Methods for reducing near-field radiation and specific absorption rate (SAR) values in communications devices
View Patent ↗A method is provided for reducing near-field radiation and specific absorption rate values in a communications device that includes a multimode antenna structure transmitting and receiving electromagnetic signals and circuitry for processing signals communicated to and from the antenna structure. The method includes adjusting the relative phase between signals fed to neighboring antenna ports of the antenna structure such that a signal fed to the one antenna port has a different phase than a signal fed to the neighboring antenna port to provide antenna pattern control and to increase gain in a selected direction toward a receive point. The method features using a transmit power lower than the transmit power used in a non-pattern control operation of the antenna structure such that the communications device obtains generally equivalent wireless link performance with the receive point using reduced transmit power compared to the non-pattern control operation, thereby reducing the specific absorption rate.
1. A method, comprising:
adjusting a relative phase between signals fed to antenna ports of an antenna structure such that a first signal fed to one of the antenna ports has a different phase than a second signal fed to another one of the antenna ports to provide antenna pattern control and to increase gain in a selected direction toward a receive point, wherein the antenna structure comprises a plurality of antenna elements, each operatively coupled to a different one of the antenna ports, wherein electrical currents flowing in the antenna structure have a magnitude such that a first antenna mode excited by one of the neighboring antenna ports is isolated in whole or in part from a second antenna mode excited by another one of the antenna ports at a desired signal frequency range; and
using a transmit power level that is lower than the transmit power used in a non-pattern control operation of the antenna structure such that a communications device utilizing the antenna structure obtains a desired wireless link performance with the receive point using reduced transmit power compared to the non-pattern control operation, thereby reducing a specific absorption rate.
2. The method of claim 1 wherein adjusting the relative phase between signals comprises adjusting the relative phase between the signals using an electrically controlled phase shift device.
3. The method of claim 1 wherein adjusting the relative phase between signals comprises adjusting the relative phase between the signals using a phase shift network.
4. The method of claim 1 wherein adjusting the relative phase between signals comprises adjusting the relative phase between the signals by controlling a phase of a carrier signal provided at each of the antenna ports.
5. The method of claim 1 wherein the communications device is a cellular handset, personal digital assistance, wireless networking device, or a data card for a computer.
6. The method of claim 1 wherein the plurality of antenna elements comprise helical coils, wideband planer shapes, chip antennas, meandered shapes, loops, or inductively shunted forms.
7. The method of claim 1 wherein the antenna structure comprises a planar structure fabricated on a printed circuit board substrate.
8. The method of claim 1 wherein the antenna structure comprises stamped metal part including a pickup feature at a center of mass of a part for use in a pick and place assembly process.
9. The method of claim 1 wherein the antenna structure comprises a flexible printed circuit mounted on a plastic carrier or on a plastic housing of a device.
10. The method of claim 1 wherein the receive point is a base station, a mobile terminal, or a router.
11. The method of claim 1 wherein adjusting the relative phase between signals comprises adjusting the relative phase between signals fed to neighboring antenna ports to maintain a desirable communications link to the receive point.
12. A method, comprising:
adjusting a phase between signals fed to antenna ports of an antenna array such that a first signal fed to one of the antenna ports has a different phase than a second signal fed to another one of antenna ports to provide antenna pattern control and to increase gain in a selected direction toward a receive point, wherein the antenna array is utilized in a communication device; and
using a transmit power level that is lower than the transmit power used in a non-pattern control operation of the antenna array such that the communications device obtains a desired wireless link performance with the receive point using reduced transmit power compared to the non-pattern control operation, thereby reducing a specific absorption rate.
13. The method of claim 12 wherein adjusting the phase between signals comprises adjusting the phase between the signals using an electrically controlled phase shift device.
14. The method of claim 12 wherein adjusting the phase between signals comprises adjusting the phase between the signals using a phase shift network.
15. The method of claim 12 wherein adjusting the phase between signals comprises adjusting the phase between the signals by controlling the phase of a carrier signal provided at each of the antenna ports.
16. The method of claim 12 wherein the communications device is a cellular handset, personal digital assistance, wireless networking device, or a data card for computer.
17. The method of claim 12 wherein radiating elements of the antenna array comprise helical coils, wideband planer shapes, chip antennas, meandered shapes, loops, or inductively shunted forms.
18. The method of claim 12 wherein the antenna array comprises a planar structure fabricated on a printed circuit board substrate.
19. The method of claim 12 wherein the antenna array comprises stamped metal part including a pickup feature at a center of mass of a part for use in a pick and place assembly process.
20. The method of claim 12 wherein the antenna array comprises a flexible printed circuit mounted on a plastic carrier or on a plastic housing of a device.
21. The method of claim 12 wherein the receive point is a base station, a mobile terminal, or a router.
22. A method, comprising:
adjusting a phase between signals fed to antenna ports of an antenna such that a first signal fed to one of the antenna ports has a different phase than a second signal fed to another one of antenna ports to provide antenna pattern control and to increase gain in a selected direction; and
using a transmit power level that is lower than the transmit power used in a non-pattern control operation of the antenna such that a desired wireless link performance is obtained at a receive point using reduced transmit power compared to the non-pattern control operation, thereby reducing a specific absorption rate.