JPS60233569A - Disturbing wave measuring method - Google Patents

Abstract

PURPOSE:To output only a disturbing wave by providing not only an antenna for receiving a disturbing wave and an external wave but an antenna for receiving exclusively only the external wave, and synthesizing the external waves received by both antennas so as to make them the same in amplitude and opposite in phase. CONSTITUTION:Antennas 1, 5 are placed so that a wave to be measured (disturbing wave) 3 generated from a testing device 2 and an external wave 4 are received by the measuring antenna 1, and only an external wave 4' is received by the external antenna 5. The external wave 4' received by the antenna 5 is supplied to a phase shifter 7 through an amplifier 6, and adjusted so as to make it opposite in phase to the external wave 4 received by the antenna 1. In such a case, the phase-shifting adjustment is executed by a control signal from a control device 12. Also, in an attenuator 8, said wave 4' is adjusted by the device 12 so as to make it the same in amplitude as the external wave 4 received by the antenna 1. In such a way, only the disturbing wave is outputted to the output of a mixer 9, and can be supplied to a measuring instrument 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for measuring the strength of high-frequency electromagnetic fields (hereinafter abbreviated as interference waves) generated by electronic equipment at open test sites, and is particularly directed to Broadcast waves, communication waves, etc. other than interference waves (hereinafter, these waves are abbreviated as foreign waves)
It is better to remove it.

This invention relates to a method for eliminating measurement errors caused by interference and the like and improving measurement accuracy.

[Conventional technology]

When measuring interference waves generated by electronic equipment (hereinafter also referred to as measured waves) at open test sites, broadcasting frequency bands and communication frequency bands (hereinafter these frequency bands are abbreviated as external frequency bands) are used. ) (for example, 80 耶z
~300 MHz) (e.g. ~300 MHz)
When performing measurements in the frequency band (MHz to I GHz), it is conventional to set up a measurement field on land that is unaffected by external waves as much as possible, or to use radio wave absorption methods. Interference waves were measured by using a so-called anechoic chamber using body and metal shielding materials to artificially create an electromagnetic environment where foreign waves would not enter.

[Problem that the invention seeks to solve]

For this reason, the conventional method requires selection of the measurement environment and has drawbacks such as requiring a huge amount of cost.

[Failure to solve the problem]

In order to solve the conventional drawbacks, the present invention provides, in addition to a first antenna that receives radio waves of both interference waves and external waves, a second antenna that receives only the external waves. a variable amplitude phase shifter for changing the amplitude and phase of the output of the second antenna; a mixer for combining the output of the variable amplitude phase shifter with the output of the first antenna; By adjusting the external wave received by the second antenna so that it has substantially the same amplitude and opposite phase as the external wave component received by the first antenna, and combining the external wave by the mixer. The apparatus is characterized in that only the interference wave component to be measured from which the foreign waves have been removed is output.

〔Example〕

Embodiments of the present invention will be described below with reference to two drawings.

Referring to FIG. 1, the measurement antenna 1 is connected to the device under test (
Each of the antennas 1 and 5 is installed in an appropriate manner so that the measured wave (disturbance wave) 3 and the external wave 4 generated from the electronic device 2 are received, and only the external wave 4' is received by the external antenna 5. Distance (e.g.

1007? Z) are placed apart. At this time, the characteristics and positions of the individual antennas are determined so that the receiving states of the external waves 4, 4' at the antennas 1, 5 are substantially the same.

The external wave 4' received by the external antenna 5 is as follows.

First, it is amplified to an appropriate value by an amplifier 6, and then adjusted by a phase shifter 7 so that it is in the opposite phase to the external wave 4 received by the measurement antenna l. The phase shift adjustment at this time is performed by a control signal from the control device 12. moreover,
The output signal from the phase shifter 7 is adjusted in the attenuator 8 by a control signal from the control device 12 so that it has the same amplitude as the external wave 4 received by the measurement antenna 1. In this way, the external waves 4 have the same amplitude and opposite phase.
．． When the waves 4' are combined by the mixer 9, the two waves cancel each other out, and only the interference wave 3 is output. This interference wave 3 is amplified to an appropriate value by an amplifier 10.

The signal is output to a measuring device 11 typified by a spectrum analyzer or an electric field strength meter. In this method, when the antenna is configured with two antennas, if the measured wave 3 is received only by antenna 1, the reception level will be lower than when it is configured with one antenna. The signal is amplified and corrected in step 10.

Further, the control device 12 is composed of, for example, a microcomputer, and by simultaneously controlling the measuring instrument 11 with the control device 12, it is possible to improve measurement accuracy and efficiency of measurement time.

Next, the one-line measurement method will be theoretically explained with reference to FIG. FIG. 2 shows an equivalent circuit of the antennas 1, 5 and a typical mixer 9 and measuring device 11.

The input voltage of external wave 4 to antenna 1 is El, external wave 4'
The input voltage to the antenna 5 is E2, and the voltage ratio is Eml
:Em2=1:x and the two phase difference is ψ(rad).

El = E, n16-j (clj ``2 = 8m2 o-j (ω = 10ψ) -j (ω = 10ψ) x Em1e where l ''ml 18m2 is the maximum induced voltage of antennas 1 and 5 (b), j=Lgo, ω=2πf, f is the receiving frequency (Hz), and t is time (see).At this time, the input voltage ER of the measuring device 11 is.

It is expressed as Therefore, the input power P to the measuring instrument 11 is:

becomes. Here, P is the input power to the measuring device 11 which is 0 when there is only one antenna, and r is the input resistance of the measuring device 11. Therefore, when there are two antennas and when there is one antenna,
The input power ratio A due to the external wave to the measuring instrument 11 at the beginning is quadratic.

Here, e'-jψ= cosψ-jsin9).

Now, as a calculation example, the input voltage ratio is Eml:Em1=1=
Assuming that the phase shifter 7 and attenuator 8 are adjusted so that the 099 phase difference is 179.5 degrees, by substituting into the above equation, the input power ratio A becomes A4@n). Become.

In this manner, the present invention can largely eliminate external waves compared to when only one antenna is used. As an example calculation, consider the external waves received by two additional antennas.

By adjusting to approach homogeneous width, antiphase,
External waves can be removed to a greater extent than the calculated value shown above.

〔Effect of the invention〕

As explained above, the interference wave measurement method according to the present invention is as follows:
Even if the external waves received by the two antennas have different phases due to multipath or the like, they can be easily removed. Therefore, there is no need to select a particular measurement environment, even in an urban environment.

This is extremely useful as it allows interference waves to be measured without being affected by external waves.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the configuration of a device for realizing the interference wave measurement method according to the present invention, and Fig. 2 shows an example of an equivalent circuit of an antenna, a mixer, and a measuring device to explain the operating principle. FIG.

Claims (1)

[Claims] 1. A method for measuring interference waves generated by electronic equipment at an open test site while eliminating the influence of external waves, the first method comprising: receiving radio waves of both the interference waves and the external waves; In addition to the above antenna, a second antenna for receiving only the external wave is provided, and a variable amplitude phase shifter for changing the amplitude and phase of the output of the second antenna, and the variable amplitude phase shifter. a mixer for combining the output of the means and the output of the first antenna, and an external wave received by the second antenna by the variable amplitude phase shifting means. It is adjusted so that it has substantially the same amplitude and opposite phase as the foreign wave among the radio waves received by the first antenna, and the combined output of the mixer includes a filter for removing the foreign wave.