Handheld radar frequency scanner for concealed object detection

1. A handheld radar frequency scanner system for detecting objects concealed on a person, the system comprising:

a radar transmitter coupled to a transmit antenna that is configured and positioned to direct a radar signal at a person;

a radar receiver coupled to a receive antenna that is configured to detect a portion of the radar signal reflected by the person; and

a processor connected to the radar receiver and operable to process the portion of the radar signal detected by the radar receiver to determine whether the person is carrying a concealed object, by conducting a test in which a first characteristic of a first dielectric constant associated with the person is determined, and a second characteristic of a second dielectric constant associated with the concealed object is determined.

2. The system of claim 1 wherein the system is configured to produce a real-time alert when a concealed object is detected.

3. The system of claim 2 wherein the real-time alert comprises an audible alert.

4. The system of claim 1 wherein the radar signal comprises a frequency between approximately 1.5 gigahertz and 12 gigahertz.

5. The system of claim 4 wherein the radar signal comprises a frequency stepped signal.

6. The system of claim 4 wherein the radar signal comprises an output power of less than one milliwatt.

7. The system of claim 1 wherein the handheld radar frequency scanner system comprises a monostatic radar system.

8. The system of claim 1 wherein the handheld radar frequency scanner system comprises a bistatic radar system.

9. The system of claim 1 wherein at least one of the transmit antenna and the receive antenna comprises a spiral antenna.

10. The system of claim 1 wherein at least one of the transmit antenna and the receive antenna comprises an endfire waveguide antenna.

11. The system of claim 1 wherein the first dielectric constant is determined during the test.

12. The system of claim 11 wherein the first dielectric constant is associated with skin of the person.

13. The system of claim 11 wherein the second dielectric constant is determined during the test.

14. The system of claim 5 wherein the processor is operable to conduct the test using a frequency-stepped scheme.

15. The system of claim 5 wherein the frequency stepped signal comprises frequencies at defined intervals throughout a defined frequency range.

16. The system of claim 1 wherein the processor is operable to conduct the test based upon a difference between the first dielectric constant and the second dielectric constant, wherein the difference is determined during the test.

17. The system of claim 1 wherein the processor is operable to determine whether the person is carrying a concealed object using a principal component analysis technique.

18. A handheld radar frequency scanner system for detecting objects concealed on a person, the system comprising:

means for directing a radar signal at a person;

means for detecting a portion of the radar signal reflected by the person; and

means for processing the portion of the radar signal detected by the radar receiver to determine whether the person is carrying a concealed object, by conducting a test in which a first characteristic of a first dielectric constant associated with the person is determined, and a second characteristic of a second dielectric constant associated with the concealed object is determined.

19. The system of claim 18 further comprising means for producing a real-time alert when a concealed object is detected.

20. The system of claim 19 wherein the real-time alert comprises an audible alert.

21. The system of claim 18 wherein the first dielectric constant is determined during the test.

22. The system of claim 21 wherein the first dielectric constant is associated with skin of the person.

23. The system of claim 21 wherein the second dielectric constant is determined during the test.

24. The system of claim 18 wherein the radar signal comprises a frequency stepped signal and wherein the test is conducted using a frequency-stepped scheme.

25. The system of claim 24 wherein the frequency stepped signal comprises frequencies at defined intervals throughout a defined frequency range.

26. The system of claim 18 wherein the means for processing is operable to conduct the test based upon a difference between the first dielectric constant and the second dielectric constant, wherein the difference is determined during the test.

27. The system of claim 18 wherein the means for processing is operable to determine whether the person is carrying a concealed object using a principal component analysis technique.

28. A method for detecting objects concealed on a person using a handheld radar frequency scanner system, the method comprising:

directing a radar signal at a person;

detecting a portion of the radar signal reflected by the person; and

processing the portion of the radar signal detected by the radar receiver to determine whether the person is carrying a concealed object, by conducting a test in which a first characteristic of a first dielectric constant associated with the person is determined, and a second characteristic of a second dielectric constant associated with the concealed object is determined.

29. The method of claim 28 further comprising producing a real-time alert when a concealed object is detected.

30. The method of claim 29 wherein the real-time alert comprises an audible alert.

31. The method of claim 28 wherein processing further comprises determining the first dielectric constant.

32. The method of claim 28 wherein processing further comprises comparing the first dielectric constant and the second dielectric constant.

33. The method of claim 28 wherein processing further comprises:

determining the first dielectric constant;

determining the second dielectric constant; and

determining that a defined discrepancy exists between the first dielectric constant and the second dielectric constant.