JP4118064B2 - Antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna device, and more particularly to an antenna device capable of switching a radiation pattern.
[0002]
[Prior art]
In general, antennas can be roughly classified according to the presence or absence of directivity.
(1) Omnidirectional (retractable antenna, fixed antenna)
(2) Directivity (antenna with parasitic element and shield version)
(3) Middle (built-in antenna)
(4) Directivity controllable (array antenna)
There is an antenna.
[0005]
[Problems to be solved by the invention]
However, a mobile phone that can identify the usage status of the mobile phone and switch to a radiation pattern suitable for the usage status has not been realized.
[0006]
In addition, there is an array antenna in which each element antenna is a radiator as an antenna that may have both non-directional and directional radiation patterns by itself. As many transmitter / receiver circuits and phase shifters are required, and the circuit becomes complicated and large, it is difficult to mount on a small device such as a mobile phone.
[0007]
Therefore, when the mobile phone is used at a position away from the operator, such as viewing the monitor, the present invention has a non-directional pattern or a radiation pattern close to it, and at the time of a call used in the vicinity of the operator, An object of the present invention is to provide an antenna device capable of switching a radiation pattern according to the use state of a mobile phone, such as a radiation pattern having directivity toward the opposite side of the installation surface of the loudspeaker facing the operator. To do.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an antenna device used in a mobile communication terminal, and has a directivity on the opposite side to a loudspeaker direction of a loudspeaker built in the mobile communication terminal. An antenna, an omnidirectional second antenna, and the portable communication terminal uses the loudspeaker close to an ear In a call In the first state or using the Internet by key operation And at the time of signal transmission Determining means for determining whether or not the mobile communication terminal is in the first state; and determining the second state using the first antenna when the mobile communication terminal is determined to be in the first state. And switching means for switching to use the second antenna when it is determined that the second antenna is used.
[0009]
The invention according to claim 2 is an antenna device used in a mobile communication terminal, comprising a non-directional main radiating conductor having a power feeding portion, and a non-feeding conductor arranged close to the main radiating conductor; The portable communication terminal uses the loudspeaker close to the ear. In a call In the first state or using the Internet by key operation And at the time of signal transmission Determining means for determining whether or not the mobile communication terminal is in the first state; and determining the main radiating conductor by grounding the parasitic conductor when the determining means determines that the mobile communication terminal is in the first state. When it is determined that the antenna is directional on the opposite side of the loudspeaker built in the portable communication terminal and is in the second state, the parasitic conductor is disconnected from the ground and And a control means for causing the main radiating conductor to function as an omnidirectional antenna.
[0011]
Claims 3 The invention according to claim 1 or 2 is characterized in that, in the invention of claim 1 or 2, the determination means uses a loudspeaker that is not connected to an external earphone and is built in the mobile communication terminal. If the mobile communication terminal is in the first state, it is determined that the mobile communication terminal is in the first state.
[0012]
Claims 4 The described invention is an antenna device used in a mobile communication terminal, and includes a non-directional main radiating conductor having a power feeding unit, a parasitic conductor disposed in proximity to the main radiating conductor, and the mobile communication terminal. When the signal is transmitted, the main radiating conductor is directed to the opposite side of the loudspeaker of the loudspeaker built in the portable communication terminal by conducting with high frequency power radiated from the main radiating conductor and grounding the parasitic conductor. Switching means for functioning as a non-directional antenna by functioning as a non-directional antenna by functioning as a non-transmitting signal and becoming non-conductive when a signal is not transmitted, and disconnecting the parasitic conductor from ground. .
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an antenna device according to the present invention will be described below in detail with reference to the accompanying drawings.
[0031]
In general, the antenna has a higher Q factor so that there is less loss, so the radiation efficiency is better. Also, since large power of 10 W to several tens of kW is used for transmission, a non-linear element such as a diode in which insertion loss or distortion is a problem is used. It was not used as part of Moreover, since the fixed station was mainly used, it was not necessary to switch the radiation pattern of the antenna.
[0032]
However, in recent years, cases and antennas seen in mobile phones and antennas have become smaller and signals have become wider, and antennas with low Q values have to be used. In addition, due to the fact that the transmission power has been reduced to 1 W or less and the characteristics of nonlinear elements have improved, there is a possibility that a high-frequency switch such as a PIN diode or MESFET (Metal Semiconductor Field Effect Transistor) can be used as a part of the antenna.
[0033]
Based on these, the antenna device according to the present invention will be described by taking an antenna used for a mobile phone terminal as an example.
[0034]
(Example 1)
In this embodiment, an antenna device that switches a radiation pattern according to how a cellular phone terminal is used will be described.
[0035]
FIG. 1 is a diagram illustrating a configuration example of the antenna device according to this embodiment.
[0036]
In FIG. 1, an antenna device 100 is mainly composed of a signal processing / generation unit 11, an omnidirectional antenna 21, and a directional antenna 31. By selectively using the antennas 21 and 31, an antenna is provided. The radiation pattern can be switched.
[0037]
A signal transmitted from the antenna 21 is generated by the signal processing / generating unit 11, amplified by the power amplifier 23, and transmitted from the antenna 21 via the duplexer 22. A signal received by the antenna 21 is amplified by a low noise amplifier (LNA) via the duplexer 22 and input to the signal processing / generation unit 11. That is, the circuit composed of the antenna 21, the duplexer 22, the LNA 23, and the PA 24 corresponds to a conventional circuit that operates with a single antenna, and thus the antenna device 100 is oriented on the conventional circuit that operates with the single antenna 21. The antenna 31, the changeover switch 32, and the switch drive circuit 33 having the same characteristics are added to each one. A portion surrounded by a dotted line is a portion added to the conventional configuration.
[0038]
Here, in the mobile phone terminal, in the mobile phone terminal, when viewing the monitor, when using the Internet by key operation, or when waiting, the antenna device 100 is in an initial state, and in this initial state, the changeover switch 32 is set to the omnidirectional antenna 21. Connecting. The antenna device 100 is placed in the vicinity of the operator when a call is received (when a call is received) or when a call is made (when a call is made) at the mobile phone terminal. Recognize that you are in a call. When the telephone line is disconnected, it is recognized that the initial state has been restored.
[0039]
Further, the loudspeaker 12 is installed on the surface of the mobile phone terminal facing the operator so that the mobile phone terminal is positioned in the vicinity of the operator's ear in a call state where the mobile phone terminal is placed in the vicinity of the operator.
[0040]
When the antenna device 100 recognizes that the mobile phone terminal is in a call state from the initial state by receiving or making a call, the signal processing / generating unit 11 changes the directivity from the non-directional antenna 21. A switching signal for switching the connection to the antenna 31 is generated. This switch signal is amplified by the switch drive circuit 33 and input to the switch 32, whereby the switch 32 switches the connection from the antenna 21 to the antenna 31.
[0041]
In addition, when the antenna device 100 recognizes that the mobile phone terminal is disconnected from the telephone line and has returned from the call state to the initial state, the signal processing / generation unit 11 changes from the directional antenna 31 to the omnidirectional antenna 21. When the switching signal is amplified by the switch drive circuit 33 and input to the changeover switch 32, the changeover switch 32 switches the connection from the antenna 31 to the antenna 21. The antenna device 100 returns to the initial state.
[0042]
Therefore, when the mobile phone terminal is used in a place relatively away from the operator, transmission / reception is performed by the omnidirectional antenna 21, and the mobile phone terminal is used in the vicinity of the operator (when in a call state). ) Can be transmitted and received by the antenna 31 having a directional pattern on the side of the operator without an obstacle.
[0043]
In addition, since there are two antennas, either the antenna 21 or the antenna 31 is selected by the changeover switch 32 according to the use state at the time of transmission, and diversity reception is performed by the antenna 21 and the antenna 31 at the time of reception. You can also. This circuit configuration can be easily realized by adding one transmission / reception selector switch and one LNA to FIG. 1 (not shown).
[0044]
FIG. 2 is a diagram showing another configuration example of the antenna device of this embodiment.
[0045]
In FIG. 2, the antenna device 100 mainly includes a signal processing / generation unit 11, an omnidirectional antenna 21, and an additional conductor 41, and the radiation pattern of the antenna 21 is switched by switching between grounding / non-grounding of the additional conductor 41. Can be switched.
[0046]
The circuit composed of the antenna 21, the duplexer 22, the LNA 23, and the PA 24 corresponds to a conventional circuit that operates with a single antenna, like the antenna device shown in FIG. The additional conductor 41, the changeover switch 42, and the switch drive circuit 43 are each added to the conventional circuit that operates at 1. A portion surrounded by a dotted line is a portion added to the conventional configuration. One terminal of the changeover switch 42 is grounded, which means that the board on which the circuit of the antenna device 100 is mounted is regarded as a ground plane and is grounded.
[0047]
The additional conductor 41 is a parasitic conductor and is designed so that two desired radiation patterns can be obtained by the changeover switch 42 when operated in combination with the antenna 21. That is, the additional conductor 41 is used for expanding the area of the waveguide, the reflector, the RF shield plate, or the ground plane.
[0048]
The changeover switch 42 is used for switching between grounding / non-grounding of the additional conductor 41. The changeover switch 42 can also be used to open / short circuit a part of the pattern of the additional conductor 41 or the antenna 21.
[0049]
Here, in the mobile phone terminal, the antenna device 100 is in an initial state when the monitor is viewed, when the Internet is used by key operation, or when it is in a standby state. In this initial state, the changeover switch 42 ungrounds the additional conductor 41. As described above, it does not contribute to the radiation pattern of the antenna 21. The antenna device 100 is placed in the vicinity of the operator when a call is received (when a call is received) or when a call is made (when a call is made) at the mobile phone terminal. Recognize that you are in a call. When the telephone line is disconnected, it is recognized that the initial state has been restored.
[0050]
Similarly to the antenna device shown in FIG. 1, the loudspeaker 12 operates the cellular phone terminal so that the cellular phone terminal is positioned in the vicinity of the operator's ear in a call state where the cellular phone terminal is in the vicinity of the operator. It is installed on the opposite surface of the person.
[0051]
When the antenna device 100 recognizes that the mobile phone terminal is in a call state from the initial state by receiving or making a call, the signal processing / generating unit 11 switches the additional conductor 41 from non-ground to ground. A switching signal is generated. This switch signal is amplified by the switch drive circuit 43 and input to the switch 42, and the switch 42 switches the additional conductor 41 from non-ground to ground based on the input switch signal. Thereby, the additional conductor 41 functions as a director, a reflector, an RF shield plate, and the like, and switches the radiation pattern of the antenna 21 from non-directional to directional.
[0052]
In addition, when the antenna device 100 recognizes that the mobile phone terminal is disconnected from the telephone line and has returned from the talking state to the initial state, the signal processing / generation unit 11 performs switching for switching the additional conductor 41 from ground to non-ground. When the signal is generated, and this switching signal is amplified by the switch driving circuit 43 and inputted to the switching switch 42, the switching switch 42 switches the additional conductor 41 from ground to non-ground, thereby the radiation pattern of the antenna 21. To the initial omnidirectional state.
[0053]
Therefore, when the additional conductor 41 is grounded, the additional conductor 41 is designed so that the radiation pattern of the antenna 21 has a directivity pattern on the opposite side to the operator. When the mobile phone terminal is used in a place away from the mobile phone (initial state), the additional conductor 41 is not grounded, the radiation pattern of the antenna 21 is omnidirectional, and the mobile phone terminal is in the vicinity of an operator such as a voice call. When used (in a call state), the radiation pattern of the antenna 21 can be switched to a directional pattern that radiates radio waves strongly in the direction opposite to the operator.
[0054]
In each of the antenna devices shown in FIGS. 1 and 2, an existing mechanical or electrical change-over switch can be used as the change-over switches 32 and 42. For example, a PN diode, a PIN diode, a MESFET, etc. A semiconductor switch can be used.
[0055]
FIG. 3 shows, as an example of a semiconductor switch, an equivalent circuit from several hundred MHz to several GHz when the MESFET is turned ON / OFF.
[0056]
In general, in the high frequency range from several hundred MHz to several GHz, the MESFET is set to 0. It has an ON resistance of several Ω to 1 Ω (shown in FIG. 3A), and when OFF, it has an OFF resistance of several MΩ and 0. It has a capacitance between terminals of several pF to 1 pF (shown in FIG. 3B). By the way, the Q value required for the antenna system is determined by the ratio between the required signal band and the center frequency. In mobile phones, the Q value calculated from the band ratio is generally about 5 to 50. On the other hand, the inductance component of the antenna varies from several tens of ohms to several hundreds of ohms depending on the design method. Therefore, the resistance loss of the antenna system that satisfies the desired band is approximately 1 to 500Ω. This is because the ON resistance of the PIN diode shown in FIG. This means that when a few Ω to 1Ω is mounted as part of the antenna, this means that the transmission / reception loss increases by 0.1% to 50%. . Therefore, MESFETs can be used for the changeover switches 32 and 42 without any problem.
[0057]
As a supplement to each of the above-described embodiments, it is conceivable that the operator listens while downloading voice or music when the operator takes a call attitude other than the exchange by telephone. This is in common with voice calls in that the loudspeaker 12 is used to play voice. Therefore, the signal processing / generating unit 11 recognizes the state where the external earphone 13 is not used and the built-in loudspeaker 12 is used as a call state, so that the mobile phone can be operated more accurately. Whether the user is in the vicinity of the person.
[0058]
(Example 2)
In this embodiment, an antenna device that switches the radiation pattern of an antenna between transmission and reception will be described.
[0059]
FIG. 4 is a diagram illustrating a configuration example of the antenna device according to this embodiment.
[0060]
FIG. 4A is a diagram showing a circuit configuration of the transmission-time conduction switch, which is a circuit that is turned on when a voltage equal to or higher than a voltage at which the cross diode is turned on (0.00 V). If the parasitic conductor connected to the conduction switch at the time of transmission is arranged in the vicinity of the feeding antenna, it is conducted by the high-frequency power at the time of signal transmission and becomes non-conducting because it is weak power at the time of reception. Here, the attached inductor L and capacitor C are added in order to absorb isolation as part of the parallel resonance circuit and improve isolation when the presence of the capacitance when the diode is OFF is not desirable in operation. .
[0061]
FIG. 4B shows a change-over switch 42 with a control line (switch drive circuit 43) in the antenna apparatus shown in FIG. 2 at the time of transmission that does not require a control line using the cross diode shown in FIG. It is a figure which shows the circuit structure of the antenna apparatus at the time of replacing with conduction | electrical_connection switch 42 '.
[0062]
First, in the antenna apparatus of FIG. 4B, it is confirmed by rough approximation that the transmission conduction switch 42 ′ in the cross diode arrangement is turned on by the transmission power of the antenna 21.
[0063]
The transmission power of the mobile phone terminal is about 1 W at the maximum, and at the time of normal good transmission, at least 0.1 W, which is about 10% of the maximum transmission power, is transmitted as a radio wave. Here, the additional conductor 41 is disposed close to the antenna 21 so that a part of the electromagnetic wave from the antenna 21 is hit. For example, if 10% of the transmission power is combined, the additional conductor 41 is 0.1 W. An electric power of 10%, that is, about 0.01 W is applied to the additional conductor 41. The additional conductor 41 may be a conductor such as a wire or plate.
Now, assuming that the inductance of the additional conductor 41 is 0.1 μH, which is easy to realize, and the transmission frequency is 1 GHz, the impedance Z of the additional conductor 41 is
Z = jωL = j600Ω
It becomes.
[0064]
Further, the voltage applied to the additional conductor 41 is W = V ^ 2 / Z,
V = 2.5Vrms = 3.5Vp-p
In general, the diode is turned on when a voltage of 0.7 Vp-p is applied, so that 3.5 Vp-p is a sufficient turn-on voltage. Therefore, the cross diode is automatically turned on when transmitting the antenna.
[0065]
Next, it is confirmed that the OFF characteristic is improved by the configuration of FIG.
[0066]
When only a diode is present, the equivalent circuit at the OFF time is as shown in FIG. 3B, and it is generally known that the isolation at the OFF time is deteriorated due to the stray capacity. Typical inter-terminal capacitance is about 0.5 pF, and at 1 GHz, this impedance is
Zc = −j × 1 / (2πfC) = − j320Ω
It becomes. That is, in FIG. 4A, when there is no external inductor L and capacitor C, and there are only two diodes connected in reverse polarity, the impedance is −j320Ω.
[0067]
Therefore, in FIG. 4B, when only the additional conductor 41 and the cross diode are present, the total impedance is calculated based on the above calculations.
Ztotal = j600−j320 = −j300
It will be about.
[0068]
On the other hand, let us consider a case where an external inductor L and a capacitor C added if necessary are added to the diode. Here, for ease of adjustment, the capacitor may be a variable capacitor or may include a stray capacitor between substrates.
[0069]
When the capacitance between the terminals of the diode is 0.5 pF and the capacitance of the external capacitor C is 0.5 pF, the total capacitance is 1 pF, and the inductor L for resonating with this at 1 GHz is 25 nH. Here, as the inductor L of 25 nH, a general-purpose 1005 type (1 mm × 0.5 mm × 0.5 mm) may be used. The impedance of this parallel resonant circuit is given by QωL, where Q is about 10.
QωL = 1600Ω
It becomes. Therefore, the overall impedance of FIG.
| Ztotal '| = | j600 + 1600 | = 1700Ω
It becomes.
[0070]
Comparing the impedance Z | Ztotal | = 300Ω when turned OFF only by the cross diode and the impedance | Ztotal ′ | = 1700Ω obtained by the circuit in which the straight capacitance of the diode is canceled by the resonance circuit,
| Ztotal '/ Ztotal | = 1700/300 = 5.7
It can be seen that the impedance is at least several times higher. Further, since the values of QωL and | Ztotal ′ | are close to each other, there is an ease of design in which the OFF characteristic can be determined to a desired constant value without depending on the state of the additional conductor 41 or the straight capacitor of the diode. I understand that.
[0071]
Therefore, in the antenna device shown in FIG. 4B, the cross diode of the transmission conduction switch 42 ′ is automatically turned on by the transmission power of the antenna 21 at the time of transmission, and the additional conductor 41 is grounded. The radiation pattern of the directional antenna 21 is switched to a directional pattern that radiates radio waves strongly on the opposite side of the additional conductor 41. That is, by providing the additional conductor 41 on the operator side from the antenna 21, an antenna device having omnidirectionality at the time of reception and directivity in the direction opposite to the operator at the time of transmission can be configured.
[0072]
FIG. 5 is a diagram showing another configuration example of the antenna device of this embodiment.
[0073]
The reception-time conduction switch shown in FIG. 5A is an effective circuit when the inductor L or the capacitor C is part of the antenna configuration. In this reception operation switch, the semiconductor becomes conductive by the high frequency power at the time of transmission, and the entire circuit of FIG. 5A becomes a parallel resonance circuit and is turned OFF. On the other hand, in the weak power at the time of reception, a current flows to the capacitor C side and turns on.
[0074]
FIG. 5B shows an example of the conductive reflector of this embodiment, and is an example in which the reception conduction switch of FIG.
[0075]
By the way, as is well known in the Yagi antenna, a conductor that is slightly longer than the feeding conductor operates as a reflector, and when it is short, it operates as a waveguide.
[0076]
In FIG. 5B, since the capacitor C arranged in parallel with the inductor L constitutes a parallel resonant circuit in high frequency power, the conductive reflector 50 shown in FIG. 5B is as shown in FIG. 5C. When used in combination with a feeding antenna, it operates as a short conductor that does not include the inductor L when transmitting a signal, that is, as a waveguide, and as a long conductor that includes the inductor L when receiving, that is, as a reflector. That is, by adding a high-frequency switch without a control line to the parasitic element, when this parasitic element is used in combination with a feeding antenna, different radiation patterns can be obtained at the time of transmission and reception.
[0077]
In FIG. 5B, the conductive reflector 50 includes a linear conductor 51, a load inductor 52 electrically connected to both ends of the linear conductor, a cross-arranged diode 53, and a capacitor 54. As shown in FIG. 5C, it is arranged in the vicinity of the linear conductor 60 having the power feeding portion 61.
[0078]
The linear conductor 60 operates as a dipole antenna when the central portion thereof is fed. The radiation pattern of this dipole antenna is circular omnidirectional. However, when the cross reflector 53 is turned on and off by the transmission / reception power of the linear conductor 60 with the conductive reflector 50 disposed close to the dipole antenna, the radiation pattern is directed to the radiation pattern. Can have sex.
[0079]
With the weak power at the time of reception, the diode 53 is not turned on, and the effective length of the conductive reflector 50 is a length including the linear conductor 51 and the load inductor 52 connected to both ends thereof. On the other hand, at the time of transmission, the diode 53 is turned on by transmission power, the load inductor 52 and the capacitor 54 constitute a parallel resonance circuit, and the effective length of the conductive reflector 50 is the length of only the linear conductor 51.
[0080]
Accordingly, the effective length of the conductive reflector 50 changes depending on transmission and reception, and the length that functions as a director, the length that functions as a reflector, Of the three patterns having a length that does not function as a waver or a reflector, any two patterns can be used.
[0081]
Here, switching of the radiation pattern of the antenna device of FIG. 5C will be described with a specific example.
[0082]
FIG. 6 is a diagram illustrating an example of a radiation pattern in the antenna configuration of FIG. 5C, and represents a vertically polarized wave in a horizontal plane when the main radiation conductor 60 is erected perpendicular to the paper surface.
[0083]
The constants used were a frequency of 1500 MHz, a length of 9.638 cm of the main radiating conductor 60, a length of 9.148 of the conductive reflector 50, a distance of 3.64 between the main radiating conductor 60 and the conductive reflector 50, and the inductor L was 2 nH each. , Capacitors C are each 5.6 pF.
[0084]
In FIG. 6, the dotted radiation pattern is a radiation pattern when the diode 53 of the conductive reflector 50 is ON, and the central circular radiation pattern is a radiation pattern of only a dipole antenna (main radiation conductor 60), a central gourd type. This radiation pattern is a radiation pattern when the diode 53 of the conductive reflector 50 is OFF.
[0085]
By the way, the conductive reflector 50 does not resonate at a desired frequency only by changing its length by several percent. For example, when the length of the conductive reflector 50 is shortened from 9.148 cm to 7.148 cm, in the antenna configuration of FIG. 5C, the radiation pattern when the diode is ON is the central circular radiation pattern of FIG. The radiation pattern is the same as that of the antenna (main radiation conductor 60) alone. Therefore, by adjusting the values of the load inductor 52 and the capacitor 54 so that the conductive reflector 50 operates as a director or a reflector when the diode 53 is OFF, an omnidirectional circular radiation pattern is generated when the diode is ON. As a result, when the diode is turned off, a radiation pattern of a dotted line or a solid line gourd having directivity is obtained.
[0086]
Therefore, any two radiation patterns of the three radiation patterns shown in FIG. 6 can be switched and used by appropriately adjusting the execution length of the conductive reflector 50.
[0087]
In the above embodiment, the cross diode 53 without the control line is used. However, the same effect can be obtained by using a PIN diode with a control line for ON / OFF instead of the cross diode 53. Can do.
[0088]
Note that the switching of the radiation pattern by the self-ON / OFF function of the cross diode described so far cannot be realized unless the transmission time and the reception time are different. Therefore, this is effective in a system that performs transmission and reception at different times, such as the TDMA system and the TDD system. On the other hand, when a control line is connected to a high-frequency switch such as a PIN diode and the PIN diode is turned ON / OFF by a bias voltage, a method of performing transmission and reception at the same time, and a method of performing transmission and reception in time division The antenna can be used for both.
[0089]
FIG. 7 is a configuration example simulating the casing of the mobile phone terminal according to the present invention.
[0090]
FIG. 7A is a front view of the resin casing of the mobile phone terminal. Only the front surface excluding the liquid crystal panel and the key operation unit is covered with the copper foil 71, and a gap 71 g is formed on the center line of the copper foil 71. Is provided. A loudspeaker 12 is provided on the upper part of the liquid crystal panel.
[0091]
FIG. 7B is a side view of the resin casing of the mobile phone terminal shown in FIG. 7A. A built-in inverted F antenna 72 is placed on the left side of the resin casing, and a conductor 73 serving as a ground plane in the center. On the right side, the above-mentioned copper foil 71 and the loudspeaker 12 are arranged above it. The copper foil 71 and the conductor 73 serving as the ground plane are connected by a PIN diode, and a PIN diode control signal is sent through inductors at both ends of the PIN diode.
[0092]
FIG. 7C is a rear view of the resin casing of the mobile phone terminal shown in FIG. 7A. The switch 74 including the PIN diode and the inductor is arranged on the upper left, and the casing copper foil 71 and the ground plane are arranged. 73 is electrically connected by a switch 74. A built-in reverse antenna is placed in the upper right.
[0093]
When the casing copper foil 71 and the ground plane 73 are in a conductive state, the radiation pattern has a directivity that radiates to the built-in inverted F antenna 72 side, that is, the side opposite to the installation surface of the loudspeaker 12 via the ground plane 73. (FIG. 8 (a)). On the other hand, when the casing copper foil 71 and the ground plane 73 are in an out-of-door state, the radiation pattern is a radiation pattern having no directivity that radiates to both sides of the built-in antenna 72 and the casing copper foil 71 via the ground plane 73. (FIG. 8B).
[0094]
A foldable (clamshell type) mobile phone terminal in which a display-side main body having a display unit such as a liquid crystal screen and an operation button-side main body having an operation button such as a numeric keypad are foldably connected. By applying the antenna device described in each of the embodiments and using an existing switch for opening / closing identification that is generally used to detect the opening / closing of the mobile phone terminal, The radiation pattern can be switched.
[0095]
For example, a non-directional radiation pattern is used when folded when waiting for an incoming call or when moving, and directivity when the display-side main unit and operation button-side main unit are opened during a call or when viewing a monitor. A radiation pattern with This makes it possible to receive a non-directional radiation pattern that can be received from any direction when folding is likely to be in a pocket, bag, etc., and the reception direction is limited when talking or viewing the monitor, but the directivity with high reception sensitivity Effective transmission / reception is possible, for example, by using a radiation pattern with a certain level.
[0096]
Furthermore, the same effect can be obtained not only for small portable devices such as mobile phone terminals and PDAs but also for mobile communication devices such as notebook personal computers capable of hand carriers. In other words, it can be received from all directions during hand carrier by using a non-directional radiation pattern in the folded state, and it is efficient because there are obstacles such as knees or steel desks when the main LCD screen is opened. A radiation pattern with directivity that does not radiate to the bottom side where no significant radiation can be expected.
[0097]
【The invention's effect】
As described above, according to the present invention, the signal processing / generation unit 11 determines whether or not the mobile phone terminal is in the vicinity of the operator based on the usage status of the loudspeaker 12 and the earphone 13. When it is determined that the telephone terminal is in the vicinity of the operator, the antenna 31 having directivity is used on the side opposite to the operator, and when it is determined that the telephone terminal is located away from the operator, the omnidirectional antenna is used. 21 is used to transmit and receive signals, so that efficient transmission and reception is possible.
[0098]
Further, the signal processing / generation unit 11 determines whether or not the mobile phone terminal is in the vicinity of the operator based on the usage status of the loudspeaker 12 and the earphone 13, and if the mobile phone terminal is in the vicinity of the operator. If it is determined, the additional conductor 41 is ungrounded and the radiation pattern of the antenna 21 is omnidirectional. If it is determined that the additional conductor 41 is away from the operator, the additional conductor 41 is grounded and the radiation pattern of the antenna 21 is determined. Since a pattern having directivity on the side without an obstacle as an operator is used, efficient transmission / reception becomes possible.
[0099]
In addition, by grounding the additional conductor 41 via a cross diode, the grounding / non-grounding of the additional conductor 41 is automatically switched according to the transmission / reception power of the antenna 21 and the radiation of the antenna 21 is transmitted and received. It is possible to perform efficient transmission / reception by switching patterns.
[0100]
Further, by using a conductive reflector 50 whose execution length varies depending on transmission / reception power and appropriately adjusting the execution length, the length that functions as a director, the length that functions as a reflector, or the waveguide Any two of the three patterns that do not function as a reflector or reflector can be switched and used, and the radiation pattern of the antenna 21 can be switched between transmission and reception for efficient transmission and reception. Can be done.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an antenna apparatus according to the present invention.
FIG. 2 is a diagram showing a configuration example of an antenna apparatus according to the present invention.
FIG. 3 is a diagram showing an equivalent circuit at several hundred MHz to several GHz when MESFET is turned on / off.
FIG. 4 is a diagram showing a configuration example of an antenna apparatus according to the present invention.
FIG. 5 is a diagram showing a configuration example of an antenna apparatus according to the present invention.
6 is a diagram illustrating an example of a radiation pattern in the antenna configuration of FIG.
FIG. 7 is a diagram showing a schematic configuration of a mobile phone terminal according to the present invention.
8 is a diagram showing an example of a radiation pattern of the mobile phone terminal of FIG.
[Explanation of symbols]
11 Signal processing / generation unit
12 Loudspeakers
13 Earphone
21 Antenna
22 Duplexer
23 Power Amplifier
31 Antenna
32 selector switch
33 Switch drive circuit
41 Additional conductors
42 selector switch
42 'Transmission switch
43 Switch drive circuit
50 Conductor reflector
51 Linear conductor
52 Load inductor
53 Cross diode
54 capacitors
60 linear conductor
61 Power supply unit
71 Copper foil
71g gap
72 Built-in antenna
73 Ground Plane
74 switches

Claims (4)

An antenna device used in a mobile communication terminal,
A first antenna having directivity on the opposite side to the loudspeaker direction of the loudspeaker built in the mobile communication terminal;
A non-directional second antenna;
Determining whether the portable communication terminal is in a first state in which the loudspeaker is used close to an ear or in a second state in which the Internet is used by key operation and a signal is transmitted Discriminating means to perform,
When it is determined that the mobile communication terminal is in the first state by the determining means, the first antenna is used, and when it is determined that the mobile communication terminal is in the second state, the second antenna is An antenna device comprising: switching means for switching to use. An antenna device used in a mobile communication terminal,
A non-directional main radiating conductor having a power feeding part;
A parasitic conductor disposed in proximity to the main radiating conductor;
Determining whether the portable communication terminal is in a first state in which the loudspeaker is used close to an ear or in a second state in which the Internet is used by key operation and a signal is transmitted Discriminating means to perform,
When the determination means determines that the mobile communication terminal is in the first state, the parasitic conductor is grounded and the main radiating conductor is connected to a loudspeaker direction of a loudspeaker built in the mobile communication terminal. Control means for functioning as an antenna having directivity on the opposite side and causing the main radiating conductor to function as an omnidirectional antenna by separating the parasitic conductor from ground when it is determined that the second state is established An antenna device comprising: The discrimination means includes
The mobile communication terminal is determined to be in the first state when no external earphone is connected to the mobile communication terminal and a loudspeaker built in the mobile communication terminal is used. The antenna device according to claim 1 or 2. An antenna device used in a mobile communication terminal,
A non-directional main radiating conductor having a power feeding part;
A parasitic conductor disposed in proximity to the main radiating conductor;
A loudspeaker direction of a loudspeaker incorporated in the portable communication terminal by conducting the high-frequency power radiated from the main radiating conductor during signal transmission of the portable communication terminal and grounding the parasitic conductor. Switching means that functions as an antenna having directivity on the opposite side and becomes non-conductive when no signal is transmitted, and causes the main radiation conductor to function as a non-directional antenna by disconnecting the parasitic conductor from ground. An antenna device characterized by the above.

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