JPH06232622A - Antenna system for portable radio equipment - Google Patents

Abstract

PURPOSE:To reduce the body effect of a user holding a portable radio equipment onto an electromagnetic wave by forming the antenna system with a reflecting element arranged apart from a radiation element by a prescribed interval and a positioning means deciding a relative position of the reflecting element with respect to the portable radio equipment main body so as to vary a radiation pattern of the electromagnetic wave radiating from an antenna. CONSTITUTION:A reflecting element 3b is provided in parallel in an axial direction of a radiation element 1C radiating an electromagnetic wave and part of the stimulated electromagnetic wave is reflected in the reflecting element 3b. The reflecting element 3b is positioned at a position by a positioning means so that an electric field strength of the radiation element at the side of a user supporting a radio equipment is weakest. The distance between the radiation element 1C and the reflecting element 3b is supported by a support base 8 and a connector 9a used to connect the radiation element 1C to a portable radio equipment 2 is provided to a lower part of the radiation element 1C. A connector 9b used to connect the radiation element 1C to the connector 9a and a reflecting element hole 10 to insert and fix the reflecting element 3b are provided to an upper face of the portable radio equipment 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna mounting structure for a portable wireless device, and more particularly to an antenna mounting device composed of a radiating element and a reflecting element.

[0002]

2. Description of the Related Art Antennas used in portable radios are
There are a so-called rod type with an exposed antenna element, a single (whipped) type, a helical type, a collinear array type and the like, and these antennas covered with rubber or vinyl.

FIG. 1 is a view showing a mounting state of a conventional antenna used in a portable wireless device used for electromagnetic waves having VHF, UHF and SHF band frequencies. A whip antenna 1a, which is a rod-shaped radiating element, is attached to the upper surface of the portable wireless device 2, and radio waves are radiated from the whip antenna 1a. Such a whip antenna 1a has a radiation pattern which is omnidirectional in a horizontal plane for the purpose of receiving radio waves from various directions and transmitting radio waves in various directions.

On the other hand, as shown in FIG. 2, in order to enable communication with a specific direction, an antenna to which a reflecting element 3 for imparting directivity in the horizontal direction is attached is used.
This antenna is composed of a radiating element 1b for radiating radio waves, a reflecting element 3 for reflecting radio waves, a coaxial line 4 for transmitting a signal, and a pedestal 5 for supporting the radiating element 1b and the reflecting element 2, such as a magnet. Then, the housing 6 is properly attached to a desired position. The radiating element 1a and the reflecting element 3 shown in FIG.
As shown in FIG. 3, the radiation pattern of the antenna composed of the
dB). In FIG. 3, the outermost circle indicates the dipole gain, and the inner circle indicates the value which is 5 dB lower than the dipole gain.

[0005]

The radiation pattern in the horizontal plane of the antenna used in the conventional portable radio is omnidirectional, but this is established only when there is no object that disturbs radio waves in the surroundings. When used on the front of the face or on the waist like a machine (the human body acts as a dielectric), the radiation pattern in the horizontal plane is no longer omnidirectional. FIG. 4 shows a horizontal plane radiation pattern in the quasi-microwave band when the portable wireless device of FIG. 1 is worn on the waist of the human body 7. The outermost circle represents the gain of the dipole antenna. It can be seen that the radiation pattern is no longer omnidirectional because the gain in the human body direction is significantly reduced due to the absorption of electromagnetic waves by the human body.

Part of the radio wave radiated from the antenna is absorbed by the human body (the beam width in this case is about 16
0 degree, gain 0 dBd), which is equivalent to the fact that the transmission / reception power in the human body direction is substantially reduced, which is a factor that deteriorates communication quality.

In recent years, with the spread of so-called "mobile communication" represented by mobile phones, car phones, MCA, cordless telephones, etc., it is the current situation that the frequencies are gradually shifting to higher frequencies. However, as the frequency of radio waves increases, the energy increases and the ratio of being absorbed by the human body increases. In particular, in a VHF, UHF, SHF band portable wireless communication device, the antenna is placed close to the head (especially the eyeball) or the abdomen (when a belt clip or the like is used) and is used, so that the influence is particularly great.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an antenna device fixed to a main body of a portable wireless device and comprising a radiating element and a reflecting element, for radiating and receiving electromagnetic waves, and an axial direction of the radiating element. An antenna device for a portable wireless device, comprising a reflective element arranged in parallel at a predetermined distance and a positioning means for determining a relative position of the reflective element with respect to the portable wireless device body.

Further, according to the present invention, a plurality of depressions are provided in a circle centered on the central axis of the radiating element on the same surface as the surface of the portable radio device for fixing the radiating element, and The antenna device for a portable wireless device has a positioning device that determines the position of a reflective element by fitting the lower end into the recess.

Further, the present invention is an antenna device comprising a radiating element coated with a dielectric material, wherein the reflecting material made of metal is embedded in the dielectric material in the axial direction of the radiating element.

Further, the present invention is the antenna device, wherein the cross section of the reflecting plate in the direction perpendicular to the axis of the radiating element has a V shape, and the radiating element is located on the narrow angle side of the reflecting plate.

Further, the present invention is the antenna device in which the cross section of the reflector in the direction perpendicular to the axis of the radiating element has a V shape, and the radiating element is located on the narrow angle side of the reflector.

Further, according to the present invention, in an antenna device comprising a radiating element coated with a dielectric substance, the dielectric substance coating the radiating element is formed of substances having different permittivities in a direction perpendicular to the axis of the radiating element. It is an antenna device.

Further, the present invention is an antenna device in which the dielectric material covering the radiating element is arranged such that the dielectric constant decreases toward the outside of the radiating element.

Further, the present invention is the antenna device, wherein the dielectric material covering the radiating element is arranged such that the dielectric constant becomes smaller toward the outside in the direction perpendicular to the axis of the radiating element.

[0016]

According to the present invention, the reflecting element is provided parallel to the axial direction of the radiating element that emits the electromagnetic wave, and the electromagnetic wave emitted from the radiating element is partially reflected by the reflecting element. The position of the reflective element is set by the positioning means, and the position of the reflective element can be determined so that the electric field strength on the human side holding the portable wireless device is the weakest.

Further, in the antenna in which the radiating element is covered with the dielectric material, the electric field radiation pattern of the antenna can be made non-uniform by embedding a metal plate that reflects electromagnetic waves in the dielectric material.

Furthermore, the electric field radiation pattern of the antenna can be made non-uniform by reducing the dielectric constant of the dielectric as the distance from the radiating element increases.

[0019]

FIG. 5 shows an embodiment of the present invention. The portable wireless device is a device for wirelessly communicating with a person located at a remote place. Radiating element 1c and reflecting element 3b
Is attached to the portable wireless device 2 by penetrating the holding table 8.
The distance between the two elements is held by a holding table 8, and a connector 9a for fixing the radiating element 1c to the portable wireless device 2 is provided below the radiating element 1c. The radiating element 1c and the holding base 8 are not fixed, and the radiating element 1c can freely rotate with respect to the holding base 8. On the upper surface of the portable wireless device 2, a connector 9b for attaching the radiating element 1c via the connector 9a and a reflecting element hole 10 for inserting and fixing the reflecting element 3b are provided.

The radiating element 1c is connected to a transmitter / receiver (not shown) provided in the portable wireless device 2 by fitting the connector 9a into the connector 9b, so that radio waves can be transmitted and received. The lower part of the reflective element 3b is inserted into the reflective element hole 10 to be electrically connected to the housing of the portable wireless device 2.

FIG. 6 shows a radiation pattern in a horizontal plane when the antenna device shown in FIG. 5 is attached to the portable radio device 2. The gain is about 2 dBd, the beam width is about 180 degrees, and the front / back ratio is about 5 dB (the outermost circle is the dipole antenna gain). In FIG. 6, when the portable wireless device 2 is used so that the human body comes to the side of the reflecting element 3b where the gain of the dipole antenna is reduced by 4 dB, the power absorbed by the human body can be reduced by at least 4 dB. Becomes In addition, the transmission / reception power can be increased by increasing the gain in the direction opposite to the human body.

In this embodiment, the number of the reflection element holes 10 is one, but in order to change the directivity of the antenna depending on the usage of the portable radio device 2, the reflection element holes 10 are centered on the connector 9b. A plurality of circles may be provided on the circle.

FIG. 7 is a perspective view of an antenna device according to another embodiment of the present invention, in which a metal reflector is embedded in a dielectric material covering a radiating element, and FIG. 8 is a perspective view of FIG. It is sectional drawing of the radiating element of an antenna in the direction orthogonal to the axis.
A dielectric material 12 is coated around the radiating element 11, and a metal reflector 13 for reflecting an electromagnetic wave emitted from the radiating element 11 is embedded in the dielectric material 12.

The principle of using the conductor reflector in this embodiment is the same as that of a so-called corner reflector type antenna or parabolic type antenna. That is, when the antenna is placed at the focal point of the reflector, the electromagnetic wave of the backside component radiated from the antenna element hits the reflector and is reflected at a reflection angle equal to its incident angle and travels in the front side direction. This component and the front side component are superimposed to improve the front gain and FB (front back) ratio. These characteristics can be changed by adjusting the position, angle or size of the reflector. However, since the electromagnetic waves wrap around at the end of the reflector due to the size restriction, the FB ratio cannot be made a perfect value.

FIG. 9 is a sectional view of an antenna in which a reflector having a radial section is embedded in a dielectric material. Radiating element 11
Electromagnetic waves radiated from are reflected by the parabolic reflector and travel in the front direction as in the case shown in FIG. This principle is the same as in the case of the antenna shown in FIG.

FIG. 10 is a cross-sectional view of an antenna device in which a radiating element is coated with dielectric materials having different dielectric constants according to still another embodiment. Dielectric material 1 covering the radiating element 14
5, 16 have different dielectric constants. The dielectric material 16 is formed in the axial direction with a semicircular cross section of the radiating element, and has a dielectric constant smaller than that of the dielectric material 15. The principle of using a dielectric as a reflector in this embodiment is that the electromagnetic waves are refracted and diffracted when passing through a medium having a different permittivity, and are further reflected. It is considered to have the same principle as the ionosphere (D, E, Es, F1, F2, etc.) in the HF and VHF bands and the electromagnetic shield effect. That is, the electromagnetic wave of the backside component radiated from the radiating element 14 hits the dielectric material 16 having a small dielectric constant and is refracted (electromagnetic wave direction 1
7) or reflect (electromagnetic wave direction 18). This is because the dielectric constant on the input side is ei, the incident angle is tan i, and the dielectric constant on the output side is e at the interface between two substances having different relative dielectric constants.
o and the reflection angle is tan o, tan i /
There is a relationship of tan o = e i / e o. Here, if e o> e i, the reflection angle becomes larger than the incident angle.

In other words, the radio wave entering at the incident angle 21 has a reflection angle of 31 at the boundary surface and is refracted. Also,
A radio wave entering at a somewhat large incident angle 22 is reflected at a reflection angle 32 and travels in the front side direction. This component and the front side component are superimposed to improve the front gain and the FB ratio.

As shown in FIG. 11, when the dielectrics 19a to 19n are concentrically coated with the dielectric constants of which are gradually decreased, the refraction described above is performed stepwise, and the layers are formed in multiple stages. The higher the ratio and the higher the ratio of the relative permittivity, the higher the degree of refraction, and the more the light travels in the front side direction. To reduce the cost, see Fig. 12.
It is also possible to stack the dielectrics 20a to 20n in a slice shape as shown by.

[0029]

As described above, the reflection element is arranged on the human body side, the gain in that direction is reduced, and the radio waves absorbed by the human body are reduced. As a result, the electromagnetic energy absorbed by the human body is reduced. A portable wireless device that suppresses the noise is provided.

By providing the antenna device with directivity, it is possible to increase the gain in the direction effective for transmitting and receiving radio waves. It is also possible to reduce the transmission output (reduce the battery capacity) by the amount of increase in the antenna gain, and as a result, it is possible to reduce the overall size of the portable wireless device.

Further, by appropriately selecting the position and shape of the reflector, the relative permittivity of the dielectric material, the difference in the relative permittivity at the boundary surface, and the position and shape of the thickness, an antenna suitable for the intended frequency and characteristics is obtained. Can be selected.

[Brief description of drawings]

FIG. 1 is a diagram showing an antenna mounting state in a conventional portable wireless device.

FIG. 2 is a diagram showing an appearance of an antenna when a reflecting element is attached.

FIG. 3 is a radiation pattern diagram in a horizontal plane of an antenna having a reflecting element.

FIG. 4 is a radiation pattern diagram in a horizontal plane when the portable wireless device is worn on the waist.

FIG. 5 is a diagram showing an embodiment of the present invention.

FIG. 6 is a radiation pattern diagram in a horizontal plane when the antenna device of the present invention is attached to a portable wireless device.

FIG. 7 is a perspective view showing an antenna device according to another embodiment of the present invention, in which a metal reflector is embedded in a dielectric material covering a radiating element.

8 is a cross-sectional view of the radiating element of the antenna of FIG. 7 in a direction perpendicular to the axis.

FIG. 9 is a cross-sectional view of an antenna in which a reflector having a radial cross section is embedded in a dielectric material.

FIG. 10 is a cross-sectional view of an antenna device in which radiating elements are coated with dielectric materials having different permittivities.

FIG. 11 is a cross-sectional view of an antenna device in the case of being covered concentrically with a dielectric material whose relative dielectric constant gradually increases.

FIG. 12 is a cross-sectional view of an antenna device when dielectrics are stacked in slices.

[Explanation of symbols]

 1 radiating element 2 portable radio device 3 reflecting element 4 coaxial line 5 pedestal 6 housing 7 human body 8 holding base 9 connector 10 reflecting element hole 11 radiating element 12 dielectric material 13 reflector 14 radiating element 15, 16, 19, 20 dielectric material 17,18 Electromagnetic wave traveling direction 21,22 Incident angle 31,32 Reflection angle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eisaburo Kashiwagi 3-20-1 Minamiazabu, Minato-ku, Tokyo Inside Japan Motorola Co., Ltd.

Claims (8)

[Claims] 1. An antenna device comprising a radiating element and a reflecting element, which is fixed to a body of a portable wireless device, wherein a radiating element that emits and receives an electromagnetic wave is separated from a radiating element by a predetermined distance in parallel with an axial direction of the radiating element. An antenna device for a mobile wireless device, comprising: a reflective element that is disposed as a unit; and positioning means that determines a relative position of the reflective element with respect to the mobile wireless device body. 2. The positioning means is a plurality of recesses provided on a circle having the central axis of the radiating element as the center, on the same surface as the surface of the portable wireless device that fixes the radiating element. The antenna device for a portable wireless device according to claim 1, wherein the position of the reflective element is determined by fitting the lower end of the reflective element into the recess. 3. An antenna device comprising a radiating element coated with a dielectric material, wherein a metallic reflector is embedded in the dielectric material in the axial direction of the radiating element. 4. The cross section of the reflecting plate with respect to the direction perpendicular to the axis of the radiating element has a V shape, and the radiating element is located on the narrow-angle side of the reflecting plate. Antenna device. 5. The cross section of the reflecting plate with respect to the direction perpendicular to the axis of the radiating element has a U-shape, and the radiating element is arranged at a position surrounded by the reflecting plate. Antenna device. 6. An antenna device comprising a radiating element coated with a dielectric substance, wherein the dielectric substance coating the radiating element is formed of substances having different permittivities in a direction perpendicular to the axis of the radiating element. An antenna device characterized by. 7. The antenna device according to claim 6, wherein the dielectric material covering the radiating element is arranged such that the dielectric constant decreases toward the outside of the radiating element. 8. The dielectric material covering the radiating element is arranged such that the dielectric constant decreases toward the outer side in the direction perpendicular to the axis of the radiating element.
The antenna device described.