Microwave phasing structures for electromagnetically emulating reflective surfaces and focusing elements of selected geometry

• US 4,905,014 A
• Filed: 04/05/1988
• Issued: 02/27/1990
• Est. Priority Date: 04/05/1988
• Status: Expired due to Term

• Current Assignee: Communications & Power Industries Incorporated, CPI Malibu Division
• Original Assignee: Malibu Research Associates, Inc.
• Inventors: Gonzalez, Daniel G., Pollon, Gerald E., Walker, Joel F.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Johnson, Doris J.
• Application Number:
  US07/178,063
• Time in Patent Office: 693 Days
• Field of Search: 343/900 MS, 343/754, 343/756, 343/778, 343/909, 343/910, 342/81, 342/360, 342/368, 342/377
• US Class Current: 343/909
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
• CPC Class Codes: H01Q 19/065 Zone plate type antennas
• CPC Class Codes: H01Q 3/46 Active lenses or reflecting arrays

Abstract

The present invention concerns an electrically thin microwave phasing structure for electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band. The microwave phasing structure comprises a support matrix and a reflective means for reflecting microwaves within the frequency operating band. The reflective means is supported by the support matrix. An arrangement of electromagnetically-loading structures is supported by the support matrix at a distance from the reflective means which can be less than a fraction of the wavelength of the highest frequency in the operating frequency range. The electromagnetically-loading structures are dimensioned, oriented, and interspaced from each other and disposed at a distance from the reflective means, as to provide the emulation of the desired reflective surface of selected geometry.

Another aspect of the present invention is the use of the electrically thin microwave phasing structure for electromagnetically emulating a desired microwave focusing element of a selected geometry.

Additionally, methods are provided for designing and manufacturing electrically thin microwave phasing structures for electromagnetically emulating desired reflective surfaces and focusing elements of selected geometry, which methods may include the use of computer-aided design and photo-etching techniques.

Claims

1. A microwave phasing structure for electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band, which comprises:

(a) a support matrix;

(b) a reflective means for reflecting microwaves within said operation frequency band, said reflective means supported by said support matrix; and

(c) a phasing arrangement of electromagnetically-loading structures supported by said support matrix and generally being resonant at some frequency outside of said operating frequency band, said electromagnetically-loading structures varying in dimension and having an orientation and interspacing from each other and being disposed at a distance from said reflective means by said support matrix so as to provide said emulation of said desired reflective surface of selected geometry.

2. The microwave phasing structure of claim 1 wherein said reflective means is a metallic reflecting layer.

3. The microwave phasing structure of claim 1 wherein said desired reflective surface is a curved surface.

4. The microwave phasing structure of claim 1 wherein said support matrix is substantially planar.

5. The microwave phasing structure of claim 4 wherein said electromagnetically-loading structures comprise an array of metallic patterns.

6. The microwave phasing structure of claim 5 wherein each metallic pattern of said array comprises a cross configuration, each said cross configuration varying in dimension and having an orientation and interspacing from each other, and being disposed at a distance from said reflective means by said support matrix so as to provide said emulation of said desired reflective surface.

7. The microwave phasing structure of claim 4 wherein said desired reflective surface comprises a parabolic reflector having a focal point and wherein all path lengths to said focal point are phase equalized.

8. The microwave phasing structure of claim 7 wherein said reflective means comprises a metallic reflective layer.

9. The microwave phasing structure of claim 1 wherein said operating frequency band is in the range of from about 0.1 GHZ to about 300 GHZ.

10. The microwave phasing structure of claim 1 wherein the geometry of said support matrix is substantially non-planar, and said desired reflective surface is curved.

11. The microwave phasing structure of claim 10 wherein said electromagnetically-loading structures comprise an array of metallic patterns.

12. The microwave phasing structure of claim 10 wherein each metallic pattern of said array comprises a cross configuration, each said cross configuration varying in dimension and having an orientation and interspacing from each other and being disposed at a distance from said reflective means by said support matrix so as to provide said emulation of said desired reflective surface of selected geometry.

13. The microwave phasing structure of claim 1 wherein said reflective means comprises a dichroic structure which is opaque to said incident electromagnetic waves within said operating frequency band, and which is transparent to said incident electromagnetic waves outside of said operating frequency band.

14. The microwave phasing structure of claim 1 wherein said support matrix is a dielectric substrate having a first side and a second side, said reflective means being disposed on said first side of said dielectric substrate, and said arrangement of electromagnetically-loading structures being disposed on said second side of said dielectric substrate, said electromagnetically-loading structures being disposed at a distance from said reflective means by said support matrix whereby said emulation of said desired reflective surface of selective geometry is provided.

34. The microwave phasing structure of claim 1, wherein said microwave phasing structure further has an operating wavelength, and said distance is greater than or equal to about 1/16th of said operating wavelength and less than or equal to about 1/4 of said operating wavelength.

15. A method of electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band, comprising:

(a) providing a microwave phasing structure including support matrix, a reflective means for reflecting microwaves within said operating frequency band, and phasing arrangement of electromagnetically-loading structures generally being resonant at some frequency outside of said operating frequency band, varying in dimension and having an orientation and interspacing from each other, and being disposed at a distance from said reflective means by said support matrix; and

(b) providing an incident electromagnetic wave within said operating frequency band to the side of said support matrix supporting said phasing arrangement of electromagnetically-loading structures, said incident electromagnetic waves being reflected, phase shifted and diffracted as said incident electromagnetic waves propagate through said support matrix and reflect from said reflective means to thereby electromagnetically emulate said desired reflective surface of selected geometry.

16. The method of claim 15 wherein said distance being less than the wavelength of the lowest frequency of said operating frequency band is in the range of from about 0.1 GHZ to about 300 GHZ.

17. The method of claim 15 wherein said reflective means is a metallic reflecting layer.

18. The method of claim 15 wherein said desired reflective surface is a curved surface.

19. The method of claim 15 wherein the geometry of said support matrix is substantially planar.

20. The method of claim 19 wherein said electromagnetically-loading structures comprise an array of metallic patterns.

21. The method of claim 20 wherein each metallic pattern of said array comprises a cross configuration,

each said cross configuration varying in dimension and having an orientation and interspacing from each other and being disposed at a distance from said reflective means by said support matrix as to provide said desired reflective surface.

22. The method of claim 21 wherein said desired reflective surface comprises a parabolic reflector having a focal point and wherein all path lengths of said reflected incident electromagnetic waves to said focal point are phase equalized.

23. The method of claim 22 wherein said reflective means comprises a metallic reflective layer.

24. A microwave phasing structure for electromagnetically emulating a desired focusing element of selected geometry over an operating frequency band, which comprises:

(a) a support matrix;

(b) a first phasing arrangement of electromagnetically-loading structures supported by said support matrix and generally being resonant at some frequency outside of said operating frequency band; and

(c) a second phasing arrangement of electromagnetically-loading structures supported by said support matrix and generally being resonant at some frequency outside of said operating frequency band, said electromagnetically-loading structures of said first phasing arrangement varying in dimension and having an orientation and interspacing from each other and being disposed at a distance from a corresponding electromagnetically loading structure of said second phasing arrangement, so as to provide said emulation of said desired focusing element of selected geometry.

25. The microwave phasing structure of claim 24 wherein said support matrix is of substantially planar geometry.

26. The microwave phasing structure of claim 25 wherein said geometry of said desired focusing element is of a plano-parabolic converging lens having a focal point and wherein all path lengths of incident electromagnetic waves to said focal point are phase equalized.

27. The microwave phasing structure of claim 25 wherein said electromagnetically-loading structures comprise an array of metallic patterns.

28. The microwave phasing structure of claim 27 wherein each metallic pattern of said array comprises a cross configuration, said cross configurations of said first phasing arrangement varying in dimension and having an orientation and interspacing from each other and each cross-configuration of said first phasing arrangement being disposed at a distance from a corresponding cross-configuration in said second phasing arrangement so as to provide said emulation of said desired focusing element.

29. The microwave phasing structure of claim 28 wherein said operating frequency band is from about 0.1 GHZ to about 300 GHZ.

30. The microwave phasing structure of claim 29 wherein said support matrix is a dielectric substrate.

31. The microwave phasing structure of claim 24 wherein the geometry of said support matrix is of substantially non-planar geometry.

32. The microwave phasing structure of claim 24 wherein the geometry of said support matrix is substantially non-planar, and wherein said geometry of said desired focusing element is of a converging lens having a focus wherein said all path lengths of incident electromagnetic waves to said focal point are phased equalized.

33. The microwave phasing structure of claim 32 wherein said first and second arrangements of electromagnetically loading structures each comprise an array of metallic patterns.

35. The microwave phasing structure of claim 31 wherein said support matrix is a dielectric substrate.

52. The microwave phasing structure according to claim 24, wherein said microwave phasing structure further has an operating wavelength, and wherein said distance is greater than or equal to about 1/16 of said operating wavelength and less than or equal to about 1/4 of said operating wavelength.

36. A method of electromagnetically emulating a desired focusing element of selected geometry over an operating frequency band, which comprises:

(a) providing a microwave phasing structure including a support matrix, a first phasing arrangement of electromagnetically-loading structures supported by said support matrix and generally being resonant at some frequency outside said operating frequency band, and a second phasing arrangement of electromagnetically-loading structures supported by said support matrix and generally being resonant at some frequency outside of said operating frequency band, said electromagnetically-loading structures of said first phasing arrangement varying in dimension and having an orientation and interspacing from each other and each said electromagnetically-loading structure of said first phasing arrangement being disposed at a distance from a corresponding electromagnetically-loading structure of said second phasing arrangement so as to provide said emulation of said desired focusing element of selected geometry; and

(b) providing an incident electromagnetic wave within said operating frequency band to one side of said support matrix, said incident electromagnetic waves being phase shifted and diffracted as said incident electromagnetic waves propagate through said microwave phasing structure, to thereby electromagnetically emulate said desired focusing element of selected geometry.

37. The method of claim 36 wherein the geometry of said support matrix is substantially planar.

38. The method of claim 36 wherein step (b) further comprises phase equalizing the path lengths of said incident electromagnetic waves as said incident electromagnetic waves propagate through said microwave phasing structure.

39. The method of claim 38 wherein said electromagnetically-loading structures comprise an array of metallic patterns.

40. The method of claim 39 wherein each metallic pattern of said array comprises a cross configuration, said cross configurations varying in dimension and having an orientation and interspacing from each other and each cross-configuration of said first phasing arrangement being disposed at a distance from a corresponding cross-configuration of said second phasing arrangement so as to provide said emulation of said desired focusing element of selected geometry.

41. The method of claim 37 wherein said geometry of said desired focusing element is of a plano-parabolic converging lens having a focal point, and wherein all path lengths of said incident electromagnetic waves to said focal point are phase equalized.

42. The method of claim 37 wherein said operating frequency band is from about 0.1 GHZ to about 300 GHZ.

43. A method of manufacturing a microwave phasing structure for electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band wherein said microwave phasing structure includes a dielectric substrate having disposed on one side thereof a reflective means and disposed on the other side thereof, a phasing arrangement of electromagnetically-loading structures generally being resonant at some frequency outside of said operating frequency band, varying in dimension and having an orientation and interspacing from each other and being disposed at a distance from said reflective means so as to provide said emulation of said desired reflective surface of selected geometry, said method comprising:

(a) providing a dielectric substrate having a reflective means disposed on one side thereof, and on the other side of which said phasing arrangement of electromagnetically-loading structures are to be disposed;

(b) selecting at least one geometry for said electromagnetically-loading structures;

(c) determining the dimensions, orientation and interspacing of said selected electromagnetically-loading structures as to provide said emulation of said desired reflective surface of selected geometry; and

(d) providing to the other side of said dielectric substrate, said phasing arrangement of electromagnetically-loading structures varying in dimension and having an orientation and interspacing from each other as determined in step (c), whereby said microwave phasing structure is formed.

44. The method of claim 43 wherein step (c) comprises constructing on a computer-aided design system, a three-dimensional ray model of said microwave phasing structure, and using said three-dimensional ray model, computing said dimensions, orientation and interspacing of said selected electromagnetically-loading structures as to provide said emulation of said desired reflective surface of selected geometry.

45. The method of claim 43 wherein each said electromagnetically-loading structure comprises a metallic pattern.

46. The method of claim 45 wherein step (d) comprises:

(i) providing a metallic layer on said other side of said dielectric substrate,

(ii) generating a composite pattern corresponding to said phasing arrangement of electromagnetically-loading structures determined in step (c), and

(iii) removing portions of said metallic layer as to leave remaining therein, said composite pattern corresponding to said phasing arrangement of electromagnetically-loading structures.

47. The method of claim 46 wherein removing portions of said metallic layer is achieved by a photo-etching process.

48. The method of claim 43 wherein said operating frequency band is from about 0.1 GHZ to about 300 GHZ.

49. The method of claim 43 wherein said dielectric substrate is substantially planar.

50. The method of claim 49 wherein said selected geometry of said desired reflective surface is of a parabolic reflector having a focal point, wherein all path lengths to said focal point are phase equalized.

51. The method of claim 45 wherein each metallic pattern is of an X configuration.

53. A method of manufacturing a microwave phasing structure for electromagnetically emulating a desired microwave focusing element of selected geometry over an operating frequency band, wherein said microwave phasing structure includes a dielectric substrate having disposed on one side thereof, a first phasing arrangement of electromagnetically-loading structures, and having disposed on the other side thereof a second phasing arrangement of electromagnetically-loading structures, said first and second phasing arrangements generally being resonant at some frequency outside of said operating frequency band, varying in dimension, and having an orientation and interspacing from each other and each said electromagnetic loading structure of said first phasing arrangement being disposed at a distance from a corresponding electromagnetically-loading structure of said second arrangement, so as to provide said emulation of said desired microwave focusing element, said method comprising:

(a) providing said dielectric substrate on which said first and second phasing arrangements of electromagnetically-loading structures are to be disposed;

(b) selecting at least one geometry for said electromagnetically-loading structures;

(c) determining the dimensions, orientation and interspacing of said selected electromagnetically-loading structures as to provide said desired focusing element of selected geometry; and

(d) providing to one side of said dielectric substrate, said first phasing arrangement of electromagnetically-loading structures, and providing to the other side of said dielectric substrate, said second phasing arrangement of electromagnetically-loading structures, said electromagnetically-loading structures having dimensions, orientation and interspacing from each other as determined in step (c).

54. The method of claim 53 wherein step (c) comprises constructing on a computer-aided design system, a three-dimensional ray model of said microwave phasing structure, and using said three-dimensional ray model, computing said dimensions, orientation and interspacing of said selected electromagnetically-loading structures as to provide said emulation of said desired microwave focusing element of selected geometry.

55. The method of claim 53 wherein each said electromagnetically-loading structure comprises a metallic pattern.

56. The method of claim 55 wherein step (d) comprises:

(i) providing a metallic layer on both said sides of said dielectric substrate;

(ii) generating a first composite pattern corresponding to said first phasing arrangement of electromagnetically-loading structures determined in step (c) and a second composite pattern corresponding to said second phasing arrangement of electromagnetically-loading structures determined in step (c); and

(iii) removing portions of said metallic layers as to leave remaining therein, said first and second composite patterns corresponding to said first and second phasing arrangements of electromagnetically-loading structures respectively.

57. The method of claim 56 wherein removing portions of said metallic layers is achieved by a photo-etching process.

58. The method of claim 53 wherein said operating frequency band is from 0.1 GHZ to about 300 GHZ.

59. The method of claim 53 wherein said dielectric substrate is substantially planar.

60. The method of claim 59 wherein said geometry of said desired microwave focusing element is of a plano-parabolic converging lens having a focal point, wherein all path lengths of incident electromagnetic waves in said frequency band to said focal point, are phase equalized.

61. The method of claim 55 wherein each metallic pattern comprises an X-shaped configuration.

62. The microwave phasing structure produced by the method of claim 53.

63. A method of designing an electrically thin microwave phasing structure for electromagnetically emulating a desired reflective surface of selected geometry over an operating frequency band, and being characterizable by a set of performance parameters, said method comprising:

(a) specifying a desired reflective surface to be electromagnetically emulated and a corresponding set of performance parameters;

(b) specifying a physical surface from which said desired reflective surface is to be electromagnetically emulated;

(c) determining path length differences between corresponding points on said physical surface and said reflective surface which path length differences are to be electromagnetically emulated;

(d) determining the desired phase shift corresponding to each said path length difference;

(e) selecting at least one electromagnetically-loading structure having a particular geometry, and which are to be dimensioned, oriented and interspaced from each other on a support matrix to form a phasing arrangement of electromagnetically-loading structures which are disposed at a distance from a reflective means supported by said support matrix and generally being resonant at some frequency outside of said operating frequency band, so as to form an electrically thin microwave phasing structure characterizable by design parameters; and

(f) determining said design parameters so that said electrically thin microwave structure is characterized by said set of performance parameters, and provides said emulation of said desired reflective surface of selected geometry over said operating frequency band.

64. The method of claim 63, wherein step (f) involves determining said design parameters using a reiterative design process.

65. The method of claim 63, wherein said support matrix in step (e) comprises a dielectric substrate.

66. The method of designing an electrically thin microwave phasing structure for electromagnetically emulating desired microwave focusing element of selected geometry over an operating frequency and, being characterizable by a set of performance parameters, said method comprising:

(a) specifying a desired focusing element to be electromagnetically emulated and a corresponding set of performance parameters;

(b) specifying a physical surface from which said desired focusing element is to be electromagnetically emulated;

(c) determining path length differences between corresponding points on said physical surface and the surface of focusing said element, which path length differences are to be electromagnetically emulated;

(d) determining the desired phase shift corresponding to each path length difference;

(e) selecting at least one electromagnetically-loading structure having a particular geometry, and which are to be dimensioned, oriented and interspaced from each other on a support matrix to form on the first side thereof a first phasing arrangement of electromagnetically-loading structures and on the second side thereof a second phasing arrangement of electromagnetically-loading structures, said first and second arrangements of electromagnetically-loading structures being disposed at a distance from each other by said support matrix, and generally being resonant at some frequency outside of said operating frequency band, so as to form an electrically thin microwave phasing structure characterizable by a set of design parameters; and

(f) determining said set of design parameters so that said electrically thin phasing structure is characterized by said set of performance parameters, and provides said emulation of said microwave focusing element of selected geometry over said operating frequency band.

67. The method of claim 66 wherein said support matrix in step (e) comprises a dielectric substrate.

68. The method of claim 66 wherein step (f) involves determining said design parameters using a reiterative design process.