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Antenna device

An antenna device, antenna element technology, applied in the direction of antenna, antenna support/mounting device, antenna coupling, etc., to achieve reliable detection effect

Active Publication Date: 2012-05-30
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0018] Therefore, even if the surrounding conditions are sensed in order to stabilize the antenna characteristics, none of the above structures can be said to be preferable.

Method used

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Effect test

no. 1 Embodiment approach

[0056] refer to Figure 2 to Figure 7 The antenna device according to the first embodiment will be described.

[0057] Between the antenna element electrode 21 and the ground electrode 51 of the substrate, as figure 2 An electric field is formed as schematically represented by lines of force in (A). For high frequencies such as wireless communication signals, electromagnetic waves are radiated to the outside by the electric field described above appearing alternately. For direct current, however, a so-called electrostatic field is formed.

[0058] exist figure 2 The right side of (A) shows that a pseudo dipole is constituted by the antenna element electrode 21 and the ground electrode 51 of the substrate.

[0059] The antenna element electrode 21 and the ground electrode 51 of the substrate can be regarded as opposing conductors in a capacitor connected by the above-mentioned electric force line, and this capacitance is a so-called parasitic capacitance that determines t...

no. 2 Embodiment approach

[0095] In the second embodiment, the reactance element provided in the wireless communication signal path that is the propagation path between the antenna element and the power supply unit, and the sensing signal path that is the propagation path between the antenna element and the capacitance detection circuit are shown. A specific example of the reactance element provided in .

[0096] Figure 8 It is a diagram showing two configurations of the antenna device according to the second embodiment.

[0097] exist Figure 8 In (A), the capacitor C is provided in the wireless communication signal path PW1 that is a propagation path between the antenna element electrode 21 and the feeding circuit 40 . Furthermore, an inductor L is provided in the sensing signal path PW2 which is a propagation path between the antenna element electrode 21 and the capacitance detection circuit 60 .

[0098] exist Figure 8 In (A), although the capacitor C provided in the wireless communication si...

no. 3 Embodiment approach

[0105] In the third embodiment, a specific configuration example of the capacitance detection circuit is shown.

[0106] Figure 10 (A) is a circuit diagram showing a capacitance detection circuit provided in the antenna device according to the third embodiment, Figure 10 (B) is a waveform diagram showing its operation.

[0107] Here, an operational amplifier is used based on two viewpoints of taking out an output signal as a voltage signal and amplifying it. The capacitance-voltage conversion circuit is composed of an inverting amplifier circuit based on an operational amplifier OP1, a detection target capacitance Cs, and a feedback capacitance Cf. A reference potential Vref1 is applied to the non-inverting input terminal of the operational amplifier OP1. The operation principle of this capacitance-voltage conversion circuit is to amplify a changing voltage (V=Q / C) caused by the movement of charge between Cs-Cf due to the capacitance change of the detection target capacit...

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PUM

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Abstract

Stable antenna characteristics are maintained at all times, by detecting ambient environments that change the antenna characteristics, and correcting the antenna characteristics, as appropriate. When a human body (a palm or a finger) comes near an electric field of a pseudo-dipole, consisting of an antenna element electrode (21) and a ground electrode (51) of a substrate, electric lines of force enter (terminate at) the human body as if being drawn-near thereby, and the capacitance (stray capacitance) between the antenna element electrode (21) and the ground electrode (51) of the substrate increases. The antenna element is used for two functions, transmitting / receiving radio communication signals and detecting an approaching of a human body, and the approaching of a human body is sensed by using the relationship between the degree of approaching of a human body, and changes in stray capacitance. Changes in the antenna characteristics due to the approaching of a human body are then corrected, as appropriate, and stable antenna characteristics are maintained.

Description

technical field [0001] The present invention relates to an antenna device provided in, for example, a mobile phone terminal. Background technique [0002] Patent Documents 1, 2, and 3 disclose techniques for sensing surrounding conditions in order to compensate antenna characteristics that change due to surrounding conditions such as approaching a human body through feedback. [0003] In Patent Document 1, the input impedance (return loss, VSWR) of the antenna fluctuating due to changes in the surrounding conditions is directly measured. Install a directional coupler in the line between the RF circuit and the antenna, and monitor the power in the direction from the RF circuit to the antenna (input direction) and from the antenna to the RF circuit (reflection direction) to grasp the input impedance in the current state . [0004] In Patent Document 2, changes in the amount of electromagnetic waves radiated from the antenna are directly measured. A sensor such as a Hall ele...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01Q1/50H01Q1/24H01Q1/52H04M1/02
CPCH03H7/38H01Q1/243H01Q9/40H01Q3/267H01Q1/44H01Q5/0041H03H7/40H01Q5/335
Inventor 南云正二高田政明植木纪行小山展正
Owner MURATA MFG CO LTD
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