed coils with voltages induced from a single rotor coil. The ratios of the voltages in the stator are proportional to the angular displacement of the rotor. An azimuth position/velocity function receives the raw sensor data from sensor 190 and provides the position as feedback to the azimuth drive servo 192. The type of sensor processing function 194 required is a function of the type of sensor used.

The azimuth drive servo 192 is capable of controlling the motor 181 to drive the rotatable ring portion 172 to cause the radar array 112 to revolve about the platform 150 at a constant angular velocity. The servo 192 is also capable of controlling the motor 181 to drive the rotatable ring portion 172 to cause the radar array 112 to revolve about the platform 150 to a specific desired azimuth position.

When the drive mechanism 160 is used to train the array 112 at a specific azimuth position, three general techniques may be used. First, the array can always be moved in the same direction. This approach may cause uneven wear on the teeth of the bullring gear 170 and pinion 180. Second, the array can be moved in a direction that requires the least travel from its current position, so that the array does not have to move through more than 180 degrees. Third, the direction of rotation can alternate each time the array is moved, so that any wear on the bullring gear 170 and 180 is more even.

Reference is again made to FIGS. 4 6. FIGS. 4 6 also show a first exemplary position sensing system, which is described in detail further below in the section entitled, "Angular Position Sensing."

FIGS. 34 37 show another embodiment of the system, in which the array 112 rotates about a track assembly 3400 that is not mounted to a fixed platform. The tracks 3452, 3454 may be free standing, or the tracks may be mounted to a skeletal support frame or truss of any desired height (not shown). Elimination of the platform makes the entire system easy to transport and rapidly deploy in the field.

System 345 includes a plurality of tracks 3452 and 3454. Although only two tracks are shown, the system may include any desired number of tracks. The outer track 3452 and the inner track 3454 are connected by a plurality of frame members or "spokes" 3455. Although six spokes 3455 are shown, any desired number of spokes may be included.

Preferably, any relatively large track (e.g., 3452) comprises a plurality of arc-shaped track sections 3452a 3452d that are separable from each other and separately transportable. Although four sections 3452a 3452d are shown, the track 3452 may be divided into any desired number of sections. Criteria for determining whether a track is divided into a plurality of sections 3452a 3452d, and the criteria for determining how many sections may include size and/or weight. Preferably, each section of the track is sized so that it can be transported in the bed of a standard automotive vehicle, such as a truck, or a trailer. In some embodiments, each section of the track may be sized to be lightweight enough to be handled and lifted by humans without any mechanical equipment. As explained further below in the signal processing section, in some configurations a large track diameter is desired to provide a large "virtual aperture." A large track diameter is easily accommodated, without increasing the size or weight of each arc section, by increasing the number of track sections, and reducing the angle of arc subtended by each arc section.

The track sections 3452a 3452d may be joined using a variety of fastening mechanisms. For example, the track sections 3452a 3452d may have (or receive) pins or bolts 3457 that connect to the spokes 3455. A similar fastening mechanism can be used to attach the spokes 3454 to the inner track 3454. Preferably, the fasteners 3457 are of a type that allows rapid disconnection, so that the track assembly 3400 can be easily disassembled for transport. If additional concentric tracks are included, similar fasteners 3457 can be used at intermediate locations along the length of each spoke 3455.

Optionally, the track assembly 3400 may include means for leveling the first track 3452 and the second track 3454. This allows deployment of the system on non-level terrain, such as in a field or desert. The leveling means may include shims, blocks, or flat support pads 3456. Other leveling means may include jack-stands, mechanical or hydraulic jacks, or other adjustable-height support devices. If the track assembly is to be deployed on a hard (as opposed to loosely packed or granular) surface, the leveling means may be a plurality of adjustable threaded bolts that screw into the bottom of the frame members. Similarly, the leveling means may include casters having threaded rods extending therefrom. The leveling means may include pins or bolts 3457 or other fastening mechanism to attach the track 3452 to the leveling means. If each shim, block or pad 3456 is positioned so as to straddle a pair of adjacent track sections (position not shown in FIG. 34), then the shim block or pad 3456 can be used to join the two track sections together. If the tracks 3452, 3454 are mounted on a skeletal support frame or truss (not shown), the leveling means may be built into the support frame.

FIG. 35A is an isometric view of the system of FIG. 34, deployed. The system may be connected via cables 3460 and 3462, to provide signals and power, respectively. A generator, command and control equipment, and signal processing equipment may be stored in a separate shelter 3461.

FIG. 35B is an isometric view of another exemplary deployment configuration. In FIG. 35B, the equipment shelter 3461 is located inside the track, where protection against own EMI is inherent.

FIG. 36 is a plan view showing a first transport configuration 3600 of the system, including two trucks or trailers 3601, 3602. In the exemplary embodiment, arc section 3452c of the track is transported on truck or trailer 3601 while connected to two spokes 3455 and the inner track 3454. In alternative embodiments, section 3452c, the two spokes 3455 and the inner track 3454 may be permanently fastened as an integral unit, or formed as a single component. In all of these variations, section 3452c, two spokes 3455 and the inner track 3454 fit on a single truck or trailer bed, and the array assembly 110 can optionally be mounted on the track section 3452c for transport. Means for preventing shifting of the array during transport (e.g., blocks, cables, and the like, not shown) are used. In addition, weight may be applied to the bottom portion of the wheel 114 to resist rotation during transport, for example, using the internal gravity drive described below, which is also used during operation to control rotation of the array 112.

The second truck or trailer 3602 carries the remaining arc sections 3452a, 3452b and 3452d, the leveling means 3456, and the frame members 3455. If the track is to be supported on an optional skeletal support structure comprising additional frame members, the additional members can also be transported on the truck or trailer 3602.

FIG. 37 shows an alternative transport configuration 3700, in which the complete system is transported on the bed of a single truck or trailer 3701. In FIG. 37, section 3452c, track 3454 and two spokes 3455 are laid across the remaining track components. Optionally, the bottom surfaces (not shown) of track section 3452, track 3454 and the two spokes 3455 may have grooves or channels shaped to conformably seat on the remaining track components during transport. As in the configuration of FIG. 36, means (not shown) are provided for preventing shifting of the array during transport.

Alternative transport configurations for the deployable track system are contemplated, including those employing one, two or more than two trucks or trailers.

Once the system is transported to the deployment site, deployment is accomplished by leveling the support surface if necessary before laying the track. Leveling can either be achieved by leveling the ground, or by placing the supports (leveling means) 3456 on the surface before laying the first portable track, so there is substantially no vertical or horizontal deviation by the tracks 3452, 3454 from the desired path. If the tracks are to be elevated by a skeletal support frame or truss, the frame is assembled from the frame members. The first portable track 3452 is assembled and laid on the support surface (or the optional skeletal support frame or truss, if present). The spokes 3455 are mounted on the first track 3452. A second portable track 3454 is laid on the spokes 3455, the first support surface or a second support surface, so that the second portable track is concentric with the first portable track. Additional concentric tracks are also assembled at this time, if used. The system is dis-assembled by following the same steps in reverse order. The deployment steps are then repeated each time the system is deployed at a new location.

Although an exemplary order has been described for laying down the components of the portable track, the components may be laid down in other sequences. For example, the second portable track 3454 may be laid down before the spokes 3455 and first track 3452.

The basic principles of a rolling array system are described above in the context of a single array system. Some missions require the use of multiple frequencies. For example, in the National Missile Defense program, a UHF radar is used for initial search and detection, and a separate X-band radar is used for high resolution targeting. This type of mission could be serviced using two separate radar systems.

FIG. 38 shows an embodiment of a multiple frequency rolling array system 3800 having two different rolling array assemblies 110, 110' on a single set of tracks 152, 154, which may be on a platform 150. The second array assembly 110' may be similar to the array assembly 110 described above, including a first wheel 114' containing the radar array 112', axle 130', and second wheel 132'.

Each array assembly 110, 110' rolls around the set of tracks 152, 154 to provide a full 360-degree coverage. Each array assembly 110, 110' has its own radar signal and data processing and drive system. The above described internal gravity drive and servo drive systems provide for the arrays' rotation while preventing them from mechanically interfering with each other.

Although FIG. 38 shows two arrays 110, 110', any desired number of arrays may be placed on an appropriately sized track. In general, as the number of rolling arrays deployed on a single platform 150 or set of tracks 152, 154 increases, it becomes more desirable to use large tracks. By using a single set of tracks 152, 154 and a single platform 150 (if a platform is used), the cost and real estate of the track and/or platform can be reduced to that of a single radar array system. This may be particularly advantageous if a portable rolling radar array system is deployed in terrain that is difficult to clear and/or difficult to level. Additionally, the reduction in the amount of equipment may reduce transportation costs.

Each of the two or more arrays 110, 110' may have a respectively different frequency. Although an example of a system using UHF and X-bands is described above, any combination of frequency bands may be used.

FIG. 39 shows another embodiment of a multiple frequency system, in which the second array assembly 3910 uses a different outer track 3953 from the track 3952 used by array assembly 110. In FIG. 39, both array assemblies 110 and 3910 share the inner track 3954, but in other embodiments, the array assemblies 110 and 3910 may have separate inner and/or outer tracks. In embodiments having more than two array assemblies 110, each array can rotate about a separate outer track. This option may be useful if the tracks 3952 and 3953 are used to transmit different power levels or signals to the respective arrays 112 and 112'.

Although the angle between the normal to the array 112 and the ground may be controlled by varying the diameters of wheels 114 and 132, the use of separate tracks provides an alternative method of controlling the angle between the normal to the array 112 and the ground. As the