Electronically steerable passive array antenna

• US 20030193446A1
• Filed: 04/14/2003
• Published: 10/16/2003
• Est. Priority Date: 04/15/2002
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Paratek Microwave Incorporated (Blackberry Limited)
• Inventors: Chen, Shuguang
• Granted Patent: US 6,987,493 B2
• Time in Patent Office: Days
• US Class Current: 343/893
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 19/32 the primary active element being end-fed and elongated
• CPC Class Codes: H01Q 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 3/446 the radiating element being at the centre of one or more rings of auxiliary elements
• CPC Class Codes: H01Q 9/32 Vertical arrangement of element H01Q9/40 takes precedence

Abstract

An electronically steerable passive array antenna and method for using the array antenna to steer the radiation beams and nulls of a radio signal are described herein. The array antenna includes a radiating antenna element capable of transmitting and receiving radio signals and one or more parasitic antenna elements that are incapable of transmitting or receiving radio signals. Each parasitic antenna element is located on a circumference of a predetermined circle around the radiating antenna element. A voltage-tunable capacitor is connected to each parasitic antenna element. A controller is used to apply a predetermined DC voltage to each one of the voltage-tunable capacitors in order to change the capacitance of each voltage-tunable capacitor and thus enable one to control the directions of the maximum radiation beams and the minimum radiation beams (nulls) of a radio signal emitted from the array antenna.

Claims

1. An array antenna comprising:

a radiating antenna element;

at least one parasitic antenna element;

at least one voltage-tunable capacitor connected to said at least one parasitic antenna element; and

a controller for applying a voltage to each voltage-tunable capacitor to change the capacitance of each voltage-tunable capacitor and thus control the directions of maximum radiation beams and minimum radiation beams of a radio signal emitted from said radiating antenna element and said at least one parasitic antenna element.

2. The array antenna of claim 1, wherein each voltage-tunable capacitor includes a tunable ferroelectric layer and a pair of metal electrodes separated by a predetermined distance and located on top of the ferroelectric layer.

3. The array antenna of claim 1, wherein each parasitic antenna element is arranged a predetermined distance from said radiating antenna element.

4. The array antenna of claim 1, wherein said radiating antenna element and said at least one parasitic antenna element are separated from one another by about 0.2λ

₀-0.5λ

₀ where λ

₀ is a working free space wavelength of the radio signal.

5. The array antenna of claim 1, wherein said radiating antenna element and said at least one parasitic antenna element each have one of the following configurations:

a monopole antenna;

a dipole antenna;

a planar microstrip antenna;

a patch antenna;

a ring antenna;

or

a helix antenna.

6. The array antenna of claim 1, wherein said minimum radiation beams are nulls and said maximum radiation beams are 360 degree steerable radiation beams.

7. The array antenna of claim 1, wherein:

said radiating antenna element is a dual band radiating antenna element; and

said at least one parasitic antenna element includes at least one low frequency parasitic antenna element and at least one high frequency parasitic antenna.

8. An array antenna comprising:

a radiating antenna element excited by radio frequency energy of a radio signal;

at least one parasitic antenna element;

at least one voltage-tunable capacitor connected to said at least one parasitic antenna element;

each parasitic antenna element receives the radio frequency energy of the radio signal emitted from said radiating antenna element and then re-radiates the radio frequency energy of the radio signal after the radio frequency energy has been reflected and phase changed by each voltage-tunable capacitor; and

a controller that phase changes the radio frequency energy at each parasitic antenna element by applying a voltage to each voltage-tunable capacitor to change the capacitance of each voltage-tunable capacitor and thus enables the steering of the radiation beams and nulls of the radio signal emitted from said radiating antenna element and said at least one parasitic antenna element.

9. The array antenna of claim 8, wherein each voltage-tunable capacitor includes a tunable ferroelectric layer and a pair of metal electrodes separated by a predetermined distance and located on top of the ferroelectric layer.

10. The array antenna of claim 8, wherein said at least one parasitic antenna element is arranged on a circumference of a predetermined circle around said radiating antenna element.

11. The array antenna of claim 8, wherein said radiating antenna element and said at least one parasitic antenna element are separated from one another by about 0.2λ

₀-0.5λ

₀ where λ

₀ is a working free space wavelength of the radio signal.

12. The array antenna of claim 8, wherein said radiating antenna element and said at least one parasitic antenna element each have one of the following configurations:

a monopole antenna;

a dipole antenna;

a planar microstrip antenna;

a patch antenna;

a ring antenna;

or

a helix antenna.

13. The array antenna of claim 8, wherein:

said radiating antenna element is a dual band radiating antenna element; and

said at least one parasitic antenna element includes at least one low frequency parasitic antenna element and at least one high frequency parasitic antenna.

14. A wireless communication network comprising:

a hub node having at least one dynamically directionally controllable communications link; and

a network controller for dynamically controlling the direction of the communications link to enable transmission of radio signals between said hub node and a plurality of remote nodes, wherein said hub node includes an array antenna comprising;

a radiating antenna element;

at least one parasitic antenna element; and

at least one voltage-tunable capacitor connected to said at least one parasitic antenna element, wherein said network controller applies a voltage to each voltage-tunable capacitor to change the capacitance of each voltage-tunable capacitor and thus control the directions of maximum radiation beams and minimum radiation beams of the radio signals emitted from said hub node to said remote users.

15. The wireless communication network of claim 14, wherein each voltage-tunable capacitor includes a tunable ferroelectric layer and a pair of metal electrodes separated by a predetermined distance and located on top of the ferroelectric layer.

16. The wireless communication network of claim 14, wherein said at least one parasitic antenna element is arranged on a circumference of a predetermined circle around said radiating antenna element.

17. The wireless communication network of claim 14, wherein said radiating antenna element and said at least one parasitic antenna element are separated from one another by about 0.2λ

₀-0.5λ

₀ where λ

₀ is a working free space wavelength of the radio signal.

18. The wireless communication network of claim 14, wherein said radiating antenna element and said at least one parasitic antenna element each have one of the following configurations:

a monopole antenna;

a dipole antenna;

a planar microstrip antenna;

a patch antenna;

a ring antenna;

or

a helix antenna.

19. The wireless communication network of claim 14, wherein:

said radiating antenna element is a dual band radiating antenna element; and

said at least one parasitic antenna element includes at least one low frequency parasitic antenna element and at least one high frequency parasitic antenna.

20. The wireless communication network of claim 14, wherein said remote nodes include mobile phones, laptop computers or personal digital assistants.

21. A method for transmitting communications signals comprising the steps of:

providing a hub node having at least one dynamically directionally controllable communications link;

providing a network controller for dynamically controlling the direction of the communications link to enable transmission of radio signals between said hub node and a plurality of remote nodes, wherein said hub node includes an array antenna comprising;

a radiating antenna element;

at least one parasitic antenna element; and

at least one voltage-tunable capacitor connected to said at least one parasitic antenna element, wherein said network controller applies a voltage to each voltage-tunable capacitor to change the capacitance of each voltage-tunable capacitor and thus control the directions of maximum radiation beams and minimum radiation beams of the radio signals emitted from said hub node to said remote users.

22. The method of claim 21, wherein each voltage-tunable capacitor includes a tunable ferroelectric layer and a pair of metal electrodes separated by a predetermined distance and located on top of the ferroelectric layer.

23. The method of claim 21, wherein said at least one parasitic antenna element is arranged on a circumference of a predetermined circle around said radiating antenna element.

24. The method of claim 21, wherein said radiating antenna element and said at least one parasitic antenna element are separated from one another by about 0.2λ

₀-0.5λ

₀ where λ

₀ is a working free space wavelength of the radio signal.

25. The method of claim 21, wherein said radiating antenna element and said at least one parasitic antenna element each have one of the following configurations:

a monopole antenna;

a dipole antenna;

a planar microstrip antenna;

a patch antenna;

a ring antenna;

or

a helix antenna.

26. The method of claim 21, wherein:

said radiating antenna element is a dual band radiating antenna element; and

said at least one parasitic antenna element includes at least one low frequency parasitic antenna element and at least one high frequency parasitic antenna.

27. The method of claim 21, wherein said remote nodes include mobile phones, laptop computers or personal digital assistants.