Antenna system for near-field magnetic induction wireless communications

• US 10,546,686 B2
• Filed: 03/14/2016
• Issued: 01/28/2020
• Est. Priority Date: 03/14/2016
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Verschueren, Pieter, Kerselaers, Anthony
• Primary Examiner(s): Smith, Graham P
• Assistant Examiner(s): Kim, Jae K
• Application Number:
  US15/069,182
• Publication Number:
  US 20170263376A1
• Time in Patent Office: 1,415 Days
• CPC Class Codes: H01F 2038/143 for signals
• CPC Class Codes: H01F 27/2823 Wires H01F27/2866 takes precedence
• CPC Class Codes: H01F 27/325 Coil bobbins formers for coils in general H01F5/02
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/44 using equipment having another main function to serve additionally as an antenna , e.g. means for giving an antenna an aesthetic aspectH01Q1/27 - H01Q1/34 take precedence
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: H04R 2225/51 Aspects of antennas or their circuitry in or for hearing aids

Abstract

An antenna system is provided that is capable of transmitting and receiving using near-field magnetic induction (NFMI). The antenna system includes a non-magnetic metallic core, a ferrite shield, and at least one electrically conducting winding. The ferrite shield is positioned between the non-magnetic metallic core and the electrically conducting winding. The non-magnetic metallic core may be a battery. The ferrite material forms a low impedance path for the magnetic field lines and increases inductance, thus providing increased energy efficiency and transmission quality. The antenna system is suitable for use in space constrained battery powered devices, such as hear instruments including hearing aids and earbuds.

Claims

1. A transmitter and a receiver for use in a near-field magnetic induction communication system, the transmitter comprising:

a first battery;

a first ferrite material covering at least a portion of the first battery;

a transmitter antenna comprising an electrical conductor looped around the first battery and the first ferrite material; and

a transmitter tuning circuit comprising a signal source, first and second amplifiers, a first variable tuning capacitor and a first variable resistance, the first and second amplifiers each having an input coupled to the signal source, an output of the first amplifier coupled to a first end of the electrical conductor and an output of the second amplifier coupled to a second end of the electrical conductor, the first variable tuning capacitor and the first variable resistance coupled together in parallel between the first and second ends of the electrical conductor, the first variable tuning capacitor for maintaining the looped electrical conductor in resonance, and the first variable resistance for maintaining a bandwidth of the looped electrical conductor, and

the receiver comprising;

a second battery;

a second ferrite material covering at least a portion of the second battery;

a receiver antenna comprising an electrical conductor looped around the second battery and the second ferrite material; and

a receiver tuning circuit comprising a third amplifier, a second variable tuning capacitor, and a second variable resistance, the second variable tuning capacitor and the second variable resistance coupled together in parallel between first and second ends of the electrical conductor of the receiver antenna, the third amplifier having first and second inputs coupled to the first and second ends, respectively, of the electrical conductor of the receiver antenna,

wherein neither of the first end or the second end of the electrical conductors of the transmitter and receiver antennas are connected to a reference voltage, and wherein during a signal transmission from the transmitter to the receiver, the looped electrical conductor of the transmitter is oriented so that an open end of the looped electrical conductor is directed toward an open end of the looped electrical conductor of the receiver and along the same axis.

2. The transmitter and receiver of claim 1, wherein the transmitter is located in a first earbud of a pair of earbuds and the receiver is located in a second earbud of the pair of earbuds, and during the signal transmission, the first and second earbuds are positioned in first and second human ears, respectively.

3. The transmitter and receiver of claim 1, wherein the first and second batteries is cylindrical and the first and second ferrite material covers only a side of the first and second batteries.

4. The transmitter and receiver of claim 1, wherein the first and second ferrite material each comprises a ferrite sheet.

5. The transmitter and receiver of claim 4, wherein the ferrite sheet includes an adhesive on one side for adhering to the first battery.

6. The transmitter and receiver of claim 1, wherein the first and second ferrite material is applied as a coating comprising ferrite particles in suspension.

7. The transmitter and receiver of claim 1, wherein a carrier frequency for communicating the signals is 10.6 Mega Hertz (MHz).

8. The transmitter and receiver of claim 1, wherein the electrical conductor is an insulated copper wire.

9. The transmitter and receiver of claim 1, wherein the electrical conductor is a conductive trace on a flexible printed circuit board.

10. A transmitter and a receiver for use in a near-field magnetic induction communication system, the transmitter comprising:

a first ferrite material covering at least a portion of a first battery, the first battery being used for powering at least a portion of the transmitter;

a transmitter antenna comprising an electrical conductor disposed around the first battery and the first ferrite material in a predetermined number of loops; and

a transmitter tuning circuit comprising a signal source, first and second amplifiers, a first variable tuning capacitor and a first variable resistance, the first and second amplifiers each having an input coupled to the signal source, an output of the first amplifier coupled to a first end of the electrical conductor and an output of the second amplifier coupled to a second end of the electrical conductor, the first variable tuning capacitor and the first variable resistance coupled together in parallel between the first and second ends of the electrical conductor, the first variable tuning capacitor for maintaining the looped electrical conductor in resonance, and the first variable resistance for maintaining a bandwidth of the looped electrical conductor, and

the receiver comprising;

a second ferrite material covering at least a portion of a second battery, the second battery being used for powering at least a portion of the receiver;

a receiver antenna comprising an electrical conductor disposed around the second battery and the second ferrite material in a predetermined number of loops; and

a receiver tuning circuit comprising a third amplifier, a second variable tuning capacitor, and a second variable resistance, the second variable tuning capacitor and the second variable resistance coupled together in parallel between first and second ends of the electrical conductor of the receiver antenna, the third amplifier having first and second inputs coupled to the first and second ends, respectively, of the electrical conductor of the receiver antenna,

wherein neither of the first end or the second end of the electrical conductors of the transmitter and receiver antennas are connected to a reference voltage, and wherein during operation the looped electrical conductor of the transmitter is oriented so that an open end of the looped electrical conductor is directed toward an open end of a looped electrical conductor of the receiver and along the same axis.

11. The transmitter and receiver of claim 10, wherein the first and second ferrite material each comprises a ferrite sheet.

12. The transmitter and receiver of claim 10, wherein the communication system provides wireless signal transmission between the earbuds of a pair of earbuds.

13. The transmitter and receiver of claim 10, wherein the first and second ferrite material is applied as a coating comprising ferrite particles in suspension.

14. The transmitter and receiver of claim 11, wherein the ferrite sheet includes an adhesive on one side for adhering to the non-magnetic metallic core.

15. The transmitter and receiver of claim 10, wherein a carrier frequency for communication system is 10.6 Mega Hertz (MHz).

16. A transmitter and a receiver for use in a battery powered near-field magnetic induction wireless communication system, the transmitter comprising:

a first magnetic material covering at least a portion of a first battery, the first battery being used for powering at least a portion of the transmitter;

a transmitter antenna comprising an insulated electrical conductor disposed around the battery and the first magnetic material in a predetermined number of loops; and

a transmitter tuning circuit comprising a signal source, first and second amplifiers, a first variable tuning capacitor and a first variable resistance, the first and second amplifiers each having an input coupled to the signal source, an output of the first amplifier coupled to a first end of the electrical conductor and an output of the second amplifier coupled to a second end of the electrical conductor, the first variable tuning capacitor and the first variable resistance coupled together in parallel between the first and second ends of the electrical conductor, the first variable tuning capacitor for maintaining the looped electrical conductor in resonance, and the first variable resistance for maintaining a bandwidth of the looped electrical conductor, and

the receiver comprising;

a second magnetic material covering at least a portion of a second battery, the second battery being used for powering at least a portion of the receiver; and

a receiver antenna comprising an insulated electrical conductor disposed around the second battery and the second magnetic material in a predetermined number of loops;

a receiver tuning circuit comprising a third amplifier, a second variable tuning capacitor, and a second variable resistance, the second variable tuning capacitor and the second variable resistance coupled together in parallel between first and second ends of the insulated electrical conductor of the receiver antenna, the third amplifier having first and second inputs coupled to the first and second ends, respectively, of the insulated electrical conductor of the receiver antenna,

wherein neither of the first end or the second end of the insulated electrical conductors of the transmitter and receiver antennas are connected to a reference voltage, and wherein during operation the insulated electrical conductor of the transmitter is oriented so that an open end of the insulated electrical conductor is directed toward an open end of a insulated electrical conductor of the receiver and along the same axis.

17. The transmitter and receiver of claim 16, wherein the first and second batteries are cylindrical shaped having a curved side and two ends, the magnetic material only covering the side of the battery.

18. The transmitter and receiver of claim 16, wherein the first and second magnetic material comprises a ferrite material.

19. The transmitter and receiver of claim 16, wherein the communication system provides wireless signal transmission between the earbuds of a pair of earbuds.

20. The transmitter and receiver of claim 16, wherein a carrier frequency for the wireless signal transmission is 10.6 Mega Hertz (MHz).