WO2008072016A1

WO2008072016A1 - Deployable antenna array

Info

Publication number: WO2008072016A1
Application number: PCT/GB2007/050756
Authority: WO
Inventors: Robert Whitehouse; Micheal Stephen Jessup
Original assignee: Roke Manor Research Limited
Priority date: 2006-12-15
Filing date: 2007-12-13
Publication date: 2008-06-19

Abstract

An antenna array (1) is provided in which a number of antenna elements (2) are moveable from a deployed to a stowed position.

Description

DEPLOYABLE ANTENNA ARRAY

This invention relates to antenna arrays.

Antenna arrays are designed to efficiently transmit or receive radio waves. This drive for efficiency can also result in a high reflectivity to illuminating radiation. Accordingly, an efficient array often leads to easy detection by RADAR targeting systems which may be undesirable.

According to the invention there is provided an antenna array deployable from a stowed position to a deployed position in which the array may be used to receive or transmit radio waves wherein the antenna array is formed from moveable antenna elements and means is provided to move the elements to the deployed position.

By providing moveable antenna elements which receive or transmit radio waves which may be moved from a stowed to a deployed position it is possible to reduce the dθtectability of the array when it is not in use and stowed. It also makes the array more compact for transportation.

The antenna elements are preferably planar and stackable.

Preferably, the antenna elements are moveable from a stacked arrangement when stowed to the deployed position. Conveniently, this may be achieved by providing a first axis of rotation to permit the elements to be rotated out of the stack. Further movement freedoms may be provided to permit the antenna elements to be rotated to a deployed state.

Preferably, the axis of rotation is provided by a joint in an antenna element feed.

A specific embodiment of the invention will now be provided, by way of example only, with reference to and as illustrated by, the drawings in which:- Figure 1 shows a first embodiment of the invention with Figure 1 a showing the antenna stowed and Figure 1 b showing the antenna deployed.

Figures 2 to 4 show further embodiments.

As is shown in Figure 1 , an antenna array 1 includes a plurality of antenna elements 2 of substantially identical configuration. One of the elements is shown in isolation and it can be seen to include a spine 3 welded to which are two semi-circular metal panels 4. Radiation is fed to the panels via antenna feed 5. The antenna feed 5 includes a co-axial cable (not shown) to carry the radiation and a first joint and motor 6 to permit rotation in direction of arrow 7. The motor in this case is an electrical one.

The array has a stowed position in which the antenna elements are almost co- planar as shown in Figure 1 a. All the motors are energised simultaneously to raise all the antenna elements into the deployed position shown in Figure 1 b. The motors are reversed to stow the array when required.

It will be appreciated that when stowed the array may be less liable to reflect incoming radiation from a search RADAR than when in the deployed position. Hence detection of the vehicle to which the array is fixed is then more difficult. It will be noted that in the stowed position the antenna elements are stacked (the arrays overlap).

Figure 2 shows an alternative embodiment in which like components carry the same reference numerals. Figure 2a shows a deployed state with figures 2b and c showing transition states as the antenna elements 2 are rotated to provide a stowed array in figure 2d. It will be seen that the antenna elements are opened outwards from an axis 8 of the array to provide an array which is stowed with no stacking. The overall area is greater but the apparent thickness of the array is less because there is no overlapping (stacking) of the elements. This will be advantageous where the lowest profile is required in terms of the apparent "thickness" of the array when viewed in the place of the stowed array towards the axis. By thickness it is meant the apparent dimension in the axial direction. A further embodiment is shown in Figure 3. In this embodiment it will be seen that each antenna element 2 has a pivot and motor 6 disposed to the centre of the length of the element. This results in a greater stacking in the stowed position shown in Figure 3a to give a greater "thickness" indicated by arrow 9 but a lower apparent area 10 when viewed along the axis 8. This embodiment will be advantageous where it is important to reduce the apparent size of the stowed array when viewed along the axis.

In further alternative embodiments of the invention it will be possible to select other positions for the pivot point 6 which will enable the appropriate balance between thickness of the stack and the axial area.

It will be appreciated that the antenna elements 4 may be of different shape whilst still utilising pivot points to open the array from a stowed position.

In the described embodiments the motor of the pivot point is an electric motor a hydraulic motor or other type of motor may be used.

The motor may also be made separate to the pivot point and attached to the array element by suitable linkages. All the elements may be driven by one motor.

The pivot may comprise a joint or a portion of flexible cable.

Figure 4 shows a yet further embodiment of the invention. The same components bear the same reference numerals. Figure 4a shows a view from above of the antenna elements in a stowed stocked position. The stack occupies a small segment of a full circle. Figure 4b shows the stacked antenna element when viewed from the side in the direction of arrow IVb. A perspective view of the stack is shown in Figure 4c.

To deploy the array the antenna elements 2 are moved radially about the axis 8 of the array as shown in Figure 4d. Thus, in this embodiment the antenna array is opened from a stowed to a deployed position by a rotation about an axis of the array.

Claims

CLAIMS:

1. An antenna array employable from a stowed position to a deployed position in which the antenna array in use radiates or receives radio waves wherein the antenna array is formed from moveable antenna elements and a means is provided to move the antenna elements to the deployed position.

2. An antenna array as claimed in claim 1 , wherein the movement is a rotation.

3. An antenna array as claimed in claim 2, wherein the movement is a rotation about a pivot to which the antenna element is connected.

4. An antenna array as claimed in claim 3 wherein the pivot is provided in an antenna feed to the antenna element.

5. An antenna array as claimed in claim 4 in which the pivot is provided substantially at a mid-point of the antenna element.

6. An antenna array as claimed in claim 1 or 2 wherein in the stowed position the antenna array has a smaller cross-sectional area in at least one axis compared to its deployed state.

7. An antenna array as claimed in claim 1 or 6, wherein the movement is about an axis of the array.

8. An antenna array substantially as hereinbefore described, with reference to, and as illustrated by Figure 1 or 2 or 3 or 4.