Modified inverted-F antenna for wireless communication

Abstract

An embodiment of the present invention is a modified inverted-F antenna for wireless communication. The antenna circuit includes a dielectric substrate having a first surface, a radiating stub on the first surface of the dielectric substrate, and a first ground plate on the first surface of the dielectric substrate to couple to ground. The first ground plate includes one or more grounded capacitive stubs spaced apart from the radiating stub. The one or more grounded capacitive stubs tune performance parameters for the antenna circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of invention may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:

FIG. 1A is a top view of a first embodiment of a modified inverted-F antenna at a corner of a printed circuit board.

FIG. 1B is a top view of a second embodiment of a modified inverted-F antenna at a corner of a printed circuit board.

FIG. 1C is a cross-sectional view of the grounded coplanar waveguide illustrated in FIGS. 1A-1B.

FIG. 2A is a top view of a third embodiment of a modified inverted-F antenna at a corner of a printed circuit board.

FIG. 2B is a cross-sectional view of the third embodiment of the modified inverted-F antenna along the radiating stub.

FIG. 2C is a top view of a fourth embodiment of a modified inverted-F antenna at a corner of a printed circuit board.

FIG. 2D is a top view of a fifth embodiment of a modified inverted-F antenna at a corner of a printed circuit board.

FIG. 3A is a top view of a sixth embodiment of a modified inverted-F antenna along an edge of a printed circuit board.

FIG. 3B is a cross-sectional view of the sixth embodiment of the modified inverted-F antenna along the radiating stub.

FIG. 3C is a top view of a seventh embodiment of a modified inverted-F antenna along an edge of a printed circuit board.

FIG. 4 is a top view of an eighth embodiment of a modified inverted-F antenna along an edge of a printed circuit board.

FIG. 5 is a top view of a pair of modified inverted-F antennas in the corners of the PCB with grounded coplanar waveguide feeding lines for use in a CardBus application.

FIG. 6 is a linear antenna array of four modified inverted-F antennas extruded from the ground plates with grounded coplanar waveguide feeding lines.

FIG. 7 is a high level block diagram including the antenna design of FIG. 5 and a system using switching diversity technology.

FIG. 8 is a high level block diagram including the antenna design of FIG. 5 and a system using 2×2 MIMO technology.

FIG. 9 illustrates a graph of the return loss of a modified inverted-F antenna for a CardBus printed circuit board such as illustrated in FIG. 5.

FIG. 10 illustrates a chart of the far field radiation pattern in a horizontal plane for the CardBus modified inverted-F antenna shown in FIG. 5.

FIG. 11 illustrates a chart of the far field radiation pattern in a vertical plane for the CardBus modified inverted-F antenna shown in FIG. 5.

FIG. 12 illustrates a wireless communication network with subscriber units employing embodiments of the invention.

FIG. 13A illustrates a wireless universal serial bus (USB) adapter including a printed circuit board with embodiments of the modified inverted-F antenna for use by a subscriber unit.

FIG. 13B illustrates another wireless card or adapter including a printed circuit board with embodiments of the modified inverted-F antenna.

FIG. 14 illustrates a functional block diagram of a wireless card including a printed circuit board with embodiments of the modified inverted-F antenna.

FIG. 15 is a flowchart illustrating a process to form a modified inverted-F antenna according to one embodiment of the invention.

Claims

1. An apparatus comprising: a dielectric substrate having a first surface;a radiating stub on the first surface of the dielectric substrate; anda first ground plate on the first surface of the dielectric substrate to couple to ground, the first ground plate including one or more grounded capacitive stubs spaced apart from the radiating stub, the one or more grounded capacitive stubs to tune performance parameters.

2. The apparatus of claim 1 wherein the one or more grounded capacitive stubs extend from a first edge of the first ground plate parallel with a side edge of the radiating stub.

3. The apparatus of claim 1 further comprising: a shortening leg having a first end coupled to a bottom of the radiating stub; andan extended feeding strip coupled to the side edge of the radiating stub spaced apart from the shortening leg; wherein the radiating stub, the shortening leg, and the extended feeding strip are coupled together to form an F shape.

4. The apparatus of claim 3 wherein the shortening leg has a second end opposite the first end is coupled to the first ground plate.

5. The apparatus of claim 1 further comprising: a second ground plate spaced apart from the first ground plate, the second ground plate to couple to ground, and wherein the shortening leg has a second end opposite the first end is coupled to the second ground plate.

6. The apparatus of claim 3 further comprising: a feeding line coupled to the extended feeding strip.

7. The apparatus of claim 6 wherein the feeding line is a grounded coplanar waveguide having a central strip spaced apart from the first ground plate and the second ground plate forming a pair of gaps.

8. The apparatus of claim 7 further comprising: a third ground plate on a second surface of the dielectric substrate opposite the first surface, the third ground plate to couple to ground, the third ground plate under the central strip and the pair of gaps.

9. The apparatus of claim 8 wherein the extended feeding strip is formed in a second metal layer on the second surface of the dielectric substrate opposite the first surface, and the feeding line is a micro-strip line coupled to the extended feeding strip and formed in the second metal layer on the second surface of the dielectric substrate.

10. The apparatus of claim 9 further comprising: a metal conductor within a via hole of the dielectric substrate coupled between the extended feeding strip and the radiating stub.

11. The apparatus of claim 1 wherein the first ground plate has a second edge perpendicular to the first edge of the first ground plate spaced apart from and parallel with a top edge of the radiating stub.

12. The apparatus of claim 1 wherein the one or more grounded capacitive stubs is a single grounded capacitive stub extending from the first edge of the first ground plate pointing towards the radiating stub, and the radiating stub is parallel with the single grounded capacitive stub such that a top edge of the radiating stub extends beyond the width of the single grounded stub into a space with the first ground plate.

13. The apparatus of claim 1 wherein the one or more grounded capacitive stubs is a first grounded capacitive stub and a second grounded capacitive stub in parallel, spaced apart, and extending from the first edge of the first ground plate pointing towards the radiating stub, and the radiating stub is parallel with the first and second grounded capacitive stubs such that a top edge of the radiating stub extends beyond the width of the first grounded capacitive stub and a space between the first and second grounded capacitive stubs, up to a midpoint in the width of the second grounded capacitive stub.

14. The apparatus of claim 1 wherein the first ground plate forms a dielectric window in the surface of the dielectric substrate that is encroached by the radiating stub and the one or more grounded capacitive stubs.

15. The apparatus of claim 5 wherein the first ground plate and the second ground plate form a dielectric window in the surface of the dielectric substrate that is encroached by the radiating stub and the one or more grounded capacitive stubs.

16. A method comprising: forming a dielectric layer on a first metal layer having a first surface;forming a pattern of a second metal layer on the dielectric layer to expose a dielectric window being part of the dielectric layer, the pattern having a radiating stub and one or more grounded capacitive stubs spaced apart from the radiating stub; andforming a first ground plate coupled to the one or more grounded capacitive stubs, the first ground plate being part of the second metal layer and coupled to ground.

17. The method of claim 16 wherein the one or more grounded capacitive stubs extend from a first edge of the first ground plate parallel with a side edge of the radiating stub.

18. The method of claim 16 further comprising: forming a shortening leg having a first end coupled to a bottom of the radiating stub; andforming an extended feeding strip coupled to the side edge of the radiating stub spaced apart from the shortening leg; wherein the radiating stub, the shortening leg, and the extended feeding strip are coupled together to form an F shape.

19. The method of claim 18 wherein the shortening leg has a second end opposite the first end is coupled to the first ground plate.

20. The method of claim 16 further comprising: forming a second ground plate spaced apart from the first ground plate, the second ground plate to couple to ground, and wherein the shortening leg has a second end opposite the first end is coupled to the second ground plate.

21. The method of claim 18 further comprising: forming a feeding line coupled to the extended feeding strip.

22. The method of claim 21 wherein the feeding line is a grounded coplanar waveguide having a central strip spaced apart from the first ground plate and the second ground plate forming a pair of gaps.

23. The method of claim 22 further comprising: forming a third ground plate on a second surface of the dielectric layer opposite the first surface, the third ground plate to couple to ground, the third ground plate under the central strip and the pair of gaps.

24. The method of claim 23 wherein the extended feeding strip is formed in a second metal layer on the second surface of the dielectric substrate opposite the first surface, and the feeding line is a micro-strip line coupled to the extended feeding strip and formed in the second metal layer on the second surface of the dielectric substrate.

25. The method of claim 24 further comprising: forming a metal conductor within a via hole of the dielectric substrate coupled between the extended feeding strip and the radiating stub.

26. A system comprising: a base-band processor to process base-band signals, the base-band processor generating a transmitting signal and processing a receiving signal;a transceiver coupled to the base-band processor to process the transmitting signal and the receiving signal;a switch coupled to the transceiver to switch between the transmitting signal and the receiving signal; andan antenna circuit coupled to the switch to transmit the transmitting signal and to receive the receiving signal, the antenna circuit comprising: a dielectric substrate having a first surface,a radiating stub on the first surface of the dielectric substrate, anda first ground plate on the surface of the dielectric substrate to couple to ground, the first ground plate including one or more grounded capacitive stubs spaced apart from the radiating stub, the one or more grounded capacitive stubs to tune performance parameters.

27. The system of claim 26 wherein the one or more grounded capacitive stubs extend from a first edge of the first ground plate parallel with a side edge of the radiating stub.

28. The system of claim 1 wherein the antenna circuit further comprises: a shortening leg having a first end coupled to a bottom of the radiating stub; andan extended feeding strip coupled to the side edge of the radiating stub spaced apart from the shortening leg; wherein the radiating stub, the shortening leg, and the extended feeding strip are coupled together to form an F shape.

29. The system of claim 28 wherein the shortening leg has a second end opposite the first end is coupled to the first ground plate.

30. The system of claim 26 wherein the antenna circuit further comprises: a second ground plate spaced apart from the first ground plate, the second ground plate to couple to ground, and wherein the shortening leg has a second end opposite the first end is coupled to the second ground plate.