Communication System, Communication Apparatus, and Electric-Field-Coupling Antenna

• US 20080076351A1
• Filed: 08/14/2007
• Published: 03/27/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: WASHIRO, Takanori
• Granted Patent: US 8,023,890 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: H04B 1/71635 Transmitter aspects H04B1/7174 takes precedence
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 for local intradevice communication

Abstract

A communication system includes the following elements: a transmitter including a transmission circuit unit configured to generate an RF signal for transmitting data and an EFC antenna configured to transmit the RF signal as an electrostatic field or an induced electric field; a receiver including an EFC antenna and a reception circuit unit configured to receive and process the RF signal received by the EFC antenna; and an impedance snatching unit configured to make an impedance of the EFC antenna of the transmitter equal to an impedance of the EFC antenna of the receiver. The RF signal is transmitted by electric-field coupling between the EFC antennas, facing each other, of the transmitter and the receiver.

Claims

1. A communication system comprising;

a transmitter including a transmission circuit unit configured to generate a radio-frequency signal for transmitting data and an electric-field-coupling antenna configured to transmit the radio-frequency signal as an electrostatic field or an induced electric field;

a receiver including an electric-field-coupling antenna and a reception circuit unit configured to receive and process the radio-frequency signal received by the electric-field-coupling antenna; and

an impedance matching unit configured to make an impedance of the electric-field-coupling antenna of the transmitter equal to an impedance of the electric-field-coupling antenna of the receiver,

wherein the radio-frequency signal is transmitted by electric-field coupling between the electric-field-coupling antennas, facing each other, of the transmitter and the receiver.

2. The communication system according to claim 1, wherein the radio-frequency signal is an ultra-wideband signal using an ultra-wideband.

3. The communication system according to claim 1, wherein the impedance matching unit serves as a band-pass filter with a desired radio-frequency band as a passband between the electric-field-coupling antennas of the transmitter and the receiver.

4. The communication system according to claim 1, wherein the electric-field-coupling antenna performs impedance conversion for reducing, relative to a characteristic impedance at an input side connecting to the transmission circuit unit, a characteristic impedance at an output side facing the other electric-field-coupling antenna.

5. The communication system according to claim 1, wherein, in the transmitter, a radio-frequency-signal transmission line for transmitting the radio-frequency signal generated by the transmission circuit unit is connected, substantially to the center of an electrode of the electric-field-coupling antenna with the impedance matching unit interposed therebetween, and

wherein, in the receiver, a radio-frequency-signal transmission line for transmitting the radio-frequency signal to the reception circuit unit is connected substantially to the center of an electrode of the electric-field-coupling antenna with the impedance matching unit interposed therebetween.

6. The communication system according to claim 5, wherein the impedance matching unit includes a conductor with a length dependent on an operating wavelength.

7. The communication system according to claim 5, wherein the impedance matching unit includes a lumped-constant circuit.

15. The communication apparatus according to claim 3, further comprising electric-power generating means for generating electric power by rectifying the radio-frequency signal transmitted between the electric-field-coupling antennas.

8. A communication apparatus comprising:

a communication circuit unit configured to process a radio-frequency signal for transmitting data; and

an electric-field-coupling antenna configured to establish electric-field coupling to a communication partner facing the communication apparatus at a very short distance,

wherein the electric-field-coupling antenna has an impedance matched to that of the communication partner with which electric-field coupling is established, the communication partner being disposed at the very short distance,

9. The communication apparatus according to claim 8, wherein the electric-field-coupling antenna includes an electrode, a series inductor, and a parallel inductor, all of which are connected to a radio-frequency-signal transmission line.

10. The communication apparatus according to claim 9, wherein the constants of the parallel and series inductors and the constant, of a capacitance are determined so that, the electric-field-coupling antenna, with a similar electric-field-coupling antenna of the communication partner facing the communication apparatus at the very short distance, serves as a band-pass filter having a desired radio-frequency band as a passband.

11. The communication apparatus according to claim 9, wherein the constant of the parallel inductor and the constant of a capacitance are determined so that the electric-field-coupling antenna serves as an impedance conversion circuit for reducing, relative to a characteristic impedance at an input side connected to the communication circuit unit, a characteristic impedance at an output side facing the communication partner.

12. The communication apparatus according to claim 9, wherein the electrode included in the electric-field-coupling antenna is mounted at a predetermined height above a printed circuit board, on which the communication circuit unit is mounted.

13. The communication apparatus according to claim 12, wherein the predetermined height is a distance for suppressing electric-field coupling to ground on the printed circuit board, a distance for forming a series inductor for achieving impedance matching, and a distance for reducing emission of unnecessary radio waves due to current flow in the series inductor.

14. The communication apparatus according to claim 9, wherein the electrode is substantially hemispherical.

16. An electric-field-coupling antenna used in communicating a radio-frequency signal using electric-field coupling, comprising:

an electrode;

a series inductor; and

a parallel inductor,

wherein the electrode, the series inductor, and the parallel inductor are connected to a radio-frequency-signal transmission line, and

wherein the electric-field-coupling antenna has an impedance matched to that of a communication partner with which electric-field coupling is established, the communication partner being disposed at a very short distance.

17. The electric-field-coupling antenna according to claim 16, wherein the radio-frequency-signal transmission line is connected substantially to the center of the electrode with the series inductor and the parallel inductor interposed therebetween.

18. The electric-field-coupling antenna according to claim 16, wherein each of the series inductor and the parallel inductor includes a conductor with a length dependent on an operating wavelength.

19. The electric-field-coupling antenna according to claim 16, wherein the constants of the parallel and series inductors and the constant of a capacitance are determined so that the electric-field-coupling antenna, with a similar electric-field-coupling antenna of the communication partner facing the electric-field-coupling antenna at the very short distance, serves as a band-pass filter having a desired radio-frequency band as a passband.

20. The electric-field-coupling antenna according to claim 16, wherein the constant of the parallel inductor and the constant of a capacitance are determined so that the electric-field-coupling antenna serves as an impedance conversion circuit for reducing, relative to a characteristic impedance at an input side to which the radio-frequency signal is input, a characteristic impedance at an output side establishing electric-field coupling to the communication partner.

21. The electric-field-coupling antenna according to claim 16, wherein the electrode is mounted at a predetermined height above a printed circuit board.

22. The electric-field-coupling antenna according to claim 21, wherein the predetermined height is a distance for suppressing electric-field coupling to ground on the printed circuit board, a distance for forming a series inductor for achieving impedance matching, and a distance for reducing emission of unnecessary radio waves due to current flow in the series inductor.

23. The electric-field-coupling antenna according to claim 16, wherein the electrode is substantially hemispherical.