JP2002223107A - Antenna system with passive element and radio terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system with a passive element capable of directivity controlling through the addition of the passive element so as to enhance the radiation efficiency and can surely reduce absorption of power to a human body and to provide a wireless terminal. SOLUTION: The antenna system with the passive element is provided with a radiator and the passive element 3 placed in the vicinity of the radiator, and the passive element 3 longer than a radiation element 2 of the radiator by 0.01λ-0.1λ is placed apart from the radiation element 2 at an interval of 0.01λ-0.1λ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device with a parasitic element and a radio terminal device suitably used for electronic equipment such as a portable terminal device.

[0002]

2. Description of the Related Art An antenna used in a portable radio is shown in FIG.
As shown in FIG. 0, a single antenna is provided on the housing. Usually, an antenna such as a whip or a helical is used. As shown in the figure, 20 radiating elements are installed on one wireless communication device. The 20 radiating elements are covered by 21 radomes, which are made of a resin such as rubber, vinyl, ABS or the like. These antennas are often omnidirectional in a horizontal plane in order to communicate with a base station whose position is not fixed, a master unit, or the like.

[0003] In order to communicate with a specific direction, there is a method of increasing a gain in a specific direction by adding a reflection element in parallel with the linear antenna element. As shown in FIG. 11, 20 radiating elements are installed on one wireless communication device, and 22 reflecting elements are λ /
By setting them apart by about four, the gain in the direction opposite to that of the reflection element can be improved. FIG. 12 shows the measurement results of the directivity in the horizontal plane of the antenna of FIG. As shown in FIG. 12, directivity can be controlled by disposing the reflector 22 at a distance of about λ / 4 from the 20 radiators. Figure 1
In No. 2, the directivity is provided in the opposite direction to the 22 reflector, and the front-to-back ratio of the gain is 5 dB. Since this type of reflector requires a distance of λ / 4 from the radiator, it becomes a large-sized antenna device.

A prior example is disclosed in Japanese Patent Application Laid-Open No. 10-31.
In such a conventional antenna, a space between the radiator and the reflector is required to add a reflector to the radiator and secure a front-to-back ratio of radiation directivity. A distance of about λ / 4 was required.

[0005]

The antenna used in the conventional portable radio is omnidirectional in a horizontal plane. But,
Absorption by the human head when used near the human head,
Due to the influence of the scattering, the directivity of the antenna is not omnidirectional in the horizontal plane. FIG. 13 shows an FDTD simulation result of the directivity characteristics when a 2.4G dipole antenna is present near the human head.

[0006] Simulation results show that the gain in the direction of the human head decreases due to the effect of the human head, and that the radiation characteristics are no longer omnidirectional.

As described above, in the case of an antenna used near the head of a human body, there is a problem in that directivity is disturbed due to power absorption and scattering in the direction of the human body, and the efficiency is thereby reduced.

Although the above-described prior art antenna device and the like can solve the above problem, they have not been sufficient.

The present invention solves such a problem.
An object of the present invention is to provide an antenna device with a parasitic element and a wireless terminal device capable of reliably improving radiation efficiency and reducing power absorption into a human body by performing directivity control by adding a parasitic element.

[0010]

SUMMARY OF THE INVENTION The present invention is an antenna device with a parasitic element having a radiator and a parasitic element provided near the radiator. 0.01 λ to 0.1 λ
It was placed 0.1 λ apart.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an antenna device having a parasitic element provided with a radiator and a parasitic element provided near the radiator. A parasitic element that is 0.01 λ to 0.1 λ longer than the
By using the antenna device with the parasitic element arranged so as to be separated from 1λ to 0.1λ, an antenna having a front-to-back ratio in directivity can be configured in a small space.

[0012] According to a second aspect of the present invention, the first element is provided in the parasitic element.
And a second portion, wherein a distance between the first portion and the radiating element is different from a distance between the second portion and the radiating element. By using the above-described antenna device with a parasitic element, it is possible to configure an antenna device in which impedance can be easily matched and the directional characteristics have a front-to-back ratio.

According to a third aspect of the present invention, the first part and the second part
3. A step portion is provided between said portions.
The antenna device with the parasitic element described above facilitates impedance matching.

According to a fourth aspect of the present invention, the first portion is opposed to the tip of the radiating element, and the second portion is provided at the root of the radiating element.
3. The space between the first part and the tip of the radiating element is made wider than the distance between the second part and the root part of the radiating element. With the antenna device with the feed element, impedance matching can be easily achieved, and the directivity before and after ratio can be improved.

According to a fifth aspect of the present invention, in the antenna device with a parasitic element according to the first aspect of the present invention, the parasitic element has a plate shape, and the front-to-back ratio of the directional characteristics is sharper than when the linear parasitic element is added. You can do it.

According to a sixth aspect of the present invention, the width of the plate-like parasitic element is different, and the antenna device with the parasitic element according to the fifth aspect can easily achieve impedance matching. You can do it.

According to a seventh aspect of the present invention, the width of the parasitic element facing the distal end of the radiating element is wider than the width of the parasitic element facing the root portion of the radiating element. By adopting the antenna device with a parasitic element according to the sixth aspect, it is possible to configure an antenna device in which impedance matching can be easily achieved and the directional characteristics have a front-to-back ratio.

The invention according to claim 8 is characterized in that the radiating element is
Using a radiating element having a length of about 3λ / 4,
Approximately λ away from 0.01 λ to 0.1 λ on the opposite side of the parasitic element
The antenna device with a parasitic element according to claim 1, wherein a stub having a length of / 4 is added, thereby making it possible to configure an antenna that facilitates impedance matching, has a high gain, and can easily supply power. .

According to a ninth aspect of the present invention, a receiving unit that converts a received signal into at least one of a received voice signal and a received data signal, and converts at least one of a transmitted voice signal and a transmitted data signal into a transmitted signal. 9. A transmitting unit, the antenna element with the parasitic element according to any one of claims 1 to 8, which receives the reception signal and transmits the transmission signal, an input unit for inputting predetermined data, and a predetermined character. Wireless device equipped with a display unit that controls each part and reduces the effect on the human body due to electromagnetic waves radiated from the antenna by the parasitic element when the wireless terminal device is used near the human body It is possible to do.

According to a tenth aspect of the present invention, there is provided a receiving section for converting a received signal to a received voice signal, a speaker for converting the received voice signal to voice, and a microphone for converting input voice to a transmission voice signal. And, a transmission unit that converts a transmission audio signal into a transmission signal, and a control unit that controls each of the units,
A first case having the speaker, a second case having the microphone, and a head cord that electrically connects the first case and the second case, and is preferably mounted on a head. With such a wireless terminal device, the head cord made of a conductor also operates as a second parasitic element, and the effect of electromagnetic waves on the human body can be further reduced.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an antenna device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a wireless communication device, in which a communication device is provided, and the outside thereof has a structure of a housing made of a relatively inexpensive resin such as a glass epoxy material having a dielectric constant of about 4.6. Become.

Reference numeral 2 denotes a radiating element. As a material of the radiating element, a good conductor wire such as a copper wire having a wire diameter of 2 mm or less (preferably 0.05 mm or more), which has a certain strength, is preferred. This radiating element is λ / 2 or 5λ in length
It is preferable that the influence of the housing current of about / 8 is small (excluding λ / 4). λ is preferably about 80 mm to 160 mm (preferably, 118 mm to 127 mm).

Numeral 3 is a parasitic element installed substantially parallel to the radiating element, and it is preferable that this parasitic element is also made of the same material as the two radiating elements. The length of the parasitic element 3 may be 0.01 λ to 0.1 λ longer than the length of the radiating element 2. If it is shorter than 0.01λ, the directivity cannot be controlled, and if it is larger than 0.1λ, the characteristics relating to the front-rear ratio of the directivity do not improve. The distance between the radiating element 2 and the parasitic element 3 may be a distance of 0.01 λ to 0.1 λ. If the distance is shorter than 0.01 λ, it is difficult to achieve impedance matching.
It is not desirable in antenna design. Experiments have shown that a directivity gain of about 3 dB is obtained as shown in FIG. By appropriately setting the length and spacing of the parasitic elements 3 as described above, the antenna device becomes a small directional antenna having a front-back ratio of about 3 dB.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described.

The present embodiment has almost the same configuration as that of the first embodiment except that the shape of the parasitic element is different from that of the first embodiment. Therefore, the following description will focus on the shape and arrangement of the parasitic element.

FIG. 3 is a diagram showing an antenna device with a parasitic element according to one embodiment of the present invention. 3 mainly shows the shapes of the radiating element 2 and the parasitic element 4, and does not show the wireless communication device shown in FIG.

In FIG. 3, reference numeral 2 denotes a radiating element, which has a wire diameter of 2 m and has a certain strength as a material of the radiating element.
A good conductor wire such as a copper wire of less than m is preferred. The radiating element preferably has a length of about λ / 2 or about 5λ / 8 and is less affected by a housing current.

Reference numeral 3 denotes a parasitic element installed in parallel with the radiating element, and the parasitic element 3 is preferably made of the same material as the radiating element 2. It is sufficient that the length of the parasitic element 4 protrudes in the height direction from 0.01λ to 0.1λ with respect to the length of the two radiating elements. If the length is shorter than 0.01λ, the directivity cannot be controlled. The characteristics related to the front-to-back ratio are not improved. The distance between the radiating element 2 and the parasitic element 3 is 0.01 at the base.
If the distance is set to λ to 0.1λ, and shorter than 0.01λ, it is difficult to achieve impedance matching. If it is larger than 0.1λ, there is a problem in space, which is not preferable in antenna design. The top is further offset from the base by 0.01λ to 0.1λ. If it is shorter than 0.01 λ, the characteristic of the directivity cannot be improved much. With such a configuration, it is easy to optimally adjust the impedance characteristics of the antenna feed unit, and an antenna having excellent directivity characteristics can be configured. With such a configuration, the front-to-back ratio of the directivity in the horizontal plane is improved by about 1 dB as compared with the configuration of FIG.

FIG. 4 is a perspective view of an antenna structure with a plate-shaped parasitic element added. As shown in FIG.
There is also a configuration in which the impedance characteristic can be easily adjusted by changing the width of the base portion and the upper portion into a plate-like configuration.

(Embodiment 3) Next, Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 5 is a perspective view showing an antenna device with a parasitic element according to one embodiment of the present invention.

In FIG. 5, reference numeral 1 denotes a wireless communication device, in which a communication device is provided, and the outside thereof has a structure formed of a relatively inexpensive resin such as a glass epoxy material having a dielectric constant of about 4.6. Become.

Reference numeral 6 denotes a radiating element. As a material of the radiating element 6, a good conductor wire such as a copper wire having a wire diameter of 2 mm or less, which has a certain strength, is preferred. The length of the radiating element 6 is preferably 3λ / 4 in the type shown in FIG.

Numeral 8 denotes a parasitic element installed in parallel with the radiating element, and the parasitic element 8 is preferably made of the same material as the radiating element 6. The length of the parasitic element 8 may be 0.01 λ to 0.1 λ longer than the length of the radiating element 6. Does not improve.). When the distance between the radiating element 6 and the parasitic element 8 is 0.01 λ to 0.1 λ, which is appropriate, the distance is shorter than 0.01 λ. This is undesirable in design.
The stub 7 is added to the opposite side of the parasitic element 8 at a distance of 0.01λ to 0.1λ. That is, as described above, the radiator does not include only the radiating element but includes the radiating element 6 and the stub 7.

The stub 7 has a length of about λ / 4 linear conductor. This antenna unit is fed only to the radiating element 6,
The stub 7 is connected to GND (earth). FIG. 6 shows a method of feeding the antenna. When the antenna is fed by the coaxial line 9, the core wire is connected to the radiating element 6, and the outer skin is connected to the stub 7. This type of antenna also has a front-to-back ratio of 3 as shown in FIG.
Experiments have shown that a directivity gain of about dB can be obtained. By setting the length and spacing of the parasitic elements 8 as described above, the antenna device becomes a small directional antenna having a front-back ratio of about 3 dB.

(Embodiment 4) Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a diagram illustrating an antenna device with a parasitic element and a wireless terminal device according to an embodiment of the present invention.

In FIG. 7, reference numeral 1 denotes a wireless communication device, in which a communication device is provided, and the outside thereof has a structure of a housing made of a relatively inexpensive resin such as a glass epoxy material having a dielectric constant of about 4.6. Become.

Reference numeral 2 denotes a radiating element, and as a material of the radiating element, a good conductor wire such as a copper wire having a wire diameter of 2 mm or less, which has a certain strength, is preferred. This radiating element has a length of λ
It is preferable that the influence of the housing current of about / 2 or 5λ / 8 is small (excluding λ / 4). Reference numeral 3 denotes a parasitic element installed in parallel with the radiating element, and the parasitic element 3 is preferably made of the same material as the radiating element 2. The length of the parasitic element 3 may be 0.01λ to 0.1λ longer than the radiating element length 2. The distance between the radiating element 2 and the parasitic element 3 is 0.01λ or more.
By setting the head cord 10 at a distance of 0.1λ and further apart by 0.1λ or more, the head cord 10 can be handled as a second parasitic element. This head cord 10 further suppresses power absorption to the human head.

Next, a specific wireless terminal device will be described.

FIGS. 8 and 9 are a diagram and a block diagram, respectively, showing a wireless terminal device according to an embodiment of the present invention. 8 and 9, reference numeral 29 denotes a microphone for converting a sound to a sound signal, 30 denotes a speaker for converting a sound signal to a sound, 31 denotes an operation unit including dial buttons and the like,
Reference numeral 32 denotes a display unit for displaying an incoming call and the like, 33 denotes an antenna, and the antenna 33 has a configuration shown in FIGS. In addition,
In FIG. 8, the antenna device with a parasitic element shown in FIGS. 1 to 7 is stored in a radome having a bottomed cylindrical body. A transmitting unit 34 demodulates an audio signal from the microphone 29 and converts it into a transmission signal. The transmission signal produced by the transmission unit 34 is emitted to the outside through the antenna 33. A receiving unit 35 converts a received signal received by the antenna into an audio signal. The audio signal created by the receiving unit 35 is converted into audio by the speaker 30. 36 is the transmitting unit 3
4, a control unit that controls the receiving unit 35, the operation unit 31, and the display unit 32.

Hereinafter, an example of the operation will be described.

First, when there is an incoming call, the receiving unit 35
Sends an incoming signal to the control unit 36, the control unit 36 displays a predetermined character or the like on the display unit 32 based on the incoming signal, and further presses a button or the like for receiving an incoming call from the operation unit 31. And a signal is sent to the control unit 36,
The control unit 36 sets each unit to the incoming call mode. That is, the signal received by the antenna 33 is converted into an audio signal by the receiving unit 35, the audio signal is output as audio from the speaker 30, and the audio input from the microphone 29 is converted into an audio signal, Through the antenna 33 to the outside.

Next, the case of transmitting a call will be described.

First, when transmitting a signal, a signal to the effect that the signal is transmitted from the operation unit 31 is input to the control unit 36. Subsequently, when a signal corresponding to the telephone number is transmitted from the operation unit 31 to the control unit 36, the control unit 36 transmits a signal corresponding to the telephone number from the antenna 33 via the transmission unit 34. When the transmission signal establishes communication with the other party,
When a signal to that effect is sent to the control unit 36 via the reception unit 35 via the antenna 33, the control unit 36 sets each unit to the transmission mode. That is, the signal received by the antenna 33 is converted into an audio signal by the receiving unit 35, the audio signal is output as audio from the speaker 30, and the audio input from the microphone 29 is converted into an audio signal, Through the antenna 33 to the outside.

In this embodiment, an example in which voice is transmitted and received has been described. However, the present invention is not limited to voice, and a similar effect can be obtained for a device that transmits and / or receives data other than voice such as character data. Can be obtained.

In FIG. 7, in the case of a headset wireless terminal device, at least a speaker 30 is provided in a case 40, and a microphone 29 is housed in the case 41. It is preferable that the above-described components other than the microphone 29 be housed in the case 40. The cases 40 and 41 are electrically connected by a cord or the like.

[0047]

According to the present invention, there is provided an antenna device with a parasitic element having a radiator and a parasitic element provided in close proximity to the radiator, wherein the radiator has a radiator of 0.01 λ or more.
By disposing the parasitic element that is 0.1λ long between 0.01λ and 0.1λ, the antenna arrangement consisting of the radiating element and the parasitic element determines the element arrangement appropriately, so that power absorption and scattering toward the human body This improves the directivity disturbance due to and the reduction in efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view of an antenna device with a parasitic element according to an embodiment of the present invention.

FIG. 2 is a view showing experimental data of directivity characteristics of the antenna device with a parasitic element according to one embodiment of the present invention;

FIG. 3 is a diagram showing an antenna device with a parasitic element according to an embodiment of the present invention;

FIG. 4 is a diagram showing an antenna device with a parasitic element according to an embodiment of the present invention;

FIG. 5 is a perspective view showing an antenna device with a parasitic element according to one embodiment of the present invention;

FIG. 6 is a diagram showing an antenna device with a parasitic element according to an embodiment of the present invention;

FIG. 7 is a diagram showing an antenna device with a parasitic element and a wireless terminal device according to an embodiment of the present invention;

FIG. 8 is a diagram showing a wireless terminal device according to an embodiment of the present invention;

FIG. 9 is a block diagram illustrating a wireless terminal device according to an embodiment of the present invention.

FIG. 10 is a side view of a conventional wireless communication device antenna.

FIG. 11 is a diagram showing an antenna in which a reflector according to the related art is arranged.

FIG. 12 is a directional characteristic diagram of an antenna in which a reflector according to the related art is arranged.

FIG. 13 is a diagram showing directivity when a dipole antenna is arranged beside a human head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wireless terminal device 2, 6 Radiation element 3, 4, 5, 8 Parasitic element 7 Stub 10 Head code 30 Speaker 31 Operation part 32 Display part 33 Antenna 34 Transmission part 35 Reception part 36 Control part 40, 41 Case

Claims (10)

[Claims] 1. An antenna device with a parasitic element, comprising a radiator and a parasitic element provided in proximity to said radiator, wherein the antenna device is longer than the radiating element of the radiator by 0.01λ to 0.1λ. An antenna device with a parasitic element in which a parasitic element is separated from 0.01λ to 0.1λ. 2. A parasitic element having a first part and a second part, wherein a distance between the first part and the radiating element and a distance between the second part and the radiating element are set. The antenna device with a parasitic element according to claim 1, wherein the antenna device is different. 3. The antenna device with a parasitic element according to claim 2, wherein a step portion is provided between the first portion and the second portion. 4. A radiating element having a first portion opposed to a tip portion thereof, a second portion opposed to a root portion of the radiating element, and having a gap between the first portion and the tip portion of the radiating element. 3. The antenna device with a parasitic element according to claim 2, wherein an interval between the second portion and a root portion of the radiating element is wider. 5. The antenna device with a parasitic element according to claim 1, wherein the parasitic element has a plate shape. 6. The antenna device with a parasitic element according to claim 5, wherein the width of the plate-like parasitic element is different. 7. The parasitic element facing the tip of the radiating element is wider than the parasitic element facing the root of the radiating element. The antenna device with a parasitic element described in the above. 8. A radiating element having a length of about 3λ / 4 is used, and a stub having a length of about λ / 4 is separated from the radiating element by 0.01λ to 0.1λ on the side opposite to the parasitic element. The antenna device with a parasitic element according to claim 1, wherein the antenna device is added. 9. A receiving section for converting a received signal into at least one of a received voice signal and a received data signal, a transmitting section for converting at least one of a transmitted voice signal and a transmitted data signal into a transmitted signal, An antenna element with a parasitic element according to any one of claims 1 to 8, which receives a signal and transmits the transmission signal, and input means for inputting predetermined data,
A wireless terminal device comprising: display means for displaying a predetermined character or the like; and a control unit for controlling each unit. 10. A receiving unit for converting a received signal into a received voice signal, a speaker for converting the received voice signal into voice, a microphone for converting an input voice into a transmitted voice signal, and a microphone for transmitting the transmitted voice signal. A transmitting unit that converts the signal into a transmission signal, a control unit that controls each unit, a first case that includes the speaker, a second case that includes the microphone, and receives the reception signal and transmits the transmission signal. Claim 1
8. A wireless terminal device comprising a parasitic element with a parasitic element according to any one of 8 and a head cord which is electrically connected to the first case and the second case and is preferably mounted on a head.