Plane Wave Generation Within A Small Volume Of Space For Evaluation of Wireless Devices

• US 20130052962A1
• Filed: 08/08/2012
• Published: 02/28/2013
• Est. Priority Date: 08/23/2011
• Status: Active Grant

• Current Assignee: Azimuth Systems, Inc. (Anritsu Corporation)
• Original Assignee: Azimuth Systems, Inc. (Anritsu Corporation)
• Inventors: Hansen, Thorkild
• Granted Patent: US 9,615,274 B2
• Time in Patent Office: Days
• US Class Current: 455/67.12
• CPC Class Codes: G01R 29/0871 Complete apparatus or systems; circuits, e.g. receivers or amplifiers G01R29/0878, G01R29/0892 take precedence; dosimeters, warning devices G01R29/0857
• CPC Class Codes: G01R 29/0892 Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value
• CPC Class Codes: G01R 29/105 using anechoic chambers; Chambers or open field sites used therefor test sites used for measuring on other objects than aerials G01R29/0828; wave absorbing devices H01Q17/00
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

Small anechoic chambers for evaluating a wireless device under test (DUT) are characterized by a set of antennas to which a test signal is applied and for which excitation coefficients are applied such that the test signal approximates a single plane wave or a preselected superposition of plane waves in the near field of the antennas. The test-equipment antennas in the chamber may be as close as one wavelength from the boundary of a test zone in which the DUT is disposed. Hence, the test zone can be in the near field of the test-equipment antennas and the test zone can be less than a wavelength from the chamber walls. Consequently, it is possible to perform tests in a small anechoic chamber that previously required a large anechoic chamber, e.g., advanced spatial channel-model tests and antenna-pattern measurements.

Claims

1. An apparatus comprising:

a plurality of antennas disposed in relation to a region of space;

logic which calculates excitation coefficients which are applied to at least one signal provided to the antennas to approximate a single plane wave in the region; and

transmission circuitry which applies the excitation coefficients to at least one signal transmitted via the antennas to generate the approximated single plane wave in the region.

2. The apparatus of claim 1 wherein the antennas are disposed on a closed surface.

3. The apparatus of claim 1 including an anechoic chamber in which the region and antennas are located.

4. The apparatus of claim 1 wherein the antennas are disposed along an arc.

5. The apparatus of claim 1 wherein the antennas are disposed along a ring.

6. The apparatus of claim 1 wherein the antennas include a set of dipoles

7. The apparatus of claim 1 wherein the logic calculates multiple sets of excitation coefficients to sequentially produce plane waves from a plurality of directions.

8. The apparatus of claim 7 further comprising logic which evaluates total isotropic sensitivity of a device under test disposed in the region.

9. The apparatus of claim 1 wherein the logic adjusts the excitation coefficients to approximate a preselected superposition of plane waves which is then generated by the transmission circuitry.

10. The apparatus of claim 1 wherein the logic uses measured data to calculate the excitation coefficients.

11. The apparatus of claim 1 wherein the logic uses simulated data to obtain the excitation coefficients.

12. The apparatus of claim 1 wherein the logic uses a least-squares solution to obtain the excitation coefficients.

13. The apparatus of claim 1 wherein the transmission circuitry applies time-varying excitation coefficients to create faded channel conditions in the region.

14. The apparatus of claim 1 further comprising a channel emulator.

15. The apparatus of claim 14 wherein the channel emulator utilizes a 2D channel model.

16. The apparatus of claim 14 wherein the channel emulator utilizes a multi-cluster channel model.

17. The apparatus of claim 14 wherein the channel emulator utilizes a single-cluster channel model.

18. The apparatus of claim 14 wherein the channel emulator utilizes an isotropic channel model.

19. An apparatus comprising:

a plurality of antennas disposed in relation to a region of space; and

logic which records outputs due to a field transmitted from a device under test in the region, and creates a weighted sum of the recorded outputs and adjusts the weights such that a far field of the device under test is determined in a desired direction.

20. The apparatus of claim 19 further comprising logic which determines total radiated power of the device under test.

21. A method comprising:

calculating excitation coefficients for application to at least one signal provided to a plurality of antennas disposed in relation to a region of space to approximate a single plane wave in the region; and

applying the excitation coefficients to at least one signal transmitted via the antennas to generate the approximated single plane wave in the region.

22. The method of claim 21 including arranging the antennas on a closed surface.

23. The method of claim 21 including locating the region and the antennas within an anechoic chamber.

24. The method of claim 21 including arranging the antennas along an arc.

25. The method of claim 21 including arranging the antennas along a ring.

26. The method of claim 21 including utilizing a set of dipoles as the antennas.

27. The method of claim 21 including calculating multiple sets of excitation coefficients to sequentially produce plane waves from a plurality of directions.

28. The method of claim 27 including evaluating total isotropic sensitivity of a device under test disposed in the region.

29. The method of claim 21 including adjusting the excitation coefficients to approximate a preselected superposition of plane waves and generating the approximated superposition of plane waves.

30. The method of claim 21 including using measured data to calculate the excitation coefficients.

31. The method of claim 21 including using simulated data to obtain the excitation coefficients.

32. The method of claim 21 including using a least-squares solution to obtain the excitation coefficients.

33. The method of claim 21 including applying time-varying excitation coefficients to create faded channel conditions in the region.

34. The method of claim 21 including utilizing a channel emulator to produce wireless test conditions.

35. The method of claim 34 including the channel emulator utilizing a 2D channel model.

36. The method of claim 34 including the channel emulator utilizing a multi-cluster channel model.

37. The method of claim 34 including the channel emulator utilizing a single-cluster channel model.

38. The method of claim 34 including the channel emulator utilizing an isotropic channel model.

39. A method comprising:

using a plurality of antennas disposed in relation to a region of space, recording outputs of a field transmitted from a device under test in the region;

creating a weighted sum of the recorded outputs; and

adjusting weightings such that a far field of the device under test is determined in a desired direction.

40. The method of claim 39 including determining total radiated power of the device under test.

41. A computer program stored on a non-transitory computer-readable medium, the program comprising:

logic which calculates excitation coefficients which are applied to at least one signal provided to a plurality of antennas disposed in relation to a region of space to approximate a single plane wave in the region, and applies the excitation coefficients to at least one signal transmitted via the antennas to generate the approximated single plane wave in the region.

42. The program of claim 41 wherein the antennas are disposed on a closed surface.

43. The program of claim 41 including an anechoic chamber in which the region and antennas are located.

44. The program of claim 41 wherein the antennas are disposed along an arc.

45. The program of claim 41 wherein the antennas are disposed along a ring.

46. The program of claim 41 wherein the antennas include a set of dipoles

47. The program of claim 41 wherein the logic calculates multiple sets of excitation coefficients to sequentially produce plane waves from a plurality of directions.

48. The program of claim 47 further comprising logic which evaluates total isotropic sensitivity of a device under test disposed in the region.

49. The program of claim 41 wherein the logic adjusts the excitation coefficients to approximate a preselected superposition of plane waves which is then generated.

50. The program of claim 41 wherein the logic uses measured data to calculate the excitation coefficients.

51. The program of claim 41 wherein the logic uses simulated data to obtain the excitation coefficients.

52. The program of claim 41 wherein the logic uses a least-squares solution to obtain the excitation coefficients.

53. The program of claim 41 wherein the logic calculates time-varying excitation coefficients to create faded channel conditions in the region.

54. The program of claim 41 further comprising a channel emulator.

55. The program of claim 54 wherein the channel emulator utilizes a 2D channel model.

56. The program of claim 54 wherein the channel emulator utilizes a multi-cluster channel model.

57. The program of claim 54 wherein the channel emulator utilizes a single-cluster channel model.

58. The program of claim 54 wherein the channel emulator utilizes an isotropic channel model.

59. A computer program stored on a non-transitory computer-readable medium, the program comprising:

logic which records, with of a set of antennas disposed in relation to a region of space, outputs due to a field transmitted from a device under test in the region, and creates a weighted sum of the recorded outputs and adjusts the weights such that a far field of the device under test is determined in a desired direction.

60. The computer program of claim 59 further comprising logic which determines total radiated power of the device under test.