JP3608287B2 - Shielding box with built-in directional antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shielded box with a built-in directional antenna, and in particular, various types for each manufacturer used in J / N-TACS (Table access Communication System), NTT system, PDC system, and PHS (Personal Handyphone System) system. The present invention relates to a shield box with a built-in directional antenna that is used by incorporating a directional antenna in a shield box when measuring transmission output, reception sensitivity, transmission / reception frequency deviation, etc. of a mobile phone terminal.
[0002]
[Prior art]
Various mobile phone terminals for each manufacturer used in J / N-TACS, NTT system, PDC system, etc. are provided with RF connectors for connecting measuring instruments for testing and adjustment.
[0003]
The transmission output, reception sensitivity, transmission frequency deviation, etc. of various mobile phone terminals in tests conducted using this RF connector are published in the specifications, but before or after passing the various mobile phone terminals to general users. In order to check the call sequence in the event of a trouble, an actual measurement as to whether or not the actual function is exhibited or not is performed for each model.
[0004]
In the actual measurement, when various mobile phone terminals were initially marketed, various measurements such as the above-mentioned transmission output, reception sensitivity, and transmission frequency deviation were performed by connecting a measuring instrument to the RF connector with a coaxial cable. It was.
[0005]
However, the digital cordless telephone system enables outdoor and indoor use, installs a large number of wireless base stations that play the role of the main unit outdoors, enables outdoor use, and has recently become commercially available. A cellular phone terminal using the PHS system does not have an RF connector and cannot be connected to a coaxial cable for reasons such as downsizing and cost reduction. For this reason, when performing the above various measurements, it has become impossible to employ a method in which a coaxial cable is connected to a mobile phone terminal and measurement is performed with a measuring instrument. In addition, a measurement request without a coaxial cable has been issued for confirmation during actual use.
[0006]
Therefore, it is necessary to perform various measurements in a space where the measuring instrument side and various mobile phone terminals are not electrically connected. Therefore, a technique is adopted in which radio waves radiated from the antennas of various mobile phone terminals are received by the measurement antenna, and the measurement antenna output is guided to the measuring instrument to perform measurement.
[0007]
In this case, the mobile phone terminal to be tested is installed in the shield box so that the various mobile phone terminals are not affected by the radio base station, and the mobile phone terminal is radiated from the mobile phone terminal in the shield box. A measurement antenna that receives radio waves is also installed in the shield box. A connector is connected to the antenna for measurement, and the antenna output for measurement is sent to the measuring instrument.
[0008]
As the antenna for measurement installed in the shield box, a dipole antenna which is an omnidirectional antenna having a broad directivity is used. FIG. 3 conceptually shows a directional characteristic diagram on a plane perpendicular to both the dipole antenna and a dipole antenna with a reflector applied to the present invention to be described later.
[0009]
Directivity A indicated by a broken line in FIG. 3 is due to a dipole antenna having a broad directivity. In FIG. 3, when the electric field intensity of the beam peak value of the directivity characteristic B is 0 dB, the beam peak value of the directivity characteristic A is −5 dB. That is, the electric field intensity at the beam peak value is 5 dB lower than the directivity characteristic B.
[0010]
Install the measurement dipole antenna with such directivity A in the shield box, connect the measurement dipole antenna to the connector, and connect the connector to the input end of the measuring instrument. This mobile phone terminal is placed in the box so that the antenna of the mobile phone terminal to be measured is parallel to the element of the measurement dipole antenna, and radio waves are emitted from the mobile phone terminal into the shield box. The radio wave is received by a dipole antenna for measurement, and the antenna output is sent to a measuring device via a connector, thereby measuring the transmission power, reception sensitivity, etc. of the cellular phone terminal to be measured.
[0011]
When carrying out such measurement, there is no problem when measuring a mobile phone terminal of the same model, but other models, for example, a mobile phone terminal manufactured by Company A and a company B manufactured by the same nominal value of the specification contents. Even when measuring these mobile phone terminals, differences in antenna directivity may occur depending on the shape of these mobile phone terminals and the difference in antenna. This difference is related to the measurement transmission power and reception sensitivity in space.
[0012]
If the electric field strength with the same beam peak value of the antenna of the mobile phone terminal manufactured by Company A and the mobile phone terminal manufactured by Company B is 10 dBm during the measurement of the transmission output, the mobile phone manufactured by Company A As a result of measuring the transmission output power by placing the terminal and the mobile phone terminal manufactured by Company B at the same position in the shield box, the electric field strength at the peak of the beam of the mobile phone terminal manufactured by Company A is 10 dBm. On the other hand, since the beam peak position of the mobile phone terminal manufactured by Company B is shifted, the electric field strength may be 1 dB lower when viewed from the beam peak of the mobile phone terminal manufactured by Company A. . In such a case, as a result of the measurement of the mobile phone terminal manufactured by Company B, the peak of the beam is deviated, so that the electric field strength is 9 dBm.
[0013]
Therefore, on the measuring instrument side, regarding the cellular phone terminal manufactured by Company B, the nominal value of the transmission output is the same, but the cellular phone terminal manufactured by Company A measures 10 dBm, and the measuring instrument side Thus, the correction of the RF coupling loss is applied assuming that there is a 1 dB coupling loss.
[0014]
Only after this correction of 1 dB, the mobile phone terminal manufactured by Company A and the mobile phone terminal manufactured by Company B will output a transmission output of 10 dBm.
[0015]
On the basis of such preconditions, in order to correct the difference of 1 dB in the transmission output of the mobile phone terminal manufactured by company B to obtain a transmission output of 10 dBm, a correction method for correcting the RF coupling loss, There is a correction method in which the measurement coordinate position of the mobile phone terminal to be measured is changed in the shield box to correct the peak shift amount.
[0016]
Of these two correction methods, in the latter correction method for changing the measurement coordinate position, the beam is measured by shifting the measurement coordinate position of the measurement target in the shield box, that is, the mobile phone terminal manufactured by Company A. At the measurement coordinate position where the peak of 1 is lower by 1 dB, the mobile phone terminal manufactured by Company A and the mobile phone terminal manufactured by Company B can reduce the RF coupling loss to zero.
[0017]
Since the beam peak value is considered to be the same between mobile phone terminals manufactured by AB companies, the measurement coordinate position of the mobile phone terminal manufactured by B company can be shifted to increase the electric field strength. In this case, the same electric field strength is not always obtained. For this reason, it is necessary to shift the mobile phone manufactured by Company A, which has a high electric field strength, to lower the electric field strength and to reduce the RF coupling loss to zero.
[0018]
[Problems to be solved by the invention]
However, in order to make the RF coupling loss constant, in the correction method for changing the measurement coordinate position in the shield box of the mobile phone terminal manufactured by the company A, as shown in the directivity characteristic A of FIG. When using a measurement dipole antenna with a distance of 1 to a position corresponding to a gain of 1 dB, the distance required to laterally shift the measurement position coordinates of the mobile phone terminal manufactured by Company A is from position a to position c. The measurement coordinate position of the mobile phone terminal manufactured by Company A must be changed. That is, it is necessary to change the measurement coordinate position significantly.
[0019]
Thus, changing the measurement coordinate position of the mobile phone terminal manufactured by Company A requires a large measurement table on which the mobile phone terminal is placed, and accordingly, the shape of the shield box also needs to be increased. There is.
[0020]
Conversely, if the measurement coordinate position of the mobile phone terminal manufactured by Company A in the shield box is to be constant, it is necessary to greatly change the RF coupling loss of the mobile phone terminal manufactured by Company B.
[0021]
When the RF coupling loss is increased, the configuration of the RF coupling loss correcting amplifier becomes complicated on the measuring instrument side, which causes a problem of increasing costs.
[0022]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a shield box with a built-in directional antenna according to the present invention includes a shield box that houses a mobile phone terminal to be measured therein, and is housed in the shield box. A directional antenna for measurement that receives a radiated radio wave; and a measurement table formed of an insulating material on which the mobile phone terminal is placed; and the radio wave of the mobile phone terminal placed on the measurement table Each measurement is performed, the peak of directivity is detected, and the measurement coordinate position of the mobile phone terminal is adjusted from the difference in value.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, radio waves radiated from the mobile phone terminal 4 to be measured housed in the shield box 1 are received by the directional antenna 5 for measurement, and the shape of the mobile phone terminal 4 and the difference in antenna are different. Even if the peak position of the beam of the radio wave radiated from the mobile phone terminal 4 is shifted due to the difference in directivity, the directivity characteristics of the measurement directivity antenna 5 are sharp, and the RF coupling loss is reduced by a slight movement of the measurement coordinate position. Make changes small.
[0024]
Next, embodiments of a shield box with a built-in directional antenna according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the configuration of this embodiment. The shield box 1 in FIG. 1 is composed of a shield box main body 1a whose cross-sectional shape is formed in an upward “U” shape, and an upper lid 1b attached to the upper surface of the shield box main body 1a so as to be openable and closable. Yes.
[0025]
The shield box main body 1a and the upper lid 1b are both made of, for example, aluminum, iron, copper, or the like so as to shield radio waves outside the shield box 1 from entering the shield box 1. The radio wave absorber 2 is made of a material that does not reflect the RF output of the internal mobile phone terminal.
[0026]
A measurement table 3 is accommodated in the shield box main body 1a. The measurement table 3 is made of an insulating material such as acrylic. A mobile phone terminal 4 to be measured is placed on the measurement table 3.
[0027]
In the shield box main body 1a, below the measurement table 3, a dipole antenna 5 with a reflection plate for measurement having, for example, an antenna element 5a and a reflection plate 5b is attached as a directional antenna. . The antenna element 5 a of the dipole antenna 5 with a reflector is kept at a predetermined distance from the measurement table 3, and the antenna element 5 a is parallel to the measurement table 3.
[0028]
The feed point of the reflector-equipped dipole antenna 5 is connected to the connector 7 via a feed line 6 made of a coaxial cable or equivalent. The connector 7 is connected to an input end of a measuring instrument (not shown). The measuring instrument measures transmission output, reception sensitivity, transmission frequency deviation, and the like output from the mobile phone terminal 4.
[0029]
Next, the operation of this embodiment will be described. The dipole antenna 5 with a reflecting plate has a sharp directivity with respect to the directional characteristic A as shown by the directional characteristic B in the directional characteristic diagram of FIG.
[0030]
Now, with the top cover 1a of the shield box 1 opened, the mobile phone terminal manufactured by Company A to be measured is stored in the shield box body 1a, placed on the measurement table 3, and the top cover 1a is closed. If a radio wave is radiated from a mobile phone terminal manufactured by company A, the radio wave is received by a dipole antenna 5 with a reflector, and the antenna output is sent to a measuring instrument through a feeder 6 and a connector 7, Measured with a measuring instrument.
[0031]
The result of this measurement will be described with reference to FIG. FIG. 2 conceptually shows a directional characteristic diagram on a plane perpendicular to the antenna by a dipole antenna, as in FIG. 3, and the beam pattern radiated from the mobile phone terminal manufactured by Company A is shown in FIG. Assume that the peak value of the electric field strength is obtained when the measurement result by the measuring instrument is 0 dB as indicated by the directional characteristic A indicated by the solid line in FIG. FIG. 2 conceptually shows, but in reality, the directivity shows an irregular shape that makes an imaginary cloud appear.
[0032]
Next, the upper lid 1a of the shield box 1 is opened, the mobile phone terminal manufactured by Company A is taken out from the shield box main body 1a, the mobile phone terminal manufactured by Company B is placed in the shield box main body 1a, and the measurement table is taken. 3, the mobile phone terminal manufactured by B company is placed at the same measurement coordinate position where the mobile phone terminal manufactured by A company is mounted, and then the upper lid 1 a is closed.
[0033]
In this state, radio waves are emitted from the mobile phone terminal manufactured by B company. The radiated radio wave is received by a dipole antenna 5 with a reflector. The output of the dipole antenna 5 with a reflector is sent to the measuring device through the feeder 6 and the beam pattern radiated from the mobile phone terminal manufactured by the company B is measured by the measuring device.
[0034]
As a result of this measurement, the cellular phone terminal manufactured by Company B differs from the cellular phone terminal manufactured by Company A in the directivity due to the difference in shape, the difference in antenna, and the like. As in the characteristic B, the position where the peak value of the electric field intensity is obtained at 0 dB is assumed to be between 0 ° and 30 °.
[0035]
In this case, in FIG. 2, the directivity characteristics A of the measurement result of the mobile phone terminal manufactured by Company A and the directivity characteristics B of the measurement result of the mobile phone terminal manufactured by Company B are clear. B is displaced laterally by 1 dB with respect to the directivity characteristic A in terms of the measurement coordinate position.
[0036]
Therefore, in order to set the directivity B to the same electric field intensity as the directivity A, the measurement coordinate position of the mobile phone terminal manufactured by the company A on the measurement table 3 is 1 dB laterally as shown from a to b in FIG. It is only necessary to displace and lower the electric field strength. As a result, the amount of displacement is smaller than when a conventional dipole antenna for measurement having a broad directivity is used.
[0037]
In other words, by using the dipole antenna 5 with a reflecting plate, it has a function of reducing the change of the RF coupling loss with a slight movement of the measurement coordinate position.
[0038]
As described above, the measurement coordinate position change and the RF coupling loss when measuring the mobile phone terminal can be reduced. Accordingly, the measurement table 3 in the shield box 1 can be downsized and the RF coupling loss correcting amplifier of the measuring instrument can be used. Can be simplified.
[0039]
In the above description of the embodiment, the case where the dipole antenna 5 with the reflector is used as the directional antenna in the shield box 1 is exemplified. However, the present invention is a dipole antenna 5 with the reflector. The dipole antenna with a reflector is not particularly limited as long as it is a beam antenna having a sharp directivity.
[0040]
【The invention's effect】
As described above, according to the shield box with a built-in directional antenna according to the present invention, a directional antenna having a sharp directivity is accommodated in the shield box, and is radiated from the mobile phone terminal of another model in the shield box. Because radio waves are received, even if there is a difference in directivity due to the shape of the mobile phone terminal and the antenna, even if the measurement coordinate position of the mobile phone terminal moves slightly, the change in RF coupling loss is reduced. The change in the measurement coordinate position of the mobile phone terminal and the RF coupling loss can be reduced, and the change in the measurement coordinate position of the mobile phone terminal between other models and the RF coupling loss can be approximated. The size of the measurement table can be reduced, and the RF coupling loss correction amplifier of the measuring instrument connected to the shield box can be simplified.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a shield box with a built-in directional antenna according to the present invention.
FIG. 2 is a directional characteristic diagram on a plane perpendicular to the antenna of two types of mobile phone terminals at the same position obtained by a dipole antenna.
FIG. 3 is a directional characteristic diagram on a plane perpendicular to a directional antenna applied to a conventional dipole antenna obtained by a dipole antenna and a shield box with a built-in directional antenna according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shield box 1a Shield box main body 1b Upper lid 2 Wave absorber 3 Measurement table 4 Mobile phone main body 5 Dipole antenna with reflector 5a Antenna element 5b Reflector 6 Feed line 7 Connector

Claims (2)

A shield box that houses the mobile phone terminal to be measured,
A directional antenna for measurement that is housed in the shield box and receives radio waves radiated from the mobile phone terminal;
A measurement table formed of an insulating material on which the mobile phone terminal is placed;
Measuring the radio wave of each of the mobile phone terminals placed on the measurement table, detecting the peak of directivity, and adjusting the measurement coordinate position of the mobile phone terminal from the difference in value Shielding box with built-in antenna. 2. The directional antenna according to claim 1 , wherein the directional antenna for measurement is a dipole antenna with a reflector that is connected to a connector for connecting a measuring instrument and receives radio waves radiated from the mobile phone terminal. Built-in shield box.

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