JPH11133079A - Electromagnetic coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact electromagnetic coupling device with accurate reproducibility by providing a metal case with a radio wave absorbing material in the inner circumferential surface, traveling-wave antennas, an isolator, an adding and synthesizing device of radiant electromagnetic waves, etc., and forming a stable and uniform electromagnetic field. SOLUTION: A radio wave absorbing material is glued to the overall area of the inner circumferential surface of a main body metal case in the shape of a square tube. The radio wave absorbing material prevents electromagnetic reflection as well as the occurrence of images such as an inner antenna. Then a lid body to which a radio wave absorbing material is glued in the same way is detachably placed. A portable telephone to be measured is placed in the centerline of the main body case. In the radio wave absorbing material, a plurality of traveling-wave antennas are arranged so as to be located in a circumference at equal distances to the center line of the case to form a concentric circular antenna array. By this constitution, beams from an antenna group (antenna array) formed of traveling waves are focused on the center axis (focal location), and it is possible to specify the coupling factor (antenna factor value) of instrument to be measured at this location. Therefore, after obtaining the antenna factor value through the use of a standard antenna, it is possible to measure the radiant electric power value of the instrument to be measured which radiates unknown electric power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accurately measuring electromagnetic wave power emitted from a radio wave device such as a VHF / UHF band, for example, a portable telephone, and a method for measuring a reception sensitivity characteristic by generating a "field" of an arbitrary electric field intensity. And an electromagnetic wave coupling device for performing the above.

[0002]

2. Related Background Art Conventionally, the following two methods have been known as electromagnetic wave coupling methods. (1) As shown in Fig. 1, an antenna for measurement is installed in a field (anechoic chamber or open site) with a sufficient distance, and this antenna receives the radiated radio wave from the device under test (the device under test). Alternatively, a known method is to transmit a known power signal from the antenna, receive the signal by a device under test, and receive its sensitivity characteristic.

(2) In order to enable measurement in a small space such as in a factory, a method has been considered in which a pseudo-electromagnetic-wave generating device is created to approximate the far-field conditions of the electromagnetic wave.
As the most typical method, as shown in FIG. 2, a TEM mode generator called a TEM cell is known. Most of the existing methods attempt to expand the band used by modifying this basic method.

[0004]

The method shown in FIG. 1 has a disadvantage that it requires a large space. In addition, this method actually emits electromagnetic waves from the device under test (test device), but since the electromagnetic waves radiate in all directions, the device under test must be rotated 360 ° to find the maximum value. In addition, in order to avoid the effect of measurement errors caused by ground reflected waves called height patterns, it was necessary to move the antenna up and down to measure each point carefully to get an overall image. For this reason, an enormous amount of time had to be spent on this operation, and it was hardly possible to enter an industrial product production process for cost reasons.

[0005] Although the method of FIG. 2 can perform approximate measurement indoors, it requires a space of about a small room, and it has been difficult to arrange them in a production line. Not only that,
Since the device to be measured is inserted between the electrodes forming the TEM mode, if the size of the device to be measured changes, it is inevitable that the upper and lower ends of the device to be measured come close to the electrodes, and this ensures measurement reproducibility. There was a difficult problem.

The present invention can reduce the size of a mobile phone or the like on a production line site so that it can be installed on a table, and obtain the accurate reproducibility required for industrial product production.
An object of the present invention is to provide an electromagnetic wave coupling device capable of creating a stable and uniform electromagnetic field area.

[0007]

Means for Solving the Problems In order to generate electromagnetic waves, a conductor wire (antenna) for flowing a current in the air is arranged,
It is well known that when a high-frequency current is applied to the space, an electromagnetic wave is emitted into the space. Generally, in order to efficiently convert the electric power to be inserted into an electromagnetic wave, the length of the conductor wire is adjusted to a high-frequency wavelength to cause resonance.

However, when a plurality of antennas including the antenna of the device under test are mixed in a narrow space, they are coupled to each other, and the total coupling constant with the antenna under test is greatly changed. It was difficult to make. Also, the amount of coupling greatly changes with the distance to the antenna. That is, the amount of coupling is inversely proportional to the distance, but is mixed up to the first to third power terms of the distance.

The present inventor has paid attention to such a point, and as a result of earnest research, has conceived of using an antenna for generating a traveling wave in order to approximate the condition when an electromagnetic wave comes from a long distance in a narrow space. In addition, in order to generate a uniform electromagnetic wave distribution over as wide a space as possible, a plurality of antennas are arranged at an equal distance from a center line, and a relatively uniform electromagnetic field intensity is set with the center point as a neutral point. And succeeded in obtaining the present invention.

That is, the present invention provides a radio wave absorbing member provided on an inner peripheral surface of a metal case, a traveling wave antenna disposed at an equal distance from a center line of the case, and a traveling wave antenna between the traveling wave antennas. An isolator to isolate the effect, a combiner that adds after adjusting the phase of the radiated electromagnetic waves collected by the antenna group, and a unit that reads the added electromagnetic waves as radiated power,
It is characterized by having.

The simplest example of generating a stable and uniform electromagnetic field is to make the radiated field strength from each antenna equal,
What is necessary is just to make each antenna the same phase. In this way, a very stable electric field strength distribution around the center point equidistant from each antenna.

Further, in order to generate a uniform electromagnetic field over a wide range, the number of antennas may be increased and the phase adjustment between the antennas may be performed.

In order to dispose the traveling wave antenna so as to be equidistant from the center line of the case, the traveling wave antenna may be arranged on a circumference equidistant from the center, or a vertical and / or horizontal center line. It is sufficient to dispose them so as to be at the same distance from each other.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a principle view showing an embodiment of the present invention, in which a radio wave absorbing material is stuck over the entire inner peripheral surface of a rectangular cylindrical main body metal case.

The radio wave absorber functions to prevent reflection of electromagnetic waves and at the same time to prevent generation of an image image of an internal antenna or the like. As the radio wave absorber, for example, a ferrite sintered plate can be suitably used.

The body case is also provided with a lid, which has a radio wave absorbing material adhered to the entire inner peripheral surface, in a removable manner.
A mobile phone to be measured is arranged on the center line of the main body case.

A plurality of, preferably three or more, traveling wave antennas are disposed on the radio wave absorbing member so as to be positioned on a circumference equidistant from the center line of the case, as shown in FIGS. 3 and 4. , Forming a concentric antenna array.

In the present invention, the traveling wave antenna is arranged at an equal distance from the center line. However, as long as the traveling wave antennas are approximately equidistant, they need not necessarily be perfectly equidistant.

The traveling wave antenna is an antenna for generating a traveling wave, and what is known as a traveling wave antenna may be used.

With the above configuration, the beam from the antenna group (antenna array) composed of traveling waves is focused on the central axis as shown in FIG. 3 (FIG. 3).
At this point), at which point the coupling coefficient (antenna factor value) of the device under test can be defined.

Therefore, after the antenna factor value is obtained using the standard antenna, the radiated power value of the device under test that radiates unknown power can be measured.

The transmission will be described as an example. As shown in FIG. 4, a mobile phone antenna (DUT antenna) to be measured is used.
The radiated power radiated in four directions is picked up by an antenna array arranged on a concentric circle, the phase is adjusted, and the sum is connected to a measuring instrument via a combiner for measurement.

As shown in FIG. 3, the antennas forming the antenna array are provided with an isolator so as not to affect each other and to make the characteristics of each antenna independent.

In order to add signals by the combiner (adder), the phases must be adjusted, so that the phases of the electromagnetic waves from the respective antennas are adjusted.

The phase can be adjusted by changing the length of the cable or changing the LC. In short, it is only necessary that the phase can be made the same, and the means for adjusting the phase is not particularly limited.

As the power measuring device (measuring device) used in the present invention, for example, a power meter, a spectrum analyzer and the like can be mentioned.

FIG. 5 shows another embodiment of the present invention, in which four sets of traveling wave antennas which are disposed at equal distances from each other when viewed from the front of the main body case are arranged in a set. An example is shown.

With the above configuration, a stable and large electromagnetic field having an elongated width can be formed, so that the portable telephone can be rotated by 90 °, and the polarization characteristics of the telephone antenna can be evaluated. Can be. In addition, it is possible to measure radio wave power or the like of a larger mobile terminal device or the like.

In the above embodiment, the traveling wave antenna is disposed above and below the main body case. Further, the number of one set of antennas arranged at an equal distance from the center line is not particularly limited.

By arranging the antennas as described above and selecting a method of arranging the antenna groups such as the number of sets of antennas, it is possible to synthesize a stable electromagnetic field having relatively free distribution characteristics.

In the above embodiment, in order to expand the distribution in the depth direction, the antennas may be arranged in the same arrangement in the depth direction with their phases adjusted.

In the embodiment shown in FIG.
Although the polarization characteristic can be measured by rotation, a large circular stable electromagnetic field must be formed, and similarly, the size of the apparatus is increased.

Next, a method of measuring radiated power from a mobile phone antenna will be described with reference to FIG. As shown in FIG. 6, most of the electromagnetic wave component radiated from the mobile phone antenna (resonant whip antenna) is distributed in the lateral direction of the antenna (the vertical direction in FIG. 6). Therefore, if reception and addition are performed in this direction, power that is directly proportional to radiation power can be measured.

If the transmitting end of the mobile phone shown in FIG. 6 and the antenna are sufficiently matched, all the transmission power is radiated from the antenna as an electromagnetic wave. As shown in FIG. 7, if the return loss is greater than 20 dB, the returned power is within the error range, so it can be said that the matching is sufficient.

Most of the electromagnetic waves radiated from the rod antenna of the mobile phone are radiated in the circumferential direction perpendicular to the antenna axis. Therefore, if the pickup antenna (traveling wave antenna) is arranged in an array on this circumference, it is possible to induce power proportional to the radiated power.

From the total sum Pa (dBm) of the power, the radiation power [Po (dBm)] of the portable telephone can be obtained by the following equation.

Pt (dBm) = Po (dBm) = Kt (dB) + Pa (dBm) As shown in FIG. 7, Kt (dB) of the above coupling amount is obtained by comparison with a value obtained by directly measuring the reference transmission power. You can ask.

In the embodiment shown in FIG. 6, an attenuator (attenuator) for equalizing the attenuation of the radiated electromagnetic waves collected by each antenna of the antenna group is provided. However, this is not necessary.

According to the present invention, since the sum of the electromagnetic power radiated in all directions is measured, even if the radiation pattern is distorted, the peripheral power is added simultaneously, so that accurate measurement can be performed.

Further, according to the present invention, since the mobile phone antenna to be measured is placed on the center line of the main body box, the distance from this to the concentric antenna array or the opposing antenna array is:
Since the relationship is uniform and extremely simple, measurement reproducibility is extremely good.

Further, according to the present invention, it is not necessary to consider the influence of the difference in the type of the mobile phone antenna to be measured. Since a traveling wave antenna is used, the wave impedance of the center line (measurement position) is the far-field wave impedance (120
π), and the antenna of the device under test is λ
This is because, even with a / 4 type resonance antenna or the like, a change due to coupling with the measurement antenna can be suppressed to a negligible level.

Since the device of the present invention has reversibility, it can be used for both the measurement of reception sensitivity and the device for generating an arbitrary electric field strength without any trouble. This is because the electric field strength can be accurately set only by adding the coefficient (dB) calculated from the antenna factor to the set level value of the connection SG.

Further, according to the present invention, since it can be designed in a compact form that can be placed on a table optimal for a production line, it can be put into practical use as a small, lightweight, easy-to-handle portable type that can be installed in the same row as other measuring instruments.

Further, according to the present invention, since the measuring instrument can be easily taken in and out, extremely good productivity can be secured. This is because there is no change in the internal electric performance even when the device is used with the front cover (the front surface of the device of the present invention) with the shield cover removed.

That is, when used on a production line or the like, accurate measurement can be performed simply by inserting the telephone to be measured or the like into a predetermined position from the front, so that a practical test through the telephone antenna can be performed quickly and in a very short time.

[0046]

According to the present invention, in addition to being small enough to be installed on a table at a production line site of a mobile phone or the like, accurate reproducibility can be obtained, and measuring instruments can be taken in and out. The present invention has solved the problem that it was easy to secure high productivity and could not be solved by this kind of conventional technology, and is therefore an extremely innovative invention.

Further, the apparatus of the present invention does not need to consider the influence of the difference in the antenna type of the mobile phone under test and the like, and can be used without any problem both for the measurement of the reception sensitivity and for the use of the arbitrary electric field strength generator. It has the great advantage of being able to.

[0048]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a conventional electromagnetic wave coupling device.

FIG. 2 is a partially cutaway perspective view showing another example of the conventional electromagnetic wave coupling device.

FIG. 3 is a principle diagram showing an embodiment of the present invention.

FIG. 4 is an operation principle view of the apparatus of the present invention as viewed from the front.

FIG. 5 is a front view showing the principle of another embodiment of the present invention.

FIG. 6 is a principle diagram showing a method of measuring radiated power from a mobile phone antenna.

FIG. 7 is a principle diagram showing a method of directly measuring a reference transmission power.

Claims (7)

[Claims] 1. A radio wave absorbing member provided on an inner peripheral surface of a metal case, a plurality of traveling wave antennas disposed at an equal distance from a center line of the case, and an influence between the traveling wave antennas. An electromagnetic wave coupling device, comprising: an isolator for isolating the electromagnetic waves, a combiner for adjusting the phase of the radiated electromagnetic waves collected by the antenna group and adding the same, and a unit for reading the added electromagnetic waves as radiated power. 2. The electromagnetic wave coupling device according to claim 1, wherein a plurality of said traveling wave antennas are arranged so as to be located on a circumference equidistant from a center. 3. The electromagnetic wave coupling device according to claim 1, wherein the traveling wave antenna is disposed so as to face the vertical and / or horizontal center line at an equal distance when viewed from the front of the case. . 4. The electromagnetic wave coupling device according to claim 1, further comprising an attenuator for equalizing an attenuation amount of radiated electromagnetic waves collected by each antenna of said antenna group. 5. The electromagnetic wave according to claim 1, wherein the radio wave absorbing material is provided on the entire inner peripheral surface of the case to prevent electromagnetic wave reflection and at the same time prevent generation of an image image of an internal antenna or the like. Coupling device. 6. A uniform electromagnetic field is generated on said center line,
2. The device under test is installed in the electromagnetic field, and electromagnetic waves radiated from the device under test are collected by the traveling wave antenna group.
The electromagnetic wave coupling device according to any one of claims 1 to 5, 7. A method for applying an arbitrary signal to the antenna group, generating a uniform electromagnetic field on the center line, installing a device under test on the electromagnetic field, and measuring the sensitivity or characteristics of the device under test. The electromagnetic wave coupling device according to any one of claims 1 to 5.