JP2004056484A - Antenna device for portable radio equipment and portable radio equipment provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small portable telephone antenna having a function for receiving radio waves from a communication satellite and to provide portable radio equipment provided with the small portable telephone antenna. <P>SOLUTION: A second antenna element 2B is arranged in the direction perpendicular to a first antenna element 2A. The first antenna element 2A is connected to an antenna sharing device 32. Meanwhile, the second antenna element 2B is connected to the second terminal 34B of a hybrid circuit 34. The third terminal 34C of the hybrid circuit 34 is connected to a receiving circuit 35. The highpass filter 32B of the antenna sharing device 32 is connected to the fourth terminal 34D of the hybrid circuit 34. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna device for a portable wireless device such as a portable telephone having a function of receiving a radio wave from a communication satellite and a portable wireless device provided with the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in mobile communication services represented by mobile phones and the like, for example, in addition to conventional cellular communication (for example, 800 MHz band and 1.5 GHz band) on the ground, a GPS (Global Positioning System) has been used. The location information service using communication satellites has begun to be deployed. Therefore, as antennas for mobile phones and the like, in addition to a linear antenna (whip antenna) for communication on the ground in a cellular system, a circularly polarized reception antenna in a satellite system is required.
[0003]
Correspondingly, the antenna of the mobile phone or the like includes a circularly polarized planar patch antenna (thin microstrip) as an antenna for receiving a radio wave from a satellite as shown in, for example, Japanese Patent No. 3122017. It has been proposed to use antennas (MSA).
[0004]
In addition, as an antenna of this mobile phone, separately, for example, as described in Japanese Patent Application Laid-Open No. 2000-16433, elements of about ４ wavelength are arranged on both sides of a dielectric substrate in a state orthogonal to each other, A configuration that performs 90-degree phase difference power supply has also been proposed.
[0005]
[Problems to be solved by the invention]
However, in the above-mentioned planar patch antenna for circularly polarized waves, it is necessary to arrange a patch antenna in addition to an antenna of a terrestrial cellular system of a mobile phone, and thus there is a problem that a mounting area of the antenna becomes large. .
On the other hand, in the latter configuration using an approximately quarter-wavelength element, a circularly polarized antenna is composed of two elements arranged in an orthogonal state, and thus there is a problem that the area becomes large.
[0006]
In addition to these problems, when a circularly polarized radio wave from a communication satellite arrives after being reflected or scattered on, for example, a building, the ground, or a tree, the polarization direction of the circularly polarized wave changes. The antenna in the wave direction has a problem that a reception level is reduced depending on a use place and a use form.
[0007]
The present invention solves such a problem, and provides an antenna device for a portable wireless device which can reduce the size of a circularly polarized antenna and improve reception characteristics, and a portable wireless device including the same. The purpose is to:
[0008]
[Means to solve the problem]
An antenna device for a portable wireless device according to the present invention includes: a first antenna element operating in a plurality of frequency bands;
A second antenna element arranged in a direction orthogonal to the first antenna element, and a plurality of feeding units for feeding the first antenna element and the second antenna element, respectively;
Means for setting a predetermined phase difference between signals fed to the first antenna element and the second antenna element.
[0009]
As a result, an antenna of the terrestrial cellular system can be shared as a part of the circularly polarized wave antenna, and there is an effect that the entire antenna for a portable radio can be reduced in size. Also, if the phase difference is set by the means for setting the phase shift so that the reception level is increased, the reception characteristics can be improved.
[0010]
Further, the antenna device for a portable wireless device of the present invention is a phase change unit that delays or advances a phase of a signal supplied to the second antenna element by a predetermined value with respect to the first antenna element,
A reception level detection unit for detecting a reception level;
Means for determining a phase condition of the phase changing means so that the reception level detected by the reception level detection unit is increased.
This has the effect of improving the reception characteristics.
[0011]
Furthermore, the antenna device for a portable wireless device of the present invention includes a first antenna element operating in a plurality of frequency bands,
A second antenna element arranged in a direction orthogonal to the first antenna element;
It is characterized in that a delay line having a wavelength of about 1/4 of a predetermined frequency is provided near the connection between the second antenna element and the first antenna element.
As a result, an antenna of the terrestrial cellular system can be shared as a part of the circularly polarized wave antenna, and there is an effect that the entire antenna for a portable wireless device can be reduced in size.
[0012]
The antenna device for a portable wireless device according to the present invention is characterized in that a helical antenna is used as the antenna element.
This has the effect that the circularly polarized antenna element can be miniaturized.
[0013]
Further, a portable wireless device according to the present invention includes the portable wireless device antenna device according to any one of claims 1 to 4.
This makes it possible to reduce the size of the circularly polarized antenna and improve the reception characteristics as an antenna of a portable wireless device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [First Embodiment]
First, a portable wireless device including the antenna device for a portable wireless device according to the first embodiment will be described with reference to FIGS.
[0015]
FIG. 1 shows a portable wireless device 1 provided with a portable wireless device antenna device according to a first embodiment of the present invention. The portable wireless device 1 is mounted in a state exposed from a housing 1A. First and second antenna elements 2A and 2B and first and second matching circuits 31A and 31B mounted on a printed circuit board 3 provided inside the housing 1A, an antenna duplexer 32, and a cellular system. An antenna device for a portable wireless device including a wireless circuit section 33, a hybrid circuit 34, and a satellite-based receiving circuit 35 is provided.
In this embodiment, in each of the drawings, the direction in which the surface of the housing 3 faces is X, and the directions of Y and Z orthogonal to X are set in a right-handed system.
[0016]
The housing 1A is made of, for example, a resin having a thickness of about 1 mm, and its dimensions are set to 120 mm long and 40 mm wide. Further, a printed circuit board 3 having a length of 115 mm, a width of 35 mm, and a thickness of 1 mm, for example, is disposed inside the housing 1A of the portable wireless device.
[0017]
The first antenna element 2A is formed of, for example, a conductive wire having a diameter of 1 mm. In FIG. 1 which is a plan view when the surface of the housing 1A is set to the upper surface, in FIG. (For example, in FIG. 1, arranged in the Z direction). The first antenna element 2A has a length of about ４ wavelength in an 800 MHz band used in a cellular system on the ground and about ２ wavelength in a 1.5 GHz band used in a satellite system. And is set to, for example, about 90 mm in total length.
[0018]
The first antenna element 2A is connected to a first matching circuit 31A mounted on the printed circuit board 2. The first matching circuit 31A has a function of converting the impedance of the first antenna element 2A to approximately 50Ω in both the 800 MHz band and the 1.5 GHz band.
[0019]
On the other hand, the second antenna element 2B is connected to a second matching circuit 31B disposed on the printed circuit board 3. The second matching circuit 31B matches the impedance of the second antenna element 2B to 50Ω in a frequency band of 1.5 GHz.
[0020]
The printed circuit board 3 is provided with a second antenna element 2B near the upper side of the short side (horizontal side parallel to the Y direction orthogonal to the vertical side parallel to the Z direction) of the housing 1A. The second antenna element 2B is arranged in a direction orthogonal to the first antenna element 2A (for example, the Y direction in FIG. 1). The second antenna element 2B is made of, for example, a conductor having a diameter of 1 mm, and is made of a conductor having a length (about 90 mm) of about 1/2 wavelength in a 1.5 GHz frequency band.
Note that a ground pattern is formed on the printed board 3, and this ground pattern operates as a ground plate for the antenna.
[0021]
The first matching circuit 31A is connected to the antenna sharing device 32. The antenna duplexer 32 includes a low-pass filter 32A that passes radio waves having a frequency of 800 MHz or less, and a high-pass filter 32B that passes radio waves having a frequency of 1.5 GHz or more.
[0022]
Among them, a cellular wireless circuit section 33 is connected to the low-pass filter 32A. On the other hand, the output of the high-pass filter 32B and the output of the second matching circuit 31B are input to the (fourth) terminal 34D and the (second) terminal 34B of the hybrid circuit 34, respectively.
[0023]
The hybrid circuit 34 constitutes a phase difference providing means for setting and providing a predetermined phase difference to a signal supplied to the first antenna element 2A and the second antenna element 2B, and includes a (first) terminal 34A. Is terminated by a terminating resistor 36.
[0024]
Next, FIG. 2 is a diagram showing frequency characteristics of a VSWR (Voltage SWR (Standing Wave Ratio)) in a state where the first antenna element 2A is matched by the first matching circuit 31A. In the figure, as can be seen from the curve (graph) α showing the characteristics of the first antenna element 2A, the resonance frequencies (the frequencies at which the VSWR is minimum) are set to 800 MHz and 1.5 GHz, respectively.
[0025]
Therefore, according to this configuration, a signal obtained by combining the signals received by the first antenna element 2A and the second antenna element 2B with a phase difference of 90 ° by the hybrid circuit 34 is received by the satellite receiving circuit 35. Is input to Thereby, the first antenna element 2A and the second antenna element 2B operate as circularly polarized wave receiving antennas.
[0026]
Next, FIG. 3 shows that the user M of the portable wireless device according to the first embodiment uses the portable wireless device according to the present embodiment to transmit satellite-based service information (for example, GPS (Global Positioning System)). (A position information service using a communication satellite).
Since the service information using the satellite system is generally displayed on the display unit 4 of the housing 1A of the portable wireless device 1, the housing 1A of the portable wireless device 1 is used at an angle close to the horizontal with respect to the ground G. It is assumed that Therefore, it can be seen that the circular polarization characteristics in the X direction are particularly important in the use state shown in FIG.
[0027]
Next, FIG. 4 shows an axial ratio characteristic of a circularly polarized antenna composed of the first antenna element 2A and the second antenna element 2B. Generally, it is desirable that the axial ratio of the circularly polarized antenna is about 6 dB or less.
Here, the axial ratio refers to a ratio (ratio) between the maximum electric field intensity E (max) and the minimum electric field intensity E (min) of (circular) polarization, and is shown in FIG. The vertical axis is 10 times the logarithmic ratio, that is, the amplification degree M (dB)
M = 10 · log [E (max) / E (min)]
Displayed with.
[0028]
Therefore, as can be seen from the curve (graph) β of the axial ratio characteristic shown in FIG. 4, this circularly polarized antenna has an axis (θ) with respect to the first antenna element 2A in the range of approximately 60 ° to 130 °. It is found that the ratio is 6 dB or less, and that good circular polarization characteristics can be exhibited when used in this state.
[0029]
As described above, according to the antenna device for a portable wireless device according to the present embodiment, the main antenna (first antenna element 2A) for the frequency band in the cellular system and the antenna for the satellite system ( A second antenna element 2B) is provided, and is configured to receive a circular polarization of a satellite system by setting a phase difference of 90 ° and synthesizing the signals for feeding them.
The shape and configuration of the second antenna element 2B are not limited to the present embodiment. For example, the second antenna element 2B has a helical structure inside the housing 1A along the width direction of the housing 1A of the portable wireless device 1. The second antenna element 2B may be accommodated. Further, the second antenna element 2B may be built in an appropriate dielectric.
[0030]
[Second embodiment]
Next, a portable wireless device 1 including a portable wireless device antenna device according to a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated. The portable wireless device 1 according to the second embodiment includes a second antenna element 2C different from the first antenna element 2B in the housing 1B instead of the second antenna element 2B in the first embodiment. And a delay line 2D.
[0031]
As shown in FIG. 5, the second antenna element 2C is arranged in a direction orthogonal to the first antenna element 2A and near the upper portion of the short side of the printed circuit board 3. The second antenna element 2C is connected to the first antenna element 2A at a connection point 20.
[0032]
The second antenna element 2C is formed of, for example, a conductive wire having a diameter of 1 mm, and has a total length of about １ ／ wavelength (90 mm) in a 1.5 GHz frequency band. Further, the second antenna element 2C includes the above-described delay line 2D having a total length of about 1/4 wavelength near the connection point 20.
[0033]
The delay line 2D is for reducing the size of the antenna device for a portable wireless device, and is arranged in parallel with the surface of the printed board 3 at a position away from the printed board 3 by, for example, 2 mm.
[0034]
Therefore, with this configuration, the radio wave from the satellite system received by the second antenna element 2C passes through the delay line 2D, so that the first antenna element 2A is set with a phase difference of 90 °. The signal is combined with the radio wave from the satellite system received by the receiver and input to the receiver 35 via the matching circuit 31A and the antenna duplexer 32.
[0035]
Thus, the first antenna element 2A and the second antenna element 2C operate as circularly polarized antennas. At this time, the axial ratio in the X direction is about 4 dB.
[0036]
As described above, according to the antenna device of portable wireless device 1 according to the present embodiment, the main antenna (first antenna element 2A) for the frequency band in the cellular system and the direction orthogonal to the main antenna are used. An antenna for a satellite system (second antenna element 2C) is provided, and the antennas can receive circularly polarized waves by feeding them in common using a delay line 2D.
[0037]
Note that the shape and configuration of the second antenna element 2C are not limited to the description of the present embodiment, and the second antenna element 2C is housed along the width direction of the housing of the portable wireless device as a helical structure, for example. It is desirable. Further, the second antenna element 2C may be built in a dielectric.
[0038]
[Third Embodiment]
Next, a portable wireless device 1 including a portable wireless device antenna device according to a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated. In the portable wireless device 1 of the present embodiment shown in FIG. 6, as a portable wireless device antenna device, inside the housing 1C, in addition to the components in the first embodiment shown in FIG. The configuration is such that a part 38 is added.
[0039]
The switch 37 is a DPDT (double pole-double throw) switch including a first terminal 37A to a fourth terminal 37D. The switch 37 is in a state where the first terminal 37A is short-circuited to the second terminal 37B and the fourth terminal 37D and the third terminal 37C are short-circuited (this is called a “first state”). , The first terminal 37A and the third terminal 37C are short-circuited, and the fourth terminal 37D and the second terminal 37B are short-circuited (this is referred to as a “second state”). Take the state.
[0040]
The second terminal 37B is terminated by a terminating resistor 36. A satellite receiving circuit 35 is connected to the third terminal 37C. The first terminal 37A and the fourth terminal 37D are connected to the first terminal 34A and the third terminal 34C of the hybrid circuit 34, respectively.
[0041]
The control section 38 includes a reception level detection section 38A for detecting a reception level at the antenna and a memory section 38B. The control unit 38 determines the level of the reception level in the reception circuit 35, and controls the switch 37 based on the determination result to appropriately select the first and second states described above. Thereby, the configuration is such that the polarization rotation direction (clockwise or counterclockwise) of the circularly polarized antenna composed of the first antenna element 2A and the second antenna element 2B can be switched.
[0042]
Generally, radio waves from communication satellites are often right-handed circularly polarized waves. However, since the radio wave arrives after being reflected and scattered on a building, the ground, a tree, or the like, the radio wave arriving at the portable wireless device may change its polarization rotation direction. Even if a right-handed circularly polarized wave is transmitted from a communication satellite, the radio wave arriving at the portable wireless device is not limited to the right-handed circularly-polarized wave but may be a left-handed circularly-polarized wave.
[0043]
Here, a case where the first state described above is selected by the control unit 38 will be described.
The electric wave from the communication satellite received by the second antenna element 2B is input to the hybrid circuit 34 through the second matching circuit 31B.
On the other hand, the radio wave from the satellite received by the first antenna element 2A is input to the hybrid circuit 34 through the first matching circuit 31A and the antenna duplexer 32.
In this case, the electric wave received by the second antenna element 2B is set by the hybrid circuit 34 in a state where the electric wave received by the first antenna element 2A is advanced by 90 °.
[0044]
FIG. 7A shows the directivity of right-handed and left-handed circularly polarized components of the antenna device for a portable wireless device in the first state.
In FIG. 7, a curve (graph) γ1 indicates the XZ plane directivity of the right-handed circularly polarized wave component. On the other hand, a curve (graph) γ2 represents the XZ plane directivity of the left-hand circularly polarized wave component. The same applies to the curves (graphs) δ1 and δ2 in FIG.
Here, the X direction on the curve (graph) indicates the surface direction where the display unit is provided on the housing 1A of the portable wireless device 1, and the Z direction indicates the zenith direction.
[0045]
As can be seen from the graph shown in FIG. 7, that is, the curves γ1 and γ2, when the first state is selected, the polarization component in the X direction is such that the left-hand circular polarization component is a right-hand circular polarization. It was confirmed to be higher than the component by 20 dB or more.
[0046]
On the other hand, as shown in FIG. 8, when the second state is selected, the radio wave received by the first antenna element 2A becomes the radio wave received by the second antenna element 2B. Are set in a state where the phase is advanced by 90 °. In this state, as shown in the figure, it was confirmed that the right-handed circular polarization component of the X-direction polarization component was higher than the left-handed circular polarization component by 8 dB or more.
[0047]
From this, even when the polarization rotation direction fluctuates due to a change in the environment around the user of the portable wireless device 1, it is possible to perform polarization diversity by switching the switch 37, thereby achieving high reception. Quality can be ensured.
[0048]
As described above, the circularly polarized antenna device for a portable wireless device according to the third embodiment has the position of the first antenna element 2A and the second antenna element 2B by the hybrid circuit 34 and the switch 37. By inverting the phase difference, polarization diversity can be performed and reception quality (reception characteristics) can be improved.
[0049]
【The invention's effect】
As is apparent from the above description, according to the present invention, a first antenna element operating in a plurality of frequency bands, a second antenna element arranged in a direction orthogonal to the first antenna element, A plurality of feeding units for feeding the first antenna element and the second antenna element, respectively, and means for setting a predetermined phase difference to a signal fed to the first antenna element and the second antenna element are provided in the antenna device. Since the antenna of the terrestrial cellular system can be used as a part of the receiving antenna of the circularly polarized wave of the satellite system, there is an effect that the whole antenna device for the portable radio can be downsized.
[0050]
Further, according to the present invention, for example, a circularly polarized radio wave from a communication satellite is reflected or scattered on a building, the ground, a tree, or the like, so that the polarization rotation direction of the circularly polarized light fluctuates (fading). Even if it occurs, polarization diversity for inverting the phase difference between the two antennas is performed, and this can be compensated or reduced to improve the reception quality (reception characteristics).
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a portable wireless device including an antenna device for a portable wireless device according to a first embodiment of the present invention.
FIG. 2 is a graph showing frequency characteristics of VSWR in the first antenna element of the present invention.
FIG. 3 is an explanatory diagram illustrating a state when a user uses the antenna device for a portable wireless device according to the first embodiment of the present invention.
4A is a graph showing an axial ratio characteristic of the portable wireless device antenna device according to the first embodiment of the present invention, and FIG. 4B is a diagram showing a portable wireless device equipped with the antenna and each of XYZ. It is explanatory drawing which shows the relationship with a component.
FIG. 5 is a block diagram illustrating a configuration of a portable wireless device including a portable wireless device antenna device according to a second embodiment of the present invention.
FIG. 6 is a block diagram illustrating a configuration of a portable wireless device having a portable wireless device antenna device according to a third embodiment of the present invention.
FIG. 7A is a graph showing the directions of right-handed and left-handed circularly polarized waves in the first state in the portable radio antenna device according to the third embodiment of the present invention, and FIG. FIG. 3 is an explanatory diagram illustrating a relationship between a portable wireless device including an antenna device and each component of XYZ.
FIG. 8 is a graph showing the directivity of right-handed and left-handed circularly polarized waves in the second state in the portable wireless device antenna device according to the third embodiment of the present invention.
[Explanation of symbols]
1A, 1B, 1C
Case 2A (of portable radio) First antenna element 2B, 2C
Second antenna element 2D Delay line 20 Connection point 3 Printed circuit board 31A First matching circuit 31B Second matching circuit 32 Antenna duplexer 32A Low-pass filter 32B High-pass filter 33 Cellular wireless circuit section 34 Hybrid circuit ( Phase difference setting means)
36 50Ω resistor 34A First terminal 34B Second terminal 34C Third terminal 34D Fourth terminal 35 Satellite-based receiving circuit 4 Display unit 37 Switch 37A Fifth terminal 37B Sixth terminal 37C Seventh terminal 37D Eighth terminal 38 Control unit 38A Reception level detection unit 38B Memory unit G Ground S Communication satellite α First graph (VSWR frequency characteristic of first antenna element 2A)
β 2nd graph (axial ratio of antenna for portable radio)
γ1 Directivity of right-hand circularly polarized wave (first state)
γ2 Left circularly polarized wave directivity (first state)
δ1 Directivity of right-handed circularly polarized wave (second state)
δ2 Directivity of left-hand circularly polarized wave (second state)

Claims (5)

A first antenna element operating in a plurality of frequency bands;
A second antenna element arranged in a direction orthogonal to the first antenna element, and a plurality of feeding units for feeding the first antenna element and the second antenna element, respectively;
Means for setting a predetermined phase difference between signals fed to the first antenna element and the second antenna element. Phase changing means for delaying or advancing a phase of a signal supplied to the second antenna element with respect to the first antenna element by a predetermined value,
A reception level detection unit for detecting a reception level;
2. The portable radio device antenna device according to claim 1, further comprising: means for determining a phase condition of said phase changing means so that the reception level detected by said reception level detection unit becomes high. A first antenna element operating in a plurality of frequency bands;
A second antenna element arranged in a direction orthogonal to the first antenna element;
An antenna device for a portable wireless device, comprising: a delay line having a wavelength of about 1/4 wavelength of a predetermined frequency provided near a connection between the second antenna element and the first antenna element. The antenna device for a portable wireless device according to claim 1, wherein a helical antenna is used as the antenna element. A portable wireless device comprising the portable wireless device antenna device according to any one of claims 1 to 4.

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