Miniature vertically polarized multiple frequency band antenna and method of providing an antenna for a wireless device

• US 20040192226A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Luen, Kong S.
• Granted Patent: US 7,369,086 B2
• Time in Patent Office: Days
• US Class Current: 455/90.1
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H01Q 9/065 Microstrip dipole antennas patch antenna H01Q9/0407
• CPC Class Codes: H01Q 9/14 Length of element or elements adjustable telescopic elements H01Q1/10

Abstract

A miniature vertically polarized multi-frequency antenna 10 is embedded in a substrate 11 and suitable for use within a wireless device. The antenna 10 includes a first lateral member 14 and a second lateral member 16, which is spaced from and parallel to the first lateral member 14. The antenna 10 has a wide tuning range due to multiple resonances provided by the lateral members 14, 16. The antenna 10 is shortened by reactive loading and by embedding the antenna in material having a high dielectric constant. Tuning circuits 30, 32 are coupled to respective ends of one of the lateral members 14, 16. The tuning circuits are located on a common plane with the lateral member to which they are connected. The tuning circuits 30, 32 electronically add reactance to the antenna to alter the frequency at which it resonates.

A method of providing the antenna 10 includes forming flat metal strips 14, 16 on layers of a laminated substrate 11 and forming the second lateral member 16 between adjacent layers 20, 22 of the substrate 11.

Claims

1. An antenna comprising:

a substantially straight main member, wherein the main member is metal and is embedded in a substrate;

a first lateral member, a central part of which is electrically coupled to an upper end of the main member such that the main member and the first lateral member generally form a T shape; and

a second lateral member, a central part of which is electrically coupled to the main member, wherein the second lateral member is spaced from and parallel to the first lateral member, and the second lateral member is embedded in the substrate.

2. The antenna of claim 1, wherein the first lateral member is a thin, flat metal strip, which is located on an upper surface of the substrate.

3. The antenna of claim 1, wherein the substrate is a multi-layer substrate, and the second lateral member is a thin, flat metal strip located between adjacent layers of the substrate.

4. The antenna of claim 1 further including a tuning circuit coupled to the antenna for varying resonance of the antenna.

5. The antenna of claim 1 further including a first tuning circuit coupled to a first end of the first lateral member and a second tuning circuit coupled to a second end of the first lateral member.

6. The antenna of claim 1, further including a first tuning circuit coupled to a first end of the second lateral member and a second tuning circuit coupled to a second end of the second lateral member.

7. The antenna of claim 4, wherein the first lateral member and the tuning circuit are located on a same layer of the substrate.

8. The antenna of claim 4, wherein the first lateral member is located on a first layer of the substrate, and the tuning circuit and the second lateral member are located on a second layer of the substrate.

9. The antenna of claim 4, wherein the tuning circuit includes a varactor diode, which adds capacitance to the antenna.

10. The antenna of claim 9, wherein a variable voltage source is coupled to the varactor diode to vary capacitance added to the antenna.

11. The antenna of claim 9, wherein the tuning circuit includes a variable voltage source, which is coupled to the varactor diode for varying a voltage applied to the varactor diode.

12. The antenna of claim 4, wherein a variable DC voltage source is coupled to the tuning circuit, wherein a variation of the voltage of the variable DC voltage source changes a resonant frequency of the antenna.

13. The antenna of claim 1, wherein the substrate includes an upper ground plane and a lower ground plane, and the first lateral member is coplanar with the upper ground plane.

14. The antenna of claim 1, wherein the substrate includes an upper ground plane and a lower ground plane, and the second lateral member is coplanar with the upper ground plane.

15. The antenna of claim 1, wherein the substrate includes a ground plane, and the main member is perpendicular to the ground plane.

16. The antenna of claim 1, wherein a lower end of the main member forms an antenna port, by which the antenna is coupled to a transmitter or a receiver.

17. A wireless communication device comprising:

one of a receiver and a transmitter;

a substrate;

a ground plane formed on the substrate; and

an antenna substantially embedded in the substrate, wherein the antenna includes;

a substantially straight main member, wherein the main member is metal and is embedded in the substrate such that the main member is perpendicular to the ground plane, and the main member has an upper end and a lower end, and the lower end forms an antenna port for coupling the antenna to the one of the receiver and the transmitter;

a first lateral member, a central part of which is electrically coupled to an upper end of the main member such that the main member and the first lateral member generally form a T shape; and

a second lateral member, a central part of which is electrically coupled to the main member, wherein the second lateral member is spaced from and parallel to the first lateral member.

18. A method of providing an antenna for a wireless device, the method comprising:

forming a first metal strip on a first substrate layer;

forming a second metal strip on a second substrate layer;

stacking the first substrate layer on the second substrate layer to form a layered substrate such that the first metal strip is parallel to and spaced apart from the second metal strip, wherein the first metal strip is coupled to the second metal strip with a main antenna member, which is perpendicular to the first metal strip and the second metal strip.

19. The method of claim 18, wherein the method includes forming the main antenna member by forming a hole in the layered substrate and by placing metal material in the hole.

20. The method of claim 18, wherein the method includes placing a tuning circuit for tuning the antenna on a same substrate layer as the first metal strip.