Compact broadband antenna

• US 20030098812A1
• Filed: 11/26/2001
• Published: 05/29/2003
• Est. Priority Date: 11/26/2001
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Ying, Zhinong, Dahlstrom, Anders
• Granted Patent: US 6,650,294 B2
• Time in Patent Office: Days
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 19/005 Patch antenna using one or more coplanar parasitic elements
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/378 Combination of fed elements with parasitic elements
• CPC Class Codes: H01Q 5/385 Two or more parasitic elements
• CPC Class Codes: H01Q 5/392 the parasitic elements having dual-band or multi-band characteristics
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0457 electromagnetically coupled to the feed line
• CPC Class Codes: H01Q 9/14 Length of element or elements adjustable telescopic elements H01Q1/10

Abstract

Broadband multi-resonant antennas utilize capacitive coupling between multiple conductive plates for compact antenna applications. The number and design of conductive plates may be set to achieve the desired bandwidth. In one exemplary embodiment the antenna may be designed for four resonant frequencies and may include three L shaped legs each including a micro-strip conductive plate and connection pin, with configurations approximately parallel to one another. The center L shaped leg may be a feed patch with a feed pin connected to a transmitter, receiver, or transceiver. The upper L shaped leg may be a dual band main patch and ground pin. The dual band main patch may have two different branches with different lengths and areas to handle three of four desired resonant frequencies. The lower L shaped leg may be a parasitic high band patch and ground pin designed to handle one of the two higher desired resonant frequencies.

Claims

1. An antenna, comprising:

a first conductive patch;

a second conductive patch capacitively coupled to the first conductive patch; and

a third conductive patch capacitively coupled to the first conductive patch, wherein the antenna is connected to a single feed port.

2. The antenna of claim 1, wherein the first conductive patch is a feed patch, the second conductive patch is a main patch, and the third conductive patch is a parasitic patch.

3. The antenna of claim 2, wherein the second conductive patch is a dual band main patch having a first branch for resonance at a first frequency band and a second branch for resonance at a second frequency band.

4. The antenna of claim 3, wherein the first frequency band is a low band and the second frequency band is a high band.

5. The antenna of claim 4, wherein the first branch is longer than the second branch.

6. The antenna of claim 5, wherein the first branch has at least a portion having a same shape as the second branch and an added portion.

7. The antenna of claim 6, wherein the first conductive patch is connected to a feed terminal, the second conductive patch is connected to a first ground terminal, and the third conductive patch is connected to a second ground terminal.

8. The antenna of claim 7, wherein the second conductive patch and first ground terminal and the third conductive patch and second ground terminal are fed by the capacitive coupling to the first conductive patch and feed terminal.

9. The antenna of claim 8, wherein the first conductive plate, the second conductive plate, and the third conductive plate are approximately parallel to one another.

10. The antenna of claim 9, wherein the first conductive plate, the second conductive plate, and the third conductive plate are supported over a substrate by a dielectric support member.

11. The antenna of claim 10, wherein the substrate includes a conductive ground plane and the first conductive plate, the second conductive plate, and the third conductive plate are approximately parallel to the ground plane.

12. The antenna of claim 11, wherein the first ground terminal and the second ground terminal are connected to the ground plane and the feed terminal is coupled to a receiver, transmitter, or transceiver.

13. The antenna of claim 12, wherein the second ground terminal is located near the feed terminal to achieve proper coupling.

14. The antenna of claim 13, wherein the second ground terminal is at a distance of from 0.1 mm to 1.0 mm from the feed terminal.

15. The antenna of claim 14, wherein the first conductive patch is proportioned relative to the second conductive patch and creates distributed capacitance to enhance the bandwidth of the antenna.

16. The antenna of claim 15, wherein the conductive patches are each two dimensional or three dimensional.

17. The antenna of claim 16, wherein the first branch is a spiral or U shape and the second branch is a spiral or U shape.

18. The antenna of claim 6, wherein the first branch is a T or M shape and the second branch is a T or M shape.

19. The antenna of claim 18, wherein distance between the first conductive patch and the second conductive patch is set to match the second conductive patch impedance to a communication system impedance.

20. The antenna of claim 19, wherein the first conductive patch, second conductive patch and third conductive patch are physically separated from one another by an insulating material.

21. The antenna of claim 20, wherein at least one of the first conductive plate, the second conductive plate, and the third conductive plate is made of a punched or etched metal.

22. The antenna of claim 21, wherein the first conductive plate, the second conductive plate, and the third conductive plate in combination produce an antenna with four resonant frequencies.

23. The antenna of claim 22, wherein the four resonant frequencies support frequency bands for GSM-800, GSM-900, DCS, and PCS.

24. The antenna of claim 1, wherein the second conductive patch is a dual band main patch having a first branch for resonance at a first frequency band and a second branch for resonance at a second frequency band.

25. The antenna of claim 24, wherein the first conductive plate, the second conductive plate, and the third conductive plate in combination produce an antenna with four resonant frequencies for support of frequency bands GSM-800, GSM-900, DCS, and PCS.

26. A mobile communication device, comprising

an antenna having a single feed port connection, variable characteristic impedance, and at least four resonant frequencies which are not multiples of a base frequency.

27. The mobile communication device of claim 26, wherein the four resonant frequencies are approximately 800 MHz, 900 MHz, 1800 MHz, and 1900 MHz so as to support GSM-800, GSM-900, DCS, and PCS radio frequency band communications.

28. The mobile communication device of claim 26, further comprising:

at least three capacitively coupled conductive antenna elements of which one element is connected to said single feed port, and wherein said at least three capacitively coupled antenna elements interoperate to provide the at least four resonant frequencies.

29. The mobile communication device of claim 28, wherein the at least three capacitively coupled conductive antenna elements includes a first conductive patch connected to a feed terminal that is associated with the feed port, a second conductive patch connected to a first ground terminal, and a third conductive patch connected to a second ground terminal, each capacitively coupled to one another.

30. The mobile communication device of claim 29, wherein the second conductive patch is a dual band main patch having a first branch for resonance at a first frequency band and a second branch for resonance at a second frequency band.

31. The mobile communication device of claim 30, wherein the conductive plates are tuned so that the DCS and the PCS resonance frequencies related antenna elements create one broad band that supports both DCS and PCS communications.

32. A mobile communication device, comprising:

an antenna including a plurality of physically separate and capacitive fed conductors that resonate at multiple frequencies so as to support radio communications at GSM-800, GSM-900, DCS, and PCS frequency bands.

33. The mobile communication device of claim 32, wherein the plurality of physically separate and capacitive fed conductors includes a first conductive patch connected to a feed point, a second conductive patch connected to a first ground point, and a third conductive patch connected to a second ground point.

34. The mobile communication device of claim 33, wherein the second conductive patch is a dual band main patch having a first branch for resonance at a first frequency band and a second branch for resonance at a second frequency band.