US 9,866,195 B2Granted

Antenna device

AssigneeMurata Manufacturing Co., Ltd.

InventorsShoji Nagumo, Masashi Nakazato, Motoyasu Nakao, Yuji Shintomi

Life of this patent

Estimating the term…

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Abstract

A stray capacitance is generated between an antenna element and a ground electrode. A capacitance detection circuit detects the stray capacitance. An antenna matching circuit, is provided along a wireless communication signal path, which is a transmission path between the antenna element and a feeder circuit. A feedback control circuit transmits a control signal to the variable matching circuit on the basis of a detection result of the capacitance detection circuit in accordance with the stray capacitance. The capacitance detection circuit includes a constant current source and a timing circuit to measure the time taken to charge the antenna from the constant current source and for the voltage to reach a predetermined voltage.

Claims7

Dependent claims

An antenna device comprising

an antenna element,
an antenna matching circuit connected between the antenna element and a feeder unit,
a capacitance detection circuit connected to the antenna element and detecting a stray capacitance of the antenna element,
a first reactance element connected to a wireless communication signal path, which is a transmission path between the antenna element and the antenna matching circuit, that allows a wireless communication signal to pass there through and that blocks a direct current, and
a second reactance element that is shunt-connected to the wireless communication signal path between the antenna matching circuit and the first reactance element to form a parallel connection of the first reactance element and the stray capacitance of the antenna element when direct current charges the first reactance element and the stray capacitance,
the capacitance detection circuit including a constant current source and a timing circuit measuring a time taken to charge an antenna from the constant current source and for a voltage to reach a predetermined voltage.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/646,774Filed 11 Jul 2017 · continuation
Priority: JP 2012-0475505 Mar 2012
Published: US 2017/0310298 A126 Oct 2017
Granted: 9 Jan 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H03H 7/40
Impedance-matching networks: automatic matching of load impedance to source impedance
H01Q 1/243
Specially adapted for hand-held use: with built-in antennas
H01Q 1/50
Details of, or arrangements associated with, antennas: structural association of antennas with earthing switches, lead-in devices or lightning…
H01Q 5/335
Using frequency dependent circuits or components, e.g. trap circuits or capacitors: at the feed, e.g. for impedance matching

Family

PCT/JP2013/053308Parent of this continuation · filed 13 Feb 2013
Application14/331,625Parent of this continuation · filed 15 Jul 2014
US 2017/0310298 A1Pre-grant publication · published 26 Oct 2017
US 9,748,917 B2Parent of this continuation
US 2015/0311881 A1Published application
US 9,866,195 B2This patent

From the US filing history. Foreign family members aren’t listed.