JPH10213614A - Method and device for measuring electromagnetic wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure an intensity of an electromagnetic wave emitted from an object to be measured by removing influence of an electromagnetic wave emitted from an object which is not to be measured. SOLUTION: Each of electromagnetic waves emitted from a device-under-test 10 and a device 11 which is not used in testing is received by antennas 5, 7 to be transmitted to antenna connection terminals 2, 3 via electric wires 4, 6, respectively. A waveshape synthesizing section 1 shifts a phase angle of one of the electromagnetic wave signals inputted to the antenna connection terminals 2, 3 by 180 degree, and synthesizes both of the signals, then the intensity of the target wave is measured in accordance with the amplitude of the wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the intensity of electromagnetic waves radiated from portable communication terminals such as portable telephones and transceivers or general electronic equipment.

[0002]

2. Description of the Related Art When measuring the intensity of an electromagnetic wave radiated from an object to be measured indoors, it is necessary to prevent the electromagnetic wave radiated by an object which is not the object to be transmitted from passing through the wall surface and to make the electromagnetic wave radiated from the object to be measured be measured on the wall surface. It is measured in an anechoic chamber made so that it does not reflect at In this case, much expense is required to install the anechoic chamber. Furthermore, an electromagnetic wave radiated from a measurement object that cannot be brought into an anechoic chamber cannot be measured.

On the other hand, when measuring the intensity of electromagnetic waves outdoors, there is no problem caused by the measurement object as in the case of measurement in an anechoic chamber, but only the electromagnetic waves radiated from the measurement object are received. There is a possibility that an accurate antenna cannot be measured by receiving an electromagnetic wave radiated from an object that is not a measurement target, for example, a broadcast wave radiated from an antenna of a broadcasting station. Therefore, when measuring outdoors, it is necessary to confirm that electromagnetic waves radiated from an object that is not a measurement target, such as broadcast waves, are not flying or that the intensity is sufficiently small.

FIG. 6 is a block diagram showing a configuration of a conventional electromagnetic wave intensity measuring device. In the figure, reference numeral 9 denotes an electromagnetic wave intensity measuring section which displays the waveform of an electromagnetic wave and measures the intensity of the electromagnetic wave signal from the amplitude thereof, for example, using an electric field intensity measuring instrument and a spectrum analyzer capable of selecting a reception frequency. The electromagnetic wave intensity measuring unit 9 includes an antenna connection terminal 2 for connecting an antenna. The feeder line 4 is connected to the antenna connection terminal 2.
The antenna 5 is connected via the. The electromagnetic wave received by the antenna 5 is provided to the antenna connection terminal 2 via the feed line 4. The electromagnetic wave intensity measuring section 9 measures the intensity of the electromagnetic wave signal applied to the antenna connection terminal 2 from the amplitude of the waveform.

On the other hand, there are a test device 10 and a non-test device 11 as an electromagnetic wave radiation source to be measured and an electromagnetic wave radiation source not to be measured, respectively. The non-test equipment 11 is an electromagnetic wave radiation source that is farther from the test equipment 10 when viewed from the antenna 5 and emits a relatively high-level electromagnetic wave, for example, a transmitting antenna of a broadcasting station. During a time period when the electromagnetic wave radiated from the non-test equipment 11 is flying, the antenna 5 receives the electromagnetic waves radiated from both the test equipment 10 and the non-test equipment 11 and Accurate measurement of emitted electromagnetic waves cannot be performed.

[0006]

As described above, in a frequency band in which a broadcast wave or a communication wave of wireless communication exists, electromagnetic waves to be received are adversely affected as long as they fly in space. The accurate measurement cannot be performed.

The present invention has been made based on such a background, and removes the influence of an electromagnetic wave radiated from an object that is not a measurement target from a received waveform to obtain a waveform of the electromagnetic wave radiated from the measurement target. Accordingly, it is an object of the present invention to provide an electromagnetic wave intensity measuring method and an apparatus capable of accurately measuring the intensity and not restricting the use form indoors or outdoors.

[0008]

According to a first aspect of the present invention, there is provided a method for measuring the intensity of an electromagnetic wave, wherein the electromagnetic wave is received simultaneously by two antennas, and the phase angle of the electromagnetic wave received by one antenna is set to 18
The phase is shifted by an odd number of 0 degrees or 180 degrees, the waveform and the waveform of the electromagnetic wave received by another antenna are combined, and the intensity of the electromagnetic wave is measured from the magnitude of the amplitude of the combined waveform. An electromagnetic wave intensity measuring method according to a second invention is characterized in that an electromagnetic wave absorber is provided between an electromagnetic wave radiation source and one antenna. An electromagnetic wave intensity measuring apparatus according to a third aspect of the present invention outputs two input terminals to which an electromagnetic wave signal is to be input, and shifts the phase angle of the electromagnetic wave signal supplied to one of the input terminals by 180 degrees or an odd multiple of 180 degrees. Means for synthesizing an output signal of the means and an electromagnetic wave signal applied to the other input terminal, and synthesizing and outputting the resultant signal. It is characterized by being measured. An electromagnetic wave intensity measuring apparatus according to a fourth aspect of the present invention includes a phase shifter that outputs a phase angle of an electromagnetic wave signal given to one of the input terminals in accordance with a phase angle of the electromagnetic wave signal given to the other input terminal. It is characterized by having. An electromagnetic wave intensity measuring apparatus according to a fifth aspect of the present invention includes an amplifying / attenuating means for outputting the amplitude of an electromagnetic wave signal given to one of the input terminals in accordance with the amplitude of the electromagnetic wave signal given to the other input terminal. It is characterized by the following.

The electromagnetic wave intensity measuring method according to the first invention and the electromagnetic wave intensity measuring device according to the third invention are simultaneously received by two antennas having different electromagnetic wave intensity characteristics and different distances from an electromagnetic wave radiation source. Based on the difference between the amplitudes of the received waveforms, the intensity of the electromagnetic wave radiated from the desired measurement target is measured, excluding the influence of the electromagnetic wave radiated from the object that is not the measurement target.

In general, the intensity (energy) of an electromagnetic wave propagating (flying) near the ground surface like a terrestrial broadcast wave is:
It becomes smaller in inverse proportion to the square of the distance from the electromagnetic wave radiation source to the measurement point. Among them, the electric field component and the magnetic field component each become smaller in inverse proportion to the distance. That is, there is a characteristic that the decreasing tendency is large near the electromagnetic wave radiation source and becomes smaller as the distance from the electromagnetic wave radiation source increases. FIG. 4 is a graph showing the intensity characteristics of the electromagnetic wave based on the electric field intensity. In the figure, the horizontal axis and the vertical axis respectively represent the distance from the electromagnetic wave radiation source to the measurement point and the measured electric field strength. As shown in the figure, the gradient of the characteristic curve at point A (distance 10 m) and the gradient of the characteristic curve at point B (distance 100 m) are gentler.

That is, a small difference in the distance between the measurement points near the electromagnetic wave radiation source appears as a large difference in the intensity of the electromagnetic wave to be measured, and at a place sufficiently far from the electromagnetic wave radiation source, some difference between the measurement points is small. Even if there is a difference in the distance, it hardly appears in the difference in the intensity of the measured electromagnetic waves. Also, the intensity of the electromagnetic wave measured sufficiently far away from the electromagnetic radiation source is negligibly small compared to that near the electromagnetic radiation source.

In accordance with the intensity characteristics of the electromagnetic wave, two antennas are provided in the vicinity of the object to be measured, respectively, and the amplitude of one received waveform is subtracted from the amplitude of one received waveform, ie, one received waveform is obtained. 180 degrees or 180 degrees
By combining this with the other received waveform with an odd multiple of the degree, the waveform equivalent to the waveform of the electromagnetic wave radiated from the object not being measured is removed from the received waveform, and the waveform of the electromagnetic wave radiated from the measured object is removed. It can be extracted.

FIG. 5 is an explanatory diagram for explaining a process of synthesizing a received waveform. The environment for measuring electromagnetic waves is as follows. An electromagnetic wave intensity measuring device in which two antennas are connected near the object to be measured is installed. Also, far enough away,
There is an object that is not the object of measurement and emits electromagnetic waves.
That is, since the two antennas are sufficiently far away from the object that is not the object to be measured, the waveforms of the electromagnetic waves radiated from the object that is not the object to be measured and received by the respective antennas are substantially the same. In addition, the two antennas are installed at positions far from the object to be measured. Therefore, a clear difference occurs between the received waveforms.

In FIG. 1, W4 represents a waveform of an electromagnetic wave received by an antenna (hereinafter referred to as an antenna An1) which is closer to an object to be measured among two antennas. W5 represents the waveform of an electromagnetic wave received by another antenna (hereinafter referred to as antenna An2). W1 represents the waveform equivalent of the electromagnetic wave radiated from the object that is not the measurement target and is included in the waveforms W4 and W5. W2 and W3 are the waveform W4 received by the antenna An1 and the waveform W5 received by the antenna An2, respectively.
Represents the waveform equivalent of the electromagnetic wave radiated from the measurement object included in the measurement target. The difference between W2 and W3 is caused by the difference in distance between each antenna receiving the electromagnetic wave and the object to be measured.

The waveform W6 is obtained by shifting the phase angle of the waveform W5 by 180 degrees. Equivalent waveform W of the electromagnetic wave radiated from the non-measurement object included in waveform W5
1 is included in the waveform W6 in a form in which the phase angle is different by 180 degrees. The waveform W7 is obtained by synthesizing the waveform W6 and the waveform W4. By this synthesizing process, the waveform W1 equivalent to the waveform of the electromagnetic wave radiated from the non-measurement object cancels out the opposite phase components, and from the amplitude of the waveform W2 equivalent to the waveform of the electromagnetic wave radiated from the measurement object, A waveform obtained by subtracting the amplitude of W3 corresponding to the waveform of the emitted electromagnetic wave is extracted. Depending on the installation conditions of the antenna An1 and the antenna An2, the waveform equivalent W3 of the electromagnetic wave radiated from the object to be measured can be neglected at a predetermined measurement accuracy, so the extracted waveform is due to the electromagnetic wave radiated from the object to be measured. May be considered to be.

Further, the electromagnetic wave intensity measuring method according to the second invention is characterized in that the electromagnetic wave radiation source and one of the antennas, for example, the antenna An2
, The electromagnetic wave W3 radiated from the measurement object reaching the antenna.
Is blocked, and only electromagnetic waves radiated from an object that is not a measurement target are received, so that measurement accuracy can be improved.

Further, the electromagnetic wave intensity measuring apparatus according to the fourth and fifth inventions adjusts the waveforms of the electromagnetic waves radiated from the object which is not the object to be measured and which is received by the two antennas, so that the waveforms of the objects to be measured are matched. Since the electromagnetic wave radiated from a non-object is canceled accurately, the measurement accuracy can be improved.

[0018]

FIG. 1 is a block diagram showing the configuration of an electromagnetic wave intensity measuring apparatus according to the present invention. In the figure, reference numeral 1 denotes a waveform synthesizing unit. The waveform synthesizing unit 1 includes antenna connection terminals 2 and 3 for connecting the first and second antennas. An antenna 5 is connected to the antenna connection terminal 2 via a power supply line 4. Similarly, an antenna 7 is connected to the antenna connection terminal 3 via a feeder line 6. The waveform synthesizing unit 1 has a synthesized waveform signal output terminal 8. The composite waveform signal output terminal 8 is connected to an electromagnetic wave intensity measuring section 9 for measuring the composite waveform signal intensity. The electromagnetic wave intensity measuring unit 9 is configured using, for example, an electric field intensity measuring device capable of selecting a reception frequency, a spectrum analyzer, and the like.

On the other hand, a device under test 10 and a non-device under test 11 exist as an electromagnetic wave radiation source to be measured and an electromagnetic wave radiation source not to be measured, respectively. The non-test equipment 11 is far enough from the test equipment 10 when viewed from the antennas 5 and 7. For example, the first antenna 7 and the second antenna 5 are installed at 3 m and 30 m from the EUT 10, respectively. Further, the distance from the non-test equipment 11 to the first antenna 7 does not exactly coincide with the distance from the non-test equipment 11 to the second antenna 5. That is, the electromagnetic wave components radiated from the non-test equipment 11 included in the respective received waveforms have slight differences in amplitude and phase.

Electromagnetic waves radiated from the EUT 10 and the non-EUT 11 are received by the antenna 5 and the antenna 7,
The power is supplied to the antenna connection terminal 2 and the antenna connection terminal 3 via the power supply line 4 and the power supply line 6, respectively. The waveform synthesizing unit 1 changes the phase angle of one of the electromagnetic wave signals supplied to the antenna connection terminals 2 and 3 by 180 degrees (or an odd multiple of 180 degrees), synthesizes the two, and outputs the synthesis result to the synthesized waveform signal output terminal 8. Output. Then, the intensity is measured from the amplitude of the waveform of the synthesized result by a spectrum analyzer or the like of the electromagnetic wave intensity measuring unit 9.

FIG. 2 is a block diagram showing the configuration of the waveform synthesizing unit 1. In the figure, reference numeral 21 denotes an amplification / attenuation circuit for amplifying or attenuating an electromagnetic wave signal, the input side terminal of which is connected to the antenna connection terminal 3. The amplification / attenuation circuit 21 eliminates a slight difference in amplitude between the input electromagnetic wave signal and the electromagnetic wave signal input from the antenna connection terminal 2. amplification·
The output side terminal of the attenuation circuit 21 is connected to a phase shift circuit 23 for finely adjusting the phase shift between the output signal of the amplification / attenuation circuit 21 and the electromagnetic wave signal input from the antenna connection terminal 3. A phase shift circuit 22 for shifting the phase angle by 180 degrees is connected to the antenna connection terminal 2. Phase shift circuit 2
The output side terminals of the phase shifter 2 and the phase shift circuit 23 are respectively connected to the input side terminals of an adder 24 that combines two electromagnetic wave signals. The output side terminal of the adding circuit 24 is connected to the composite waveform signal output terminal 8.

Prior to the start of the measurement, in a state where the power of the EUT 10 is turned off or in a state where the electromagnetic waves radiated by the EUT 10 are cut off or stopped, that is, in a state where the electromagnetic waves radiated from the EUT 10 do not exist. An electromagnetic wave radiated from the non-test equipment 11 is received and measured. The measurer observes the level with a spectrum analyzer or the like of the electromagnetic wave intensity measuring unit 9 and adjusts the amplification / attenuation circuit 21 and the phase shift circuit 23 so that the observed level is minimized. Thereby, the amplification / attenuation amount and the phase angle of the electromagnetic wave signal for equalizing the amplitude of the electromagnetic wave signal given to the antenna connection terminals 2 and 3 are set in the amplification / attenuation circuit 21 and the phase shift circuit 23, respectively.

The electromagnetic wave signal reaching the antenna connection terminal 3 after the power of the EUT 10 is turned on or after the emission of the electromagnetic wave from the EUT 10 is amplified or attenuated to an appropriate amplitude by the amplification / attenuation circuit 21. Attenuated, followed by a phase shift circuit 2
3 as appropriate. The electromagnetic wave signal applied to the antenna connection terminal 2 is shifted by the phase shift circuit 22 to a phase difference of 180 degrees (or an odd multiple of 180 degrees) from the output waveform signal of the phase shift circuit 23 described above. The output waveform signals of the phase shift circuits 22 and 23 are combined by the adder circuit 24, and the result is supplied to the combined waveform signal output terminal 8.

With the above operation, the electromagnetic wave component radiated from the test equipment 10 of the electromagnetic wave signal given to the antenna connection terminal 2 is taken out to the composite waveform signal output terminal 8, and the intensity is measured by the electromagnetic wave intensity measuring section 9. You can do it.

FIG. 3 is a block diagram showing the configuration of another electromagnetic wave intensity measuring device according to the present invention. In the figure, reference numeral 12 denotes an electromagnetic wave absorber provided between the second antenna 7 and the EUT 10. The other components corresponding to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The electromagnetic wave radiated from the EUT 10 is absorbed by the electromagnetic wave absorber 12 and the antenna 7
Do not reach. Therefore, since the antenna 7 receives only the electromagnetic wave radiated from the non-test equipment 11,
Unnecessarily canceling or increasing the electromagnetic wave component radiated from the EUT 10 is eliminated, and the measurement accuracy is improved.

The phase shift circuit 23 may be provided between the phase shift circuit 22 and the antenna connection terminal 2 so as to adjust the phase shift of the electromagnetic wave signal given to the antenna connection terminal 2. Further, a configuration may be provided between the phase shift circuit 22 and the adder circuit 24 to adjust the phase shift of the output waveform signal of the phase shift circuit 22. Further, it may be provided between the amplification / attenuation circuit 21 and the antenna connection terminal 3 so as to adjust the phase shift of the electromagnetic wave signal given to the antenna connection terminal 3.

[0027]

According to the first, second, third, fourth and fifth aspects of the present invention, the influence of the electromagnetic wave radiated from the object which is not the object to be measured is determined so that the received waveform does not affect the predetermined measurement accuracy. By obtaining the waveform of the electromagnetic wave radiated from the measurement object, the intensity of the electromagnetic wave radiated from the measurement object can be accurately measured. Moreover, the same effect can be obtained not only indoors but also outdoors.

In the second invention, an electromagnetic wave absorber is provided between the object to be measured and one of the antennas or the other antenna, and only electromagnetic waves radiated from an object which is not the object to be measured from the antenna are provided. Is received, and the waveform of the electromagnetic wave received by the other antenna is canceled with this waveform, so that the cancellation or increase of the electromagnetic wave component radiated from the measurement object can be suppressed, and the measurement accuracy can be improved.

In the fourth and fifth aspects of the present invention, the waveforms of electromagnetic waves radiated from non-measurement objects included in the reception waveforms of one antenna and the other antennas, respectively, are made to match as much as possible, so The waveform can be canceled to the extent that the predetermined measurement accuracy is not affected, and the measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electromagnetic wave intensity measuring device according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a waveform synthesis unit.

FIG. 3 is a block diagram showing a configuration of another electromagnetic wave intensity measuring device according to the present invention.

FIG. 4 is a graph showing intensity characteristics of an electromagnetic wave.

FIG. 5 is an explanatory diagram illustrating a synthesis process of a received waveform.

FIG. 6 is a block diagram showing a configuration of a conventional electromagnetic wave intensity measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waveform synthesis part 2, 3 Antenna connection terminal 4, 6 Feeder line 5, 7 Antenna 12 Electromagnetic wave absorber 21 Amplification / attenuation circuit 22, 23 Phase shift circuit 24 Addition circuit

Claims (5)

[Claims] 1. An electromagnetic wave intensity measuring method for measuring the intensity of an electromagnetic wave emitted from an electromagnetic wave radiation source from the amplitude of the waveform of an electromagnetic wave received by an antenna, wherein the electromagnetic waves are received simultaneously by two antennas, and The phase angle of the electromagnetic wave received by the antenna is 180 degrees or 180 degrees.
An electromagnetic wave intensity measuring method comprising: synthesizing the waveform and an electromagnetic wave received by another antenna with a phase shift of an odd number of degrees, and measuring the intensity of the electromagnetic wave from the magnitude of the amplitude of the synthesized waveform. 2. The method according to claim 1, wherein an electromagnetic wave absorber is provided between the electromagnetic wave radiation source and one of the antennas. 3. An electromagnetic wave intensity measuring device for measuring the intensity of an electromagnetic wave radiated by an electromagnetic wave radiation source from the magnitude of the amplitude of the electromagnetic wave waveform. The phase angle of the obtained electromagnetic wave signal is 18
Means for outputting a phase shifted by 0 degrees or an odd number, and synthesizing means for synthesizing an output signal of the means and an electromagnetic wave signal applied to the other input terminal, and outputting the synthesized signal, An electromagnetic wave intensity measuring device for measuring the intensity of the electromagnetic wave from the magnitude of the amplitude of the electromagnetic wave. 4. A phase shifter which outputs a phase angle of an electromagnetic wave signal supplied to one of the input terminals in accordance with a phase angle of the electromagnetic wave signal supplied to the other input terminal. The electromagnetic wave intensity measuring device according to claim 3. 5. An amplifying / attenuating means for outputting the amplitude of an electromagnetic wave signal applied to one of the input terminals in accordance with the amplitude of the electromagnetic wave signal applied to the other input terminal. Item 4. An electromagnetic wave intensity measuring device according to Item 3.