Detection of objects

• US 9,335,407 B2
• Filed: 09/17/2010
• Issued: 05/10/2016
• Est. Priority Date: 09/17/2009
• Status: Active Grant

• Current Assignee: Radio Physics Solutions Ltd.
• Original Assignee: Radio Physics Solutions Ltd.
• Inventors: Bowring, Nicholas, Andrews, David, Rezgui, Nacer Ddine, Harmer, Stuart
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US13/496,646
• Publication Number:
  US 20120256786A1
• Time in Patent Office: 2,062 Days
• Field of Search: 342/22
• US Class Current: 1/1
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: G01S 7/025 involving the transmission of linearly polarised waves
• CPC Class Codes: G01S 7/026 involving the transmission of elliptically or circularly polarised waves
• CPC Class Codes: G01S 7/411 Identification of targets based on measurements of radar reflectivity G01S7/415 takes precedence
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values

Abstract

A detection method comprising directing radiation such that it is incident upon a target, the radiation containing a component having a first polarisation and a component having a second orthogonal polarisation, detecting radiation which is scattered from the target, and analysing the polarisation state of the detected scattered radiation to determine whether the target includes an object.

Claims

1. A detection method comprising:

directing radiation such that the radiation is incident upon a target, the radiation containing a component having a first polarisation, and detecting radiation which is scattered from the target;

subsequently transmitting radiation such that the subsequently transmitted radiation is incident upon the target, the subsequently transmitted radiation containing a component having a different polarisation which is non-orthogonal to the first polarisation, and detecting the subsequently transmitted radiation which is scattered from the target, the radiation which is scattered from the target and the subsequently transmitted radiation which is scattered from the target comprising detected scattered radiation; and

analysing a polarisation state of the detected scattered radiation to determine whether the target includes an object.

2. The detection method of claim 1, wherein the analysis comprises comparing the polarisation state of the detected scattered radiation with polarisation states of scattered radiation which would be expected if an object was present.

3. The detection method of claim 1, wherein the radiation is swept frequency radiation.

4. The detection method of claim 3, wherein the analysis comprises comparing a pattern in the frequency response of the detected scattered radiation with previously recorded patterns, or performing a substantially equivalent comparison in the time domain.

5. The detection method of claim 3, wherein the swept frequency radiation comprises radiation which is stepped through a plurality of discrete frequencies.

6. The detection method of claim 1, wherein the analysis determines whether the object is a threat object or a non-threat object.

7. The detection method of claim 1, wherein the analysis provides an identification of the object.

8. The detection method of claim 1, wherein the detected scattered radiation is cross-polarised scattered radiation.

9. The detection method of claim 1, wherein the radiation is provided with a rotating linear polarisation.

10. The detection method of claim 9, wherein the radiation is detected using a receiver which provides rotating detection of linear polarisation.

11. The detection method of claim 9, wherein the radiation is detected using a first receiver configured to receive radiation having a first linear polarisation and a second receiver configured to receive radiation having a second linear polarisation.

12. The detection method of claim 1, wherein the radiation is generated using a first transmitter configured to transmit radiation having a first linear polarisation and is subsequently generated using a second transmitter configured to transmit radiation having a second linear polarisation.

13. The detection method of claim 12, wherein the radiation is detected using a first receiver configured to receive radiation having a third linear polarization and a second receiver configured to receive radiation having a fourth linear polarisation.

14. The detection method of claim 13, wherein the third linear polarization is substantially orthogonal to the first linear polarisation and the fourth linear polarisation is substantially orthogonal to the second linear polarisation.

15. The detection method of claim 12, wherein the second linear polarisation subtends an angle of around 45°

relative to the first linear polarisation.

16. The detection method of claim 1, wherein the radiation is generated using a transmitter which transmits circularly or elliptically polarised radiation.

17. The detection method of claim 16, wherein the detected scattered radiation is received by a receiver which is configured to receive radiation having the same handedness of polarisation as the transmitted radiation.

18. The detection method of claim 1, wherein the analysis of the detected scattered radiation does not include phase information.

19. The detection method of claim 1, wherein the analysis of the detected scattered radiation includes phase information.

20. The detection method of claim 1, wherein the analysis is performed using an artificial neural network which has been trained to identify patterns from previously detected objects.

21. A detection system comprising:

a transmitter configured to direct radiation containing a component having a first polarisation such that the radiation is incident upon a target,

the transmitter being configured to subsequently direct radiation such that the subsequently directed radiation is incident upon the target, the subsequently directed radiation containing a component having a different polarisation which is non-orthogonal to the first polarisation,

wherein the detection system further comprises a receiver and detector configured to receive and detect radiation which is scattered from the target, and

a processor which is configured to analyse a polarisation state of the detected scattered radiation to determine whether the target includes an object.

22. The detection system of claim 21, wherein the detection system is sufficiently portable that it may be used in a hand held manner.