ROTARY ANTENNA, SCANNER USING SUCH AN ANTENNA, AND DEVICE FOR INSPECTING PERSONS

• US 20160025852A1
• Filed: 04/01/2014
• Published: 01/28/2016
• Est. Priority Date: 04/02/2013
• Status: Active Grant

• Current Assignee: SAS SWS
• Original Assignee: SAS SWS
• Inventors: CHEKROUN, Claude, CHEKROUN, Gilles
• Granted Patent: US 10,162,050 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: H01Q 1/525 between emitting and receiving antennas
• CPC Class Codes: H01Q 13/12 Longitudinally slotted cylinder antennas; Equivalent structures
• CPC Class Codes: H01Q 13/18 the slot being backed by, or formed in boundary wall of, a resonant cavity longitudinally slotted cylinder H01Q13/12 ; Open cavity antennas
• CPC Class Codes: H01Q 13/22 Longitudinal slot in boundary wall of waveguide or transmission line H01Q13/203 takes precedence
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/12 using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements

Abstract

The antenna comprises at least one waveguide of rectangular section and a cylinder having an opening along a helical line, the cylinder having a relative rotational movement in relation to the waveguide placed inside the cylinder, the waveguide being open facing the inner face of the cylinder which forms a microwave short-circuit to close the guide, wherein two cavities are produced on each side of the guide, parallel thereto, over its entire length, the openings of the cavities being substantially in the plane of the opening of the guide. The invention applies, for example, to the detection of hidden objects carried by persons, in particular dangerous objects.

Claims

1. An antenna comprising at least one waveguide of rectangular section and a cylinder having an opening along a helical line, said cylinder having a relative rotational movement in relation to the waveguide placed inside said cylinder, the waveguide being open facing the inner face of said cylinder which forms a microwave short-circuit to close the guide, two cavities being produced on each side of the guide, parallel thereto, over its entire length, the openings of the cavities being substantially in the plane of the opening of the guide.

2. The antenna as claimed in claim 1, wherein the opening is formed by a succession of individual openings arranged on each side of the helical line, a first series of individual openings being arranged on one side and a second series of individual openings being arranged on the other side, the positions of the openings of the second series being staggered relative to the positions of the openings of the first series such that the radiant opening is formed in succession by an opening on one side of said line then an opening arranged on the other side, and so on.

3. The antenna as claimed in claim 2, wherein said openings are rectangular, the large side being arranged along the helical line.

4. The antenna as claimed in claim 1, wherein, the guide being connected at one end to the transmission and reception circuits of a radar and at its other end to a matched load, at least one cavity emerges on the guide at said other end.

5. The antenna as claimed in claim 1, wherein it comprises four pairs of waveguides each arranged at right angles to one another, each pair comprising a transmission guide and a reception guide.

6. The antenna as claimed in claim 1, wherein the cylinder is driven in a rotational movement by means of a motor.

7. The antenna as claimed in claim 1, wherein it is suitable for operating with a millimetric radar.

8. A scanner delivering a radar image, comprising at least:

an antenna as claimed in claim 1,

a millimetric radar and

means for displaying said image,

the antenna being linked to the transmission and reception circuits of said radar, an antenna beam (F1, F2, F3, F4) radiated by a waveguide being displaced parallel to the axis of the antenna when the cylinder is rotating, the processing means of said radar producing an image of SAR type of a target from the signals received from said target.

9. The scanner as claimed in claim 8, wherein, the antenna comprising a plurality of pairs of waveguides, each pair comprising a transmission guide and a reception guide, the transmission and reception circuits comprise at least:

a generator of frequencies (f₁, f₂, f₃, f₄), each frequency being assigned to a given pair;

a first switch switching the signals from said generator to the transmission guides synchronously with the generation of frequencies;

a second switch switching the signals from the reception guides to the reception circuits, synchronously with the frequency generation.

10. The scanner as claimed in claim 8, wherein, the reception being of homodyne type, the reception circuits comprise at least:

a coupler connected to the transmission line;

a first mixer;

a second mixer

the first mixer receiving as input the signal from the coupler and the reception signal and the second mixer receiving as input the signal from the coupler and the reception signal phase-offset by π

/2.

11. The scanner as claimed in claim 8, wherein the antenna comprises a number of pairs of waveguides such that altogether the antenna beams (F1, F2, F3, F4) scan the space by 360°

about the antenna axis.

12. A device for inspecting persons, comprising:

at least one curved corridor, exhibiting a first curvature and a second curvature opposite to the first curvature;

scanners as claimed in claim 11, two scanners per corridor being placed substantially at the point where the curvature changes direction, the persons to be inspected passing between said two scanners, said scanners producing radar images over 360°

.

13. The inspection device as claimed in claim 12, characterized in that wherein the corridors are contiguous.

14. The inspection device as claimed in claim 12, wherein it is suitable for use in embarkation zones for the inspection of passengers.