Multilevel ground-plane for a mobile device

• US 7,928,915 B2
• Filed: 09/20/2005
• Issued: 04/19/2011
• Est. Priority Date: 09/21/2004
• Status: Expired due to Fees

• Current Assignee: Fractus SA
• Original Assignee: Fractus SA
• Inventors: Sanz Arronte, Alfonso, Gala Gala, David, Condes Martinez, Antonio, Puente Baliarda, Carles
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): DUONG, DIEU HIEN
• Application Number:
  US11/662,044
• Publication Number:
  US 20080074332A1
• Time in Patent Office: 2,037 Days
• Field of Search: 343/700.MS, 343/702, 343/846, 343/849
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/48 Earthing means; Earth screens; Counterpoises

Abstract

In accordance with the teachings described herein, a multilevel ground-plane for a mobile device is provided. The multilevel ground-plane includes a first conductive surface, a second conductive surface, and a conducting strip that couples the first conducting surface to the second conducting surface. A mobile device having a multilevel ground-plane may include a printed circuit board, an antenna radiating element attached to a surface of the printed circuit board, and the multilevel ground plane integral with the printed circuit board and electromagnetically coupled to the antenna radiating element.

Claims

1. A mobile device, comprising:

a printed circuit board;

an antenna radiating element attached to a surface of the printed circuit board; and

a multilevel ground plane integral with the printed circuit board and electromagnetically coupled to the antenna radiating element;

the multilevel ground plane comprising;

a first conducting surface;

a second conducting surface; and

a conducting strip that couples the first conducting surface to the second conducting surface;

wherein at least a portion of the multilevel ground plane defines a space-filling curve;

wherein the antenna radiating element comprises at least one hole defining an empty area on the antenna radiating element;

wherein a shape of said empty area is formed by a plurality of polygonal shapes connected or overlapping at a contact region of a perimeter of said plurality of polygonal shapes;

wherein the contact region between directly connected polygonal shapes of the plurality of polygonal shapes is narrower than 50% of the perimeter of said directly connected polygonal shapes;

wherein the polygonal shapes of the plurality of polygonal shapes have the same number of sides but not all the polygonal shapes of the plurality of polygonal shapes have the same size;

wherein at least one edge of the antenna radiating element is aligned with a slot defined between the first conducting surface and the second conducting surface;

wherein an end of the slot is in contact with a perimetric edge of the multilevel ground plane; and

wherein at least a part of the at least one hole is positioned over a part of the slot.

2. An antenna system, comprising:

a ground plane having a substantially rectangular shape;

a radiating element being placed over the ground plane;

the radiating element having at least one edge and the ground plane having a first slot and a second slot;

wherein the radiating element comprises at least one hole defining an empty area on the radiating element;

wherein a shape of said empty area is formed by a plurality of polygonal shapes connected or overlapping at a contact region of a perimeter of said plurality of polygonal shapes;

wherein the contact region between directly connected polygonal shapes of the plurality of polygonal shapes is narrower than 50% of the perimeter of said directly connected polygonal shapes;

wherein the polygonal shapes of the plurality of polygonal shapes have the same number of sides but not all the polygonal shapes of the plurality of polygonal shapes have the same size;

wherein the first slot has a first end that intersects a first edge of the ground plane and the second slot has a second end that intersect a second edge of the ground plane, wherein the second edge being opposite to the first edge;

wherein the first slot and the second slot are arranged in a projection area of the radiating element on the ground plane;

wherein the first slot and the second slot are not symmetrically arranged with respect to an axis parallel to a long dimension of the ground plane and dividing the ground plane into two substantially equal halves;

wherein at least a part of the at least one edge of the radiating element is aligned to and positioned over a part of at least one of the first slot and the second slot; and

wherein at least a part of the at least one hole is positioned over a part of at least one of the first slot and the second slot.

3. The antenna system according to claim 2, wherein the first slot and the second slot are substantially parallel to an edge of the ground plane.

4. The antenna system according to claim 3, wherein one edge of the radiating element extends over the first slot and the second slot.

5. The antenna system according to claim 2, wherein the first slot, the second slot and the at least one edge of the radiating element placed over the first slot and the second slot are substantially straight.

6. The antenna system according to claim 2, wherein a part of at least one of the first slot and the second slot has a constant width, wherein said width is within the range from approximately 0.3 mm to approximately 3 mm.

7. The antenna system according to claim 2, wherein at least one slot of the first slot and the second slot has a slot segment at one of the ends of said at least one slot, wherein said slot segment defines an angle with respect to said slot.

8. The antenna system according to claim 7, wherein said slot segment is placed below the radiating element.

9. The antenna system according to claim 2, wherein at least a portion of the radiating element that operates within a determined band is positioned over a part of at least one of the first slot and the second slot.

10. The antenna system according to claim 2, further comprising a printed circuit board having at least one conducting layer, and wherein the radiating element is attached to the printed circuit board, and the ground plane is formed as one of said conducting layers and electromagnetically coupled to said radiating element.

11. The antenna system according to claim 10, wherein the ground plane is embedded within the printed circuit board and formed as an inner conducting layer of said printed circuit board.

12. The antenna system according to claim 10, wherein the printed circuit board is provided with said conducting layers on upper and lower faces of the printed circuit board, wherein the ground plane is formed as each of said conducting layers.

13. The antenna system according to claims 12, wherein the ground planes have the same shape.

14. The antenna system according to claim 2, wherein the first slot and the second slot define in the ground plane a first conducting surface, a second conducting surface, and a conducting strip that couples the first conducting surface to the second conducting surface.

15. The antenna system according to claim 14, wherein the width of the first and the second slot of at least one ground plane is greater than the width of the first and the second slot of the other ground planes.

16. The antenna system according to claim 15, wherein the width of the first and the second slot of at least one ground plane is greater than approximately 3 mm.

17. The antenna system according to claim 16, wherein the at least one ground plane comprising the first and the second slot, further comprises at least one via in the surface located between the first and the second slot to ground any other ground planes.

18. The antenna system according to claim 17, wherein at least one of a grounded pad and a grounded track comprised in the said printed circuit board is not placed over the first and the second slot.

19. The antenna system according to claim 14, wherein the conducting strip is shaped as at least one of a zigzag curve and a meandering curve.

20. The antenna system according to claim 2, wherein the polygonal shapes are rectangles.

21. The antenna system according to claim 2, wherein one of the polygonal shapes is connected to a perimetric edge of the radiating element.

22. The antenna system according to claim 2, wherein the radiating element is substantially rectangular.

23. The antenna system according to claim 2, wherein at least one of the corners of the radiating element is cut off in order to facilitate its integration into a communication device.

24. The antenna system according to claim 2, wherein at least one of the first slot and the second slot is at least in part shaped as a space-filling curve.

25. The antenna system according to claim 24, wherein said space-filling curve comprises at least ten connected segments, wherein said segments are smaller than a tenth of the operating free-space wave length and are spatially arranged in such a way that none of said adjacent and connected segments form another longer straight segment.

26. The antenna system according to claim 24, wherein said space-filling curve features a box-counting dimension larger than one.

27. The antenna system according to claim 2, wherein at least a portion of the geometry of said ground plane is a multilevel structure, said multilevel structure including a set of conducting polygons, all of said polygons featuring the same number of sides, wherein said polygons are electromagnetically coupled either by means of a capacitive coupling or ohmic contact, wherein the contact region between directly connected polygons is narrower than 50% of the perimeter of said polygons.

28. The antenna system according to claim 2, wherein the antenna is a multiband antenna.

29. A mobile communications device comprising:

an antenna system, the antenna system comprising;

a ground plane having a substantially rectangular shape;

a radiating element being placed over the ground plane;

the radiating element having at least one edge and the ground plane having a first slot and a second slot;

wherein the radiating element comprises at least one hole defining an empty area on the radiating element;

wherein a shape of said empty area is formed by a plurality of polygonal shapes connected or overlapping at a contact region of a perimeter of said plurality of polygonal shapes;

wherein the contact region between directly connected polygonal shapes of the plurality of polygonal shapes is narrower than 50% of the perimeter of said directly connected polygonal shapes;

wherein the polygonal shapes of the plurality of polygonal shapes have the same number of sides but not all the polygonal shapes of the plurality of polygonal shapes have the same size;

wherein the first slot has a first end that intersects a first edge of the ground plane and the second slot has a second end that intersect a second edge of the ground plane, wherein the second edge being opposite to the first edge;

wherein the first slot and the second slot are arranged in a projection area of the radiating element on the ground plane;

wherein the first slot and the second slot are not symmetrically arranged with respect to an axis parallel to a long dimension of the ground plane and dividing the ground plane into two substantially equal halves;

wherein at least a part of the at least one edge of the radiating element is aligned to and positioned over a part of at least one of the first slot and the second slot; and

wherein at least a part of the at least one hole is positioned over a part of at least one of the first slot and the second slot.

30. The mobile communications device according to claim 29, wherein the antenna system conserves space inside the said mobile communication device enabling at least one component to be mounted on the printed circuit board opposite to the antenna structure.

31. The mobile communications device according to claim 30, wherein the at least one component comprises at least one of a speaker and a vibration mechanism.

32. The mobile communication device according to claim 29, wherein the mobile communication device is selected from the group consisting of:

a cellular telephone, a PDA, and a pager.

33. The mobile communications device according to claim 29, wherein the mobile communications device operates in at least one typical cellular frequency band between approximately 800 MHz and approximately 3000 MHz.