SAR reduction architecture and technique for wireless devices

Patent metadata

Field	Value
Publication number	US-9608331-B1
Application number	US-201213608988-A
Country	US
Kind code	B1
Filing date	Sep 10, 2012
Priority date	Sep 8, 2011
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

A modal antenna is proposed that provides for dynamic tuning and optimization of antenna system parameters for SAR (Specific Absorption Rate) management in mobile wireless devices. A modular approach is described where the radiator and active components are integrated into a module, allowing the fixed radiator to be used across multiple wireless products and form factors. Multiple radiation modes can be generated by a single antenna structure with one or several of the modes designed to minimize SAR while maintaining efficient communication link performance. Proximity sensors or other sensors provide indicators to determine when mode selection is necessary.

First claim

We claim:

1. A multi-mode antenna system configured to reduce specific absorption rate (SAR) and optimize antenna efficiency associated with the antenna system, the antenna system comprising:
a multi-mode antenna structure, the multi-mode antenna structure including:
an antenna radiating element, the antenna radiating element comprising an antenna element having a feed connection, a fixed ground connection and an adjustable ground connection;
and

a first parasitic element positioned adjacent to the IMD element;
the antenna system further comprising:
an antenna tuning circuit coupled to the antenna structure with at least a first port of the antenna tuning circuit coupled to the first parasitic element and a second port of the antenna tuning circuit coupled to ground, the antenna tuning circuit including one or more active components, said one or more active components configured to change an impedance loading associated with the first parasitic element, wherein the combination of the antenna radiating element, first parasitic element, and antenna tuning circuit provides two or more antenna radiating modes associated with the multi-mode antenna structure, wherein each of the two or more radiating modes yields distinct near field characteristics of an electromagnetic field radiated by the antenna structure; and
a processor coupled to the antenna tuning circuit, the processor configured to communicate control signals to the antenna tuning circuit, wherein upon receiving the control signals the antenna tuning circuit is configured to adjust the one or more active components for varying a mode of the multi-mode antenna structure;
characterized in that:
the antenna system is configured to determine a use case or loading associated with the device and communicate inputs to the processor;
wherein the processor is further configured to receive the inputs, determine an optimal mode of the antenna system for reducing SAR and optimizing signal efficiency, and communicate the control signals to the antenna tuning circuit for reconfiguring the antenna system in the optimal mode.

2. The antenna system of claim 1 , wherein the antenna radiating element is positioned above a ground plane;
the first parasitic conductor element is disposed adjacent to the antenna radiating element;
the one or more active components including at least a first active component, wherein the first active component is coupled to the first parasitic element and further coupled to ground;
the first active component being configured to adjust a reactance associated with the parasitic conductor element for controlling the mode of the multi-mode antenna structure.

3. The antenna system of claim 2 , wherein the first active component is contained within the antenna tuning circuit, and the first active component constitutes one of the one or more active components of the antenna tuning circuit.

4. The antenna system of claim 2 , wherein the radiating element and the first parasitic element are combined with a dielectric substrate to form a modular antenna assembly.

5. The antenna system of claim 4 , wherein the first active component is embedded within a volume of the modular antenna assembly.

6. The antenna system of claim 4 , wherein the modular antenna assembly is attached to a circuit board, the ground plane being disposed on the circuit board, wherein a portion of the ground plane is removed at an area beneath the modular antenna assembly.

7. The antenna system of claim 6 , wherein the removed portion of the ground plane forms an aperture configured to be excited by the antenna radiating element for radiating an electromagnetic signal.

8. The antenna system of claim 4 , wherein the modular antenna assembly is attached to a circuit board, the ground plane being disposed on the circuit board, the circuit board further comprising a delay line, wherein the delay line is coupled to a ground connection and a feed connection of the antenna radiating element.

9. The antenna system of claim 8 , wherein the delay line further comprises a switch assembly connected therebetween, the switch assembly including a firs switch, a second switch, and a plurality of lumped components each with a distinct reactive load thereof; wherein the switch assembly is configured to select from the plurality of lumped components for associating a reactive load with the delay line.

10. The antenna system of claim 8 , wherein the modular antenna assembly is disposed within a metal housing of a wireless communication device, the housing including an opening disposed within the metal housing of the device and positioned adjacent to the modular antenna assembly, wherein the modular antenna assembly is configured to excite the opening which in turn radiates an electromagnetic signal therefrom.

11. The antenna system of claim 1 ,
characterized in that the multi-mode antenna structure further comprises:
a first switch assembly, the first switch assembly including: a first switch coupled to the adjustable ground connection of the IMD element at a first end, a second switch coupled to ground at a second end, and a plurality of inductive loads disposed between ports of the first and second switches; wherein the first switch assembly is configured to select from the plurality of inductive loads for coupling between the adjustable ground connection of the IMD element and said ground; and
a second switch assembly, the second switch assembly including: a third switch coupled to the first parasitic element, a fourth switch coupled to ground, and a plurality of lumped reactance components disposed between ports of the first and third switches; wherein the second switch assembly is configured to select from the plurality lumped components for coupling between the first parasitic element and said ground.

12. The antenna system of claim 1 ,
characterized in that the multi-mode antenna structure further comprises:
a first switch assembly, the first switch assembly including: a first switch coupled to the adjustable ground connection of the IMD element at a first end, a second switch coupled to ground at a second end, and a plurality of delay lines disposed between ports of the first and second switches; wherein the first switch assembly is configured to select from the plurality of delay lines for coupling between the adjustable ground connection of the IMD element and said ground; and
a second switch assembly, the second switch assembly including: a third switch coupled to the first parasitic element, a fourth switch coupled to ground, and a plurality of lumped reactance components disposed between ports of the first and third switches; wherein the second switch assembly is configured to select from the plurality lumped components for coupling between the parasitic conductor element and said ground.

13. The antenna system of claim 1 , wherein the antenna system further comprises one or more proximity sensors each configured to sense a load about the device and communicate a load input to the processor; wherein the processor is further configured to receive the load input from the one or more proximity sensors, determine the optimal mode of the antenna system for reducing SAR and optimizing signal efficiency, and communicate the control signals to the antenna tuning circuit for reconfiguring the antenna system in the optimal mode.

14. The antenna system of claim 1 , wherein the antenna is configured to select the optimal mode based on the frequency required of the antenna.

15. The antenna system of claim 1 , wherein the antenna system is configured to select the optimal mode based on a use case of

Assignees

• Rowson Sebastian
• Desclos Laurent
• Shamblin Jeffrey
• Singh Abhishek
• Ethertronics Inc

Inventors

• Rowson Sebastian
• Desclos Laurent
• Shamblin Jeffrey
• Singh Abhishek

Classifications

• H01Q9/0442

  with particular tuning means · CPC title

• H01Q9/16 Primary

  with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole (H01Q9/44 takes precedence) · CPC title

• H01Q9/42 Primary

  with folded element, the folded parts being spaced apart a small fraction of the operating wavelength · CPC title

• H01Q1/245

  with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure · CPC title

• H04B1/3838

  Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use · CPC title