Microstrip wide band antenna

• US 5,734,350 A
• Filed: 04/08/1996
• Issued: 03/31/1998
• Est. Priority Date: 04/08/1996
• Status: Expired due to Term

• Current Assignee: Laird Technologies Incorporated (DuPont de Nemours, Inc.)
• Original Assignee: Xertex Technologies, Inc. (Laird Limited)
• Inventors: Deming, Douglas Robert, Munson, Robert Eugene, Craig, Dax, Negler, Joseph Theofil
• Primary Examiner(s): Le, Hoanganh T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/629,230
• Time in Patent Office: 722 Days
• Field of Search: 343/700 MS, 343/830, 343/846, 343/872, 343/878, 343/882
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/42 Housings not intimately mechanically associated with radiating elements, e.g. radome
• CPC Class Codes: H01Q 3/02 using mechanical movement of antenna or antenna system as a whole
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/0471 Non-planar, stepped or wedge-shaped patch

Abstract

A Radio Frequency (RF) microstrip antenna employs a planar or curved radiator element that is mounted or supported in spaced relation to a planar or curved ground plane element. A RF feed is attached near one edge of the radiator element for receiving and/or transmitting RF signals in a lobe that is substantially perpendicular to the ground plane element. The radiator element and the ground plane element are maintained in a converging or tilted physical relationship. When a coaxial cable is employed as the antenna feed, the cable'"'"'s outer insulation is secured to the ground plane element, the cable'"'"'s center conductor extends away from the ground plane element to provide a signal feed to the radiator element and to provide physical support for one edge of the radiator element, and two insulator posts extend away from the ground plane element to provide support for the opposite edge of the radiator element.

Claims

1. A microstrip antenna, comprising:

a metallic and generally planar ground plane element occupying a first physical plane, said ground plane element being formed as first quadrilateral having a first shape and a first physical size;

a metallic and generally planar radiating element, said radiating element being formed as second quadrilateral having second shape that is generally identical to said first shape of said first quadrilateral, said second shape being of a second physical size that is equal to or smaller than said first physical size;

mounting means positioning said radiating element at a fixed position and so as to be generally centered over said first physical size of said ground plane element, said mounting means operating to physically mount said radiating element away from said ground plane element so as to define a dielectric space between said radiating element and said ground plane element, said mounting means operating to mount said planar radiating element in an inclined attitude relative to said planar ground plane element; and

signal feed means extending into said dielectric space, said signal feed means including metallic electrical conductor means fixed to a feed point on a surface of said radiating element that faces said ground plane element.

2. The antenna of claim 1 wherein said first and second quadrilateral shapes are selected from the group square and rectangular.

3. The antenna of claim 1 wherein said second size of said radiating element is in the range of from about 18% to about 30% of said first size of said ground plane element.

4. The antenna of claim 1 including:

a radome secured to said first shape and covering said ground plane element and said radiating element.

5. The antenna of claim 1 wherein said feed point comprises a point on said surface of said radiating element that is adjacent to a first edge of said radiating element, and wherein said mounting means comprises:

said metallic electrical conductor means operating to physically support said radiating element; and

first and second dielectric-material and physically spaced support posts of generally equal length, each of said posts extending between said ground plane element and said radiating element, to engage said surface of said radiating element adjacent a second edge that is opposite to said first edge.

6. The antenna of claim 5 wherein said first and second support posts comprise linear posts having adjustable lengths.

7. The antenna of claim 6 wherein said second size of said radiating element is in the range of from about 18% to about 30% of said first size of said ground plane element.

8. A microstrip antenna, comprising:

a flat ground plane member;

said ground plane member having a flat top metallic surface that defines a first metallic area;

said first metallic area having first and second sides that are mutually parallel, and having second and third sides that are mutually parallel, and are perpendicular to said first and second sides;

a flat radiating member;

said radiating member having a flat bottom metallic surface that defines a second metallic area that is equal to or smaller than said first metallic area;

said second metallic area having first and second sides that are mutually parallel, and having second and third sides that are mutually parallel, and are perpendicular to said first and second sides;

dielectric mounting means physically engaging said first and second metallic surfaces and operating to mount said radiating member at a fixed position on said ground plane member with said second metallic area generally centered over said first metallic area;

said fixed position providing that respective first, second, third and fourth sides of said first and second metallic areas are parallel;

said mounting means operating to mount said radiating member out of physical engagement with said ground plane member, so as to define a dielectric space between said radiating member and said ground plane member;

said mounting means operating to mount said radiating member at an incline relative to said ground plane members so that said first edge of said second metallic area is positioned a first distance from said first metallic area, and so that said second edge of said second metallic area is positioned a second distance from said second metallic area;

said first and second distance being unequal; and

antenna signal feed means extending into said dielectric space, said signal feed means including a metallic electrical conductor that is fixed to a feed point on said bottom surface of said radiating member that is adjacent to said first edge of said radiating member.

9. The antenna of claim 8 wherein said first distance is greater than said second distance.

10. The antenna of claim 8 wherein said second distance is greater than said first distance.

11. The antenna of claim 8 wherein said first metallic area and said second metallic area are selected from the group square-shaped area and rectangular-shaped area.

12. The antenna of claim 8 wherein said second metallic area is in the range of from about 18% to about 30% the size of said first metallic area.

13. The antenna of claim 8 including:

a radome covering said ground plane member and said radiating member.

14. The antenna of claim 13 wherein said radome comprises:

an box-like housing having four walls that define an open bottom that generally conforms to said first area; and

means securing said four walls to said first, second, third and fourth sides of said first metallic area.

15. The antenna of claim 8 wherein said mounting means comprises:

said metallic electrical conductor means operating to physically support said radiating member at a first support point that is adjacent to said first edge of said second metallic area, and

first and second dielectric-material, physically spaced support posts of generally equal length;

said first and second support posts individually extending between said first metallic area and second and third support points on said second metallic area that are adjacent to said second edge of said second metallic area.

16. The antenna of claim 15 wherein said first and second support posts comprise linear posts having adjustable lengths.

17. The antenna of claim 15 wherein said metallic electrical conductor means comprises a center conductor of a coaxial cable having a metallic sheath, and including:

means electrically connecting said metallic sheath to said first metallic area at a point that is adjacent to said first edge of said first metallic area.

18. The antenna of claim 15 wherein:

said dielectric space is an air dielectric space;

said first metallic area and said second metallic area are square-shaped areas; and

said second area is in the range of from about 18% to about 30% of said first area.

19. The antenna of claim 18 wherein said first distance is greater than said second distance.

20. The antenna of claim 18 wherein said second distance is greater than said first distance.

21. A method of making a microstrip antenna in accordance with a desired standing wave ratio, said antenna having a ground plane member and a radiating member, said ground plane member providing a top metallic surface with a first edge and an opposite edge, and said radiating member providing a bottom metallic surface that faces said top metallic surface, said radiating member having a first edge and a second edge, the method comprising the steps of:

providing first mounting means physically engaging said top and bottom metallic surfaces adjacent to said first edges, and mounting said radiating member at a position overhanging said ground plane member, with said first edge of said bottom metallic surface being located a first distance from said top metallic surface;

providing adjustable length dielectric mounting means engaging said top and bottom metallic surfaces adjacent to said second edges, and mounting said radiating member at said position overhanging said ground plane member, with said second edge of said bottom metallic surface being located at a second distance from said top metallic surface;

said first and second distances being unequal so as to position said second metallic surface at an incline to said first metallic surface;

applying a signal to a feed point on said second metallic surface adjacent to said first edge of said second metallic surface;

monitoring a standing wave ratio of said antenna for an occurrence of said desired standing wave ratio;

iteratively (1) moving said feed point relative to said first edge of said second metallic surface, and/or (2) changing said second distance, until said monitored standing wave ratio is generally equal to said desired standing wave ratio; and

upon said monitored standing wave ratio being generally equal to said desired standing wave ratio, measuring a location of said feed point on said second metallic surface, and measuring said second distance.

22. The method of claim 21 including the step of:

mass producing antennas having said desired standing wave ratio by using said first distance, said measured location of said feed point on said second metallic surface, and said measured second distance to construct said mass produced antennas.

23. The method of claim 21 including the step of:

providing a radome for each of said mass produced antennas.

24. A microstrip antenna, comprising:

a metallic ground plane element having a first shape and a first size;

a metallic radiating element, said radiating element having second shape that is generally identical to said first shape, said second shape being of a second size that is equal to or smaller than said first size;

mounting means positioning said radiating element at a fixed position and so as to be generally centered over said ground plane element, said mounting means operating to physically mount said radiating element away from said ground plane element so as to define a dielectric space between said radiating element and said ground plane element, said mounting means operating to mount said radiating element in an inclined attitude relative to said ground plane element; and

signal feed means extending into said dielectric space, said signal feed means including metallic electrical conductor means fixed to a feed point on a surface of said radiating element that faces said ground plane element.

25. The antenna of claim 24 wherein said first and second shapes are both selected from the group flat-planar shape or partial-cylinder shape.

26. The antenna of claim 24 wherein said second size of said radiating element is in the range of from about 18% to about 30% of said first size of said ground plane element.

27. The antenna of claim 24 including:

a radome secured to said ground plane element and covering said ground plane element and said radiating element.

28. The antenna of claim 24 wherein said feed point comprises a point on said surface of said radiating element that is adjacent to a first edge of said radiating element, and wherein said mounting means comprises:

said metallic electrical conductor means operating to physically support said radiating element; and

first and second dielectric-material and physically spaced support posts, each of said posts extending between said ground plane element and said radiating element, to engage said surface of said radiating element adjacent a second edge that is opposite to said first edge.

29. The antenna of claim 28 wherein said second size of said radiating element is in the range of from about 18% to about 30% of said first size of said ground plane element, and wherein said first and second shapes are both selected from the group flat-planar shape or partial-cylinder shape.

30. A microstrip antenna, comprising:

a ground plane member formed as a partial cylinder, said ground plane member having a curved top metallic surface with a plurality N of sides;

a radiating member formed as a partial cylinder, said radiating member having a curved bottom metallic surface with said plurality N of sides;

dielectric mounting means physically engaging said first and second metallic surfaces and operating to mount said radiating member at a fixed position on said ground plane member with said second metallic surface generally centered over said first metallic surface;

said fixed position providing that corresponding sides of said first and second metallic surfaces are in general alignment;

said mounting means operating to mount said radiating member out of physical engagement with said ground plane member, so as to define a dielectric space between said radiating member and said ground plane member;

said mounting means operating to mount said radiating member at an incline relative to said ground plane member; and

antenna signal feed means extending into said dielectric space, said signal feed means including a metallic electrical conductor that is fixed to a feed point on said bottom surface of said radiating member.

31. The antenna of claim 30 wherein said mounting means operates to mount said radiating member at said incline relative to said radiation member such that all points on said radiating member are at different distances from corresponding underlying points on said ground plane member.

32. The antenna of claim 30 wherein N equals four, and wherein said mounting means operates to mount said radiating member at said incline relative to said ground plane member such that first sides of said radiating member and said ground plane member are parallel and spaced a first distance, such that second opposite sides of said radiating member and said ground plane member are parallel and spaced a second distance that is greater than said first distance, such that third sides of said radiating member and said ground plane member are non-parallel and are spaced an increasing distance as measured from said first side to said opposite second side, and such that fourth sides of said radiating member and said ground plane member are non-parallel and are spaced said increasing distance as measured from said first side to said opposite second side.

33. A microstrip antenna, comprising:

a ground member having a top metallic surface with a plurality N of sides;

a radiating member having a bottom metallic surface with said plurality N of sides;

dielectric mounting means physically engaging said first and second metallic surfaces and operating to mount said radiating member at a fixed position on said ground member with said second metallic surface generally centered over said first metallic surface;

said fixed position providing that corresponding sides of said first and second metallic surfaces are in general alignment;

said mounting means operating to mount said radiating member out of physical engagement with said ground member, so as to define a dielectric space between said radiating member and said ground member;

said mounting means operating to mount said radiating member at an incline relative to said ground member; and

antenna signal feed means extending into said dielectric space, said signal feed means including a metallic electrical conductor that is fixed to a feed point on said bottom surface of said radiating member.

34. The antenna of claim 33 wherein said mounting means operates to mount said radiating member at said incline relative to said radiation member such that all points on said radiating member are at different distances from corresponding underlying points on said ground member.

35. The antenna of claim 33 wherein N equals four, and wherein said mounting means operates to mount said radiating member at said incline relative to said ground member such that first sides of said radiating member and said ground member are parallel and spaced a first distance, such that second opposite sides of said radiating member and said ground member are parallel and spaced a second distance that is greater than said first distance, such that third sides of said radiating member and said ground member are non-parallel and are spaced an increasing distance as measured from said first side to said opposite second side, and such that fourth sides of said radiating member and said ground member are non-parallel and are spaced said increasing distance as measured from said first side to said opposite second side.

36. A microstrip antenna, comprising:

a generally planar ground plane element in the shape of a first quadrilateral having a first physical size, said ground plane element having an upper metal surface;

a generally planar radiating element in the shape of a second quadrilateral that is generally identical to said first quadrilateral, said second quadrilateral being of a second physical size that is equal to or smaller than said first physical size, said radiating element having a lower metal surface;

mounting means positioning said radiating element at a fixed position and so as to be generally centered over said ground plane element;

said mounting means operating to physically mount said radiating element away from said ground plane element so as to define a dielectric space between said radiating element and said ground plane element;

said mounting means operating to mount said planar radiating element at an incline relative to said planar ground plane element in such a manner that all points on said top metal surface are spaced at a different distance from a corresponding point on said bottom metal surface; and

signal feed means extending into said dielectric space, said signal feed means including metallic electrical conductor means fixed to said bottom metal surface of said radiating element.

37. The antenna of claim 36 wherein said first and second quadrilaterals are selected from the group square and rectangular.

38. The antenna of claim 36 wherein said second size is in the range of from about 18% to about 30% of said first size.

39. The antenna of claim 36 including:

a radome secured to said ground plane element and covering said radiating element.

40. The antenna of claim 36 wherein said signal feed means comprises:

a first and a second feed conductor connected to said lower metal surface in a manner to provide a circular polarized antenna.

41. The antenna of claim 36 wherein said signal feed means comprises:

a feed conductor connected to said lower metal surface in a manner to provide a dual polarized antenna.

42. An omni-directional/directional microstrip antenna, comprising:

a ground plane element having a first physical size, said ground plane element having an upper metal surface;

a radiating element having a second physical size, said radiating element having a lower metal surface;

mounting means positioning said radiating element at a fixed position and so as to be generally centered over said ground plane element;

said mounting means operating to physically mount said radiating element out of physical engagement with from said ground plane element so as to define a dielectric space between said radiating element and said ground plane element;

said mounting means operating to mount said planar radiating element at an incline relative to said planar ground plane element; and

signal feed means extending into said dielectric space, said signal feed means including metallic electrical conductor means fixed to said bottom metal surface of said radiating element;

wherein when said first physical size is appreciably greater than said second physical size said antenna is directionally, and when said first physical size is generally equal to said second physical size said antenna is omni-directional.