Methods and apparatus for implementation of an antenna for a wireless communication device

• US 20060092080A1
• Filed: 10/20/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Southern Methodist University
• Original Assignee: Southern Methodist University
• Inventors: Lee, Choon Sae
• Granted Patent: US 7,205,944 B2
• Time in Patent Office: Days
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 9/0471 Non-planar, stepped or wedge-shaped patch

Abstract

A wireless communication device includes an antenna configured with two conductive elements separated by an insulating medium. One conductive element is a ground plane and the other is a microstrip line. The ground plane is formed with a bend proximate an end. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line from the ground plane is changed to reduce the resonant frequency of the microstrip line. A second microstrip line with an open end and another end shorted to the ground plane is operative to prevent RF current from flowing on the backside of the ground plane. A backside of the ground plane and the second microstrip line may be covered with a lossy magnetic medium to reduce the near field above the backside of the ground plane.

Claims

1. An antenna comprising:

an insulating substrate;

a conductive strip with two ends disposed on a first surface of the substrate, the conductive strip having a characteristic impedance that may vary along its length wherein the conductive strip is separated from the ground plane by a separation distance, the separation distance being changed at at least one location along the conductive strip; and

a ground plane disposed on a second surface of the substrate, the second surface being opposed to the first surface, wherein the ground plane is formed with a bend proximate an edge.

2. The antenna of claim 1, wherein the conductive strip is insulated from the ground plane except at a point.

3. The antenna of claim 1, wherein the bend in the ground plane is an angular bend.

4. The antenna of claim 1, wherein the bend in the ground plane is substantially a right angle.

5. The antenna of claim 1, wherein a second bend is formed in the ground plane to form a segment of the ground plane lying over the conductive strip.

6. The antenna of claim 1, wherein the conductive strip is formed with a tapered section proximate an end.

7. The antenna of claim 6, wherein the tapered section is hollow.

8. The antenna of claim 1, wherein said separation distance of the conductive elements is changed abruptly along the length of the conductive patch.

9. The antenna of claim 1 and further comprising a feed point proximate the shorted end of said microstrip line.

10. The antenna of claim 1 and further comprising a lossy magnetic material disposed over at least a portion of said ground plane.

11. The antenna of claim 1 and further comprising another conductive element disposed over a side of said ground plane opposing the conductive strip and insulated from said ground plane except at a point.

12. The antenna of claim 11, wherein the another conductive element has an end that is proximate an edge of said ground plane and wherein a bend is formed in said another conductive element proximate said edge.

13. The antenna of claim 11, wherein the bend formed in said another conductive element is an angular bend.

14. The antenna of claim 11, and further comprising an insulating material having a varied thickness disposed between the another conductive element and said ground plane.

15. The antenna of claim 11, wherein the thickness of the insulating material disposed between the another conductive element and said ground plane varies abruptly at at least one location.

16. The antenna of claim 1, wherein the substrate is formed from a material with a relative dielectric constant substantially equal to 1.

17. A method of producing an antenna, the method comprising:

forming an insulating substrate;

configuring a conductive strip on a first surface of the substrate, the conductive strip having a characteristic impedance that may vary along its length, wherein the conductive strip is separated from the ground plane by a separation distance, the separation distance being changed at at least one location along the conductive strip; and

configuring a ground plane on a second surface of the substrate, the second surface being opposed to the first surface, wherein a bend is formed in the ground plane proximate an edge.

18. The method of claim 17, wherein the bend is an angular bend.

19. The method of claim 17, wherein said separation distance of the conductive elements is changed abruptly along the length of the conductive strip.

20. The method of claim 17, wherein another conductive element is disposed over a side of the ground plane opposing the conductive strip and insulated from the ground plane except at a point.

21. The method of claim 17, wherein the another conductive element has an end that is proximate an edge of said ground plane.

22. The method of claim 17, wherein the bend in the ground plane is substantially a right angle.

23. The method of claim 17 including forming a second bend in the ground plane to form a segment of the ground plane lying over the conductive strip.

24. The method of claim 17, wherein the conductive strip is formed with a tapered section proximate an end.

25. An RF communication device comprising:

a transmitter;

a receiver; and

an antenna coupled to the transmitter and receiver, the antenna having an insulating substrate, a conductive strip disposed on a first surface of the substrate, and a ground plane disposed on a second surface of the substrate, the second surface being opposed to the first surface, wherein the conductive strip is separated from the ground plane by a separation distance, the separation distance being changed at at least one location along the conductive strip, and wherein the ground plane is formed with a bend proximate an edge.

26. The device of claim 25, wherein said separation distance of the conductive elements is changed abruptly along the length of the conductive patch.

27. The device of claim 25 and further comprising another conductive element disposed over a side of the ground plane

28. The device of claim 25, wherein the another conductive element has an end that is proximate an edge of said ground plane.

29. The device of claim 25, wherein the RF communication device comprises a cellular telephone.

30. The device of claim 25, wherein the RF communication device comprises an RF identification tag.