JP2004336742A - Antenna device for radio and radio communication device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna having a simple structure and reducing SAR and to provide a radio communication device using the antenna. <P>SOLUTION: In the radio communication device having a whip antenna 12 connected to a radio communication circuit 15 for receiving/transmitting a radio signal, a load impedance element 14 is connected between a passive element 13 being a conductive board and the ground of a case 11 of the radio communication device including the radio communication circuit 15. Additionally, when the radio communication device performs transmission, the element value of the load impedance element 14 is set or controlled so that the value of current flowing in the case 11 becomes a specific value or smaller, thus setting or controlling a ratio absorption rate (SAR) to a specific value or smaller. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless antenna device and a wireless communication device using the same, such as a mobile phone or a car phone.

  2. Description of the Related Art In recent years, wireless communication devices such as mobile phones and automobile phones have rapidly become widespread. These wireless communication devices have been miniaturized year by year. Due to the miniaturization, radio waves are also radiated from the radio communication device housing of the radio communication device in addition to the radio wave radiation from the antenna. That is, electromagnetic waves are radiated by the entire wireless communication device.

  Some of the electromagnetic waves radiated from the antenna and the wireless communication device are absorbed by the human body. The ratio of the amount of electric power at which the human body absorbs the electromagnetic wave in the emitted radio waves is represented by a specific absorption rate (SAR). For the past several years, guidelines for suppressing the SAR value have been created, and it is obliged that the SAR value be reduced to a specified value or less (for example, see Non-Patent Document 1). For example, a mobile phone is used close to the head during a call, and therefore absorbs radio waves at the head. In particular, the SAR may be the largest because the housing contacts the human ear or cheek.

  FIG. 45 is a front view when a wireless communication device having a wireless antenna according to the related art is supported on the head of a human body, and FIG. 46 is a perspective view illustrating an appearance of the wireless communication device in FIG.

  The wireless communication device shown in FIGS. 45 and 46 is provided so that the whip antenna 1112 extends upward from the upper part of the rectangular parallelepiped housing 1111, and the front surface opposite to the back surface on the whip antenna 1112 side (user A conductor plate 1113 connected to the housing 1111 is provided so as to be parallel to the face facing the face of the user. By connecting the conductor plate 1113 to the housing 1111, of the electromagnetic waves in the radiation direction indicated by arrows 1113 A and 1113 B from the wireless communication device, the electromagnetic waves in the direction of the human body can be shielded. (For example, see Patent Document 1).

JP-A-2001-308622. Niels Kuster et al., "Energy Absorption Mechanism by Biological Bodies in the Near Field of Dipole Antennas Above 300MHz", IEEE Transactions on Vehicular technology, Vol. 41, No. 1, pp. 17-23, February 1992. Published by Association of Radio Industries and Business in Japan, "Standard for Specific Absorption Rate Measurement Method for Portable Wireless Terminals", ARIB STB-T56 Ver.2.0, revised and published on January 24, 2002.

  However, the shape of the conductor plate 1113 according to the related art is limited, and it has not been possible to shield all radio waves radiated from the wireless communication device. Therefore, the effect of reducing the SAR cannot be said to be sufficient simply by blocking some radio waves.

  SUMMARY OF THE INVENTION The object of the present invention is to solve the problems described above, and to shield a radio wave radiated from a wireless communication device from a human body with a radio wave radiated from a wireless communication device, with a very simple structure. An object of the present invention is to provide a wireless antenna device capable of greatly reducing SAR and a wireless communication device using the same.

A wireless antenna device according to a first invention is a wireless antenna device including an antenna connected to a wireless communication circuit that transmits and receives a wireless signal,
A parasitic element,
The parasitic element, a load impedance element connected between the ground of the housing of the wireless communication device including the wireless communication circuit,
By controlling the element value of the load impedance element so that the current value flowing through the housing at the time of transmission of the wireless communication device is equal to or less than a predetermined value, the specific absorption rate (SAR) is equal to or less than the predetermined value. And control means for controlling.

A wireless antenna device according to a second invention is a wireless antenna device provided with first and second antennas,
When the first antenna is connected to a wireless communication circuit provided in the wireless communication device for transmitting and receiving a wireless signal, the second antenna is connected to the wireless communication device including the wireless communication circuit via the load impedance element. When the second antenna is connected to a wireless communication circuit that transmits and receives wireless signals while the second antenna is connected to the ground of the housing, the first antenna is connected to the ground of the housing via the load impedance element. Switching means for switching to perform
By controlling the element value of the load impedance element so that the current value flowing through the housing at the time of transmission of the wireless communication device is equal to or less than a predetermined value, the specific absorption rate (SAR) is equal to or less than the predetermined value. And control means for controlling.

  The wireless antenna device further includes a storage unit configured to store, as a table, an element value of the load impedance element, wherein a current value flowing through the housing during transmission of the wireless communication device is equal to or less than a predetermined value. Is characterized in that the element value of the load impedance element is controlled with reference to a table stored in the storage means. Instead, in the wireless antenna device, the element value of the load impedance element that causes the current value flowing through the housing to be equal to or less than a predetermined value at the time of transmission of the wireless communication device is stored as a table for each frequency. A storage unit is further provided, wherein the control unit controls an element value of the load impedance element based on a communication frequency of the wireless communication device with reference to a table stored in the storage unit. Alternatively, in the wireless antenna device, the wireless antenna device further includes a measuring unit that measures a value of a current flowing through the housing when the wireless communication device transmits, and the control unit controls the housing based on the measured current value. The value of the load impedance element is controlled so that the value of the current flowing through the body is equal to or less than a predetermined value.

  Further, in the wireless antenna device, the load impedance element may include a plurality of impedance elements having element values different from each other and an element of the load impedance element by selectively switching one of the plurality of impedance elements. Switch means for changing the value. Instead, in the wireless antenna device, the load impedance element includes an impedance element that can change an element value, and changes an element value of the impedance element that can change the element value. Thus, the element value of the load impedance element is changed. Alternatively, in the wireless antenna device, the load impedance element includes an impedance circuit including a variable capacitance diode, and changes an impedance value of the impedance circuit by changing a reverse bias voltage applied to the variable capacitance diode. The element value of the load impedance element is changed.

  Furthermore, the wireless antenna device further includes a human body proximity sensor that detects that a human body has approached the housing of the wireless communication device, and that the human body has approached the wireless communication device by the human body proximity sensor. An element value of the load impedance element is controlled such that a value of a current flowing through the casing during detection and transmission by the wireless communication device is equal to or less than a predetermined value. Instead, in the wireless antenna device, a human body proximity sensor that detects that a human body has approached the housing of the wireless communication device, and a body temperature when the human body comes into contact with the housing of the wireless communication device. A temperature sensor for measuring, wherein the body temperature measured by the temperature sensor is equal to or higher than a predetermined value, the human body proximity sensor detects that the human body has approached the wireless communication device, and transmits the wireless communication device. At this time, the element value of the load impedance element is controlled so that a current value flowing through the housing becomes a predetermined value or less. Alternatively, in the wireless antenna device, a human body proximity sensor that detects that a human body has approached the housing of the wireless communication device, and a touch that measures stress when the human body comes into contact with the housing of the wireless communication device. Further comprising a sensor, wherein the stress measured by the touch sensor is equal to or greater than a predetermined value, the human body proximity detection sensor detects that a human body has approached the wireless communication device, and the wireless communication device transmits when The element value of the load impedance element is controlled so that the value of the current flowing through the housing is equal to or less than a predetermined value. Further instead, in the wireless antenna device, a human body proximity sensor that detects that a human body has approached the housing of the wireless communication device, and a stress generated when the human body contacts the housing of the wireless communication device. A touch sensor for measuring, further comprising a temperature sensor for measuring a body temperature when a human body comes into contact with the housing of the wireless communication device, wherein the body temperature measured by the temperature sensor is a predetermined value or more, and the touch sensor The measured stress is equal to or greater than a predetermined value, the human body proximity sensor detects that the human body has approached the wireless communication device, and the current value flowing through the housing at the time of transmission of the wireless communication device is equal to or less than a predetermined value. The element value of the load impedance element is controlled so that

  Still further, in the wireless antenna device, the antenna is a monopole antenna or a helical antenna, and the parasitic element is a conductor plate. Alternatively, in the wireless antenna device, the first antenna is a monopole antenna or a helical antenna, and the second antenna is a planar antenna or an inverted-F antenna.

  A wireless communication device according to a third aspect of the present invention includes the wireless antenna device and a wireless communication circuit connected to the antenna or the first antenna or the second antenna for transmitting and receiving a wireless signal. It is characterized by. Here, the wireless communication device is a portable wireless communication device.

  Therefore, according to the wireless antenna device and the wireless communication device using the same according to the present invention, the radio wave radiated from the wireless communication device can be substantially reduced in almost all radio waves as compared with the related art. Can be shielded from the human body, and SAR can be greatly reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same components are denoted by the same reference numerals.

First embodiment.
FIG. 1 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a first embodiment of the present invention.

  In FIG. 1, a wireless communication circuit 15 provided in a housing 11 of a wireless communication device includes a wireless transmitter circuit 17, a wireless receiver circuit 18, and one (1/4) wavelength whip antenna 12 as two circuits. A circulator 16 is provided for common use by the devices 17 and 18. Here, the wireless transmitter circuit 17 performs processing such as modulation, high frequency conversion, and power amplification on the input voice signal and data signal to generate a wireless transmission signal, and the wireless transmission signal is , The circulator 16, the power supply cable 25, and the power supply point Q, are output to the whip antenna 12, and the radio wave of the wireless transmission signal is radiated from the whip antenna 12. The wireless reception signal received by the whip antenna 12 is input to the wireless receiver circuit 18 via the feeding point Q, the feeding cable 25 and the circulator 16, and the processing such as low-noise amplification, low-frequency conversion, and demodulation is performed. Done.

  On the other hand, a parasitic element 13 and a load impedance element 14 are provided in the housing 11. Here, the parasitic element 13 is, for example, a rectangular flat conductive plate, and is, for example, parallel to a front surface of the housing 11 (a surface corresponding to the head of a human being, a user) and is electromagnetically connected to the housing 11. Are provided adjacent to each other. The parasitic element 13 is connected to the load impedance element 14 and connected to the housing 11 via the load impedance element 14 to be grounded.

  FIG. 2 shows the squared value of the normalized magnetic field and the normalized ratio with respect to the position in the longitudinal direction of the half-wavelength dipole antenna 20 in the electromagnetic field near the radio wave radiated from the half-wavelength dipole antenna 20 as the experimental measurement antenna. It is the graph which showed the relationship of the absorption rate (SAR). In FIG. 2, a transmission signal from a radio transmitter circuit 17 is fed to a half-wavelength dipole antenna 20 composed of two antenna elements 21 and 22, and a nearby magnetic field at that time is detected using a magnetic field probe. The electric field is measured by using a known electric field probe method (for example, see Non-Patent Document 2) using an electric field probe, and calculating by using the following equation.

[Equation 1]
SAR = (σ · E ² ) / ρ (1)

  Here, the unit of the SAR is W / kg, σ is the conductivity of the human body tissue (dielectric), E is the electric field strength to the human body, and ρ is the specific gravity of the human body tissue (dielectric).

As apparent from FIG. 2, the square value H ² and SAR of near magnetic field is found to be substantially the same distribution. Than this, the square value H ² and SAR of near magnetic field is proportional to each other. Further, since the near magnetic field H is proportional to the antenna current as is known, the square value of the current is proportional to SAR. That is, the SAR can be changed by changing the current distribution.

  By the way, when a radio wave is radiated from the whip antenna 12, a case current flows in the case 11 of the wireless communication device toward a feeding point Q on an upper portion of the case 11, for example, as shown in FIG. ing. Therefore, the present inventors have proposed a method of lowering the SAR by lowering the current flowing through the housing 11 of the wireless communication device or dispersing the current distribution and lowering the local maximum value by the following method. Invented. In order to change the current flowing through the housing 11 of the wireless communication device, a parasitic element 13 is provided in the wireless communication device as shown in FIG. The parasitic element 13 is connected to the housing 11 via the load impedance element 14 and is grounded. By changing the impedance value of the load impedance element 14, the value of the current flowing through the housing 11 is changed. Thereby, it is possible to suppress the current distribution flowing through the housing 11 from being locally increased, and to reduce the SAR.

  FIG. 3 is a perspective view of a wireless communication device model having a transmission frequency f = 900 MHz according to the first embodiment, and FIG. 4 is a cross-sectional view showing a current generated near a feeding point Q of the wireless communication device model of FIG. is there.

  In FIG. 3, the whip antenna 12 is provided so as to extend upward from a front corner (the side close to the back surface) of the upper surface of the housing 11, and has a feeding point Q at the corner. The parasitic element 13, which is a rectangular conductive plate for shielding, is provided so as to be opposed to and close to the upper part of the front surface of the housing 11, and the load impedance element 14 is disposed at a point on the upper side of the parasitic element 13. In addition to being connected to the upper part of the front of the housing 11 via a wire, another point on the upper side of the parasitic element 13 is connected to the upper part of the front of the housing 11 via the short-circuit line 19 and grounded.

  In the embodiment of the wireless communication device model shown in FIG. 3, the whip antenna 12 is a monopole antenna, and is made of a metal wire having a total length of 83 mm. The parasitic element 13 is formed of a 35 mm × 60 mm flat metal plate, is short-circuited to the housing 11 by a short-circuit wire 19, and is grounded. This embodiment is a model for a 900 MHz mobile phone. The SAR rapidly decreases as the distance from the radiation source increases. Conversely, the SAR may become large at the part in contact with the human body, and the SAR may become maximum even when the current density does not become maximum. Here, in this embodiment, the current value is also checked at point A (see FIG. 3) at the point in contact with the cheek of the human body during a call. The case current and the power supply current at the power supply point Q flow as shown in FIG.

  FIG. 5 shows a case of the wireless communication apparatus when the reactance value X of the load impedance element 14 connected to the parasitic element 13 in FIG. 3 is changed when transmitting a transmission signal having a transmission frequency f = 850, 900, and 950 MHz. 4 is a graph showing a maximum current value flowing through a body 11. In the graphs of FIGS. 5, 6, 14, and 15, as an example, when power is supplied to the monopole antenna and a load impedance element is connected to the inverted-F plate antenna, 1 W of power is applied to the monopole antenna. Shows the current value when

  In FIG. 5, when the reactance value X is changed from −200 to 200Ω at the frequency f = 900 MHz, as is clear from FIG. 5, the reactance value X is 0Ω, the maximum current value becomes maximum, and as the distance from 0Ω is increased. , The current maximum value decreases. At this time, it can be seen that the reactance value X should be set to X <−25Ω or X> 20Ω to make the maximum current value 10 mA or less. Further, it can be seen from the change in the frequency f that the load impedance at which the current becomes maximum changes. However, it can be seen that the current decreases as the absolute value of the load impedance increases. That is, when | Z |> 100 [Ω], 8 mA or less can be realized at all frequencies.

  FIG. 6 shows a case of the wireless communication apparatus when the reactance value X of the load impedance element 14 connected to the parasitic element 13 in FIG. 3 is changed at the time of transmitting a transmission signal having a transmission frequency f = 850, 900, and 950 MHz. 4 is a graph showing a current value flowing at a point A on a body 11. The graph of FIG. 6 shows a change in current at point A on the housing 11 that is in contact with the cheek during a call in FIG. 3. At this time, at a frequency f = 900 MHz, the current value at point A is 2 mA (for example, 2 mA). In order to make the value smaller than the threshold value, the reactance value X may be set to 5Ω <X <50Ω. As apparent from FIGS. 5 and 6, when the reactance value X is set to 20 to 50Ω, the maximum current value and the local current at the point A in FIG. It can be less than or equal to the value. It can also be seen that by changing the frequency f, the load impedance that minimizes the current changes. However, it can be seen that the current decreases as the absolute value of the load impedance increases. In other words, 1 mA or less can be realized at all frequencies when Z> -j50 [Ω]. Further, from FIGS. 5 and 6, when Z> j100 [Ω], the maximum current is 8 mA or less, and at the point A, 1 mA or less can be realized.

  In the present embodiment, based on FIG. 5, the reactance value of the load impedance element such that the maximum current value flowing on the housing 11 becomes equal to or less than a predetermined threshold value for each frequency is stored in the table memory 61 of FIG. Preferably, the reactance value is adjusted according to the frequency used. Further, based on FIG. 6, a load impedance is set such that the maximum current value flowing at point A (an example of a point closest to the human body) on the housing 11 is equal to or less than a predetermined threshold value for each frequency. It is preferable that the reactance value of the element is stored in the table memory 61 in FIG. 11 in advance, and the reactance value is adjusted according to the frequency used. In these modifications, a current flowing through a predetermined point (for example, point A) of the housing 11 is actually measured by using a current detection method described later, and the current value is determined based on the measured current value. The reactance value of the load impedance element may be controlled to be equal to or less than the threshold value.

  In the above embodiments, the parasitic element 13 made of a rectangular flat conductor is used. However, the present invention is not limited to this, and as a parasitic element, a linear conductor or a rectangular flat conductor may be used. A conductor plate formed with a slit or the like may be used, whereby the same operation and effect as those of the parasitic element 13 can be obtained.

  FIG. 7A is a circuit diagram showing a configuration of a load impedance element 14a as a first embodiment of the load impedance element 14 of FIG. 1, and FIG. 7B is a circuit diagram showing a second example of the load impedance element 14 of FIG. FIG. 7C is a circuit diagram illustrating the configuration of a load impedance element 14b according to a third embodiment of the load impedance element 14 of FIG. 1. FIG. 7D is a circuit diagram showing a configuration of a load impedance element 14d according to a fourth embodiment of the load impedance element 14 of FIG. That is, the load impedance element 14 of FIG. 1 or FIG. 3 may be the load impedance elements 14a, 14b, 14c, and 14d shown in FIGS. 7A to 7D.

  Here, when the reactance value X is set to be positive, as shown in FIG. 6 (a), the ground between the terminal T1 connected to the parasitic element 13 of FIG. The load impedance element 14a is configured and inserted by the inductor L1 connected in series. When the reactance value X is set to a negative value, as shown in FIG. 6B, between the terminal T1 connected to the parasitic element 13 of FIG. The load impedance element 14b is configured and inserted by the capacitor C1 connected in series. Further, as shown in FIG. 6C, a load impedance element 14c is formed by a series circuit of a capacitor C2 and an inductor L2 between the terminal T1 connected to the parasitic element 13 of FIG. 1 and the housing ground. And insert. Further, as shown in FIG. 6D, a load impedance element 14d is connected between a terminal T1 connected to the parasitic element 13 of FIG. 1 and the housing ground by a parallel circuit of a capacitor C3 and an inductor L3. Configure and insert. Here, these inductors L1, L2, L3 can be constituted by, for example, chip inductors or, for example, meander-shaped conductor wires. Further, these capacitors C1, C2, C3 can be constituted by chip capacitors, parallel plate capacitors, MIM capacitors, or the like. By using the former chip inductor or chip capacitor, the wireless communication device can be significantly reduced in size.

  Further, as the load impedance element 14, a distributed constant line in which one end on the ground side is short-circuited or open, for example, a distributed constant line of a coaxial line can be used. Also at this time, the impedance can be changed and set depending on the termination condition and the line length, and the reactance value X is changed in the same manner as the load impedance elements 14a to 14d in FIGS. 7A to 7D. And similar effects can be obtained. Further, a microstrip line may be used instead of the coaxial line as the distributed constant line. In this case, it can be formed on a substrate of a wireless communication device such as a mobile phone. With such a configuration, there is a specific effect that the number of parts of the wireless communication device can be reduced and the size and thickness can be reduced.

Second embodiment.
FIG. 8 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a second embodiment of the present invention. As shown in FIG. 8, the wireless communication device according to the second embodiment includes a whip antenna 12 extending upward from an upper portion of a housing 11, and a planar antenna 23 provided in the housing 11, These two antennas 12, 23 form a space diversity.

  8, a planar antenna 23 and two load impedance elements 31 and 41 are provided in a housing 11. Here, the planar antenna 23 is, for example, a rectangular flat conductor plate, and is, for example, parallel to the front surface of the housing 11 (a surface corresponding to the head of a human being, a user) and is electromagnetically connected to the housing 11. They are provided close together so as to be connected.

  In the wireless communication device of FIG. 8, when the switch 30 is switched to the contact a side, the wireless transmission signal from the wireless communication circuit 15 provided in the housing 11 of the wireless communication device is transmitted to the contact a side of the switch 30 by the power supply. After being output to the (１ ／) wavelength whip antenna 12 via the cable 25 and the feeding point Q, the radio wave of the wireless transmission signal is radiated from the whip antenna 12. Here, the feeding point Q is grounded to the housing 11 via the switch 32 and the load impedance element 31. When the switch 30 is switched to the contact b side, the wireless transmission signal from the wireless communication circuit 15 is output to the planar antenna 23 via the contact b side of the switch 30 and then the radio wave of the wireless transmission signal is output. Radiated from the planar antenna 23. Here, the planar antenna 23 is grounded to the housing 11 via the switch 42 and the load impedance element 41.

  In the wireless communication device configured as described above, for example, when the intensity of the received signal received by the whip antenna 12 is larger than the intensity of the received signal received by the planar antenna 23, the switch 30 is switched to the contact a side. The wireless signal is transmitted and received using the whip antenna 12. At this time, when the switch 32 is turned off and the switch 42 is turned on, the planar antenna 23 is electrically disconnected from the wireless communication circuit 15 and is grounded via the switch 42 and the load impedance element 41. In this case, the planar antenna 23 operates in the same manner as the parasitic element 13 according to the first embodiment, and changes the reactance value X of the load impedance element 41 in the same manner as in the first embodiment. The SAR can be significantly reduced by setting the current flowing through the body 11 to be small and the near magnetic field on the front surface of the housing 11 to be small. Here, it is preferable that the current flowing through the housing 11 of the wireless communication device is set to be substantially the minimum value, and the SAR is set to the minimum value.

  On the other hand, for example, when the intensity of the received signal received by the planar antenna 23 is larger than the intensity of the received signal received by the whip antenna 12, the switch 30 is switched to the contact b side, and the wireless communication using the planar antenna 23 is performed. Send and receive signals. At this time, by turning on the switch 32 and turning off the switch 42, the whip antenna 12 is electrically disconnected from the wireless communication circuit 15 and grounded via the switch 32 and the load impedance element 31. In this case, the whip antenna 12 operates in the same manner as the parasitic element 13 according to the first embodiment, and changes the reactance value X of the load impedance element 31 in the same manner as in the first embodiment. The SAR can be significantly reduced by setting the current flowing through the body 11 to be small and the near magnetic field on the front surface of the housing 11 to be small.

  In the above-described second embodiment, as the load impedance elements 31 and 41, for example, the load impedance elements 14a to 14d illustrated in FIGS. 7A to 7D may be used. Further, as the load impedance elements 31 and 41, for example, a distributed constant line in which one end on the ground side is short-circuited or open, for example, a coaxial line may be used. Also at this time, the impedance can be changed and set depending on the termination condition and the line length, and the reactance value X is changed in the same manner as the load impedance elements 14a to 14d in FIGS. 7A to 7D. And similar effects can be obtained. Further, a microstrip line may be used instead of the coaxial line as the distributed constant line. In this case, it can be formed on a substrate of a wireless communication device such as a mobile phone. With such a configuration, there is a specific effect that the number of parts of the wireless communication device can be reduced and the size and thickness can be reduced.

  The wireless communication apparatus according to the second embodiment configured as described above can transmit and receive a wireless signal in a space diversity system using two antennas 12 and 23, and can transmit and receive a wireless signal according to the first embodiment. It has the same effect as the wireless communication device.

  In the above embodiment, the whip antenna 12 and the planar antenna 23 are provided. However, the present invention is not limited to this, and the planar antenna 23 may be constituted by a whip antenna, an inverted-F antenna, or the like instead. Alternatively, the whip antenna 12 may be constituted by a planar antenna or an inverted-F antenna instead.

Third embodiment.
FIG. 9 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a third embodiment of the present invention. As shown in FIG. 9, the wireless communication device according to the second embodiment includes a whip antenna 12 extending upward from an upper portion of a housing 11, and a planar antenna 23 provided in the housing 11, These two antennas 12 and 23 form a space diversity, and instead of the two load impedance elements 31 and 41 and the two switches 32 and 42 according to the second embodiment of FIG. It is characterized by comprising one load impedance element 51 that can change and one changeover switch 52.

  In FIG. 9, a planar antenna 23 and one load impedance element 51 are provided in a housing 11. Here, the planar antenna 23 is, for example, a rectangular flat conductor plate, and is, for example, parallel to the front surface of the housing 11 (a surface corresponding to the head of a human being, a user) and is electromagnetically connected to the housing 11. They are provided close together so as to be connected.

  In the wireless communication apparatus of FIG. 9, for example, when the intensity of the received signal received by the whip antenna 12 is larger than the intensity of the received signal received by the planar antenna 23, the switch 30 is switched to the contact a side, and In conjunction with this, the changeover switch 52 is switched to the contact b side in conjunction therewith. At this time, the wireless transmission signal from the wireless communication circuit 15 provided in the housing 11 of the wireless communication device is transmitted to the (1/4) wavelength whip antenna via the contact a of the switch 30, the power supply cable 25 and the power supply point Q. After being output to the whip antenna 12, the radio wave of the wireless transmission signal is radiated from the whip antenna 12. The planar antenna 23 is grounded via the contact b of the changeover switch 52 and the load impedance element 51. In this case, the planar antenna 23 operates in the same manner as the parasitic element 13 according to the first embodiment, and changes the reactance value X of the load impedance element 51 in the same manner as in the first embodiment. The SAR can be significantly reduced by setting the current flowing through the body 11 to be small and the near magnetic field on the front surface of the housing 11 to be small.

  On the other hand, for example, when the intensity of the received signal received by the planar antenna 23 is greater than the intensity of the received signal received by the whip antenna 12, the switch 30 is switched to the contact b side, and accordingly, the switch is switched. The switch 52 is switched to the contact a side. At this time, the wireless transmission signal from the wireless communication circuit 15 provided in the housing 11 of the wireless communication device is output to the planar antenna 23 via the contact b side of the switch 30, and then the radio wave of the wireless transmission signal is Radiated from the antenna 23. The whip antenna 12 is grounded via the contact a of the switch 52 and the load impedance element 51. In this case, the whip antenna 12 operates in the same manner as the parasitic element 13 according to the first embodiment, and changes the reactance value X of the load impedance element 51 in the same manner as in the first embodiment. The SAR can be significantly reduced by reducing the current flowing through the body 11 and reducing the near magnetic field on the front surface of the housing 11.

  FIG. 10A is a circuit diagram showing a configuration of a load impedance element 51a which is a first embodiment of the load impedance element 51 of FIG. 9, and FIG. 10B is a circuit diagram showing a second example of the load impedance element 51 of FIG. FIG. 10C is a circuit diagram illustrating a configuration of a load impedance element 51c according to a third embodiment of the load impedance element 51 of FIG. 9. FIG. 10D is a circuit diagram showing a configuration of a load impedance element 51d which is a fourth embodiment of the load impedance element 51 of FIG. That is, the load impedance element 51 of FIG. 9 may be the load impedance elements 51a, 51b, 51c, 51d shown in FIGS. 10 (a) to 10 (d).

  Here, as shown in FIG. 10 (a), a series circuit of an inductor L11 and a variable capacitance diode D1 connects a load between a terminal T2 connected to a common terminal of the changeover switch 52 of FIG. The impedance element 51a is configured and inserted. Further, as shown in FIG. 10B, a load impedance is provided between the terminal T2 connected to the common terminal of the changeover switch 52 of FIG. 9 and the housing ground by a parallel circuit of the inductor L12 and the variable capacitance diode D2. The element 51b is formed and inserted. Further, as shown in FIG. 10C, a load impedance is established between the terminal T2 connected to the common terminal of the changeover switch 52 of FIG. 9 and the housing ground by a parallel circuit of the capacitor C11 and the variable capacitance diode D3. The element 51c is formed and inserted. Further, as shown in FIG. 10 (d), a series circuit of a capacitor C12 and a variable capacitance diode D4 connects a load between a terminal T2 connected to the common terminal of the changeover switch 52 of FIG. The impedance element 51d is formed and inserted.

  In each of the embodiments shown in FIGS. 10A to 10D, by changing the reverse bias voltage applied to each variable capacitance diode D1, D2, D3, D4, each variable capacitance diode D1, D2, The capacitance values of D3 and D4 can be changed. These change controls can be executed by, for example, a controller 60 in FIG. 11 described later. The table memory 61 connected to the controller 60 previously stores, for each frequency, the reactance value of the load impedance element that can reduce the SAR below a predetermined threshold value. , The capacitance value of each of the variable capacitance diodes D1, D2, D3, and D4 is changed in accordance with the operating frequency, and the reactance value X of the load impedance element 51 is changed in the same manner as in the first embodiment. The SAR can be significantly reduced by reducing the current flowing through the housing 11 of the communication device and setting the magnetic field near the front surface of the housing 11 to be small.

  Here, by increasing the change width of the reverse bias voltage applied to each of the variable capacitance diodes D1, D2, D3, and D4, the change width of the capacitance value of each of the variable capacitance diodes D1, D2, D3, and D4 is increased. And the change width of the reactance value X of the load impedance elements 51a to 51d can be increased. On the other hand, by reducing the change width of the reverse bias voltage applied to each of the variable capacitance diodes D1, D2, D3, and D4, the change width of the capacitance value of each of the variable capacitance diodes D1, D2, D3, and D4 is reduced. Therefore, the change width of the reactance value X of the load impedance elements 51a to 51d can be reduced.

  Further, as the load impedance element 51, a distributed constant line in which one end on the ground side is short-circuited or open, for example, a distributed constant line of a coaxial line can be used. Also at this time, the impedance can be changed and set depending on the termination condition and the line length, and the reactance value X can be set in the same manner as each of the load impedance elements 51a to 51d in FIGS. 10 (a) to 10 (d). Similar effects such as changing can be obtained. Further, a microstrip line may be used instead of the coaxial line as the distributed constant line. In this case, it can be formed on a substrate of a wireless communication device such as a mobile phone. With such a configuration, there is a specific effect that the number of parts of the wireless communication device can be reduced and the size and thickness can be reduced.

  The wireless communication apparatus according to the third embodiment configured as described above can transmit and receive a wireless signal in a space diversity system using two antennas 12 and 23, and can transmit and receive a wireless signal according to the first embodiment. It has the same effect as the wireless communication device.

  In the above embodiments, the variable capacitance diodes D1, D2, D3, and D4 are used. However, the present invention is not limited to this, and an impedance element whose element value can be changed, such as a variable capacitor or a variable inductor, is used. May be used.

Fourth embodiment.
FIG. 11 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a fourth embodiment of the present invention. The wireless communication device according to the fourth embodiment differs from the wireless communication device according to the first embodiment in FIG. 1 in the following points.
(1) Instead of the load impedance element 14, the load impedance element 51 of FIG. 9 capable of changing the reactance value X is provided.
(2) The reactance value X of the load impedance element 51 is controlled by the controller 60.

  Here, the load impedance element 51 is, for example, an impedance element including variable capacitance diodes D1, D2, D3, and D4 as shown in FIG. The controller 60 changes the reverse bias voltage (that is, the capacitance value) applied to the variable capacitance diodes D1, D2, D3, and D4 to the current flowing through the housing 11 of the wireless communication device in the same manner as in the first embodiment. The SAR can be significantly reduced by setting the near magnetic field on the front surface of the housing 11 to be small by adjusting and setting to be small.

FIG. 12 is a block diagram showing a partial configuration of a wireless communication device including a wireless antenna according to a modification of the fourth embodiment according to the present invention. The wireless communication circuit 15) is the same as in FIG. This modification is different from the fourth embodiment in FIG. 11 in the following point.
(1) In place of the load impedance element 51, four load impedance elements 71, 72, 73, 74 having fixed impedance values Z1, Z2, Z3, and Z4 different from each other and a changeover switch 62 are provided.
(2) A controller 60a to which a table memory 61 is connected is provided instead of the controller 60.

  12, the changeover switch 62 has four contacts a, b, c, d and a common terminal, and is controlled by the controller 60a to change the common terminal to any one of the four contacts a, b, c, d. Or one of the contacts. Here, the contact a of the switch 62 is grounded via the load impedance element 71, the contact b of the switch 62 is grounded via the load impedance element 72, and the contact c of the switch 62 is grounded via the load impedance element 73. The contact d 62 is grounded via a load impedance element 74.

  In the circuit of the wireless communication apparatus configured as described above, when the changeover switch 62 is switched to the contact a, the planar antenna 23 is grounded via the contact a of the changeover switch 62 and the load impedance element 71. When the changeover switch 62 is switched to the contact b, the planar antenna 23 is grounded via the contact b of the changeover switch 62 and the load impedance element 72. Further, when the changeover switch 62 is switched to the contact c, the planar antenna 23 is grounded via the contact c of the changeover switch 62 and the load impedance element 73. Further, when the changeover switch 62 is switched to the contact d, the planar antenna 23 is grounded via the contact d of the changeover switch 62 and the load impedance element 74. The switching of these load impedance elements 71 to 74 is controlled by the controller 60a to reduce the current flowing through the housing 11 of the wireless communication device by referring to the table in the table memory 61, as in the first embodiment. By selectively switching one such load impedance element (one of 71 to 74; preferably having a substantially minimum current value), the near magnetic field on the front surface of the housing 11 is reduced. The SAR can be significantly reduced by setting to be small.

  Although the circuit of the wireless communication apparatus according to the modification of FIG. 12 includes four load impedance elements 71 to 74, the present invention is not limited to this, and may include a plurality of load impedance elements.

  FIG. 13 is a perspective view of a wireless communication device model having a transmission frequency f = 1.5 GHz according to the fourth embodiment. In this wireless communication device model, the whip antenna 12 is provided so as to extend upward from the front corner (the side close to the back surface) of the upper surface of the housing 11, similarly to the wireless communication device model in FIG. A feed point Q is provided at the corner. The parasitic element 13, which is a rectangular conductive plate for shielding, is provided so as to be opposed to and close to the upper portion of the front surface of the housing 11, and the load impedance element 51 is located at one point on the upper side of the parasitic element 13. In addition to being connected to the upper part of the front of the housing 11 via a wire, another point on the upper side of the parasitic element 13 is connected to the upper part of the front of the housing 11 via the short-circuit line 19 and grounded. Here, the whip antenna 12 as a monopole antenna was formed of a 50 mm metal wire, and the parasitic element 13 was a 35 mm × 60 mm metal flat plate.

  FIG. 14 shows wireless communication when the reactance value X of the load impedance element 51 connected to the parasitic element 13 in FIG. 11 or 13 changes at the time of transmission of a transmission signal having a transmission frequency f = 900 MHz and 1.5 GHz. 6 is a graph showing a maximum current value flowing through a housing 11 of the device. As is clear from FIG. 14, when transmitting a transmission signal having a transmission frequency f = 900 MHz, the maximum current value is maximum when the reactance value X is about −20Ω, and is about 5 mA when the reactance value X is equal to or more than + 100Ω or equal to or less than −100Ω. It is as follows. On the other hand, when a transmission signal having a transmission frequency f = 1.5 GHz is transmitted, the maximum current value is relatively small within the range of -230 to 200Ω even when the reactance value X changes, and is 6 mA or less. This indicates that the set value of the reactance value X may be any value from -230 to 200 Ω.

  FIG. 15 shows wireless communication when the reactance value X of the load impedance element 14 connected to the parasitic element 13 of FIG. 11 or 13 changes when transmitting a transmission signal of a transmission frequency f = 900 MHz and 1.5 GHz. 4 is a graph showing a current value flowing at a point A on a housing 11 of the device. As is clear from FIG. 15, when transmitting a transmission signal having a transmission frequency f = 1.5 GHz, the reactance value X that minimizes the current value at point A is −180Ω. On the other hand, at the time of transmission of the transmission signal having the transmission frequency f = 900 MHz, the current value at the point A is maximum when the reactance value X is −30Ω and the reactance value X is minimum when + 20Ω. From this, it can be seen that, when the transmission frequency f changes, the reactance value X at which the current flowing through the housing 11 of the wireless communication device becomes minimum also changes. The parasitic element 13 is provided inside or outside the housing 11 of the wireless communication device, and more preferably, in order to reduce the influence of the human body, as shown in FIG. 15 and FIG. It is provided in the vicinity of the surface of the housing on the opposite side.

  Therefore, in the wireless communication device operating at a large number of frequencies, if the circuit configuration shown in FIG. 11 or FIG. 12 is used, when the transmission frequency changes, the controller 60, 60a controls the load impedance element 51, X can be set so as to reduce the value of the current flowing through the housing 11 of the wireless communication device, and more preferably to substantially reduce it to the minimum value. Therefore, the SAR can be significantly reduced by setting the near magnetic field on the front surface of the housing 11 to be small. Specifically, for example, a reactance value X at which the current value at the point A becomes minimum in accordance with the operating frequency is determined in advance by an experiment and stored in the table memory 61, and the controller 60, 60a controls the entire wireless communication apparatus. Is controlled such that the reactance value X of the load impedance element 51 substantially becomes the minimum current value at the point A with reference to the table memory 61 based on operating frequency information from a controller (not shown) for controlling To reduce the SAR.

Fifth embodiment.
FIG. 16 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a fifth embodiment of the present invention. The wireless communication device according to the fifth embodiment differs from the wireless communication device according to the fourth embodiment in FIG. 11 in the following points.
(1) Instead of the controller 60, a controller 70 to which a table memory 61 is connected is provided.
(2) The human body proximity sensor 71s is connected to the controller 70.

  In FIG. 16, a human body proximity sensor 71s detects whether or not a human body has approached using, for example, infrared rays. The sensor 71s emits infrared rays toward the human body and detects reflected waves thereof. Detects the proximity of the human body based on the distance to the human body and the intensity of the reflected wave. When the human body approaches the housing 11 of the wireless communication device at a distance of, for example, about 10 mm or less, the human body proximity sensor 71 s detects the proximity of the human body and outputs a detection signal to the controller 70. The controller 70 starts the control process of the load impedance element 51 in response to the detection signal, and refers to the control data in the table memory 61 to determine the reactance value X of the load impedance element 51 in the housing 11 of the wireless communication device. Is controlled so as to reduce the value of the current flowing to the point A of the above, and to reduce the SAR.

  FIG. 17 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a modification of the fifth embodiment of the present invention. In this modification, the human body proximity sensor 71s in FIG. 16 is applied to the wireless communication device in FIG. 17, in response to a detection signal from the human body proximity sensor 71s, the controller 70a starts control processing of the switch 62 for selectively switching the load impedance elements 71 to 74, and transmits control data in the table memory 61. One load impedance element (one of 71 to 74) that reduces the value of the current flowing to the point A of the housing 11 of the wireless communication device is selected with reference to the load impedance element. The SAR is greatly reduced by reducing the value of the current flowing to the point A of the housing 11, preferably to a substantially minimum value.

  FIG. 18 is a perspective view showing the direction of the XYZ coordinate system provided for the wireless communication device when the radiation pattern from the wireless communication device of FIG. 16 is measured. In FIG. , A direction perpendicular to the front surface with the microphone and speaker sound holes) and the direction toward the human body is defined as the X direction, and the lateral or horizontal direction of the front surface is defined as the Y direction. The upward direction is defined as the Z direction.

  19 is a graph showing the averaging gain in the horizontal plane (XY plane in FIG. 16) when the reactance value X of the load impedance element 51 connected to the parasitic element 13 in FIG. 16 is changed in the wireless communication apparatus in FIG. It is. Here, the averaging gain refers to an average gain at all azimuth angles. As is apparent from FIG. 19, when the reactance value X of the load impedance element 51 changes, the radiation averaging gain also changes. The reactance value X at which the radiation averaging gain is greater than 1 dBi is when X> 40Ω or X <−100. On the other hand, when the reactance value X is set to 20 to 50Ω in the maximum current value shown in FIG. 5 and the current at the local point A in FIG. 6, the maximum current value and the local current value become small. It can be seen that the average gain in FIG. 19 becomes larger than 1 dBi in this reactance value range when the reactance value X is 50Ω.

  FIG. 20A is a plan view showing a radiation pattern on the XY plane when the radiation pattern from the wireless communication device of FIG. 16 is measured, and FIG. 20B is a graph showing the experiment result. FIG. 20C is a plan view showing a radiation pattern on the YZ plane, and FIG. 20C is a plan view showing the experimental result and showing a radiation pattern on the ZX plane. 20, Pθ indicates a θ component of a radiation relative gain (based on a half-wavelength dipole antenna) with respect to an angle θ from the longitudinal direction of the antenna, and Pφ indicates a value on a plane including the longitudinal direction of the antenna. 9 shows the φ component of the radiation relative gain (based on a half-wave dipole antenna) according to the azimuth angle φ.

  When measuring the radiation pattern of FIG. 20, the reactance value X of the load impedance element 51 is 50Ω. At this time, the radiation averaging gain is 1.42 dBi, the current value of the housing 11 is 5.7 mA, and the current value at the point A is 2.0 mA. Therefore, when the reactance value X is 50Ω, the antenna according to the present embodiment radiates strongly with a relatively large radiation gain and the SAR value is relatively low, so it can be said that this is an optimum value.

  Further, in the embodiment of FIG. 16 or FIG. 17, when the human body is not close, the reactance value X of the load impedance element 51 is set to the reactance value X at which the radiation gain increases, while when the human body is close, It is also possible to set the reactance value X to reduce the current flowing through the housing 11 of the wireless communication device. For example, when the human body is not close, the reactance value X of the load impedance element 51 is set to 100Ω to 200Ω, while when the human body is close, the reactance value X of the load impedance element 51 is set to 50Ω. By performing such control, the SAR can be reduced and the radiation gain can be improved.

  In the above embodiment, the detection signal from the human body proximity sensor 71s only when receiving a busy signal from a controller (not shown) that controls the entire wireless communication device. May be received and the load impedance element 51 is controlled in consideration of the received signal.

Another modified example.
FIG. 21 is a block diagram illustrating a partial configuration of a wireless communication device including a wireless antenna according to a first modification of the present invention. A helical antenna 81 shown in FIG. 21 may be used instead of the whip antenna 12 used in the above embodiment.

  FIG. 22 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a second modification of the present invention. Instead of the whip antenna 12 used in the above embodiment, an antenna device 90 of FIG. 22 may be used. The antenna device 90 includes a helical antenna 91 and a (1/4) wavelength whip antenna 92 via a dielectric portion serving as an electrical insulating portion 93 such that the longitudinal directions thereof extend substantially on the same straight line. It is composed by connecting. The wireless communication circuit 15 is connected to a contact 95 with the whip antenna 92 via the power supply cable 25, and a connection between the contact 95 and the whip antenna 92 serves as a power supply point Q. When the antenna device 90 is extended, as shown in FIG. 22, the whip antenna 92 is connected to the wireless communication circuit 15 to be in an operating state, while the whip antenna 92 of the antenna device 90 is stored in the housing 11 in the housing 11. In this case, the contact 95 is connected to the lower end of the helical antenna 91, and the helical antenna 91 is connected to the wireless communication circuit 15 to be in an operating state.

  In the embodiment of FIG. 1, the circulator 16 is used to separate the transmission signal and the reception signal. However, the present invention is not limited to this, and a duplexer filter or a transmission / reception switch may be used.

Sensor and its mounting position.
In the above embodiment, the human body proximity sensor 71s is used. However, the present invention is not limited to this. In order to prevent erroneous detection of only the human body proximity sensor 71s, a temperature sensor or a touch sensor, a temperature sensor It is preferable to further use a combination of touch sensors. That is, the load impedance element 51 is detected only when a temperature above a predetermined threshold is detected by the temperature sensor (when a human body comes into contact with the housing 11 of the wireless communication device) and a detection signal from the human body proximity sensor 71s is received. May be controlled. Alternatively, the load impedance element 51 may be controlled only when a stress equal to or greater than a predetermined threshold is detected by the touch sensor and a detection signal from the human body proximity sensor 71s is received. Further, the load impedance element 51 is detected only when the temperature sensor detects a body temperature equal to or higher than a predetermined threshold, the touch sensor detects stress equal to or higher than the predetermined threshold, and receives a detection signal from the human body proximity sensor 71s. May be controlled.

That is, in the embodiment, at least one of the human body proximity sensor 71s, the temperature sensor, and the touch sensor (hereinafter, generically referred to as the sensor 111 or 113) may be mounted. In the portable wireless communication device, (A) a sound hole for a speaker which is in contact with an ear of a human body, which is a side in contact with a human body, or the vicinity thereof;
(B) a microphone contacting the cheek of the human body or its vicinity,
(C) In the case of a foldable portable wireless communication device, the portable wireless communication device is mounted on at least one of a hinge portion that comes into contact with the cheek of the human body (there is a possibility that the projecting shape of the hinge portion comes into contact with the human body). Is preferred.

  When a plurality of sensors are mounted, mounting at different positions enables SAR reduction control at a position where SAR suppression is required. For example, when both the above (A) and (B) are present, when the detection is made in the above (A), the load impedance is switched so that the SAR near the sound hole becomes small, and the detection is made in the above (B). In this case, the load impedance is switched so as to reduce the SAR near the microphone. This makes it possible to effectively reduce SAR. Further, it is preferable that the current control by the load operates only at the time of a call or data communication. As a result, unnecessary control is not performed, so that power consumption can be reduced and the battery can last longer. Hereinafter, a description will be given with reference to the drawings of specific implementation examples of the sensors 111 and 113.

  FIG. 23 is a front view of a first embodiment according to the present invention, in which a sensor 111 is mounted on an upper housing 102 of a foldable portable wireless communication device. FIG. 24 is a side view of the foldable portable wireless communication device of FIG. In the following drawings, the same components are denoted by the same reference numerals.

  23 and 24, the foldable portable wireless communication device is configured such that an upper housing 102 and a lower housing 103 are foldable via a hinge portion 104. Here, the upper housing 102 includes an inner upper first housing portion 102a and an outer upper second housing portion 102b, and a liquid crystal display arranged in the center of the upper first housing portion 102a. The upper first housing portion 102a and the upper second housing portion 102a are screwed to the screw receiving portion 102b of the upper second housing portion 102b using screws 108 and 109 near the left and right end portions below the 105. It is attached and fixed to the housing 102b. A speaker sound hole 106 is provided above the liquid crystal display 105, and a rectangular sensor 111 is mounted at a position between the sound hole 106 and the liquid crystal display 115. Note that a keypad 115 is disposed at the center of the inner surface of the lower housing 103, and a microphone 107 is mounted below the keypad 115.

  FIG. 25 is a front view of a second embodiment according to the present invention, in which a sensor 111 is mounted on a lower housing 103 of a foldable portable wireless communication device. FIG. 26 is a side view of the foldable portable wireless communication device of FIG. 25 and 26, a sensor 111 is mounted between the keypad 115 and the microphone 107 on the inner surface of the lower housing 103.

  FIG. 27 is a front view of a third embodiment according to the present invention, in which a sensor 111 is mounted on a hinge 104 of a foldable portable wireless communication device. FIG. 28 is a side view of the foldable portable wireless communication device of FIG. 27 and 28, a sensor 111 is mounted at a central portion inside the hinge portion 104.

  FIG. 29 is a front view of a fourth embodiment according to the present invention, in which a sensor 111 is mounted on a housing 112 of a straight-type portable wireless communication device. FIG. 30 is a side view of the straight-type portable wireless communication device of FIG. 29 and 30, a liquid crystal display 105 is provided above the inner surface 112a of a housing 112 having an inner surface 112a and an outer surface 112b, and a keypad 115 is provided below the same. A speaker sound hole 106 is provided between the liquid crystal display 105 and the upper end of the housing 112, and a sensor 111 is mounted between the sound hole 106 and the liquid crystal display 105. Further, a microphone 107 is provided between the keypad 115 and the lower end.

  FIG. 31 is a front view of a fifth embodiment according to the present invention, in which a sensor 111 is mounted on a housing 112 of a straight-type portable wireless communication device. FIG. 32 is a side view of the straight-type portable wireless communication device of FIG. 31 and 32, a sensor 111 is mounted between the keypad 115 and the microphone 107.

  FIG. 33 is a front view of a sixth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a sound hole 106 of an upper housing 102 of a foldable portable wireless communication device. . FIG. 34 is a side view of the foldable portable wireless communication device of FIG. 33 and 34, a sensor 113 having a substantially elliptical shape is mounted around the sound hole 106 of the upper housing 102.

  FIG. 35 is a front view of a seventh embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a microphone 107 of a lower housing 103 of a foldable portable wireless communication device. FIG. 36 is a side view of the foldable portable wireless communication device of FIG. 35 and 36, a sensor 113 is mounted around the microphone 113.

  FIG. 37 shows an eighth embodiment according to the present invention, and is a front view when a substantially elliptical sensor 113 is mounted on a hinge portion 104 of a foldable portable wireless communication device. FIG. 38 is a side view of the foldable portable wireless communication device of FIG. 37 and 38, a sensor 113 is mounted on the inner surface of the hinge portion 104.

  FIG. 39 is a front view of a ninth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a sound hole 106 of a casing 112 of a straight-type portable wireless communication device. FIG. 40 is a side view of the straight-type portable wireless communication device of FIG. 39 and 40, a sensor 113 is mounted around the sound hole 106 of the housing 112.

  FIG. 41 is a front view of a tenth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a microphone 107 of a housing 112 of a straight-type portable wireless communication device. FIG. 42 is a side view of the straight-type portable wireless communication device of FIG. 41 and 42, a sensor 113 is mounted around the microphone 107 on the inner surface of the housing 112.

A method for detecting the current flowing in the housing.
Further, a method for detecting a current flowing through the housing of the portable wireless communication device will be described below with reference to FIGS. 43 and 44.

  FIG. 43 is a cross-sectional view for describing a method of detecting a current I flowing through the upper housing 102 using the magnetic field detection probe 201. In FIG. 43, the magnetic field detection probe 201 is a probe formed of a minute loop having a square shape with one side length d, and is close to the upper casing 102 of the portable wireless communication device and has a small loop length. It is mounted so that the axis is substantially parallel to the surface of the upper housing 102. Here, the electromotive force at the terminal of the magnetic field detecting probe 201 is V, and the input impedance when the magnetic field detecting probe 201 is viewed at the terminal is Z. At this time, the magnetic field H at the center of the axis of the magnetic field detecting probe 201 when the current I flows is expressed by the following equation according to Ampere's law.

[Equation 2]
H = I / (2πh) (2)
Also,
[Equation 3]
B = μ ₀ · H (3)
Where μ ₀ is the vacuum permeability.

  Further, according to Faraday's law of electromagnetic induction, the electromotive force V is expressed by the following equation.

[Equation 4]
V = − (dΦ / dt) (4)

  Here, Φ is a magnetic flux, and if its area is S = d × d (the maximum width in the interval d), it is expressed by the following equation.

[Equation 5]
Φ
= B ・ S
= Μ ₀ · H · d ²
= Μ ₀ · I / (2πh) · d ² (5)

Therefore, the following equation is obtained by substituting equation (4) into equation (5).

[Equation 6]
V = −μ ₀ / (2πh) · d ² (dI / dt) (6)

here,
[Equation 7]
(DI / dt) = jωI (7)
Thus, the following equation is obtained.

[Equation 8]
V = −jω · μ ₀ · I / (2πh) · d ² (8)

  Assuming that the input impedance of the magnetic field detection probe 201 is Z, the received power Pr is represented by the following equation.

[Equation 9]
Pr
= ^V 2 / Z
= (Ω · μ ₀ · I ₀ · d ² / (2πh)) ² / Z (9)

here,
[Equation 10]
ω = 2π / λ (10)
The following equation is obtained from:

[Equation 11]
Pr = (μ ₀ · I ₀ · d ² / (h · λ)) ² / Z (11)

Thus, by measuring the received power Pr, it is possible to calculate the current I ₀ using the above equation.

  FIG. 44 is a cross-sectional view for explaining a method of detecting the current I flowing through the upper housing 102 using the small dipole 202 for magnetic field detection. In FIG. 44, the magnetic field detection probe 202 is a probe composed of a minute dipole having a minute length d (d≪λ; where ω = 2πf, λ = c / f, where c is the speed of light), and is a portable radio. The small dipole is placed close to the upper housing 102 of the communication device at a distance h so that the longitudinal direction of the small dipole is substantially parallel to the surface of the upper housing 102. Here, the electromotive force at the terminal of the magnetic field detecting minute dipole 202 is V, and the input impedance when the magnetic field detecting minute dipole 202 is viewed at the terminal is Z. In the case of the small dipole 102 for magnetic field detection, the maximum value of the distance h is determined by the received power Pr as described below. Assuming that the electric field at the minute dipole 202 at a distance h from the current I is E, the electromotive force V is represented by the following equation.

[Equation 12]
V = E · d (12)

  Here, assuming that the ratio between the electric field and the magnetic field is η, it is expressed by the following equation.

[Equation 13]
E = η · H (13)

  Therefore, the following equation is obtained by substituting equation (12) into equation (13).

[Equation 14]
E = η · I ₀ / (2πh) (14)

  Therefore, the electromotive force V and the received power Pr are represented by the following equations.

[Equation 15]
V
= E · d
= Η · I ₀ · d / (2πh) (15)

[Equation 16]
Pr
= ^V 2 / Z
= (Η · I ₀ · d / (2πh)) ² / Z (16)

As is clear from the equation (16), the current I ₀ can be detected by measuring the reception power Pr.

1 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a first embodiment of the present invention. The relationship between the squared value of the normalized magnetic field and the normalized specific absorption rate (SAR) with respect to the longitudinal position of the half-wavelength dipole antenna 20 in the electromagnetic field near the radio wave radiated from the half-wavelength dipole antenna 20 It is the graph shown. FIG. 2 is a perspective view of a wireless communication device model having a transmission frequency f = 900 MHz according to the first embodiment. FIG. 4 is a cross-sectional view illustrating a current generated near a feeding point Q in the wireless communication device model of FIG. 3. Maximum value of the current flowing through the housing 11 of the wireless communication apparatus when the reactance value X of the load impedance element 14 connected to the parasitic element 13 in FIG. 3 changes when transmitting a transmission signal having a transmission frequency f = 900 MHz. FIG. At the time of transmission of a transmission signal having a transmission frequency f = 900 MHz, the point A on the housing 11 of the wireless communication apparatus when the reactance value X of the load impedance element 14 connected to the parasitic element 13 in FIG. 6 is a graph showing a flowing current value. 1A is a circuit diagram showing a configuration of a load impedance element 14a which is a first embodiment of the load impedance element 14 of FIG. 1, and FIG. 2B is a circuit diagram of a second embodiment of the load impedance element 14 of FIG. It is a circuit diagram showing the configuration of a certain load impedance element 14b, (c) is a circuit diagram showing the configuration of a load impedance element 14c which is a third embodiment of the load impedance element 14 of FIG. 1, (d) is FIG. 11 is a circuit diagram showing a configuration of a load impedance element 14d which is a fourth embodiment of the load impedance element 14 of FIG. It is a block diagram showing the composition of the radio communication equipment provided with the radio antenna which is a 2nd embodiment concerning the present invention. FIG. 11 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a third embodiment of the present invention. (A) is a circuit diagram showing a configuration of a load impedance element 51a which is a first embodiment of the load impedance element 51 of FIG. 9, and (b) is a second embodiment of the load impedance element 51 of FIG. FIG. 10C is a circuit diagram showing a configuration of a certain load impedance element 51b, FIG. 10C is a circuit diagram showing a configuration of a load impedance element 51c which is a third embodiment of the load impedance element 51 of FIG. 9, and FIG. FIG. 11 is a circuit diagram showing a configuration of a load impedance element 51d which is a fourth embodiment of the load impedance element 51 of FIG. FIG. 14 is a block diagram illustrating a configuration of a wireless communication device including a wireless antenna according to a fourth embodiment of the present invention. FIG. 16 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a modification of the fourth embodiment according to the invention. FIG. 14 is a perspective view of a wireless communication device model with a transmission frequency f = 1.5 GHz according to a fourth embodiment. When transmitting a transmission signal having a transmission frequency f = 900 MHz and 1.5 GHz, the case of the wireless communication apparatus when the reactance value X of the load impedance element 51 connected to the parasitic element 13 in FIG. 11 or 13 changes. 4 is a graph showing a maximum current value flowing through a body 11. When transmitting a transmission signal having a transmission frequency f = 900 MHz and 1.5 GHz, the case of the wireless communication apparatus when the reactance value X of the load impedance element 14 connected to the parasitic element 13 in FIG. 11 or 13 changes. 4 is a graph showing a current value flowing at a point A on a body 11. It is a block diagram showing the composition of the radio communication equipment provided with the radio antenna which is a 5th embodiment concerning the present invention. FIG. 16 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a modification of the fifth embodiment of the present invention. FIG. 17 is a perspective view illustrating a direction of an XYZ coordinate system provided for the wireless communication device when a radiation pattern from the wireless communication device in FIG. 16 is measured. 17 is a graph illustrating an average gain on a horizontal plane when a reactance value X of a load impedance element 51 connected to the parasitic element 13 of FIG. 16 is changed in the wireless communication device of FIG. 16. 16A is a plan view showing an experimental result when measuring a radiation pattern from the wireless communication apparatus in FIG. 16 and showing a radiation pattern on the XY plane, and FIG. 16B is a view showing the experimental result and showing a radiation pattern on the YZ plane. It is a top view which shows a pattern, (c) is a top view which is the said experimental result and shows the radiation pattern of a ZX plane. FIG. 9 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a first modification of the present invention. FIG. 9 is a block diagram illustrating a configuration of a part of a wireless communication device including a wireless antenna according to a second modification of the present invention. FIG. 4 is a front view of the first embodiment according to the present invention when a sensor 111 is mounted on an upper housing 102 of the foldable portable wireless communication device. FIG. 24 is a side view of the foldable portable wireless communication device of FIG. 23. FIG. 9 is a front view of the second embodiment according to the present invention, in which a sensor 111 is mounted on a lower housing 103 of a foldable portable wireless communication device. FIG. 26 is a side view of the foldable portable wireless communication device of FIG. 25. FIG. 13 is a front view of a third embodiment according to the present invention, in which a sensor 111 is mounted on a hinge section 104 of a foldable portable wireless communication device. FIG. 28 is a side view of the foldable portable wireless communication device of FIG. 27. FIG. 14 is a front view of the fourth embodiment according to the present invention, when a sensor 111 is mounted on a housing 112 of a straight-type portable wireless communication device. FIG. 30 is a side view of the straight-type portable wireless communication device of FIG. 29. FIG. 13 is a front view of a fifth embodiment according to the present invention, when a sensor 111 is mounted on a housing 112 of a straight-type portable wireless communication device. FIG. 32 is a side view of the straight-type portable wireless communication device of FIG. 31. FIG. 14 is a front view of a sixth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a sound hole 106 of an upper housing 102 of a foldable portable wireless communication device. FIG. 34 is a side view of the foldable portable wireless communication device of FIG. 33. FIG. 17 is a front view of the seventh embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a microphone 107 of a lower housing 103 of a foldable portable wireless communication device. FIG. 36 is a side view of the foldable portable wireless communication device of FIG. 35. FIG. 18 is a front view of an eighth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted on a hinge portion 104 of a foldable portable wireless communication device. FIG. 38 is a side view of the foldable portable wireless communication device of FIG. 37. FIG. 19 is a front view of a ninth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a sound hole 106 of a housing 112 of a straight-type portable wireless communication device. FIG. 40 is a side view of the straight-type portable wireless communication device of FIG. 39. FIG. 16 is a front view of a tenth embodiment according to the present invention, in which a substantially elliptical sensor 113 is mounted around a microphone 107 of a housing 112 of a straight-type portable wireless communication device. FIG. 42 is a side view of the straight-type portable wireless communication device of FIG. 41. FIG. 4 is a cross-sectional view for describing a method of detecting a current I flowing through an upper housing 102 using a magnetic field detection probe 201. FIG. 4 is a cross-sectional view for explaining a method of detecting a current I flowing through an upper housing 102 using a magnetic field detecting minute dipole 202. It is a front view when the radio | wireless communication apparatus provided with the radio | wireless antenna which concerns on a prior art is supported by the head of a human body. FIG. 46 is a perspective view illustrating an appearance of the wireless communication device in FIG. 45.

Explanation of reference numerals

11 ... housing,
12 ... Whip antenna,
13 ... parasitic element,
14, 14a, 14b, 14c, 14d, 31, 41, 51, 51a, 51b, 51c, 51d, 71, 72, 73, 74 ... load impedance elements,
15 ... wireless communication circuit,
16 ... Circulator,
17 ... wireless transmitter circuit,
18 ... Wireless receiver circuit,
19 ... short-circuit line,
20: half-wave dipole antenna,
21, 22, ... antenna elements,
23 ... Planar antenna,
25 ... power supply cable,
30, 32, 42 ... switch,
52, 62 ... changeover switch,
60, 60a, 70, 70a ... controller,
61 ... Table memory,
71s ... human body proximity sensor,
81, 91 ... helical antenna,
90 ... antenna device,
92 ... whip antenna,
93 ... electrical insulation part,
95 ... contact point,
102 ... upper case,
102a ... upper first housing part,
102b ... upper second housing part,
103 ... lower housing,
104: hinge part,
105 ... Liquid crystal display,
106 ... Sound hole,
107 ... microphone,
108, 109 ... screws,
110 ... screw receiving part,
111, 113 ... sensors,
112 ... housing,
112a ... front side,
112b ... back side,
115 ... keypad,
201: magnetic field detection probe,
202: Small dipole for magnetic field detection,
C1, C2, C3, C11, C12 ... capacitors,
D1, D2, D3, D4 ... variable capacitance diode,
L1, L2, L3, L11, L12 ... inductor,
Q: Feeding point,
T1, T2 ... terminals.

Claims (18)

In a wireless antenna device having an antenna connected to a wireless communication circuit that transmits and receives wireless signals,
A parasitic element,
The parasitic element, a load impedance element connected between the ground of the housing of the wireless communication device including the wireless communication circuit,
By controlling the element value of the load impedance element so that the current value flowing through the housing at the time of transmission of the wireless communication device is equal to or less than a predetermined value, the specific absorption rate (SAR) is equal to or less than the predetermined value. A wireless antenna device, comprising: control means for controlling. In a wireless antenna device having first and second antennas,
When the first antenna is connected to a wireless communication circuit provided in the wireless communication device for transmitting and receiving a wireless signal, the second antenna is connected to the wireless communication device including the wireless communication circuit via the load impedance element. When the second antenna is connected to a wireless communication circuit that transmits and receives wireless signals while the second antenna is connected to the ground of the housing, the first antenna is connected to the ground of the housing via the load impedance element. Switching means for switching to perform
By controlling the element value of the load impedance element so that the current value flowing through the housing at the time of transmission of the wireless communication device is equal to or less than a predetermined value, the specific absorption rate (SAR) is equal to or less than the predetermined value. A wireless antenna device, comprising: control means for controlling. When the wireless communication device transmits, the current value flowing through the casing is equal to or less than a predetermined value, and further includes a storage unit that stores an element value of the load impedance element as a table,
3. The wireless antenna device according to claim 1, wherein the control unit controls an element value of the load impedance element with reference to a table stored in the storage unit. When the wireless communication device transmits, the current value flowing through the housing is equal to or less than a predetermined value, further comprising a storage unit that stores the element value of the load impedance element as a table for each frequency,
3. The device according to claim 1, wherein the control unit controls an element value of the load impedance element based on a communication frequency of the wireless communication device with reference to a table stored in the storage unit. Wireless antenna device. Measuring means for measuring a current value flowing through the housing at the time of transmission of the wireless communication device,
3. The device according to claim 1, wherein the control unit controls an element value of the load impedance element based on the measured current value such that a current value flowing through the housing becomes a predetermined value or less. The wireless antenna device according to the above.   The load impedance element includes a plurality of impedance elements having different element values from each other, and switch means for changing an element value of the load impedance element by selectively switching one of the plurality of impedance elements. The wireless antenna device according to any one of claims 1 to 5, wherein:   The load impedance element includes an impedance element that can change an element value, and changes an element value of the load impedance element by changing an element value of the impedance element that can change the element value. The wireless antenna device according to any one of claims 1 to 5, wherein:   The load impedance element includes an impedance circuit including a variable capacitance diode, and changes the element value of the load impedance element by changing a reverse bias voltage applied to the variable capacitance diode to change the impedance value of the impedance circuit. The wireless antenna device according to any one of claims 1 to 5, wherein: The wireless communication device further includes a human body proximity sensor that detects that a human body has approached the housing of the wireless communication device,
The element value of the load impedance element is detected by the human body proximity sensor to detect that a human body has approached the wireless communication device, and to reduce a current value flowing through the housing to a predetermined value or less when transmitting the wireless communication device. The wireless antenna device according to claim 1, wherein: A human body proximity sensor that detects that a human body has approached the housing of the wireless communication device;
A temperature sensor for measuring a body temperature when a human body comes into contact with the housing of the wireless communication device,
The body temperature measured by the temperature sensor is equal to or higher than a predetermined value, the human body proximity detection sensor detects that a human body has approached the wireless communication device, and the current value flowing through the housing at the time of transmission of the wireless communication device The wireless antenna device according to any one of claims 1 to 8, wherein an element value of the load impedance element is controlled so that a value of the load impedance element is equal to or less than a predetermined value. A human body proximity sensor that detects that a human body has approached the housing of the wireless communication device;
A touch sensor for measuring a stress when a human body contacts the housing of the wireless communication device,
The stress measured by the touch sensor is equal to or greater than a predetermined value, the human body proximity sensor detects that the human body has approached the wireless communication device, and the current value flowing through the housing at the time of transmission of the wireless communication device The wireless antenna device according to any one of claims 1 to 8, wherein an element value of the load impedance element is controlled so that a value of the load impedance element is equal to or less than a predetermined value. A human body proximity sensor that detects that a human body has approached the housing of the wireless communication device;
A touch sensor that measures stress when a human body contacts the housing of the wireless communication device,
A temperature sensor for measuring a body temperature when a human body comes into contact with the housing of the wireless communication device,
The body temperature measured by the temperature sensor is equal to or higher than a predetermined value, the stress measured by the touch sensor is equal to or higher than a predetermined value, the human body proximity sensor detects that the human body has approached the wireless communication device, and 9. The device according to claim 1, wherein an element value of the load impedance element is controlled such that a value of a current flowing through the housing during transmission of the wireless communication device is equal to or less than a predetermined value. 3. The wireless antenna device according to 1.   The wireless antenna device according to claim 1, wherein the antenna is a monopole antenna or a helical antenna, and the parasitic element is a conductor plate.   3. The antenna according to claim 2, wherein the first antenna is a monopole antenna or a helical antenna, and the second antenna is a planar antenna or an inverted-F antenna. Wireless antenna device. A wireless antenna device according to claim 1 or claims dependent on claim 1;
A wireless communication device comprising: a wireless communication circuit connected to the antenna and configured to transmit and receive a wireless signal.   The wireless communication device according to claim 15, wherein the wireless communication device is a portable wireless communication device. A wireless antenna device according to claim 2 or claim 2 dependent on claim 2;
A wireless communication device, comprising: a wireless communication circuit connected to the first antenna or the second antenna for transmitting and receiving a wireless signal.   The wireless communication device according to claim 17, wherein the wireless communication device is a portable wireless communication device.

Images