SENSOR-DRIVEN ADAPTIVE COUNTERPOISE ANTENNA SYSTEM

• US 20030210203A1
• Filed: 05/09/2002
• Published: 11/13/2003
• Est. Priority Date: 05/09/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Alameh, Rachid M., Scheer, Roger L., Phillips, James P., Krenz, Eric L., Efanov, Andrew A.
• Granted Patent: US 6,657,595 B1
• Time in Patent Office: Days
• US Class Current: 343/850
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas

Abstract

An adaptive antenna system having a counterpoise conductor contained within a housing of a communication device and located distally from such surfaces of the housing that can be held by or placed in proximity to a user or external objects which detune the counterpoise. A tuning circuit is coupled between the counterpoise conductor and a ground. The tuning circuit is operable to adapt the resonant frequency of the counterpoise conductor to divert operational RF currents away from the ground located in proximity the user or external objects and onto the counterpoise conductor.

Claims

1. An adaptive antenna system for a communication device having a transceiver disposed within a housing, the system comprising:

an antenna being electrically coupled to the transceiver;

at least one conductor counterpoise to the antenna, the at least one counterpoise conductor being contained within the housing and located distally from such surfaces of the housing that can be held by or placed in proximity to a user;

a second conductor coupled to a ground connection of the antenna and being contained within the housing; and

a tuning circuit coupled between the at least one counterpoise conductor and the second conductor, the tuning circuit is operable to adapt the resonant frequency of the at least one counterpoise conductor to attract operational RF currents onto the at least one counterpoise conductor and divert operational RF currents away from the second conductor.

2. The system of claim 1, wherein the housing is a conductive ground plane and constitutes the second conductor such that the tuning circuit adapts the counterpoise conductor to draw RF currents away from the housing and subsequently the user.

3. The system of claim 1, wherein the tuning circuit adapts the resonant frequency of the counterpoise conductor in response to detuning effects caused by location of the device in proximity to the user.

4. The system of claim 1, further comprising a plurality of proximity sensors disposed on the housing, the proximity sensors are operable to detect a proximity of the device to external objects and provide a signal for the tuning circuit to direct currents away from that portion of the second conductor near the activated proximity sensors.

5. The system of claim 1, further comprising a controller, the controller controlling the operation of the tuning circuit in response to inputs indicating the proximity of the user.

6. The system of claim 1, wherein the antenna is tunable in response to at least one of the group of the counterpoise conductor tuning, antenna efficiency, user proximity, RF currents and an external RF environment.

7. The system of claim 1, further comprising at least one current sensor disposed in proximity to the second conductor, the at least one current sensor is operable to detect current in the second conductor and provide a signal for the tuning circuit to direct the detected current away from the second conductor.

8. An adaptive antenna system for a communication device having a transceiver disposed within a conductive housing, the system comprising:

an antenna being electrically coupled to the transceiver, the housing forming a ground plane for the antenna;

at least one conductor counterpoise to the antenna, the at least one counterpoise conductor being contained within the housing and located distally from such surfaces of the housing that can be held by or placed in proximity to a user;

a tuning circuit coupled between the at least one counterpoise conductor and the housing; and

a controller for controlling the operation of the tuning circuit in response to inputs indicating the proximity of the device to external objects that detune the at least one counterpoise conductor, the controller directs the tuning circuit to adapt the resonant frequency of the at least one counterpoise conductor to attract operational RF currents onto the at least one counterpoise conductor and divert operational RF currents away from the housing.

9. The system of claim 8, further comprising a plurality of proximity sensors disposed on the housing, the proximity sensors are operable to detect a proximity of the device to external objects and provide a signal to the controller to direct the tuning circuit to provide coarse tuning to draw currents away from that portion of the second conductor near the activated proximity sensors onto the at least one counterpoise conductor.

10. The system of claim 8, further comprising at least one current sensor disposed in proximity to a ground plane of the device, the at least one current sensor is operable to detect current in the ground plane and provide a signal to the controller to direct the tuning circuit to provide fine tuning to draw the detected current away from the housing onto the at least one counterpoise conductor.

11. The system of claim 8, further comprising at least one current sensor disposed in proximity to the at least one counterpoise conductor, the at least one current sensor is operable to detect current in the counterpoise and provide a signal to the controller to confirm currents drawn away from the housing onto the at least one counterpoise conductor.

12. The system of claim 8, further comprising a VSWR monitor and matching circuit coupled to the antenna and the controller wherein the processor monitors VSWR of the antenna and controls the matching circuit to provide optimal antenna efficiency.

13. The system of claim 8, wherein a plurality of counterpoise conductors are contained within the housing with a portion of the tuning circuit between each of the counterpoise conductors and the ground plane, and further comprising a proximity sensor grid disposed on the housing, wherein the proximity sensor grid is operable to detect a proximity of the device to external objects and provide a signal to the controller to direct the tuning circuit to provide tuning to draw currents away from that portion of the ground plane located near the activated proximity sensors onto the counterpoise conductor located most distally from the activated proximity sensors.

14. A method for antenna counterpoise tuning in a communication device with a housing, the method comprising the steps of:

providing at least one conductor counterpoise to the antenna, a second conductor contained within the housing, and a tuning circuit coupled between the counterpoise conductor and the second conductor;

monitoring a detuning of the counterpoise conductor; and

tuning the at least one counterpoise conductor to resonance to effect;

an attracting of RF currents onto the at least one counterpoise conductor, and

a diverting of RF currents away from the second conductor.

15. The method of claim 14, wherein in the providing step the housing is a conductive ground plane and constitutes the second conductor and the at least one counterpoise conductor is internal to the housing such that the tuning step adapts the counterpoise conductor to draw RF currents away from the housing and subsequently a user.

16. The method of claim 14, wherein the monitoring step includes monitoring of the a least one counterpoise conductor in response to detuning effects caused by location of the device in proximity to an external object.

17. The method of claim 14, wherein the providing step includes providing a plurality of proximity sensors disposed on the housing, and wherein the monitoring step includes the proximity sensors detecting a proximity of the device to external objects and providing a signal for the tuning step to direct currents away from that portion of the second conductor near the activated proximity sensors.

18. The method of claim 14, wherein the providing step includes providing a controller to control the operation of the tuning step in response to inputs from the monitoring step.

19. The method of claim 14, wherein the providing step includes providing an antenna tuning circuit, and further comprising the step of adapting the antenna in response to at least one of the group of the counterpoise conductor tuning, antenna efficiency, user proximity, RF currents and an external RF environment.

20. The method of claim 14, wherein the providing step includes providing at least one current sensor disposed in proximity to the second conductor, and the monitoring step includes the at least one current sensor detecting current in the second conductor and outputting a signal for the tuning step to direct the detected current away from the second conductor.

21. The method of claim 17, further comprising the step of using the proximity sensor input to set maximum power limits for the communication device.

22. The method of claim 17, further comprising the step of using the current sensor input to detect and control maximum power limits for the communication device.