Multi-band monopole antenna for a mobile communications device

• US 8,674,887 B2
• Filed: 07/24/2012
• Issued: 03/18/2014
• Est. Priority Date: 12/22/2002
• Status: Expired due to Term

• Current Assignee: Fractus SA
• Original Assignee: Fractus SA
• Inventors: Sanz, Alfonso, Puente Baliarda, Carles
• Primary Examiner(s): Ho, Tan
• Application Number:
  US13/556,626
• Publication Number:
  US 20120287001A1
• Time in Patent Office: 602 Days
• Field of Search: 343/700.MS, 343/702, 343/895
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 19/005 Patch antenna using one or more coplanar parasitic elements
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

A multi-band monopole antenna for a mobile communications device includes a common conductor coupled to both a first radiating arm and a second radiating arm. The common conductor includes a feeding port for coupling the antenna to communications circuitry in a mobile communications device. In one embodiment, the first radiating arm includes a space-filling curve. In another embodiment, the first radiating arm includes a meandering section extending from the common conductor in a first direction and a contiguous extended section extending from the meandering section in a second direction.

Claims

1. A mobile communication device comprising:

communications circuitry;

a circuit board comprising a ground plane and a feeding point, the feeding point being coupled to the communications circuitry;

a mounting structure positioned within the mobile communication device, a section of the mounting structure extending over the circuit board; and

a multi-band antenna secured to the mounting structure and laterally offset from an edge of the ground plane, the multi-band antenna comprising;

a common conductor coupled to the feeding point;

first and second radiating arms coupled to and extending from the common conductor; and

a space-filling curve constituting at least a part of the first radiating arm, wherein the space-filling curve comprises at least ten segments that are shorter than a tenth of a free-space operating wavelength of the multi-band antenna, each of the segments being connected to its neighboring segments at an angle such that no pair of adjacent segments defines a longer straight segment, wherein any periodicity of the space-filling curve along a fixed straight direction of space involves a periodic structure having a period defined by a non-periodic curve comprising at least ten connected segments in which no pair of adjacent ones of the connected segments defines a longer straight segment.

2. The mobile communication device of claim 1, wherein the antenna feeding point is located at a position on the circuit board corresponding to a corner of the ground plane.

3. The mobile communication device of claim 1, wherein a total length of the first radiating arm is greater than a total length of the second radiating arm.

4. The mobile communication device of claim 3, wherein the second radiating arm of the multi-band antenna includes a linear section adjacent to the first radiating arm.

5. The mobile communication device of claim 4, wherein the first radiating arm comprises a first section extending away from the common conductor in a first direction and a second section extending in a second direction that is different from the first direction.

6. The mobile communication device of claim 3, wherein the mobile communication device is a cellular telephone.

7. The mobile communication device of claim 3, wherein the multi-band antenna is configured to operate in at least three frequency bands.

8. A mobile communication device comprising:

communications circuitry;

a circuit board comprising a ground plane and a feeding point, the feeding point being coupled to the communications circuitry, the circuit board including a slot along an edge thereof;

a mounting structure coupled to the circuit board in the vicinity of the slot; and

a multi-band antenna secured to the mounting structure and comprising;

a common conductor coupled to the feeding point;

a first radiating arm extending from the common conductor; and

a second radiating arm extending from the common conductor and including at least three linear portions,

wherein an orthogonal projection of a footprint of the multi-band antenna on a plane of the circuit board overlaps a metallization of the ground plane in less than fifty percent of an area of the footprint.

9. The mobile communication device of claim 8, wherein a total length of the first radiating arm is greater than a total length of the second radiating arm.

10. The mobile communication device of claim 9, wherein the first radiating arm comprises a space-filling curve extending from the common conductor, wherein the space-filling curve comprises at least ten segments that are shorter than a tenth of a free-space operating wavelength of the multi-band antenna, each of the segments being connected to its neighboring segments at an angle such that no pair of adjacent segments defines a longer straight segment, wherein any periodicity of the space-filling curve along a fixed straight direction of space involves a periodic structure having a period defined by a non-periodic curve comprising at least ten connected segments in which no pair of adjacent ones of the connected segments defines a longer straight segment.

11. The mobile communication device of claim 10, wherein the first radiating arm comprises a first section extending away from the common conductor in a first direction and a second section extending in a second direction that is different from the first direction.

12. The mobile communication device of claim 8, wherein the antenna feeding point is located at a position on the circuit board corresponding to a corner of the ground plane.

13. The mobile communication device of claim 8, wherein the antenna comprises a third radiating arm coupled to the common conductor.

14. A mobile communication device comprising:

a circuit board including an antenna feeding point and a ground plane;

communications circuitry coupled to the antenna feeding point of the circuit board; and

a multi-band antenna mounted within the mobile communication device and comprising;

a common conductor coupled to the feeding point;

a first radiating arm coupled to the common conductor and having a section comprising a space-filling curve extending from the common conductor in a first direction and a contiguous extended substantially straight section extending from the section comprising the space-filling curve in a substantially opposite direction as the first direction; and

a second radiating arm coupled to the common conductor,

wherein an orthogonal projection of a footprint of the multi-band antenna on a plane of the circuit board intersects a metallization of the ground plane by less than fifty percent.

15. The mobile communication device of claim 14, wherein the circuit board is mounted in a first plane within the mobile communication device and the multi-band antenna is mounted in a second plane within the mobile communication device.

16. The mobile communication device of claim 15, wherein the antenna feeding point is located at a position on the circuit board corresponding to a corner of the ground plane.

17. The mobile communication device of claim 15, wherein an edge of the antenna is laterally aligned with an edge of the circuit board.

18. The mobile communication device of claim 15, wherein the antenna is offset laterally from the ground plane.

19. The mobile communication device of claim 14, wherein a total length of the first radiating arm is greater than a total length of the second radiating arm.

20. The mobile communication device of claim 14, wherein the mobile communication device is a cellular telephone.