Radio device

Patent metadata

Field	Value
Publication number	US-9601831-B2
Application number	US-201113580637-A
Country	US
Kind code	B2
Filing date	Nov 24, 2011
Priority date	Nov 25, 2010
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A radio device of the present invention includes a radiation conductor which converts a radio frequency signal into an electric wave and radiates the electric wave; a circuit board electrically connected to the radiation conductor and incorporating an electric circuit for supplying the radio frequency signal to the radiation conductor a planar grounded conductor electrically connected to the electric circuit on the circuit board and placed such that the grounded conductor faces the radiation conductor, the grounded conductor constituting a ground of the radiation conductor; and a resin-made casing for accommodating the radiation conductor, the circuit board and the grounded conductor; wherein the grounded conductor, the circuit board and the radiation conductor are placed in this order in a thickness direction of the circuit board.

First claim

The invention claimed is:

1. A radio device for attachment to a meter box having a planar obverse wall made of metal, the radio device comprising:
a radiation conductor which converts a radio frequency signal into an electric wave and radiates the electric wave;
a circuit board electrically connected to the radiation conductor and incorporating an electric circuit for supplying the radio frequency signal to the radiation conductor;
a planar grounded conductor electrically connected to the electric circuit on the circuit board and placed such that the grounded conductor faces the radiation conductor and faces the planar obverse wall of the meter box upon attachment of the radio device to the meter box, the planar grounded conductor constituting a ground of the radiation conductor, the planar grounded conductor facing the planar obverse wall of the meter box to be spaced apart by a distance d from the surface of the meter box upon attachment of the radio device to the meter box such that the planar grounded conductor and the planar obverse wall of the meter box are electrically capacitively joined together and are substantially parallel, such that the planar grounded conductor and the planar obverse wall of the meter box cooperate as an enlarged ground plane of the radiation conductor to prevent or reduce increase in impedance between the radiation conductor and the planar grounded conductor upon attachment of the radio device to the meter box; and
a resin-made casing sized to surroundingly contain the radiation conductor, the circuit board and the planar grounded conductor;
wherein the planar grounded conductor, the circuit board and the radiation conductor are placed in this order along a linear axis in a thickness direction of the circuit board.

2. The radio device according to claim 1 ,
wherein the grounded conductor and a surface of the casing which faces the grounded conductor are placed in parallel with each other.

3. The radio device according to claim 1 ,
wherein the radiation conductor, the grounded conductor and the circuit board are placed in parallel with each other.

4. The radio device according to claim 1 , wherein the radiation conductor comprises a planar conductor element.

5. The radio device according to claim 4 ,
wherein the radiation conductor comprises a planar inverted-F antenna.

6. The radio device according to claim 1 , further comprising:
a power feeding terminal which electrically connects the electric circuit on the circuit board to the radiation conductor and feeds the radio frequency signal from the circuit board to the radiation conductor;
a short-circuit terminal which electrically connects a ground section of the electric circuit on the circuit board to the radiation conductor and electrically grounds the radiation conductor on the ground section of the electric circuit; and
a ground terminal which electrically connects the grounded conductor to the ground section of the electric circuit on the circuit board and is placed on the ground section, in the vicinity of a location at which the short-circuit terminal is grounded on the ground section.

7. The radio device according to claim 1 ,
wherein the radiation conductor comprises a wire formed on a main surface of an obverse surface and a reverse surface of the circuit board, the main surface being more distant from the grounded conductor.

8. The radio device according to claim 1 ,
wherein the radiation conductor comprises a linear conductor element.

9. The radio device according to claim 1 ,
wherein a conductor layer which is the grounded conductor is provided on a main surface of an obverse surface and a reverse surface of the circuit board, the main surface being more distant from the radiation conductor.

10. The radio device according to claim 9 ,
wherein a layer including the electric circuit is provided on a main surface of the obverse surface and the reverse surface of the circuit board, the main surface being closer to the radiation conductor.

11. The radio device according to claim 1 , wherein the casing includes a container-shaped body having an opening and a lid closing the opening of the body;
wherein a linear conductor element is placed on one of the body and the lid such that the linear conductor element encloses the opening; and
wherein the radiation conductor, the circuit board and the grounded conductor are accommodated into the body such that the radiation conductor is positioned in the vicinity of the opening.

12. The radio device of claim 1 wherein, when the radio device is attached to the meter box, the planar grounded conductor is closer to the planar obverse wall of the meter box than the radiation conductor so that, even if the size of the grounded conductor is small with respect to a wavelength of the radio frequency signal, decrease in the impedance between the radiation conductor and the planar grounded conductor is prevented or reduced when the radio device is attached to the meter box.

13. The radio device of claim 1 wherein the radio device and the meter box are configured to place the planar grounded conductor close enough to the planar obverse wall of the meter box to increase coupling capacitance between the planar grounded conductor and the planar obverse wall of the meter box to increase antenna gain of the radio device.

14. The radio device of claim 1 wherein the distance d is set to 1/50 or less of a wavelength of interest.

15. The radio device of claim 1 wherein the resin made casing comprises:
a first casing having a container shape having an opening; and
a second casing configured to close the opening of the first casing when the radiation conductor, the circuit board and the grounded conductor are contained in the casing.

16. The radio device of claim 15 wherein each of the first casing and the second casing are made of a resin having a low-loss property with respect to the electric wave.

Assignees

• Watanabe Takashi
• Uno Hiroyuki
• Sugiyama Masaki
• Yokoajiro Yoshiyuki
• Yoshikawa Yoshishige
• Panasonic Ip Man Co Ltd

Inventors

• Watanabe Takashi
• Uno Hiroyuki
• Sugiyama Masaki
• Yokoajiro Yoshiyuki
• Yoshikawa Yoshishige

Classifications

• H01Q1/48

  Earthing means; Earth screens; Counterpoises · CPC title

• H01Q1/52

  Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure (absorbing means H01Q17/00) · CPC title

• H01Q1/2233

  used in consumption-meter devices, e.g. electricity, gas or water meters · CPC title

• H01Q9/0421 Primary

  with a shorting wall or a shorting pin at one end of the element (H01Q9/0414 takes precedence) · CPC title