JPH09236628A - Shield box with built-in directional antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield box with built-in directional antenna wherein installation coordinate position and RF bonding loss of portable telephone terminal with other types are approximated, a measurement table in a shield box is miniaturized and an RF banding lass compensating amplifier of a measurement device is simplified. SOLUTION: A measurement table 3 of insulation material is housed in a shield box 1 formed out of electric wave absorber 2, and on the measurement table 3, a sample portable telephone terminal 4 is mounted on a measurement coordinate position, and a dipole antenna 5 with reflecting plate provided with an antenna element 5a and a reflecting plate 5b is assigned under the measurement table 3, and electric wave emitted by the portable telephone terminal 4 is received with a dipole antenna 5 with reflecting plate, and the output is measured with a measurement device through a feeder line 6 and a connector 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional antenna built-in shield box, and more particularly to a J / N-TAC.
S (Table access Communication System), NTT system, PDC system, PHS (Personal Handy phone System)
Directional antenna that is used by incorporating a directional antenna in the shield box when measuring the transmission output, reception sensitivity, transmission / reception frequency deviation, etc. of various mobile phone terminals of each manufacturer used in the m) method. Regarding the built-in shield box.

[0002]

2. Description of the Related Art J / N-TACS, NTT system, PDC
Various mobile phone terminals of each manufacturer used in the method and the like are provided with RF connectors for connecting measuring instruments for testing and adjustment.

The transmission output, reception sensitivity, transmission frequency deviation, etc. of various portable telephone terminals in the test conducted using this RF connector are disclosed in the specifications, but before the various portable telephone terminals are handed to general users or In case of trouble after handing over, in order to check the call sequence, it is actually measured for each model whether or not it actually exhibits the function according to the published value.

At the time of actual measurement, when various mobile phone terminals were put on the market, various measuring devices such as the above-mentioned transmission output, reception sensitivity, and transmission frequency deviation were connected by connecting a measuring instrument to the RF connector with a coaxial cable. I was taking measurements.

However, the digital cordless telephone system enables outdoor and indoor use, and a large number of wireless base stations serving as a base unit are installed outdoors to enable outdoor use, which will soon be commercially available. The mobile phone terminal based on the PHS method, which has reached the above, does not have an RF connector and cannot be connected to a coaxial cable because of downsizing and cost reduction. For this reason, it has become impossible to employ a method of connecting a coaxial cable to a mobile phone terminal and measuring with a measuring instrument when performing the above-described various measurements.
In addition, there is a request for measurement without a coaxial cable for confirmation during actual use.

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 method is adopted in which radio waves radiated from the antennas of various mobile phone terminals are received by a measurement antenna and the output of the measurement antenna is guided to a measuring instrument for measurement.

In this case, the mobile phone terminals to be tested are installed in the shield box so that the various mobile phone terminals are not affected by the radio base station. A measurement antenna for receiving the radiated radio waves is also installed in the shield box. A connector is connected to the measuring antenna to send the measuring antenna output to the measuring instrument.

A dipole antenna, which is an omnidirectional antenna having a broad directivity, is used as the measurement antenna installed in the shield box. FIG.
FIG. 3 is a conceptual illustration of 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 described later.

The directional characteristic A shown by the broken line in FIG. 3 is due to a dipole antenna with broad directivity. In FIG. 3, assuming that the electric field strength of the beam peak value of the directivity characteristic B is 0 dB, the beam peak value of the directivity characteristic A is −5 d.
B. That is, the electric field strength of the beam peak value is 5 dB lower than the directivity characteristic B.

A measuring dipole antenna having such a directional characteristic A is installed in a shield box,
Connect the dipole antenna for measurement to the connector, and connect the connector to the input end of the measuring instrument.
This mobile phone terminal is placed so that the antenna of the mobile phone terminal to be measured is parallel to the element of the dipole antenna for measurement inside the box, and the radio wave is emitted from the mobile phone terminal into the shield box. This radio wave is received by a dipole antenna for measurement, and the antenna output is sent to a measuring instrument via a connector to measure the transmission power and reception sensitivity of the mobile phone terminal to be measured.

In carrying out such a measurement, there is no problem in the case where the same type of mobile phone terminal is measured, but with another model, for example, a mobile phone terminal manufactured by the same company A with the same nominal value of specifications. Even when measuring the mobile phone terminals manufactured by Company B, the directivity of the antenna may differ due to the shape of these mobile phone terminals and the difference in the antennas. This difference is related to the transmission power and the reception sensitivity of the measurement in space.

If it is assumed that the beam peak values of the antennas of the mobile phone terminal manufactured by the A company and the mobile phone terminal manufactured by the B company are similar to each other during the measurement of the transmission output and the electric field strength is 10 dBm, the manufacture by the A company is performed. As a result of measuring the transmission output power of the mobile phone terminal manufactured by Company B and the mobile phone terminal manufactured by Company B at the same position in the shield box, the peak electric field intensity of the beam of the mobile phone terminal manufactured by Company A is 10d.
While the beam peak position of the mobile phone terminal manufactured by Company B is deviated from Bm, the electric field strength is 1 dB lower when viewed from the beam peak of the mobile phone terminal manufactured by Company A. Sometimes 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.

Therefore, on the measuring instrument side, regarding the mobile phone terminal manufactured by company B, although the specification nominal value of the transmission output is the same, even though the mobile phone terminal manufactured by company A is 10 dBm, it is measured as 9 dBm, RF on the measuring instrument side
The correction called the coupling loss is applied assuming that there is a 1 dB coupling loss.

For the first time after applying this correction of 1 dB, both the mobile phone terminal manufactured by the company A and the mobile phone terminal manufactured by the company B are 10d.
It is supposed to output the transmission output of Bm.

Based on these prerequisites, the difference of 1 dB in the transmission output of the mobile phone terminal manufactured by Company B is corrected to 10
A correction method for correcting the above RF coupling loss in order to obtain a transmission output of dBm, and a correction for correcting the peak shift amount by changing the measurement coordinate position of the mobile phone terminal to be measured in the shield box. There is a method.

Of the two correction methods, in the latter case of changing the measurement coordinate position, the measurement coordinate position of the object to be measured, that is, the mobile phone terminal manufactured by A company is shifted in the shield box. As a result, the RF coupling loss can be set to 0 for both the mobile phone terminal manufactured by A company and the mobile phone terminal manufactured by B company at the measurement coordinate position where the beam peak is lowered by 1 dB.

Since the peak value of the beam is assumed to be the same between the mobile phone terminals manufactured by A and B, it is possible to shift the measurement coordinate position of the mobile phone terminal manufactured by B company to increase the electric field strength. In the case of an actual machine, the electric field strength is not always the same. Therefore, it is necessary to shift the mobile phone manufactured by Company A, which has a large electric field strength, to reduce the electric field strength and reduce the RF coupling loss to zero.

[0018]

However, in order to make the RF coupling loss constant, the correction method of changing the measurement coordinate position in the shield box of the mobile phone terminal manufactured by A company uses the directivity characteristic A shown in FIG. As shown in, when a measuring dipole antenna having broad directional characteristics is used, it is necessary to laterally displace the measurement position coordinates of the mobile phone terminal manufactured by Company A by an amount corresponding to a gain of 1 dB. As for the distance, the measurement coordinate position of the mobile phone terminal manufactured by Company A must be changed from the position a to the position c. That is, it is necessary to greatly change the measurement coordinate position.

As described above, in order to largely change the measurement coordinate position of the mobile phone terminal manufactured by Company A, the measurement table on which the mobile phone terminal is mounted must be enlarged, and the shape of the shield box is accordingly increased. Need to be bigger.

On the contrary, in order to make the measurement coordinate position of the mobile phone terminal manufactured by A company within the shield box constant, it is necessary to greatly change the RF coupling loss of the mobile phone terminal manufactured by B company.

When the RF coupling loss is increased, there is a problem that the structure of the RF coupling loss correcting amplifier becomes complicated on the measuring instrument side, which causes a cost increase.

[0022]

In order to solve the above problems, a shield box with a directional antenna according to the present invention includes a shield box 1 for accommodating a mobile phone terminal 4 to be measured, and the shield box. A directional antenna 5 for measurement, which is housed in the box 1 and receives radio waves radiated from the mobile phone terminal 4, is provided.

[0023]

According to the present invention, the radio wave radiated from the mobile phone terminal 4 to be measured, which is housed in the shield box 1, is received by the directional antenna 5 for measurement, and the mobile phone terminal 4 is received. Even if the peak position of the beam of the radio wave radiated from the mobile phone terminal 4 is deviated due to the difference in the directivity due to the shape of the
Has a sharp directional characteristic, and changes in the RF coupling loss are reduced by a slight movement of the measurement coordinate position.

Next, an embodiment of the shield box with a directional antenna according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view showing the configuration of this embodiment. The shield box 1 in FIG. 1 is composed of a shield box body 1a having a U-shaped cross section and an upper lid 1b attached to the upper surface of the shield box body 1a so as to be openable and closable. There is.

The shield box body 1a and the upper lid 1
b is made of, for example, a metal such as an aluminum material, an iron material, or a copper material in order to shield radio waves outside the shield box 1 from entering the shield box 1, and the radio wave absorber 2 is It is made of a material that does not reflect the RF output of the internal mobile phone terminal.

A measurement table 3 is housed in the shield box body 1a. The measurement table 3 is made of, for example, an insulating material such as acrylic. The mobile phone terminal 4 to be measured is placed on the measurement table 3.

In the shield box body 1a,
Below the measurement table 3, as a directional antenna, for example, a dipole antenna 5 with a reflecting plate for measurement having an antenna element 5a and a reflecting plate 5b is attached. The antenna element 5a of the dipole antenna 5 with a reflector is kept at a predetermined distance from the measurement table 3, and the antenna element 5a is parallel to the measurement table 3.

The feed point of the dipole antenna 5 with a reflector is connected to the connector 7 via a feed line 6 of a coaxial cable or its equivalent. Connector 7
Is connected to the input end of a measuring device (not shown). The measuring device measures the transmission output, the reception sensitivity, the transmission frequency deviation, etc. output from the mobile phone terminal 4.

Next, the operation of this embodiment will be described. The dipole antenna 5 with a reflector is the reflector 5
By attaching a, the directivity is sharp with respect to the directivity A as shown by the directivity B in the directivity diagram of FIG.

Now, the upper lid 1a of the shield box 1 is opened, the mobile phone terminal manufactured by the company A manufactured to be measured is stored in the shield box main body 1a, placed on the measurement table 3, and the upper lid 1a is closed. In this state, if a radio wave is radiated from the mobile phone terminal manufactured by Company A, this radio wave is received by the dipole antenna 5 with a reflection plate, and its antenna output is fed to the measuring instrument through the feeder line 6 and the connector 7. It is sent out and measured by a measuring instrument.

The result of this measurement will be described with reference to FIG. Similar to FIG. 3, FIG. 2 conceptually shows a directional characteristic diagram on a plane perpendicular to the antenna by the dipole antenna, and the beam pattern emitted from the mobile phone terminal manufactured by A company is It is assumed that the peak value of the electric field strength is obtained when the measurement result by the measuring device is 0 dB as in the directional characteristic A shown by the solid line in FIG. Although FIG. 2 shows conceptually, the directivity actually shows an irregular shape that makes us imagine a floating cloud.

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 body 1a, and the mobile phone terminal manufactured by Company B is put in the shield box body 1a. After mounting the mobile phone terminal manufactured by company B on the measurement table 3 at the same measurement coordinate position where the mobile phone terminal manufactured by company A was mounted, the upper lid 1a is closed.

In this state, radio waves are emitted from the mobile phone terminal manufactured by company B. The radiated radio wave is received by the dipole antenna 5 with a reflector. The output of the dipole antenna 5 with a reflector is sent to the measuring instrument through the feeder 6, and the measuring instrument measures the beam pattern emitted from the mobile phone terminal manufactured by company B.

As a result of the measurement, the directivity of the mobile phone terminal manufactured by the company B differs from that of the mobile phone terminal manufactured by the company A due to a difference in shape, a difference in antenna, and the like.
It is assumed that the position where the peak value of the electric field intensity is obtained at 0 dB is between 0 ° and 30 ° as indicated by the directional characteristic B indicated by the broken line in.

In this case, as shown in FIG. 2, the directivity characteristic A of the measurement result of the mobile phone terminal manufactured by the company A and the directivity characteristic B of the measurement result of the mobile phone terminal manufactured by the company B are compared. The directivity characteristic B is displaced laterally by 1 dB with respect to the directivity characteristic A when converted into the measurement coordinate position.

Therefore, in order to make the directivity characteristic B the same electric field strength as the directivity characteristic A, the measurement coordinate position of the mobile phone terminal manufactured by the company A is moved by 1 dB horizontally on the measurement table 3 from a to b in FIG. It is sufficient to displace as shown to reduce the electric field strength. As a result, the amount of displacement is smaller than in the case where a conventional dipole antenna for measurement having broad directional characteristics is used.

In other words, by using the dipole antenna 5 with a reflector, it has a function of reducing the change in the RF coupling loss with a slight movement of the measurement coordinate position.

As described above, it is possible to reduce the measurement coordinate position change and the RF coupling loss when measuring the mobile phone terminal, and accordingly, the measurement table 3 in the shield box 1 is downsized and the RF coupling loss of the measuring instrument. The correction amplifier can be simplified.

In the description of the above embodiment, as the directional antenna in the shield box 1,
The case where the dipole antenna 5 with a reflector is used is illustrated, but the present invention is not limited to the dipole antenna with a reflector.
The beam antenna is not limited to the antenna 5, but may be a dipole antenna with a reflector, as long as it is a beam antenna having a sharp directional characteristic.

[0040]

As described above, according to the shield box with a built-in directional antenna of the present invention, a directional antenna having a sharp directivity is housed in the shield box, so that the shield box can be shielded from a mobile phone terminal of another model. Since the radio waves radiated inside are received, even if the directivity difference due to the shape of the mobile phone terminal or the difference in the antenna appears, even if the measurement coordinate position of the mobile phone terminal moves slightly, the RF coupling loss Can be reduced, the measurement coordinate position change of the mobile phone terminal and the RF coupling loss can be reduced, and the measurement coordinate position change and the RF coupling loss of the mobile phone terminal between other models can be approximated. The measurement table in the shield box can be downsized, and the RF coupling loss correction amplifier of the measuring instrument connected to the shield box can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a shield box with a directional antenna according to the present invention.

FIG. 2 is a directional characteristic diagram obtained by a dipole antenna on a plane perpendicular to the antennas of two types of mobile phone terminals at the same position.

FIG. 3 is a directional characteristic diagram on a plane perpendicular to the directional antenna applied to the conventional dipole antenna obtained by the dipole antenna and the shield box with a directional antenna according to the present invention.

[Explanation of symbols] 1 shield box 1a shield box body 1b upper lid 2 radio wave absorber 3 measurement table 4 mobile phone body 5 dipole antenna with reflector 5a antenna element 5b reflector 6 feeder line 7 connector

Claims (2)

[Claims] 1. A shield box (1) for accommodating a mobile phone terminal (4) to be measured inside; and a shield box (1) housed in the shield box (1) and radiated from the mobile phone terminal (4). A shield box with a built-in directional antenna, comprising: a directional antenna (5) for receiving radio waves for measurement. 2. The shield box with a directional antenna according to claim 1, wherein the shield box (1) is provided.
Is connected to the measuring table (3) made of an insulating material on which the mobile phone terminal (4) is placed and the connector (7) for connecting the measuring device, and the radio wave radiated by the mobile phone terminal (4) is emitted. A shield box with a built-in directional antenna, which has a built-in dipole antenna (5) with a reflector for receiving signals.