GB2189079A

GB2189079A - Corner radar reflector

Info

Publication number: GB2189079A
Application number: GB08407133A
Authority: GB
Inventors: Barry John James; Michael Anthony Mccully
Original assignee: British Aerospace PLC
Current assignee: BAE Systems PLC
Priority date: 1983-04-28
Filing date: 1984-03-19
Publication date: 1987-10-14
Also published as: GB8407133D0; FR2717951A1

Abstract

A corner radar reflector for use as a decoy to attract active radar homing missiles away from an intended target, say a ship, includes an inflatable frame- work or cage formed of three similar intersecting hoops 1, 2, 3 lying orthogonal to one another, and housed within the cage, three square flexible radar reflective panels 10, 11, 12, attached at their corners to adjacent points on respective hoops and lying orthogonally to, and intersecting, one another to form eight corner reflectors. By this arrangement, the inflated reflector tends to float in a given attitude, namely that in which any three hoop intersections lie in a horizontal plane so that the corner reflectors can be positioned within the cage to give a high radar reflection at a chosen angle of elevation. <IMAGE>

Description

SPECIFICATION Corner radar reflector This invention relates to corner radar reflector assemblies particularly, although not exclusively, suitable for use as decoys to attract active radar homing missiles away from an intended target, such as a marine vessel. Accordingly, the reflector assembly has to provide a relatively large radar reflection in order to compete with the radar reflection from the intended target and hence attract the missile. Thus, the assembly is sufficiently large to necessitate it being collapsibie for stowage purposes. Naturally, the assembly needs to be readily deployed so that erection to the operative condition must be possible in a relatively short period of time.

According to the present invention, a corner radar reflector assembly includes a three-dimensional inflatable frame-work comprising, when inflated, three similarly dimensioned intersecting hoops lying orthogonally to one another, three flexible radar reflective panels and attachment means connecting each panel with the frame-work to effect tensioning of the panel, the panels lying orthogonally to one another and intersecting to form corner reflecting regions.

By this arrangement it is found that, when used in a marine environment, the inflated assembly tends to float in a given attitude, namely that in which any three intersecting regions of the hoops lie in a horizontal plane. Thus the corner reflecting regions can be positioned with respect to the frame-work such that a high radar reflection is provided at a chosen angle of elevation.

Conveniently, each panel lies in the plane of, and is attached to, one hoop. In this case, a particular angle of elevation is readily chosen, since the attachment means for any one panel can be placed as desired around the periphery of an associated hoop.

An inflatable corner reflector radar decoy according to the invention is described by way of example with reference to the accompanying drawing.

The decoy is for a marine environment and comprises an inflatable frame-work made from a flexible tubular material. The description and drawing reiate to the decoy in an inflated condition.

Naturally, when in a deflated condition, it is readily stowable in a compact manner. The decoy is shown floating in the drawing.

The frame-work is formed of three hoops 1,2 and 3 lying orthogonally to one another such that they form in effect a spherical cage, each single hoop, e.g. that referenced 1, has intersection regions where it intersects with the other two hoops 2 and 3.

The intersection regions with hoop 2 are referenced 4 and 5, and the intersection regions with the hoop 3 are referenced 6 and 7 respectively. The hoops 2 and 3 have their intersecting regions at 8 and 9 respectively. The interiors of the hoops are in fluid flow connection to facilitate inflation.

It is found that when the decoy floats, it tends to sit in the position illustrated, that is to say, with any three of its intersecting regions in a horizontal plane.

As illustrated, these regions are referenced 5, 7 and 9.

Within the cage formed by the hoops when inflated is located a corner reflector assembly. This, for ease of description, although it may be fabricated in many different ways, can be taken to be formed of three identical polygonal, in this case square, panels 10,11 and 12, of radar reflective material. That panel referenced 10 lies within the plane of that hoop referenced 1, that panel referenced 11 lies within the plane of that hoop referenced 2, and that panel referenced 12 lies within the plane of that hoop referenced 3. Each panel is connected at each of its apices, that is to say its corners by means of a tie 13 to a point on its associated hoop. As illustrated, in the case of square panels, the points of connection are approximately midway between the intersections on each hoop.

The panels intersect one another along lines 14to provide eight corner reflecting regions each having their three adjoining surfaces of square form.

It is found that this shape of adjoining surface for corner reflecting regions provides a high level of radar reflection. Moreover, in the structural sense, it aids tensioning of the panels.

The choice of location of the ties 13 on the hoops ensures that when the decoy is settled in its floating position, some corner reflecting regions are directed at a chosen angle in elevation.

The described assembly is economical in its use of inflating gas and it is therefore rapidly deployable. Moreover, it is relatively easy and therefore cheap to fabricate in quantity.

A suitable material for the inflatable hoops is a rubberised fabric of the type used for life rafts.

Conveniently, the hoops are fabricated from a plurality of straight-sided tubular portions of the rubberised fabric material.

A suitable material forthe panels is a silver coated nylon mesh.

The ties are formed of rubber strip, loops being carried by the corners of the panels and by the hoops to carry the strips.

In the inflated state, a typical decoy is about 5 metres in internal diameter and the diameter of the hoop tubes is about 26 cm. This is found to require two 300 cu.in (4,917 cm3) bottles of compressed gas pressurised at 2,200 p.s.i. (150 ATM) to give full inflation in about 7-8 seconds.

1. A corner radar reflector assembly including a three-dimensional inflatable frame-work comprising, when inflated, three similarly dimensioned intersecting hoops lying orthogonally to one another, three flexible radar reflective panels and attachment means connecting each panel with the frame-work to effect tensioning of the panels, the panels lying orthogonally to one another and intersecting to form corner reflecting regions.

2. A corner radar reflector assembly according to Claim 1, in which each panel lies in the plane of, and is attached to, one hoop.

3. A corner radar reflector assembly according to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Corner radar reflector This invention relates to corner radar reflector assemblies particularly, although not exclusively, suitable for use as decoys to attract active radar homing missiles away from an intended target, such as a marine vessel. Accordingly, the reflector assembly has to provide a relatively large radar reflection in order to compete with the radar reflection from the intended target and hence attract the missile. Thus, the assembly is sufficiently large to necessitate it being collapsibie for stowage purposes. Naturally, the assembly needs to be readily deployed so that erection to the operative condition must be possible in a relatively short period of time. According to the present invention, a corner radar reflector assembly includes a three-dimensional inflatable frame-work comprising, when inflated, three similarly dimensioned intersecting hoops lying orthogonally to one another, three flexible radar reflective panels and attachment means connecting each panel with the frame-work to effect tensioning of the panel, the panels lying orthogonally to one another and intersecting to form corner reflecting regions. By this arrangement it is found that, when used in a marine environment, the inflated assembly tends to float in a given attitude, namely that in which any three intersecting regions of the hoops lie in a horizontal plane. Thus the corner reflecting regions can be positioned with respect to the frame-work such that a high radar reflection is provided at a chosen angle of elevation. Conveniently, each panel lies in the plane of, and is attached to, one hoop. In this case, a particular angle of elevation is readily chosen, since the attachment means for any one panel can be placed as desired around the periphery of an associated hoop. An inflatable corner reflector radar decoy according to the invention is described by way of example with reference to the accompanying drawing. The decoy is for a marine environment and comprises an inflatable frame-work made from a flexible tubular material. The description and drawing reiate to the decoy in an inflated condition. Naturally, when in a deflated condition, it is readily stowable in a compact manner. The decoy is shown floating in the drawing. The frame-work is formed of three hoops 1,2 and 3 lying orthogonally to one another such that they form in effect a spherical cage, each single hoop, e.g. that referenced 1, has intersection regions where it intersects with the other two hoops 2 and 3. The intersection regions with hoop 2 are referenced 4 and 5, and the intersection regions with the hoop 3 are referenced 6 and 7 respectively. The hoops 2 and 3 have their intersecting regions at 8 and 9 respectively. The interiors of the hoops are in fluid flow connection to facilitate inflation. It is found that when the decoy floats, it tends to sit in the position illustrated, that is to say, with any three of its intersecting regions in a horizontal plane. As illustrated, these regions are referenced 5, 7 and 9. Within the cage formed by the hoops when inflated is located a corner reflector assembly. This, for ease of description, although it may be fabricated in many different ways, can be taken to be formed of three identical polygonal, in this case square, panels 10,11 and 12, of radar reflective material. That panel referenced 10 lies within the plane of that hoop referenced 1, that panel referenced 11 lies within the plane of that hoop referenced 2, and that panel referenced 12 lies within the plane of that hoop referenced 3. Each panel is connected at each of its apices, that is to say its corners by means of a tie 13 to a point on its associated hoop. As illustrated, in the case of square panels, the points of connection are approximately midway between the intersections on each hoop. The panels intersect one another along lines 14to provide eight corner reflecting regions each having their three adjoining surfaces of square form. It is found that this shape of adjoining surface for corner reflecting regions provides a high level of radar reflection. Moreover, in the structural sense, it aids tensioning of the panels. The choice of location of the ties 13 on the hoops ensures that when the decoy is settled in its floating position, some corner reflecting regions are directed at a chosen angle in elevation. The described assembly is economical in its use of inflating gas and it is therefore rapidly deployable. Moreover, it is relatively easy and therefore cheap to fabricate in quantity. A suitable material for the inflatable hoops is a rubberised fabric of the type used for life rafts. Conveniently, the hoops are fabricated from a plurality of straight-sided tubular portions of the rubberised fabric material. A suitable material forthe panels is a silver coated nylon mesh. The ties are formed of rubber strip, loops being carried by the corners of the panels and by the hoops to carry the strips. In the inflated state, a typical decoy is about 5 metres in internal diameter and the diameter of the hoop tubes is about 26 cm. This is found to require two 300 cu.in (4,917 cm3) bottles of compressed gas pressurised at 2,200 p.s.i. (150 ATM) to give full inflation in about 7-8 seconds. CLAIMS

3. A corner radar reflector assembly according to Claim 2, wherein the panels are polygonal and the attachment means connect the apices of each panel to adjacent regions on a respective hoop.

4. A corner radar reflector assembly according to Claim 3, wherein the panels are quadrilateral, and the panels intersect one another to provide corner reflecting regions having three adjoining surfaces of quadrilateral form.

5. A corner radar reflector assembly according to Claim 4, wherein the panels are square and the regions of connection of the attachment means on each hoop are located approximately midway between the hoop intersections.

6. A corner radar reflector assembly including a three-dimensional inflatable frame-work comprising, when inflated, three similarly dimensioned intersecting hoops lying orthogonally to one another, three flexible radar reflective panels of square form, and resilient attachment means at each corner of each panel connecting with adjacent points on respective hoops approximately midway between the hoop intersections, to effect tensioning of the panel, the panels lying orthogonally to one another and intersecting to form corner reflecting regions, each region having three adjoining square surfaces.

7. A corner radar reflector assembly substantially as described with reference to the accompanying drawing.