Title:
ANTENNA APPARATUS
Document Type and Number:
WIPO Patent Application WO/2013/132972
Kind Code:
A1
Abstract:
A floating capacitance (Ca) is generated between an antenna element (21) and a ground electrode (51). A capacitive detection circuit (60) detects the floating capacitance (Ca). A variable matching circuit (30), i.e., an antenna matching circuit, is provided on a wireless communication signal path, which is a transmitting path between the antenna element (21) and a power supply circuit (40). On the basis of detection results obtained from the capacitive detection circuit (60), namely, corresponding to the floating capacitance (Ca), a feedback control circuit (70) transmits control signals to the variable matching circuit (30). The capacitive detection circuit (60) is configured of a constant current source, and a timer means, which measures a time needed to charge the antenna with charges from the constant current source and to have the voltage reach a predetermined voltage. Consequently, while solving problems due to use of extremely low frequency signals, and problems due to influence of environmental noise and small signal amplification, surrounding environments that change antenna characteristics are detected, the antenna characteristics are corrected as needed, and the stable antenna characteristics are stably maintained.
Inventors:
NAGUMO SHOJI (JP)
NAKAZATO MASASHI (JP)
NAKAO MOTOYASU (JP)
SHINTOMI YUJI (JP)
NAKAZATO MASASHI (JP)
NAKAO MOTOYASU (JP)
SHINTOMI YUJI (JP)
Application Number:
PCT/JP2013/053308
Publication Date:
September 12, 2013
Filing Date:
February 13, 2013
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H01Q1/50
Domestic Patent References:
| WO2011024506A1 | 2011-03-03 |
Foreign References:
| JP2011113506A | 2011-06-09 |
Attorney, Agent or Firm:
Kaede Patent Attorneys' Office (JP)
Patent business corporation Kaede Patent Attorneys' Office (JP)
Patent business corporation Kaede Patent Attorneys' Office (JP)
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Claims: