Method and device for realizing specific absorption rate (SAR) control

• US 9,559,415 B2
• Filed: 06/01/2011
• Issued: 01/31/2017
• Est. Priority Date: 01/24/2011
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Zhang, Lu
• Primary Examiner(s): Hsieh, Ping
• Application Number:
  US13/980,753
• Publication Number:
  US 20130293441A1
• Time in Patent Office: 2,071 Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/2275 associated to expansion card or bus, e.g. in PCMCIA, PC cards, Wireless USB
• 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 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 3/00 Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system means for positioning H01Q1/125
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use

Abstract

The disclosure discloses a method and device for realizing Specific Absorption Rate (SAR) control, in both of which phase shifters can be provided on a metal ground edge of a wireless terminal, and an induced current of the metal ground edge can be altered by applying the phase shifters, so as to reduce an antenna near field radiation characteristic of an SAR. The method and device of the disclosure can alter current phase and amplitude distribution of the metal ground without affecting the reception and transmission performance of the terminal, so as to reduce a local SAR peak value and lessen the harm of radiation to human bodies. Furthermore, the disclosure does not require any major change in a structure, circuit, and, antenna of a designed model, and can save space. The disclosure bears great flexibility and adaptability in an application, thereby realizing the objective of miniaturized design of the wireless terminal.

Claims

1. A method for realizing Specific Absorption Rate (SAR) control, comprising:

providing phase shifters on the metal ground edge of a wireless terminal; and

altering an induced current of the metal ground edge by applying the phase shifters, such that an antenna near field radiation characteristic of an SAR can be reduced,

wherein the altering an induced current of the metal ground edge is;

altering an induced current distribution on a PCB of the wireless terminal by altering magnitudes of phase shift and locations of the phase shifters on the metal ground,

wherein the phase shifters are provided on specific locations determined by the induced current distribution on the PCB, in surface induced current accumulation areas to introduce additional phase shift to a surface current for phase cancellation among current elements or for random perturbation to the surface current to maximize uniformity in distribution of near-field radiation.

2. The method according to claim 1, wherein the providing phase shifters is:

introducing the phase shifters consisting of a plurality of lumped circuit elements on the PCB metal ground edge of the wireless terminal.

3. The method according to claim 2, wherein the antenna near field radiation characteristic is reduced by:

altering phases and amplitudes of the current elements on the metal ground edge by applying the phase shifters, so that the current elements produce a reversed-phase superposition during near-field radiation to reduce the value of the SAR.

4. The method according to claim 2, further comprising:

performing real-time monitoring of a phase and amplitude of the induced current on the metal ground edge through electronic tuning control, and adjusting phase shift values of the phase shifters correspondingly to realize dynamical/real-time adjustment of an SAR value.

5. The method according to claim 1, wherein the antenna near field radiation characteristic is reduced by:

altering phases and amplitudes of the current elements on the metal ground edge by applying the phase shifters, so that the current elements produce a reversed-phase superposition during near-field radiation to reduce the value of the SAR.

6. The method according to claim 1, further comprising:

performing real-time monitoring of a phase and amplitude of the induced current on the metal ground edge through electronic tuning control, and adjusting phase shift values of the phase shifters correspondingly to realize dynamical/real-time adjustment of an SAR value.

7. A device for realizing Specific Absorption Rate (SAR) control, comprising a structure of a wireless terminal, wherein phase shifters are provided on the metal ground edge of the device, the phase shifters being configured to alter an induced current of the metal ground edge such that an antenna near field radiation characteristic of an SAR can be reduced,

wherein an induced current distribution on a PCB of the device is altered by altering magnitudes of phase shift and locations of the phase shifters on the metal ground,

wherein the phase shifters are provided on specific locations determined by the induced current distribution on the PCB, in surface induced current accumulation areas to introduce additional phase shift to a surface current for phase cancellation among current elements or for random perturbation to the surface current to maximize uniformity in distribution of near-field radiation.

8. The device according to claim 7, wherein the phase shifters are realized through a passive lumped element or an active element;

the passive lumped element comprises one of a Resistor-Capacitor (RC) phase shifting network, an inductor-Capacitor (LC) phase shifting network, a diode phase shifter, and a ferrite phase shifter; and

the active element comprises one of an operational amplifier, a switch, a variable capacitance diode, and a reversible dual-mode ferrite phase shifter.

9. The device according to claim 8, wherein

a PCB metal edge area and a PCB central area in the device are divided through slotting, and the phase shifters bridge both sides of a slot formed by the slotting;

or

a ground plane of an interlayer of a multi-layer PCB is used as a reference ground (GND), and a circuit network of the phase shifters is connected through an inter-layer through hole structure.

10. The device according to claim 8, wherein the phase shifters are further configured to perform real-time monitoring of a phase and amplitude of the induced current on a PCB metal ground edge, and to adjust phase shift values correspondingly to realize dynamical/real-time adjustment of an SAR value.

11. The device according to claim 7, wherein

a PCB metal edge area and a PCB central area in the device are divided through slotting, and the phase shifters bridge both sides of a slot formed by the slotting;

or

a ground plane of an interlayer of a multi-layer PCB is used as a reference ground (GND), and a circuit network of the phase shifters is connected through an inter-layer through hole structure.

12. The device according to claim 7, wherein the phase shifters are further configured to perform real-time monitoring of a phase and amplitude of the induced current on a PCB metal ground edge, and to adjust phase shift values correspondingly to realize dynamical/real-time adjustment of an SAR value.