Methods and apparatus for RFID tag placement

1. A method of determining a location to place an RFID tag on a object, the method comprising: scanning an object, with a scanning device having an antenna in the near field of the object, to measure at least one RF property of a reflected signal from the object; and analyzing the reflected signal to determine a suggested location for placement of an RFID tag; and

indicating a result of an analysis, and a location corresponding to the result, to at least one of a second device and an end-user of the scanning device.

2. The method of claim 1 wherein the scanning comprises scanning the object in the near field of the object to measure the permeability of the object at one or more locations on a surface of the object.

3. The method of claim 1 wherein the scanning comprises scanning the object in the near field of the object to measure the permittivity of the object at one or more locations on a surface of the object.

4. The method of claim 1 wherein the scanning comprises scanning the object in the near field of the object to measure the loss tangent of the object at one or more locations on a surface of the object.

5. The method of claim 1 wherein the scanning comprises electrically scanning the object with an antenna.

6. The method of claim 1 wherein the scanning comprises scanning the object in the near field of the object to measure the impedance of the antenna when influenced by the object at one or more locations on a surface of the object.

7. The method of claim 1 wherein the scanning comprises scanning the object in the near field of the object to measure the complex return loss of the antenna when influenced by the object.

8. The method of claim 1 wherein the antenna is an array of antenna elements.

9. The method of claim 8 wherein at least one antenna of the array is selected from the group consisting of a dipole antenna, a resonant coil antenna, an non-resonant coil antenna, a microstrip antenna, a patch antenna, a slot antenna, a spiral antenna, and a logarithmic antenna.

10. The method of claim 1 wherein the scanning comprises electrically scanning the object with an interchangeable antenna.

11. The method of claim 1 wherein the antenna is selected to substantially mimic an RFID tag antenna.

12. The method of claim 1 wherein the scanning comprises mechanically scanning the object.

13. The method of claim 1 wherein the analyzing comprises estimating the far-field radiation pattern of an antenna on the object based on the measured at least one property.

14. The method of claim 1 wherein the analyzing comprises analyzing the magnitude of the reflected signal.

15. The method of claim 1 wherein the analyzing comprises analyzing the phase of the reflected signal.

16. The method of claim 1 wherein the analyzing comprises analyzing the reflected signal for nonlinear behavior.

17. The method of claim 1 further comprising calibrating the scanning device prior to scanning the object.

18. The method of claim 17 wherein the calibrating comprises reading calibration data stored with an antenna element that is part of the scanning device.

19. The method of claim 17 wherein the calibrating comprises executing a free-space calibration routine.

20. The method of claim 18 wherein the analyzing comprising generating a ratio of the reflected signal to the calibration signal.

21. The method of claim 18 wherein the analyzing comprises generating a figure of merit of location quality.

22. The method of claim 21 wherein the indicating comprises providing an audio alert to the end-user of the scanning device.

23. The method of claim 21 wherein the indicating comprises marking the object in the location suggested for tag placement.