FR2497003A1 - Passive tethered radar reflector - uses inflated aerofoil coated with metallic surface to reflect electromagnetic rays and has blade structure for wind stability - Google Patents

Abstract

The passive radar reflector includes a container housing a cylinder of compressed gas. This is connected via a valve and pressure controlling assembly to an inflatable envelope. The envelope is folded within the container, but may be released under the pressure of the gas from the cylinder. A line restraining the unfolded envelope is attached to a drum. The envelope is made of flexible material coated with a metallic layer, and when inflated forms an aerofoil structure. When tethered by the line at an appropriate angle, the aerofoil is held up by the wind. The aerofoil is released automatically when it is fully inflated, using the differential pressure effect inside the aerofoil envelope. The arrangement can be used in light dinghies for transmission of distress signals.

Description

 The present invention relates to devices of the "radar reflector" type, making it possible to cause the echo of a beam of electromagnetic waves.

 The efficiency of conventional reflectors depends on the possibilities of their users to install them high enough to enter the radar field. The need to support these reflectors by rigid means, limits the possible height of their installation. Such devices become totally ineffective in the event of dismasting or capsizing of a boat, and are not suitable for conventional survival equipment such as inflatable boats or life jackets. Other means are known for tracking, such as radio transmitters, energy consumers, or flares, whose effect is limited in time.

 The reflector according to the invention makes it possible to avoid these drawbacks, and to extend the use of research by ra dar detection. It is in fact designed so that its optical or radar visualization is done at an altitude sufficiently high to escape masking. -relief. On the other hand, its packaging in reduced volume and its simplicity of implementation make it an inconvenient accessory for the user.

 The reflector is an inflatable structure, made of metallized flexible material, maintained at altitude by ballooning, connected to the user by a rope secured to a packaging and filling assembly.

 According to a first variant, the means of implementation is.

manual, therefore requiring user intervention.

 According to a second variant, the means of implementation is associated with a trigger adapted to the use of the wearer and to the environment in which he operates.

The attached drawing 1/4 represents all the equipment not in use, when the means of implementation is manual
The attached drawing 2/4 shows the ejection connector G.

 The attached drawing 3/4 shows the inflatable casing 4 in service, and the action of the nozzles with which it is provided.

 The attached drawing 4/4 shows the reflector in service, fitted to a lifeboat.

 As shown in drawing l / 4, the entire equipment includes a packaging envelope 1 and its means of attachment to the user, a compressed gas cartridge 2, a tap 3 controlling the filling of the casing 4, by means of a regulator 5 and a set of ejectable fittings 6. The rope T ensuring the connection between the casing 4 and the user, is wound on the reel 8.

 As shown in drawing 2/4, the electrical connection 6 operates by pressure difference. The pressure exerted on the piston 10 by the non-expanded gas, passing through the orifice i, causes the clamp t2 to be tightened. This ensures the positioning of the filling connector of 11 casing 4 on the expanded gas inlet 9. The expanded gas- exerts a pressure opposite to the previous one passing through the orifice BI At the end of filling, the gas pressure , previously dosed in quantity, decreased in k, and balances the pressure applied at B. The spring tt then causes the piston tO to recede, thus controlling the opening of the clamp 12 which releases the filling connection from the casing 4. From then on, this one gains altitude until the wire X is completely unwound.

As shown in the drawing 3/4, the casing 4 includes a nozzle system making it possible to cause a reaction tending to limit the inclination of the reflector under the effect of the wind
As shown in drawing 4/4, the reflector in service has a large reflecting surface, at an altitude sufficient to be viewed by a radar fitted to an airplane or a ship.

 The device which is the subject of the invention can be used in all cases where the climatic conditions, at night, the large extent of a research area, make them long and difficult. Let us cite in particular the oceans, deserts, snow-covered areas, regions with uneven relief or dense vegetation. It is additional equipment particularly suitable for inflatable boats, life jackets, light boats.

Its use can also relate to aircraft forced to a forced landing, land vehicles immobilized or lost, as well as all objects whose research is of particular interest.

Claims (4)

 1. Passive radar reflector associated with a conditioning and filling assembly, characterized in that the reflecting envelope (4) is an inflatable, captive structure, maintained in altitude by aerostation.  2. Reflector according to claim t, characterized in that the envelope (4) is made of metallized flexible material.  3. Reflector according to claim 1, characterized in that the casing (4) is provided with a nozzle system ensuring its maintenance in altitude under the effect of the wind.  4. Reflector according to claim t, characterized in that the release of the envelope (4) is done automatically as soon as its filling is completed, by means of an anne ze device (6) using the differential pressure effect.