Multi-mode broadband patch antenna

• US 6,292,143 B1
• Filed: 05/04/2000
• Issued: 09/18/2001
• Est. Priority Date: 05/04/2000
• Status: Expired due to Fees

• Current Assignee: National Aeronautics and Space Administration US Government As Represented By The Administrator of The
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Romanofsky, Robert R.
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US09/566,839
• Time in Patent Office: 502 Days
• Field of Search: H01/Q.138, 343/700.MS
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 25/04 Multimode antennas corrugated horns H01Q13/0208
• CPC Class Codes: H01Q 9/0435 using two feed points
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H01Q 9/14 Length of element or elements adjustable telescopic elements H01Q1/10

Abstract

A multi-mode broad band patch antenna is provided that allows for the same aperture to be used at independent frequencies such as reception at 19 GHz and transmission at 29 GHz. Furthermore, the multi-mode broadband patch antenna provides a ferroelectric film that allows for tuning capability of the multi-mode broadband patch antenna over a relatively large tuning range. The alternative use of a semiconductor substrate permits reduced control voltages since the semiconductor functions as a counter electrode.

Claims

1. A tunable microstrip patch antenna element comprising;

a ground plane comprised of a conductive material;

a substrate comprised of a material selected from the group consisting of dielectric and semiconductive materials and mounted on said ground plane;

a radiator having an apparent electrical dimension and with parameters selected so as to operate in a fundamental mode at an odd order common denominator of desired fundamental frequencies, said radiator having a circuit for connecting to a variable bias voltage comprising means for generating a dc electric field between said radiator and said ground plane; and

a ferroelectric film placed on said substrate and in cooperation with said substrate being deterministic of said apparent electrical dimension of said radiator.

2. The tunable microstrip patch antenna element according to claim 1, wherein said radiator comprises an annular ring.

3. The tunable microstrip patch antenna element according to claim 1, wherein said substrate is comprised of silicon.

4. The tunable microstrip patch antenna element according to claim 3, wherein said silicon has a resistivity in the range from about 1000 ohm-cm to about 10,000 ohm-cm.

5. The tunable microstrip patch antenna element according to claim 1, further comprising a capacitive coupling arrangement comprising a microstrip spaced apart from said radiator.

6. The tunable microstrip patch antenna element according to claim 1, wherein said circuit comprises a quarter-wavelength radial stub having a vertex which is connected by a high impedance microstrip transmission line to said radiator and to said means for generating said electric field.

7. The tunable microstrip patch antenna element according to claim 6, wherein said means for generating said dc electric field is connected to said radiator by a wire bond.

8. The tunable microstrip patch antenna element according to claim 7, wherein said means for generating said dc electric field is variable.

9. The tunable microstrip patch antenna element according to claim 1, wherein said tunable microstrip patch antenna element has a desired fundamental frequency and said fundamental mode is TM₀₁ with said apparent dimension comprises a length (l) of said radiator which is one-half (½

) wavelength long at the desired fundamental frequency.

10. The tunable patch antenna according to claim 2, wherein said annular ring is operated in a selectable TM_nm mode.

11. The tunable microstrip patch antenna element according to claim 1, wherein said ferroelectric film is a thin film.

12. The tunable microstrip patch antenna element according to claim 1, wherein said ferroelectric film is a material selected from the group consisting of SrTiO₃, Ba₁₋

x Sr_x TiO₃ and other perovskites and ferroelectrics.

13. The tunable microstrip patch antenna element according to claim 1, wherein said dielectric substrate is a thick layer.

14. The tunable microstrip patch antenna element according to claim 1, wherein said substrate is a material selected from the group consisting of LaAlO₃, MgO and Si.

15. The tunable microstrip patch antenna according to claim 1, wherein said radiator is of a metallic material and has a desired shape.

16. The tunable microstrip patch antenna element according to claim 15, wherein said tunable microstrip patch antenna element has a desired fundamental frequency and said fundamental mode is TM₀₁ with said apparent electrical dimension comprising a length of said radiator which is one-half (½

) wavelength long at the desired fundamental frequency.

17. The tunable microstrip patch antenna element according to claim 1, wherein said substrate comprises a material of LaAlO₃ having a thickness of about 0.25 mm and said ferroelectric film has a thickness of about 2 μ

m and is comprised of a material comprising SrTiO₃.

18. The tunable microstrip patch antenna element according to claim 1 further comprising means for exciting said tunable microstrip antenna element.

19. The tunable microstrip patch antenna element according to claim 18, wherein said means for exciting comprises a probe that enters the central region of said ground plane and passes into said ground plane then vertically up through and out of said substrate and then into said radiator.

20. The tunable microstrip patch antenna element according to claim 19, wherein said radiator is shaped to have orthogonal edges and has width (w) and length (l) dimensions that are about equal to each other and wherein said means for exciting comprises a plurality of contacts one for each of said orthogonal edges that each enters near the respective orthogonal edge.

21. An antenna system including a plurality of tunable microstrip patch antenna elements each comprising;

a ground plane comprised of a conductive material;

a substrate comprised of a material selected from the group consisting of dielectric and semiconductive materials and mounted on said ground plane;

a radiator having an apparent electrical dimension and with parameters selected so as to operate in a fundamental mode at an odd order common denominator of desired fundamental frequencies, said radiator having a circuit for connecting to a variable bias voltage comprising means for generating a dc electric field between said radiator and said ground plane; and

a ferroelectric film placed on said substrate and in cooperation with said substrate being deterministic of said apparent electrical dimension of said radiator.

22. The antenna system according to claim 21, wherein said radiator comprises an annular ring.

23. The antenna system according to claim 21, wherein said substrate is comprised of silicon.

24. The antenna system according to claim 23, wherein said silicon has a resistivity in the range from about 1000 ohm-cm to about 10,000 ohm-cm.

25. The antenna system according to claim 21, further comprising a capacitive coupling arrangement comprising a microstrip spaced apart from said radiator.

26. The antenna system according to claim 21, wherein said circuit comprises a quarter-wavelength radial stub having a vertex which is connected by a high impedance microstrip transmission line to a respective radiator and to a respective means for generating said dc electric field.

27. The antenna system according to claim 26, wherein said respective means for generating said dc electric field is connected to said respective radiator by a wire bond.

28. The antenna system according to claim 27, wherein said means for generating said dc electric field is variable.

29. The antenna system according to claim 21, wherein each tunable microstrip patch antenna element has a desired fundamental frequency and said fundamental mode is TM₀₁ with said apparent electrical dimension of the respective radiator having a length which is one-half (½

) wavelength long at the respective fundamental frequency.

30. The antenna system according to claim 21, wherein each of said radiator is of a metallic material and has a desired shape.

31. The antenna system according to claim 30, wherein each of said tunable microstrip patch elements has a desired fundamental frequency and wherein said fundamental mode being TM₀₁ with said apparent electrical dimension having a length which is one-half (½

) wavelength long at the fundamental frequency.

32. The antenna system according to claim 21, wherein each of said tunable microstrip patch antenna elements further comprising means for exciting each of said tunable microstrip antenna elements.

33. The antenna system according to claim 31, wherein each of said means for exciting comprises a probe that enters the central region of each of said ground plane and passes into said ground plane thereof then vertically up through and out of said substrate thereof and then into said radiator thereof.

34. The antenna system according to claim 31, wherein each of said radiators is shaped to have orthogonal edges and has width (w) and length (l) dimensions that are about equal to each other and wherein said means for exciting comprises a plurality of contacts one for each of said orthogonal edges that each enters said ground plane of each radiator near the orthogonal edges.

35. The antenna system according to claim 21, wherein said antenna system is mounted on a surface into a one-dimensional array.

36. The antenna system according to claim 21, wherein said antenna system is mounted on a surface into a two-dimensional array.

37. The antenna system according to claim 21, wherein said antenna system is mounted on a curved surface.

38. A method to provide a tunable microstrip patch antenna element selected to operate at a frequency range having a fundamental frequency thereof comprising the steps of;

providing a ground plane comprised of a conductive material;

providing a substrate comprised of a material selected from the group consisting of dielectric and semiconductive materials and mounted on said ground plane;

providing a radiator having an apparent electrical dimension and with parameters selected so as to operate in a fundamental mode at an odd order common denominator of said fundamental frequency, said radiator having a circuit for connecting to a variable bias voltage comprising means for generating a dc electric field between said radiator and ground plane;

providing a ferroelectric film placed on said substrate and in cooperation with said substrate being deterministic of said apparent electrical dimension of said radiator; and

applying and varying said dc electric field so as to tune said radiator over said frequency range.

39. The method according to claim 38, wherein said circuit comprises a quarter-wavelength radial stub having a vertex which is connected by a high impedance microstrip transmission line to said radiator and to said means for generating said electric field.

40. The method according to claim 38, wherein the tunable microstrip patch antenna element has a desired fundamental frequency and said fundamental mode is TM₀₁ with said apparent electric dimension comprising a length of said radiator which is about one-half (½

) wavelength long at the fundamental frequency.

41. The method according to claim 38, wherein said radiator is of a metallic material and has a desired shape.

42. The method according to claim 38, wherein said tunable microstrip patch antenna element further comprising means for exciting said tunable microstrip antenna element.

43. The method according to claim 42, wherein said means for exciting comprises a probe that enters the central region of said ground plane and passes into said ground plane then vertically up through and out of said substrate and then into said radiator.

44. The method according to claim 42, wherein said radiator is shaped to have orthogonal edges and has width (w) and length (l) dimensions that are about equal to each other and wherein said means for exciting comprises a plurality of contacts one for each of said orthogonal edges that each enters said ground plane near the respective orthogonal edge.