JPH0476466A - Electromagnetic wave measuring device - Google Patents

Abstract

PURPOSE:To enable accurate and automatic measurement by receiving only external environmental electromagnetic wave on a first and a second wideband antennas and receiving artificial electromagnetic wave in addition to the former, obtaining a gain coefficient ratio from the former and a space transmitting coefficient ratio from the latter, and obtaining emitting electromagnetic wave component from both. CONSTITUTION:A first and a second wideband antennas A1, A2 having nearly equal electric characteristic are provided in the same direction and at different distances L1, L2 from a device to be detected EUT. A gain coefficient ratio of both antennas A1, A2 is obtained from the measured output of a first and a second spectrum analyzers SA1, SA2 at receiving only external electromagnetic wave on the antennas, and a space transmitting coefficient ratio is obtained from the measured output at receiving the external electromagnetic wave together with artificial electromagnetic wave from the device EUT position. The electromagnetic wave component emitted from the device EUT is obtained from the measured output, the gain coefficient ratio, the space transmitting coefficient ratio of the latter. Hereby, measurement can be performed accurately and automatically.

Description

Detailed Description of the Invention: Industrial Field of Application With the spread of electrical or electronic devices, especially digital electrical or electronic devices, interference with radio receivers, television receivers, etc. due to electromagnetic waves emitted from these devices has arisen. became a problem, and the International Special Committee on Radio Interference, a subordinate organization of the International Electrotechnical Commission, established standards regarding the permissible limits of electromagnetic waves emitted from electrical or electronic devices and their measurement methods, and the governments of each country are required to adopt them. Recommendations have been made, and each country is implementing the system in a manner that suits its national circumstances.

The present invention relates to an apparatus for measuring electromagnetic waves emitted by electric or electronic devices.

BACKGROUND ART FIG. 8 is a diagram showing a conventional measuring device for electromagnetic waves emitted from electric or electronic equipment, in which A is a broadband antenna, SA is a spectrum analyzer, and PL is a plotter.

When measuring electromagnetic waves emitted from the electrical or electronic device under test using this measurement device, select a location (oven area test site) where there are no objects that reflect electromagnetic waves around the electrical or electronic device under test. The distance between the antenna and wideband antenna A is maintained at a predetermined value, the electromagnetic waves emitted from the electrical or electronic device under test are received by the wideband antenna A, and the frequency distribution of the received electromagnetic waves and the electric field strength for each frequency are measured by the spectrum analyzer SA. and record it with plotter PL.

Problems to be Solved by the Invention The conventional measuring device described above has the advantage of being able to measure the electric field strength for each frequency even when the electrical or electronic device under test emits electromagnetic waves in a distributed manner over a wide frequency range. However, if the selection of the oven area test site is inappropriate, for example, external environmental electromagnetic waves such as broadcast waves or electromagnetic waves emitted from electrical or electronic equipment installed in factories etc. may cause electromagnetic waves emitted by the electrical or electronic equipment under test. Since it is not possible to separate and identify these,
When the frequency of electromagnetic waves emitted by the electrical or electronic device under test is the same as the frequency of external environmental electromagnetic waves, or when the frequency difference between the two waves is small, the electric field strength of the superimposed waves shall be measured. Therefore, accurate measurements cannot be made not only when the intensity of the external electromagnetic waves is higher, but also when the intensity of the external electromagnetic waves is comparable to the intensity of the electromagnetic waves emitted by the electrical or electronic device under test.

Therefore, in the standards of the International Special Committee on Radio Interference,
It is stipulated that measurements be performed under conditions where the intensity of external environmental electromagnetic waves is 6 dB or more lower than the intensity of electromagnetic waves emitted by the electrical or electronic device under test, and oven area test sites that meet these conditions are It is extremely inconvenient to carry out measurements as it is limited to remote mountainous areas far away from the mountains.

In addition to the above-mentioned conventional measuring devices, a device that combines a dipole antenna and a field strength measuring device is also used, but its performance is not only equivalent to the conventional measuring device described above, but also It has the drawback of requiring a lot of manpower and time.

Means for Solving the Problems The device of the present invention is installed at different distances L1 and L2 in the same direction from the electrical or electronic device to be tested in a place where there are no objects reflecting electromagnetic waves around it, and at substantially the same distances L1 and L2. or eighteenth and second wideband antennas having substantially equal electrical characteristics; and the receiving outputs of the first and second broadband antennas are applied separately and have substantially the same or substantially equal electrical characteristics. 1st. t3 and a second spectrum analyzer, and each measurement output of the first and second spectrum analyzers when the first and second broadband antennas are made to receive only external environmental electromagnetic waves is input, and the riser = F (f) A2(f)・N (f) A, (fl: Gain coefficient of the first broadband antenna A2(f): Gain coefficient of the second broadband antenna N(f): Level of external environmental electromagnetic waves f: a first calculation means that calculates the gain coefficient ratio F(f) by calculating an arbitrary frequency; a first storage means that stores the gain coefficient ratio obtained by the first calculation means; When the first and second broadband antennas are made to receive external environmental electromagnetic waves and receive pseudo-electromagnetic waves that are radiated from the installation position of the electrical or electronic device under test and have a higher intensity than the external environmental electromagnetic waves, With each measurement output of the first and second spectrum analyzers as input, α, (t,,,fl: Spatial transmission coefficient of electromagnetic waves between the distance L1 α2 (L2.f): Space of electromagnetic waves between the distance L2 a second calculation means for calculating the spatial transmission coefficient ratio β of electromagnetic waves by calculating a transmission coefficient; a second storage means for storing the spatial transmission coefficient ratio of electromagnetic waves calculated by the second calculation means; The measurement outputs p, (f) and p2 (f ) and the storage information of the first and second storage means as input, α, (Ll, f)・A, (f)・S (f), '−
1(P,(f)-pg(f)・F(f)); a third calculation means for determining the electromagnetic wave component emitted by the electrical or electronic device under test; and an output of the third calculation means. By providing a display device, the drawbacks of the conventional device are eliminated.

The gain coefficient ratio of the first and second broadband antennas is determined from each measurement output of the first and second spectrum analyzers when the first and second broadband antennas are made to receive only external environmental electromagnetic waves. .

When the first and second broadband antennas are made to receive external environmental electromagnetic waves and receive pseudo-electromagnetic waves emitted from the installation position of the electrical or electronic device under test and which are stronger than the external environmental electromagnetic waves, A spatial transmission coefficient ratio of electromagnetic waves between the electrical or electronic device under test and the first and second broadband antennas is determined from each measurement output of the first and second spectrum analyzers.

Measured outputs of the first and second spectrum analyzers when the first and second broadband antennas receive external environmental electromagnetic waves as well as electromagnetic waves emitted by the electrical or electronic device under test; and the first and second broadband antennas. The electromagnetic wave component emitted by the electrical or electronic device under test is determined from the antenna gain coefficient ratio and the electromagnetic wave spatial transmission coefficient ratio.

Embodiment FIG. 1 is a diagram showing an embodiment of the present invention. and A
2 are receiving antennas, each having substantially the same or almost the same electrical characteristics, and a wide band capable of receiving electromagnetic waves over the required frequency range (at least 30 MHz to 100,100 O according to the standards of the International Special Committee on Radio Interference). It consists of an antenna.

When installing receiving antennas A and A2,
Select a location (oven area test site) where there are no electromagnetic wave reflecting objects around, and separate it from the electrical or electronic device under test EUT by different distances L1 and L2 in the same direction, as shown in the schematic plan view in Figure 2. At the same time, for external environmental electromagnetic waves from a distance (for example, broadcast waves or electromagnetic waves emitted by electrical or electronic devices installed in factories, etc.), the receiving electric field strengths of the receiving antennas A1 and A2 are approximately equal to each other. Provided as follows.

Returning to FIG. 1, SA and SA2 are spectrum analyzers, each having substantially the same or almost the same electrical characteristics, and configured to sweep and receive the same frequency in response to a start signal from a computer, which will be described later. be. M++, Mi□, M21 and M2□ are internal memories of the spectrum analyzers SA+ and SA2, respectively, INTt and IIIJT2 are interfaces, respectively, and the CPU is a computer, for example, a personal computer. SL is a signal transmission line for applying a common start signal from the computer CPU to the spectrum analyzers SA and SA2, and DIS is a display device.

To carry out measurements using the apparatus of the present invention, preliminary measurements are first made to derive and store the required parameters.

That is, the electrical or electronic device under test E shown in FIG.
Temporarily install a wideband transmitting antenna with characteristics similar to those of the receiving antennas A1 and A2 at the UT position, and use the receiving frequency range of the spectrum analyzers SA and SA2 (at least 30 MHz, which is the standard of the International Special Committee on Radio Interference).
It is excited by the output of a tracking oscillator which outputs a frequency signal that substantially coincides with 100,100 O).

In addition, increase the output of the tracking oscillator as appropriate,
When the radiated electromagnetic waves from the temporary transmitting wideband antenna are received by the receiving antennas A1 and A2, the reception level of this electromagnetic wave is 6 times higher than the reception level of external environmental electromagnetic waves.
Adjust so that it is at least dB (standard of the International Special Committee on Radio Interference).

First, the oscillation of the tracking oscillator is stopped, and only external environmental electromagnetic waves (hereinafter abbreviated as external noise) are received by the receiving antennas A1 and A2, and the output circuits of the spectrum analyzers SA+ and SA2 are transferred to the memory M□.
1 and M21, a start signal from the computer CPU is applied to the spectrum analyzers SA+ and SA2 via the transmission line SL, and when these are operated synchronously, the receiving outputs of the receiving antennas A1 and A2 become the spectrum analyzers SA+ and SA2. They are applied to analyzers SAt and SA2 separately, and the measurement outputs for each frequency are sequentially read into memories M11 and M21.

The external noise is N(f) (f is an arbitrary frequency), the gain coefficients of the receiving antennas A1 and A2 are A, (fl and A
2(f), the memories M11 and M2
The external noise information stored in 1 is At(f)・N(f)
8 and A2(f)·N(f).

The external noise information stored in the memories M11 and M2□ is read out according to a program stored in advance in the computer CPU, and
2 to the computer CPU, and the gain coefficient ratio F (f) obtained by the calculation becomes
It is stored in a predetermined memory in U.

Next, when the tracking oscillator is oscillated and the pseudo electromagnetic waves are sequentially radiated from the temporary transmitting antenna, the receiving antennas A and A2, together with the external noise N (f),
Receive pseudo electromagnetic waves radiated from a temporary transmission antenna.

When the spectrum analyzers SA and SA2 are operated synchronously by a start signal from the computer CPU, the respective reception outputs of the reception antennas A+ and A2 are applied to the spectrum analyzers SA and SA2, and the measurement output for each frequency is stored in the memory. M++, t3 and M
2 □ are read sequentially.

Pseudo electromagnetic waves (hereinafter referred to as
The spatial transmission coefficient of the pseudo signal (S) between the temporary transmitting antenna and the receiving antenna A8 is set α, f), the temporary transmitting antenna and the receiving antenna A2 The spatial transmission coefficient of the pseudo signal 5T(f) between A2(L2.f) and the measured outputs of the spectrum analyzer SA and SA2 are PTI(f) and PA. (f), the information stored in the memories M11 and M21 is expressed by the following equation.

PTI (f) = at (Ll, f) - At (
f) −3T(f) +AI (f) −N(f)・
... (2) PT□(f)=α2 (t2.f)・A2 (f)・S
A(fl +Az(f)・N (f)... (3
) The information stored in the memories M11 and M21 is read out by a program previously stored in the computer CPU, and introduced into the computer CPU via the interfaces INT and INT2 to obtain the spatial transmission coefficients a, (
t, , f) and A2 (Lz, f), and if Ll<L2, as shown in Fig. 2, for example, α
Since at (t, +, f) = β, (2z (L2.f)
−−−−(4) holds, the spatial transmission coefficient ratio β (β
〉■) is calculated and stored in a predetermined memory in the computer CPU.

This completes the preliminary measurement, and then performs the main measurement. In this case, except for the temporary transmitting antenna and tracking oscillator, place the electrical or electronic device under test EIJT in the specified position and turn on the power. When the output circuits of the spectrum analyzers SA and SA2 in the measuring device of the present invention are switched and connected to the memories M+2 and M2□, and a start signal is output from the computer CPU, the spectrum analyzers SA, SA8 and SA2 are operated in synchronization. The outputs corresponding to the electromagnetic waves received by the receiving antennas At and A2, that is, the electromagnetic waves emitted by the electrical or electronic device under test EIJT and the external environmental electromagnetic waves, are output from the spectrum analyzers SA and SA.
2, and the measurement output for each frequency is sequentially stored in the memory M1.
Read into □ and M2□.

Electromagnetic waves emitted by the electrical or electronic device EUT under test (hereinafter referred to as
If the outputs of the spectrum analyzers SA+ and SA2, that is, the measurement outputs corresponding to each frequency are expressed as p+(fl and P2(f), then the measurement outputs p+(f) and P2 (fl is expressed by the following formula.

p, (fl=α, (t, , fl・At(fl・S
(f) +A+ (f)・N (f)・・・・ (5) P2(f)=α2 (L2.f)・A2 (f)・5(
f) + A2 (f)・N (f)... (6) The measurement outputs expressed by equations (5) and (6) are read separately into memories M1□ and M2° at -1. , the information p+(t) and p2(f) read from the memories M1□ and M2□ are connected to the interface INT and I N
It is introduced into the computer CPU via T'x, and the following calculations are performed.

When both sides of equation (5) are multiplied by A2(f), p, (t')
・A2(f)=α, (1,,,f)・A, (fl・A
2(fl・S (f)+A, (f)・A2 (fl・N
(f) From the above equation, N (f)... (7) If both sides of equation (6) are multiplied by A and (fl), P2(f).
A, (fl=α2(L2.f)・A, (f)・A2 (
f)・S (f)+AI(f)・A2 (f)・N (
f) From the above formula, N (f) ... (8) From formulas (7) and (8), P+(f)42(f) at(Ll, f)4+(f
)42(f)・5(f)=p2(f)・AI(f)−A
2 (Lz, f)・At(t)・A2(t)・S (f
) From the above equation, ... (9) Substituting equation (4) into equation (9), ... (10) or ... (11) From equation (10), α, ( L,,f)・A,(f)・S (f)(11)
From the formula, α2 (Lg, f)・Aa(f)・S (f) (12)
Substituting equation (1) into the equation, we get a, (L,,f) ・A, (f) ・5(f) Nigoshi-(P, (f)-P2(f)・Fge))・・・
(14) β-1 Substituting equation (1) into equation (13), α2 (L2.f)・A2(f)・S (f)I
P, (f) = (P2ge)) ・ ・ ・ ・ ・ (15
) β-I Fff) From equation (14) or equation (15), S (f), that is,
The frequency distribution of electromagnetic waves emitted by the electrical or electronic device under test and the intensity of each frequency can be determined.

FIG. 3 shows the gain coefficient ratio F, (f
) is a flowchart of the operation for determining the electrical or electronic device under test EtJT and the first
FIG. 5 is a flowchart of the operation of the above-mentioned main measurement.

FIG. 6 is a diagram showing another embodiment of the present invention, in which LO is a local oscillator common to the receiving sections of spectrum analyzers SA and SA2, SMP is a sampling signal oscillator common to both spectrum analyzers, and SWP is a local oscillator common to both spectrum analyzers SA and SA2. This is a frequency sweep signal oscillator common to spectrum analyzers, and other symbols and configurations are the same as in FIG.

In this example, the spectrum analyzer SA+
Even after SA2 and SA2 are started simultaneously by a common start signal output from the computer CPU, the local oscillator LO, sampling signal oscillator SMP, and frequency sweep signal oscillator S common to both spectrum analyzers
Each output signal of the WP ensures synchronization and accurate measurements.

FIG. 7 is a diagram corresponding to the claims, in which ARTI is a first calculation means, MEMO,
is a first storage means for storing the gain coefficient ratio F(f) determined by the first calculation means ARTt; MEMO3 is a second calculation means for calculating the spatial transmission coefficient ratio β of electromagnetic waves obtained in the second calculation means ART2, and ARTa is a second storage means for storing the spatial transmission coefficient ratio β of electromagnetic waves obtained in the second calculation means ART2. The third calculation means for determining the electromagnetic wave component emitted by the test electrical or electronic device EUT, DIS is a display device,
Other symbols are the same as in FIG.

Effects of the Invention The device of the present invention can separate the electromagnetic waves emitted by electrical or electronic devices under test from the external electromagnetic waves even in areas where the arrival of external environmental electromagnetic waves is inevitable, and can almost accurately determine the frequency distribution and intensity of the electromagnetic waves. The present invention is extremely effective in taking countermeasures against interference caused by electromagnetic waves emitted by electrical or electronic devices under test.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a schematic plan view of the main part thereof, FIGS. 3 to 5 are flowcharts for explaining the operation, and FIG. FIG. 7 is a diagram showing another embodiment of the invention, FIG. 7 is a diagram corresponding to claims, and FIG. 8 is a diagram showing an example of a conventional measuring device.
Antenna, SA, . SA2 and SA Nispectrum Analyzer, MIl+
M+2, M21 and M22: Memo 1 INT
, and INT2: Interface, CPU: Computer, SL: Signal transmission line, DIS: Display device, EU
T: Electrical or electronic device under test, LO: Local oscillator,
SMP: sampling signal oscillator, swp: frequency sweep signal oscillator, ARTt: first calculation means, ME
MO,: first storage means, ART,: second calculation means, MEMO2: second storage means, ART3: third calculation means, PL: plotter.

Claims (1)

[Claims] 1. In a place where there are no electromagnetic wave reflecting objects around, installed at different distances L_1 and L_2 in the same direction from the electric or electronic device under test, and with substantially the same or almost equal electric power. first and second wideband antennas having a characteristic of
a first having substantially the same or nearly equal electrical characteristics;
and a second spectrum analyzer; inputting each measurement output of the first and second spectrum analyzers when the first and second broadband antennas receive only external environmental electromagnetic waves, [A_1(f)・N(f)]/[A_2(f)・N(f
)]=F(f)A_1(f): Gain coefficient of the first broadband antenna A_2(f): Gain coefficient of the second broadband antenna N(f): Intensity of external environmental electromagnetic waves f: Arbitrary frequency a first calculation means for calculating the gain coefficient ratio F(f) by performing the calculation; a first storage means for storing the gain coefficient ratio obtained by the first calculation means; and the first and second calculation means. The above-mentioned first and second when the broadband antenna is made to receive external environmental electromagnetic waves and receive pseudo electromagnetic waves that are radiated from the installation position of the electrical or electronic device under test and have a higher intensity than the external environmental electromagnetic waves. α_1(L_1, f)/α_2(L_2, f
)=βα_1 (L_1, f): Spatial transmission coefficient of electromagnetic waves between the distance L_1 α_2 (L_2, f): Spatial transmission coefficient of electromagnetic waves between the distance L_2 Calculate the spatial transmission coefficient ratio β of electromagnetic waves. a second calculation means; a second storage means for storing the spatial transmission coefficient ratio of electromagnetic waves obtained in the second calculation means; The measurement outputs P_1(f) and P_2(f) of the first and second spectrum analyzers when receiving the emitted electromagnetic waves and the external environmental electromagnetic waves and the storage information of the first and second storage means are input. , α_1(L_1,f)・A_1(f)・S(f)={β
/(β-1)}{P_1(f)-P_2(f)・F(f
)}; and a display device for displaying the output of the third calculation means. 2. The electromagnetic wave measuring device according to claim 1, wherein the first and second spectrum analyzers each include a common local oscillator, a common sampling signal oscillator, and a common frequency sweep signal oscillator.