Microstrip array antenna

• US 20040080455A1
• Filed: 10/23/2002
• Published: 04/29/2004
• Est. Priority Date: 10/23/2002
• Status: Active Grant

• Current Assignee: Southern Methodist University
• Original Assignee: Southern Methodist University
• Inventors: Lee, Choon Sae
• Granted Patent: US 7,705,782 B2
• Time in Patent Office: Days
• US Class Current: 343/700MS
• CPC Class Codes: H01Q 21/065 Patch antenna array

Abstract

A microstrip antenna has a single dielectric layer with a conductive ground plane disposed on one side, and an array of spaced apart radiating patches disposed on the other side of the dielectric layer. The radiating patches are interconnected with a feed terminal via stripline elements. Responsive to electromagnetic energy, a high-order standing wave is induced in the antenna and a directed beam is transmitted from and/or received into the antenna. A dual-mode embodiment is configured such that standing wave nodes occur at the intersection of orthogonally situated striplines to minimize cross-polarization levels of the signals and the cross-talk between the two modes of operation.

Claims

1. An antenna (100-3300), comprising:

a dielectric layer defining a first side and a second side;

a conductive ground plane disposed on the first side of the dielectric layer;

an array of spaced-apart, radiating patches disposed on the second side of the dielectric layer; and

at least one stripline disposed on the second side of the dielectric layer and electrically connected to at least one corner of each patch.

2. The antenna (100-3300) of claim 1, wherein the patches and striplines are sized and positioned so that, responsive to electromagnetic energy, a high-order standing wave is induced in the antenna.

3. The antenna (100-3300.) of claim 1 wherein the antenna is planar.

4. The antenna (100-1800) of claim 1, further comprising at least one feeding means electrically connected to the ground plane and at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

5. The antenna (100-1800) of claim 1, further comprising at least one feeding means having a first conducting element electrically connected to the ground plane and a second conducting element electrically connected to at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

6. The antenna (100-1800) of claim 1, further comprising at least one of a probe, an SMA probe, an aperture-coupled line, and a microstripline electrically connected to the ground plane and at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

7. The antenna (100-1800) of claim 1, further comprising at least two feeding means, each of which comprise one of a probe, an SMA probe, an aperture-coupled line, and a microstripline, each of which feeding means are orthogonally electrically connected to the ground plane and at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

8. The antenna (100-1300) of claim 1, wherein the patches are arranged in a square array of equal rows and columns.

9. The antenna (100) of claim 1, further comprising at least one tuning stub disposed on the second side of the dielectric layer and extending substantially perpendicularly from at least one of said at least one stripline.

10. The antenna (400-800) of claim 1, wherein the patches include at least four patches, and each patch includes first and second diametrically opposed corners and third and fourth diametrically opposed corners, and wherein the striplines are apportioned between a first group of parallel striplines and a second group of parallel striplines, the striplines in the first group of striplines being oriented substantially perpendicular to the striplines in the second group of striplines, and wherein the first group of striplines electrically interconnects together at least one of the first and second diametrically opposed corners of each of at least two of the at least four patches, and wherein the second group of striplines electrically interconnects together at least one of the third and fourth diametrically opposed corners of each of at least two of the at least four patches.

11. The antenna (400-600) of claim 1, wherein the patches include at least four patches, and each patch includes first and second diametrically opposed corners and third and fourth diametrically opposed corners, and wherein the striplines are apportioned between a first group of parallel striplines and a second group of parallel striplines, the striplines in the first group of striplines being oriented substantially perpendicular to the striplines in the second group of striplines, and wherein the first group of striplines electrically interconnects together at least one of the first and second diametrically opposed corners of each of at least two of the at least four patches, and wherein the second group of striplines electrically interconnects together at least one of the third and fourth diametrically opposed corners of each of at least two of the at least four patches, and wherein the antenna further comprises one tuning stub extending outwardly from each corner of a patch.

12. The antenna (800) of claim 1, wherein the patches include at least four patches, and each patch includes first and second diametrically opposed corners and third and fourth diametrically opposed corners, and wherein the striplines are apportioned between a first group of parallel striplines and a second group of parallel striplines, the striplines in the first group of striplines being oriented substantially perpendicular to the striplines in the second group of striplines, and wherein the first group of striplines electrically interconnects together at least one of the first and second diametrically opposed corners of each of at least two of the at least four patches, and wherein the second group of striplines electrically interconnects together at least one of the third and fourth diametrically opposed corners of each of at least two of the at least four patches, and wherein the antenna further comprises one tuning stub extending outwardly from one corner of each of four patches toward a common point.

13. The antenna (1000) of claim 1, wherein the patches include at least four patches, and each patch includes first and second diametrically opposed corners and third and fourth diametrically opposed corners, and wherein the striplines are apportioned between a first group of parallel striplines, a second group of parallel striplines, and a third group of striplines, the striplines in the first group of striplines being oriented substantially perpendicular to the striplines in the second group of striplines, the striplines in the third group of striplines being oriented at substantially 45°

to the striplines in the first and second groups of striplines, and wherein the first group of striplines electrically interconnects together at least one of the first and second diametrically opposed corners of each of at least two of the at least four patches, and wherein the second group of striplines electrically interconnects together at least one of the third and fourth diametrically opposed corners of each of at least two of the at least four patches, and wherein, for at least one group of four patches, the antenna further comprises one tuning stub extending outwardly toward a common point from one corner of each of the four patches constituting the at least one group of patches, and one stripline from the third group of stripline interconnects each tuning stub with each of two closest tuning stubs.

14. The antenna (1300) of claim 1, wherein the patches include at least four patches, and each patch includes first and second diametrically opposed corners and third and fourth diametrically opposed corners, and wherein the striplines are apportioned between a first group of parallel striplines, a second group of parallel striplines, and a third group of striplines, the striplines in the first group of striplines being oriented substantially perpendicular to the striplines in the second group of striplines, the striplines in the third group of striplines being oriented at substantially 45°

to the striplines in the first and second groups of striplines; and

wherein the first group of striplines electrically interconnects together at least one of the first and second diametrically opposed corners of each of at least two of the at least four patches, and wherein the second group of striplines electrically interconnects together at least one of the third and fourth diametrically opposed corners of each of at least two of the at least four patches; and

wherein, for at least one first group of four patches, the antenna further comprises one short stub extending outwardly toward a common point from one corner of each of the four patches constituting the at least one group of patches, and one stripline from the third group of striplines interconnects each short stub with each of two closest short stubs; and

wherein, for at least one second group of four patches, the antenna further comprises one tuning stub extending outwardly toward a common point from one corner of each of the four patches constituting the at least one group of patches, and one stripline from the third group of stripline interconnects each tuning stub with each of two closest tuning stubs, each tuning stub extending beyond the interconnection point of the respective striplines and tuning stubs.

15. The antenna (1600) of claim 1, wherein the antenna is a linear array antenna defining a first side and a second side, and wherein the antenna includes at least three patches, each of which define first corners proximate to the first side, and second corners proximate to the second side;

and wherein, between two adjacent patches, the striplines electrically interconnect a first corner of each patch with a second corner of the adjacent patch and those two striplines are crisscrossed; and

wherein the antenna further comprises at least one tuning stub extending outwardly from at least one corner of one patch, which corner is also connected to a stripline.

16. The antenna (1900-3300.) of claim 1, further comprising at least one feeding means electrically connected to the ground plane and through at least one transmission line and at least one stripline to at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

17. The antenna (1900-3300.) of claim 1, further comprising at least one feeding means having a first conducting element electrically connected to the ground plane and a second conducting element electrically connected through at least one transmission line and at least one stripline to at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

18. The antenna (1900-3300.) of claim 1, further comprising at least one of a probe, an SMA probe, an aperture-coupled line, and a microstripline electrically connected to the ground plane and through at least one transmission line and at least one stripline to at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

19. The antenna (2300, 2900, 3200) of claim 1, further comprising at least two feeding means, each of which comprise one of a probe, an SMA probe, an aperture-coupled line, and a microstripline, each of which feeding means are orthogonally electrically connected to the ground plane and through at least one transmission line and at least one stripline to at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

20. The antenna (1900, 2100, 2500) of claim 1, further comprising at least one feeding means electrically connected to the ground plane and through a transmission line connected to a plurality of striplines connected to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna.

21. The antenna (1900, 2500) of claim 1, further comprising at least one feeding means electrically connected to the ground plane and through a transmission line connected to a plurality of striplines connected to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, and wherein the transmission line is centrally disposed on the second side of the dielectric layer.

22. The antenna (2100) of claim 1, further comprising at least one feeding means electrically connected to the ground plane and through a transmission line connected to a plurality of striplines connected to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, and wherein the transmission line is disposed on the second side of the dielectric layer outside the array of patches.

23. The antenna (2300, 2900) of claim 1, further comprising:

a first feeding means electrically connected to the ground plane and through a first transmission line connected to a plurality of substantially parallel first striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the first transmission line is substantially perpendicular to the first striplines and positioned outside the array of patches; and

a second feeding means electrically connected to the ground plane and through a second transmission line connected to a plurality of substantially parallel second striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the second transmission line is substantially perpendicular to the second striplines and positioned outside the array of patches, and wherein the first striplines are substantially perpendicular to the second striplines.

24. The antenna (2700) of claim 1, further comprising:

at least one feeding means electrically connected to the ground plane and through a transmission line connected to a plurality of substantially parallel first striplines connected to at least one first corner of each of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, and wherein the transmission line is generally centrally disposed on the second side of the dielectric layer within the array of patches; and

a plurality of substantially parallel second striplines connected to at least one second corner of each of at least one patch, wherein the first striplines are substantially perpendicular to the second striplines, and the first corners are diametrically opposed to the second corners.

25. The antenna (2900) of claim 1, further comprising:

a first feeding means electrically connected to the ground plane and through a first transmission line connected to a plurality of substantially parallel first striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the first transmission line is substantially perpendicular to the first striplines and generally centrally disposed on the second side of the dielectric layer within the array of patches; and

a second feeding means electrically connected to the ground plane and through a second transmission line connected to a plurality of substantially parallel second striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the second transmission line is substantially perpendicular to the second striplines and generally centrally disposed on the second side of the dielectric layer within the array of patches, wherein the first striplines are substantially perpendicular to the second striplines, and wherein the second transmission line further comprises a bridge configured generally at the intersection of the first and second transmission lines, the bridge comprising vias extending from the second transmission line on each side of the first transmission line through apertures formed in the dielectric, the ground plane, and a second dielectric to a microstrip disposed on the second dielectric for the transmission of electromagnetic energy across the second transmission line.

26. The antenna (3200) of claim 1, further comprising:

a first feeding means electrically connected to the ground plane and through first and second portions of a first transmission line connected to a plurality of substantially parallel first striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the first transmission line is substantially perpendicular to the first striplines and generally centrally disposed on the second side of the dielectric layer within the array of patches;

a second feeding means electrically connected to the ground plane and through first and second portions of a second transmission line connected to a plurality of substantially parallel second striplines to at least one corner of at least one patch for feeding electromagnetic energy to and/or extracting electromagnetic energy from the antenna, wherein the second transmission line is substantially perpendicular to the second striplines and generally centrally disposed on the second side of the dielectric layer within the array of patches, wherein the first striplines are substantially perpendicular to the second striplines; and

a directional coupler configured for providing electrical continuity between the first and second portions of the first transmission line, and for providing electrical continuity between the first and second portions of the second transmission line, such that transmission of electromagnetic energy between the first and second transmission lines is substantially inhibited, the coupler comprising;

a first microstrip longitudinal section defining a first end connected to the first portion of the first transmission line, a second end connected to the first portion of the second transmission line;

a second microstrip longitudinal section defining a first end connected to the second portion of the first transmission line, a second end connected to the second portion of the second transmission line;

a first microstrip end connection section connected between the first end of the first longitudinal section and the first end of the second longitudinal section;

a second microstrip end connection section connected between the second end of the first longitudinal section and the second end of the second longitudinal section; and

an intermediate microstrip connection section connected between the mid-section of the first longitudinal section and the mid-section of the second longitudinal section, wherein the first, second, and intermediate connection sections are sized so that the centerlines of the first and second longitudinal sections are spaced apart by about a quarter-wavelength, and so that the centerlines of the first and intermediate connection sections are spaced apart by about a quarter-wavelength, and so that the centerlines of the second and intermediate connection sections are spaced apart by about a quarter-wavelength, and wherein the widths of the first and second longitudinal sections and the intermediate sections are determined assuming an impedance of X, and the widths of the first and second end connection sections are determined assuming an impedance of about 2X, wherein X is about 25 to 100 ohms.

27. A planar microstrip directional coupler configured for providing electrical continuity between first and second portions of a first transmission line, and for providing electrical continuity between first and second portions of a second transmission line, such that transmission of electromagnetic energy between the first and second transmission lines is substantially inhibited, the coupler comprising:

a first microstrip longitudinal section defining a first end connected to the first portion of the first transmission line, a second end connected to the first portion of the second transmission line;

a second microstrip longitudinal section defining a first end connected to the second portion of the first transmission line, a second end connected to the second portion of the second transmission line;

a first microstrip end connection section connected between the first end of the first longitudinal section and the first end of the second longitudinal section;

a second microstrip end connection section connected between the second end of the first longitudinal section and the second end of the second longitudinal section; and

an intermediate microstrip connection section connected between the midpoint of the first longitudinal section and the midpoint of the second longitudinal section, wherein the first, second, and intermediate connection sections are sized so that the centerlines of the first and second longitudinal sections are spaced apart by about a quarter-wavelength, and so that the centerlines of the first and intermediate connection sections are spaced apart by about a quarter-wavelength, and so that the centerlines of the second and intermediate connection sections are spaced apart by about a quarter-wavelength, and wherein the widths of the first and second longitudinal sections and the intermediate sections are determined assuming an impedance of X, and the widths of the first and second end connection sections are determined assuming an impedance of about 2X, wherein X is about 25 to 100 ohms.

28. The coupler of claim 27, wherein each of the first and second ends of the first and second longitudinal sections are chamfered at an angle of about 45°

.

29. A microstrip array antenna, comprising:

a single layer of dielectric material;

a ground plane contiguous a first side of said dielectric material;

a plurality of patches contiguous a second side of said dielectric material opposite said first side;

a feed terminal; and

a plurality of stripline conductors whereby said feed terminal is physically connected to each of said plurality of patches, a cavity formed between the patches, the striplines and the ground plane being configured such that standing waves are formed in the cavity whereby some nodes of the standing wave exist at each of said stripline conductors.

30. A method of designing a microstrip array antenna, comprising the steps of:

attaching a ground plane to a first side of a planar dielectric; and

configuring radiating patches, a feed terminal and associated conductive material that connects the feed terminal to each of the radiating patches, on a second side of said planar dielectric, opposite said first side, to insure that a standing wave having a plurality of nodes is formed in a cavity between the patches, the associated conductive material and the ground plane wherein at least some nodes of the standing wave are coincident with the position of said associated conductive material.

31. The method of claim 30, wherein the associated conductive material is configured as striplines.

32. A method of designing a microstrip array antenna, comprising the steps of:

attaching a ground plane to a first side of a planar dielectric; and

configuring radiating patches, a feed terminal and associated conductive material that connect the feed terminal to each of the radiating patches, on a second side of said planar dielectric, opposite said first side, to insure that a standing wave having a plurality of nodes is formed in a cavity between the patches, the associated conductive material and the ground plane to provide a predetermined distribution of electromagnetic power over the radiating patches.

33. The method of claim 32, wherein the associated conductive material is configured as striplines and the predetermined distribution is substantially uniform.

34. The method of claim 32, wherein the associated conductive material is configured as striplines and the predetermined distribution is tapered to minimize sidelobe energy distribution.

35. A planar microstrip array antenna, comprising:

a single layer of dielectric material;

a ground plane contiguous a first side of said dielectric material;

a plurality of patches contiguous a second side of said dielectric material opposite said first side wherein all of the patches used in an operational mode are of the same physical size;

a feed terminal; and

a plurality of stripline conductors directly interconnecting said feed terminal to each of said plurality of patches.

36. A method of distributing EM (electromagnetic) energy between first and second energy sources and their respective energy sinks where the first and second energy sources are physically connected to their respective energy sinks via first and second sets of intersecting conductors in the same plane but having different angular orientations, comprising the steps of:

providing a resonant cavity contiguous the plane of said intersecting conductors; and

generating first and second standing waves of first and second angular orientations from said first and second EM sources whereby nodes of said first and second standing waves occur at the intersections of at least some of said first and second sets of intersecting conductors such that excitations of the two modes are independent with each other.

37. The method of claim 36, wherein the intersecting conductors are striplines.

38. An antenna, comprising:

a ground plane;

a surface area including radiating array elements, a signal source terminal and associated conductive material interconnecting said radiating patches and said signal source terminal; and

a resonant signal cavity between said ground plane and said surface area configured to create, upon the application of EM (electromagnetic) power to said antenna, a standing wave the nodes of which exist at both the radiating array element and the associated conductive material.

39. The apparatus of claim 38, wherein the radiating array elements are patches of conductive material and the associated conductive material comprises stripline elements.

40. A microstrip planar array antenna, comprising:

a plurality of radiating array elements in a planar array;

a feed terminal in said planar array;

a plurality of associated conductive material elements, in said planar array, whereby said feed terminal is physically connected to each of said plurality of substantially identical size patches; and

a resonant cavity contiguous said planar array configured such that standing waves formed in the cavity have nodes at the cross points of two vertical and horizontal striplines.

41. The apparatus of claim 40, wherein:

the radiating array elements are radiating patches and are substantially identical size for maximum directivity; and

the associated conductive material elements are striplines.

44. The antenna of either claims 41 or 43, wherein the patches are square.

42. A microstrip single planar array antenna that can be used, without modification, for circular and linear polarized beam signals, comprising:

a plurality of radiating patches in a planar array;

first and second feed terminals in said planar array;

first and second sets of stripline conductors, in said planar array, whereby each of said feed terminals is physically connected to each of said plurality of substantially identical size patches with said first and second sets of stripline conductors being oriented in different angular directions such that they form a plurality of criss-cross intersections; and

a resonant cavity contiguous said planar array configured such that standing waves formed in the cavity have nodes coincident with a majority of said stripline criss-cross intersections and said radiating patches.

43. The apparatus of claim 42, wherein the radiating patches are substantially identical size for maximum directivity.

45. A method of increasing the transmission efficiency of a microstrip array antenna including radiating patches and a signal source terminal in a given plane juxtaposed a resonant cavity, comprising the steps of:

electrically connecting the source terminal to each of the radiating patches with a plurality of conductive strips; and

configuring the antenna elements whereby a standing wave occurring in said resonant cavity has nodes at the cross points of a majority of said conductive strips in a modal excitation manner whereby the cross-talk levels are minimized.

46. An antenna (100-3300), comprising:

a dielectric layer defining a first side and a second side;

a conductive ground plane disposed on the first side of the dielectric layer;

an array of spaced-apart, radiating patches disposed on the second side of the dielectric layer; and

at least one interconnecting element disposed on the second side of the dielectric layer and electrically interconnecting at least one corner of each patch of said array of patches.

47. The antenna of claim 46, wherein the at least one interconnecting element and said patches defines one surface of a leaky cavity operationally including a standing wave.

48. The antenna of claim 46, wherein the at least one interconnecting element operates to guide the power flow of standing waves formed in cavity the boundaries of which are delineated by said dielectric layer.

49. The antenna of claim 46, wherein the at least one interconnecting element operates in conjunction with said patches to define antenna bandwidth.

50. The antenna of claim 46, wherein the at least one interconnecting element operates in conjunction with said patches to define a standing wave resonant frequency of a cavity formed within the boundaries of the dielectric layer.