JP2006234602A - Device for measuring electromagnetic field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the intensity of electromagnetic field while reducing the propagation loss of an electromagnetic wave radiated from an object to be measured. <P>SOLUTION: A device is provided with a plurality of receiving antennas 2 provided at the positions apart from the object 1 to be measured radiating the electromagnetic wave, and receiving the electromagnetic wave from the object 1; a plurality of frequency conversion circuits 3 connected to the receiving antennas 2, respectively, adding local signals having frequencies different from each other to the receiving signals received by the receiving antennas 2, and outputting them; and a synthesizer 4 connected to the plurality of frequency conversion circuits 3 via a coaxial cable 18, and synthesizing the output signal of each frequency conversion circuit 3 to output it to a measuring instrument measuring the intensity of the electromagnetic field of the electromagnetic wave radiated from the object 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic field measurement apparatus for measuring the electromagnetic field intensity of an electromagnetic wave radiated from an object to be measured, and more specifically, receives a signal output by adding a local signal to reception signals of a plurality of reception antennas by wire. Thus, the present invention relates to an electromagnetic field measurement apparatus that enables measurement of electromagnetic field intensity by reducing the propagation loss of electromagnetic waves radiated from the object to be measured.

A conventional electromagnetic field measuring apparatus is provided with a plurality of modulated scattering elements arranged on the circumference of a predetermined radius to which local signals of different frequencies are applied, and at an equidistant position from each modulated scattering element. A receiving antenna that receives a modulated scattered signal obtained by modulating a radiation signal of an electromagnetic wave radiated from the object to be measured, and performing a complex analysis of the electromagnetic field characteristics of the electromagnetic wave radiated from the object to be measured. This is not necessary and can be detected instantaneously (see, for example, Patent Document 1).
JP 2000-251679 A

  However, in such a conventional electromagnetic field measuring apparatus, a radiation signal of an electromagnetic wave radiated from an object to be measured is received by a modulated scattering element, and a modulated radiation signal (modulated scattered wave) is emitted from the modulated scattering element. Since this radiation signal (modulated scattered wave) is received and measured by the receiving antenna, the propagation loss of the electromagnetic wave is large and the intensity of the received signal received by the receiving antenna is reduced. Therefore, when the electromagnetic field intensity radiated from the object to be measured is weak, the S / N is bad and it is difficult to measure accurately. Furthermore, since the intensity of the received signal is low, it is easily affected by unnecessary electromagnetic waves incident from the outside, and there is a risk that the measurement accuracy of the electromagnetic field intensity will be worse.

  Further, since the modulated scattered wave from the plurality of modulated scattering elements arranged on the circumference is received by the receiving antenna, the installation position of the receiving antenna is the same distance from each modulated scattering element as the bottom surface. It is limited to the apex position of the cone. Therefore, the range in which the electromagnetic field can be measured by the reception antenna of the modulated scattered wave is limited to the above circle, and it is difficult to measure the three-dimensional electromagnetic field intensity.

  Furthermore, the modulated scattered wave receiving antenna is arranged at an equidistant position from each modulated scattering element so as to receive the modulated scattered wave from each modulated scattering element. However, there is no such antenna. Therefore, it is difficult to perform measurement by switching between the vertically polarized wave receiving antenna and the horizontally polarized wave receiving antenna which are integrally formed.

  In the electromagnetic field measuring apparatus, since the modulation and scattering element is composed of a dipole antenna and a diode inserted in parallel to the feeding end of the dipole antenna, a coaxial cable and a dipole antenna for feeding a local signal to the diode It is difficult to achieve impedance matching between Therefore, when a radiation signal radiated from the object to be measured is frequency-converted with a local signal and radiated as a modulated scattered wave, conversion loss may increase.

  Accordingly, the present invention aims to provide an electromagnetic field measurement device that addresses such problems and that enables measurement of electromagnetic field intensity by reducing the propagation loss of electromagnetic waves radiated from the object to be measured. To do.

  In order to achieve the above object, an electromagnetic field measuring apparatus according to the present invention is disposed at a position away from a measurement object that radiates electromagnetic waves, and a plurality of receiving antennas that receive the electromagnetic waves radiated from the measurement object; A plurality of frequency conversion circuits that are connected to the respective reception antennas, output local signals having different frequencies to reception signals received by the reception antennas, and are connected to the plurality of frequency conversion circuits by wires. And a synthesizer that synthesizes the output signal of the frequency conversion circuit and outputs the synthesized signal to a measuring instrument that measures the electromagnetic field intensity of the electromagnetic wave radiated from the object to be measured.

  With such a configuration, the frequency conversion circuit that receives the electromagnetic waves radiated from the measured object by the plurality of receiving antennas arranged at positions away from the measured object that radiates the electromagnetic waves, and is connected to each receiving antenna. The local signals of different frequencies are added to the received signals received by the respective receiving antennas and output, and the output signals of the respective frequency converting circuits are synthesized by a synthesizer connected by wire to the plurality of frequency converting circuits. And output to a measuring device for measuring the electromagnetic field intensity of the electromagnetic wave radiated from the object to be measured.

  The frequency conversion circuit includes an oscillator that generates the local signal, a low-pass filter that removes harmonic components included in the local signal generated by the oscillator, a reception signal that is input from the reception antenna, and the low-pass filter. And a mixer that mixes the local signal that has passed through. Accordingly, a local signal is generated by the oscillator, a harmonic component included in the local signal is removed by the low-pass filter, and the reception signal input from the reception antenna and the local signal that has passed through the low-pass filter are mixed by the mixer.

  Further, the receiving antenna includes a horizontally polarized wave receiving antenna that receives horizontally polarized waves of electromagnetic waves and a vertically polarized wave receiving antenna that receives vertically polarized waves. As a result, the horizontally polarized wave receiving antenna receives the horizontally polarized wave and the vertically polarized wave receiving antenna receives the vertically polarized wave.

  Furthermore, the receiving antenna is integrally formed by orthogonally crossing the pole of the horizontally polarized wave receiving antenna and the pole of the vertically polarized wave receiving antenna. Thus, the electromagnetic wave radiated from the object to be measured is received by the receiving antenna formed integrally by orthogonalizing the pole of the horizontally polarized wave receiving antenna and the pole of the vertically polarized wave receiving antenna.

  The horizontally polarized wave receiving antenna pole and the vertically polarized wave receiving antenna pole are obtained by forming a conductor film on a printed circuit board. Thus, the electromagnetic wave radiated from the object to be measured is received by the pole of the horizontally polarized wave receiving antenna and the pole of the vertically polarized wave receiving antenna in which the conductor film is formed on the printed board.

  A succeeding stage of the receiving antenna is provided with a polarization changeover switch for switching the received signals of the horizontally polarized wave receiving antenna and the vertically polarized wave receiving antenna to be supplied to the frequency conversion circuit. As a result, the received signals of the horizontally polarized wave receiving antenna and the vertically polarized wave receiving antenna are switched by the polarization switching switch provided at the subsequent stage of the receiving antenna and supplied to the frequency conversion circuit.

  Further, the plurality of receiving antennas are arranged in a matrix in the vertical and horizontal directions or in a vertical row on the surface of the vertically extending frame on the electromagnetic wave arrival side. Thus, the electromagnetic waves radiated from the object to be measured are received by a plurality of receiving antennas arranged in a matrix in the vertical and horizontal directions on the surface on the electromagnetic wave arrival side of the vertically extending frame or in a line in the vertical direction.

  Furthermore, the plurality of receiving antennas are movable in a direction orthogonal to the direction of arrival of electromagnetic waves. Accordingly, the plurality of receiving antennas are moved in a direction orthogonal to the arrival direction of the electromagnetic wave.

  The plurality of receiving antennas are arranged in a line on the surface of the arc-shaped frame on the electromagnetic wave arrival side, and receive the electromagnetic waves from the object to be measured rotatably installed at the center of the arc-shaped frame. Is. Thus, the electromagnetic waves from the object to be measured that are rotatably installed at the center of the arc-shaped frame are received by a plurality of receiving antennas arranged in a line on the electromagnetic wave arrival side surface of the arc-shaped frame.

  The plurality of receiving antennas are movable in the same direction as the arrival direction of electromagnetic waves. Accordingly, the plurality of receiving antennas are moved in the same direction as the arrival direction of the electromagnetic wave.

  Furthermore, a radio wave absorber that reduces electromagnetic waves reflected on the electromagnetic wave arrival side surface of the frame is provided on the electromagnetic wave arrival side surface of the frame on which the plurality of receiving antennas are arranged. Accordingly, the electromagnetic wave reflected on the electromagnetic wave arrival side surface of the frame is reduced by the radio wave absorber provided on the electromagnetic wave arrival side surface of the frame in which the plurality of receiving antennas are arranged.

  Further, the plurality of receiving antennas are arranged inwardly on six inner surfaces of a cubic room. Thus, the electromagnetic field intensity distribution in the room is measured with a plurality of antennas arranged inward on the six inner surfaces of the cubic room.

  The plurality of receiving antennas are arranged inwardly on the inner surface of a spherical anechoic chamber for measuring electromagnetic field strength. As a result, the electromagnetic field strength is measured by a plurality of receiving antennas arranged inwardly on the inner surface of the spherical anechoic chamber.

  According to the first aspect of the present invention, electromagnetic waves from the object to be measured are received by the plurality of receiving antennas arranged at positions away from the object to be measured, and the signals received by the respective receiving antennas have different frequencies. By adding local signals and combining and outputting them, the electromagnetic field strength can be measured, so that the propagation path of electromagnetic waves is only between the device under test and each receiving antenna, and is radiated from the device under test. The electromagnetic wave propagation loss is reduced and the reception S / N is improved. Therefore, even when the electromagnetic field radiated from the object to be measured is weak, it is possible to accurately measure the electromagnetic field intensity. In addition, since the propagation loss of electromagnetic waves is reduced, electromagnetic waves from the object to be measured can be received at a high level, making it difficult to be affected by unnecessary electromagnetic waves incident from the outside. Accuracy can be improved. Furthermore, by adding a local signal of a different frequency to the received signal received by each receiving antenna, the position information of each receiving antenna can be obtained by the local signal and radiated from the device under test. Electromagnetic waves can be simultaneously received and processed by each receiving antenna. Therefore, the electromagnetic field strength can be measured at high speed.

  According to the second aspect of the present invention, the harmonic component contained in the local signal generated by the oscillator is removed by the low pass filter and mixed with the received signal input from the receiving antenna. Can be prevented from erroneously detecting that the received signal is frequency-converted. Therefore, the measurement accuracy of the electromagnetic field strength can be further improved.

  Further, according to the invention of claim 3, the receiving antenna is composed of a horizontally polarized wave receiving antenna that receives horizontal polarized waves of electromagnetic waves and a vertically polarized wave receiving antenna that receives vertically polarized waves. Both horizontal polarization and vertical polarization of electromagnetic waves radiated from the object to be measured can be received.

  Furthermore, according to the invention of claim 4, the horizontal polarization receiving antenna pole and the vertical polarization receiving antenna pole are integrally formed to be orthogonal to each other. Both waves and vertically polarized waves can be received.

  According to the fifth aspect of the present invention, a conductor film is formed on the printed circuit board for the pole of the horizontally polarized wave receiving antenna and the pole of the vertically polarized wave receiving antenna. It can be easily manufactured using a lithography technique, and the manufacturing cost can be reduced. Further, the antenna can be downsized due to the effect of shortening the effective wavelength by the dielectric of the printed circuit board.

  According to the invention of claim 6, the polarization changeover switch for switching the received signal of the horizontally polarized wave receiving antenna and the vertically polarized wave receiving antenna to the frequency conversion circuit after the receiving antenna is provided. As a result, the number of frequency conversion circuits can be reduced. Therefore, the cost of the apparatus can be reduced.

  Further, according to the invention of claim 7, the plurality of receiving antennas are arranged in a matrix form in the vertical and horizontal directions on the surface on the electromagnetic wave arrival side of the vertically extending frame, or arranged in a line in the vertical direction. Two-dimensional or one-dimensional measurement of intensity can be performed instantaneously.

  According to the invention of claim 8, the plurality of receiving antennas can be moved in a direction orthogonal to the arrival direction of the electromagnetic wave, so that the receiving antenna moves following the moving object to be measured, and the object to be measured The time change of the electromagnetic field intensity of the electromagnetic wave radiated from the object can be measured in real time.

  According to the ninth aspect of the present invention, the plurality of receiving antennas are arranged in a line on the electromagnetic wave arrival side surface of the arc-shaped frame, and are rotatably installed at the center of the arc-shaped frame. Since the electromagnetic wave from the measurement object is received, the three-dimensional electromagnetic field intensity of the electromagnetic wave radiated from the measurement object can be measured at a high speed with a small number of receiving antennas. Therefore, the cost of the apparatus can be reduced.

  Further, according to the invention of claim 10, since the plurality of receiving antennas can be moved in the same direction as the arrival direction of the electromagnetic wave, the receiving antennas can be shifted backward when installing the object to be measured. Can be done easily.

  According to the eleventh aspect of the present invention, since the radio wave absorber is provided on the electromagnetic wave arrival side surface of the frame in which the plurality of receiving antennas are disposed, the electromagnetic wave is reflected on the electromagnetic wave arrival side surface of the frame. Electromagnetic waves can be reduced. Therefore, the measurement accuracy can be improved by reducing the influence of the reflected wave by the frame.

  According to the invention of claim 12, the electromagnetic field intensity distribution in the cubic room is measured by arranging a plurality of receiving antennas facing inward on the six inner surfaces of the cubic room. be able to. Therefore, it is suitable for setting the installation location of the wireless LAN receiver, for example.

  According to the thirteenth aspect of the present invention, the plurality of receiving antennas are radiated from the object to be measured by being disposed inwardly on the inner surface of the spherical anechoic chamber for measuring the electromagnetic field strength. It is possible to instantaneously measure the three-dimensional electromagnetic field strength of electromagnetic waves.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an enlarged perspective view showing a main part of a first embodiment of an electromagnetic field measuring apparatus according to the present invention, and FIG. 2 is a front view showing a plurality of receiving antennas in the first embodiment. 3 is a side view of FIG. This electromagnetic field measuring apparatus measures the electromagnetic field intensity of an electromagnetic wave radiated from the device under test 1, and includes a receiving antenna 2, a frequency conversion circuit 3, and a combiner 4.

  The receiving antenna 2 receives an electromagnetic wave radiated from the device under test 1 and, as shown in FIG. 3, a plurality of receiving antennas 2 are arranged at positions separated from the device under test 1 radiating an electromagnetic wave. . The receiving antenna 2 is, for example, a dipole antenna having a pole extending in a straight line, and receives a pole and a vertically polarized wave of a horizontally polarized wave receiving antenna 6 that receives a horizontally polarized wave of an electromagnetic wave as shown in FIG. It is formed integrally with the pole of the vertically polarized wave receiving antenna 7 so as to be orthogonal to each other. In this embodiment, the pole of the horizontally polarized wave receiving antenna 6 and the pole of the vertically polarized wave receiving antenna 7 are obtained by forming conductor films 6 a and 6 b and 7 a and 7 b on the printed circuit board 8.

  The plurality of receiving antennas 2 are arranged in a matrix in the longitudinal and lateral directions as shown in FIG. 2 on the electromagnetic wave arrival side (arrow A side shown in the figure) of the vertically extending frame 10 as shown in FIG. The electromagnetic wave radiated from the DUT 1 can be received simultaneously in a two-dimensional plane. The plurality of receiving antennas 2 may be arranged in a zigzag shape in the vertical and horizontal directions. Thereby, the space | interval of each receiving antenna 2 can be narrowed, and precise | minute electromagnetic field distribution can be measured. In addition, a radio wave absorber 11 is provided on the electromagnetic wave arrival side surface of the frame 10 in which the plurality of receiving antennas 2 are arranged, so that the electromagnetic wave reflected by the electromagnetic wave arrival side surface of the frame 11 is reduced. ing.

As shown in FIG. 1, the frequency conversion circuit 3 is connected to each of the plurality of receiving antennas 2 by a coaxial cable (wired) 12. This frequency conversion circuit 3 uses local signals (reference symbols f ₁ , f ₂ , f ₃ ,... Shown in FIG. 4) for received signals (see reference symbol f ₀ shown in FIG. 4) received by the respective reception antennas 2. the f reference _n) to output the result is added as the position information of each reception antenna 2, as shown in FIG. 4, an oscillator 13, a low-pass filter 14, a mixer 15, consisting of amplifier 16..

The oscillator 13 generates a local signal as position information of the plurality of receiving antennas 2, and oscillates signals having frequencies f _{1 to} f _n set in advance corresponding to the positions of the receiving antennas 2. It is supposed to be. The low-pass filter 14 removes harmonic components contained in the local signal generated by the oscillator 13, and the cut-off frequency f _c is set to f _c <f ₀ . Further, the mixer 15 mixes the local signals f _{1 to} f _n that have passed through the low-pass filter 14 and the received signals f ₀ input from the receiving antennas 2 to obtain the received signal f ₀ as (f ₀ ± f _1). ), (F ₀ ± f ₂ ), (f ₀ ± f ₃ ),... (F ₀ ± f _n ). The amplifier 16 amplifies the frequency-converted received signals (f ₀ ± f ₁ ) to (f ₀ ± f _n ) to a predetermined level. The receiving antenna 2 is provided with a polarization changeover switch 17 for switching the received signals of the horizontally polarized wave receiving antenna 6 and the vertically polarized wave receiving antenna 7 and supplying the received signals to the frequency conversion circuit 3. The frequency conversion circuit 3 can measure both horizontally polarized waves and vertically polarized waves.

A synthesizer 4 is connected to the plurality of frequency conversion circuits 3 by a coaxial cable (wired) 18. The synthesizer 4 synthesizes the output signals (f ₀ ± f ₁ ) to (f ₀ ± f _n ) of the frequency conversion circuits 3 to obtain (f ₀ ± f ₁ ) + (f ₀ ± f ₂ ) + ( _{f 0 ± f 3) + ...} + ( and outputs by f ₀ ± f _n) and to for example one signal line 19. Then, the combined output (f ₀ ± f ₁ ) +... + (F ₀ ± f _n ) is input to the measuring device 5 connected to the combiner 4 and processed to be radiated from the device under test 1. Measure the electromagnetic field strength of the electromagnetic wave. The measuring instrument 5 includes a waveform analyzer that analyzes the frequency of the signal input from the synthesizer 4 through the signal line 19 and measures the intensity of the signal at each frequency, a personal computer, a display device, a printer, and the like.

Next, the operation of the electromagnetic field measuring apparatus configured as described above will be described.
First, as shown in FIG. 3, it protrudes in the electromagnetic wave arrival direction from the surface of the radio wave absorber 11 provided on the surface of the vertically extending frame 10 on the electromagnetic wave arrival side (arrow A side shown in FIG. 3). As shown, a plurality of receiving antennas 2 provided in a matrix form in the vertical and horizontal directions are placed facing the DUT 1 placed at a distant position.

  As shown in FIG. 1, the receiving antenna 2 used here is integrally formed by orthogonalizing the pole of the horizontally polarized wave receiving antenna 6 and the pole of the vertically polarized wave receiving antenna 7. The two receiving antennas 2 can receive both horizontal and vertical polarized waves of electromagnetic waves. Here, first, as shown in FIG. 4, the connection of the received signal is switched to the side of the horizontally polarized wave receiving antenna 6 by the polarization changeover switch 17 provided between the receiving antenna 2 and the frequency conversion circuit 3.

  Next, the device under test 1 is activated to emit electromagnetic waves, and the electromagnetic waves are simultaneously received by the plurality of receiving antennas 2. An electromagnetic wave reception signal received by each receiving antenna 2 is input to the frequency conversion circuit 3 connected by the coaxial cable 12 through the polarization switching switch 17.

In this case, for example, in the frequency conversion circuit 3 shown in FIG. 4, a local signal f ₁ set in advance corresponding to the arrangement position of each reception antenna 2 is generated by the oscillator 13, and the harmonic component is generated by the low-pass filter 14. Is removed and supplied to the mixer 15. In the mixer 15, the local signal f ₁ is added as position information of the receiving antenna 2 to the received signal f ₀ input from the receiving antenna 2, and the frequency is converted into a signal of (f ₀ + f ₁ ). Then, it is amplified to a predetermined level by the amplifier 16 and output from the frequency conversion circuit 3.

When a local signal is added as position information to the reception signal of the reception antenna 2 as described above, for example, when the frequency of the reception signal of the reception antenna 2 is f ₀ = 1 GHz, the frequency of the local signal f ₇₁ = The frequency f ₀ + f ₇₁ of the signal frequency-converted by adding ₇₁ MHz is 1.071 GHz. Further, since the harmonic component of the local signal f ₅₁ = ₅₁ MHz multiplied by 21 is also 1.071 GHz, this harmonic component may be erroneously detected as the received signal of the receiving antenna 2 subjected to frequency conversion. However, in this embodiment, the false detection can be prevented by removing the harmonic component of the local signal through the low-pass filter 14.

Output signals (f ₀ ± f ₁ ) to (f ₀ ± f _n ) that are frequency-converted and output from each frequency conversion circuit 3 are input to the synthesizer 4 through the coaxial cable 18, where they are respectively synthesized (f ₀ ± f ₁ ) +... + (F ₀ ± f _n ) and is output from one signal line 19.

The output (f ₀ ± f ₁ ) +... + (F ₀ ± f _n ) of the synthesizer 4 is input to the measuring device 5 through a single signal line 19, where waveform analysis is performed and processed. Then, the electromagnetic field distribution of horizontal polarization is measured. The result is displayed on a display unit (not shown) of the measuring instrument 5 and printed out.

  Next, the connection between the receiving antenna 2 and the frequency conversion circuit 3 is switched from the horizontally polarized wave receiving antenna 6 side to the vertically polarized wave receiving antenna 7 side by the polarization changeover switch 17 shown in FIG. Thus, the electromagnetic field distribution of vertical polarization is measured.

  FIG. 5 is a perspective view showing a second embodiment of the electromagnetic field measuring apparatus according to the present invention. In this electromagnetic field measuring apparatus, the receiving antennas 2 are arranged in two rows in the vertical direction on the surface of the electromagnetic wave arrival side (arrow A side shown in the figure) of the frame 10 in which the plurality of receiving antennas 2 extend vertically. It is arrange | positioned so that it may become. Also in this case, similarly to the first embodiment, the electromagnetic wave absorber 11 is provided on the electromagnetic wave arrival side surface of the frame 10 in which the plurality of receiving antennas 2 are arranged, and the electromagnetic wave arrival side surface of the frame 10 is provided. It is designed to reduce the electromagnetic waves reflected by the. A wheel 20 is provided on the bottom surface of the base member of the frame 10 so that the frame 10 can move on the rail 21 provided on the installation surface, and the plurality of receiving antennas 2 are orthogonal to the direction of arrival of electromagnetic waves. It can be moved in the directions of arrows B and C shown in FIG.

  Thereby, the receiving antenna 2 can be made to follow the moving device under test 1 and the frame 10 can be moved, and the time change of the electromagnetic field intensity of the electromagnetic wave radiated from the device under test 1 can be measured in real time. The plurality of receiving antennas 2 may be arranged in a line vertically with respect to the frame 10 as shown in FIG.

  FIG. 7 is a perspective view showing a third embodiment of the electromagnetic field measuring apparatus according to the present invention. In this electromagnetic field measuring apparatus, a plurality of receiving antennas 2 are arranged in a line on the surface of the arc-shaped frame 10 on the electromagnetic wave arrival side (arrow A side shown in the figure), and the center of the arc-shaped frame 10 is arranged. The electromagnetic wave radiated | emitted from the to-be-measured object 1 rotatably installed in can be received now. Also in this case, similarly to the first embodiment, the electromagnetic wave absorber 11 is provided on the electromagnetic wave arrival side surface of the frame 10 in which the plurality of receiving antennas 2 are arranged, and the electromagnetic wave arrival side surface of the frame 10 is provided. The electromagnetic waves reflected by the light are reduced. The plurality of receiving antennas 2 can be moved in the same direction as the direction of arrival of electromagnetic waves (the direction of arrow A shown in the figure) so that the wheels 20 can be provided on the bottom surface of the base member of the frame 10 to move. ing.

  As a result, the three-dimensional electromagnetic wave radiated from the DUT 1 can be measured at a speed 10 to 20 times faster than when the single receiving antenna 2 is measured while moving along the arcuate frame 10 by a predetermined angle. The electromagnetic field strength can be measured. In FIG. 7, the DUT 1 rotates around the vertical axis at the tip of the arm-like support means 22 that extends horizontally, but is perpendicular to the installation surface as shown in FIG. 8. Alternatively, the pole-shaped support means 22 may extend around the central axis of the pole-shaped support means 22.

  FIG. 9 is a perspective view showing a fourth embodiment of the electromagnetic field measuring apparatus according to the present invention. In this electromagnetic field measuring apparatus, a plurality of receiving antennas 2 are arranged inwardly on six inner surfaces of a cubic room 23 or an anechoic chamber, and a wireless LAN transmitted from a personal computer as the device under test 1 is used. The electromagnetic field distribution of electromagnetic waves can be measured. Thus, for example, if the installation location of the wireless LAN receiver is set to a location where the electromagnetic field strength is the strongest, or a location where the electromagnetic field distributions of the wireless LAN electromagnetic waves radiated from a plurality of personal computers overlap, The LAN connection can be reliably performed.

  FIG. 10 is a perspective view showing a fifth embodiment of the electromagnetic field measuring apparatus according to the present invention. In this electromagnetic field measuring apparatus, a plurality of receiving antennas 2 are disposed inwardly on the inner surface of a spherical anechoic chamber 24 for measuring the electromagnetic field strength, and the object to be measured is disposed at the center position of the sphere. The electromagnetic wave from 1 can be received. Thereby, the three-dimensional electromagnetic field intensity of the electromagnetic wave radiated from the DUT 1 can be instantaneously measured.

  In the above description, the case where the reception antenna 2 is an integration of the horizontally polarized wave receiving antenna 6 and the vertically polarized wave receiving antenna 7 has been described. However, the present invention is not limited to this. Any one of the horizontally polarized wave receiving antenna 6 and the vertically polarized wave receiving antenna 7 may be used. In this case, the receiving antenna 2 is directly connected to the frequency conversion circuit 3 by a wire without passing through the polarization switching switch 17 shown in FIG. Therefore, when the electromagnetic field is measured by switching the polarization plane, the one antenna is replaced with the other antenna, or one antenna is rotated by 90 degrees.

It is a perspective view which expands and shows the principal part of 1st Embodiment of the electromagnetic field measuring device by this invention. It is a front view which shows the several receiving antenna in the said 1st Embodiment. FIG. 3 is a side view of FIG. 2. It is a block diagram which shows the frequency conversion circuit of the said electromagnetic field measuring apparatus. It is a perspective view which shows 2nd Embodiment of the electromagnetic field measuring device by this invention. FIG. 6 is a perspective view showing another installation example of the receiving antenna shown in FIG. 5. It is a perspective view which shows 3rd Embodiment of the electromagnetic field measuring device by this invention. It is a perspective view which shows the other structural example of the support means of the to-be-measured object shown in FIG. It is a perspective view which shows 4th Embodiment of the electromagnetic field measuring device by this invention. It is a perspective view which shows 5th Embodiment of the electromagnetic field measuring device by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Device under test 2 ... Reception antenna 3 ... Frequency conversion circuit 4 ... Synthesizer 5 ... Measurement device 6 ... Horizontal polarization receiving antenna 6a, 6b, 7a, 7b ... Conductor film 7 ... Vertical polarization receiving antenna 8 ... Printed circuit board 10 ... Frame 11 ... Radio wave absorber 12,18 ... Coaxial cable (wired)
DESCRIPTION OF SYMBOLS 13 ... Oscillator 14 ... Low pass filter 15 ... Mixer 17 ... Polarization changeover switch 19 ... Signal line 23 ... Room 24 ... Anechoic chamber

Claims (13)

A plurality of receiving antennas disposed at a position away from the object to be electromagnetically radiated and receiving electromagnetic waves radiated from the object to be measured;
A plurality of frequency conversion circuits that are connected to the respective reception antennas and output local signals having different frequencies to the reception signals received by the reception antennas;
A synthesizer that is connected to the plurality of frequency conversion circuits in a wired manner, synthesizes output signals of the frequency conversion circuits, and outputs them to a measuring instrument that measures the electromagnetic field intensity of the electromagnetic waves radiated from the object to be measured;
An electromagnetic field measuring apparatus comprising:   The frequency conversion circuit passes through an oscillator that generates the local signal, a low-pass filter that removes harmonic components contained in the local signal generated by the oscillator, a reception signal that is input from the reception antenna, and the low-pass filter. The electromagnetic field measuring apparatus according to claim 1, further comprising a mixer that mixes the local signal.   3. The electromagnetic field according to claim 1, wherein the receiving antenna includes a horizontally polarized wave receiving antenna that receives horizontally polarized waves of electromagnetic waves and a vertically polarized wave receiving antenna that receives vertically polarized waves. measuring device.   4. The electromagnetic field measuring apparatus according to claim 3, wherein the receiving antenna is integrally formed by orthogonalizing a pole of the horizontally polarized wave receiving antenna and a pole of the vertically polarized wave receiving antenna.   5. The electromagnetic field measuring apparatus according to claim 4, wherein the pole of the horizontally polarized wave receiving antenna and the pole of the vertically polarized wave receiving antenna are obtained by forming a conductor film on a printed circuit board.   4. The polarization changeover switch for switching the reception signals of the horizontal polarization reception antenna and the vertical polarization reception antenna to supply the frequency conversion circuit after the reception antenna. The electromagnetic field measuring apparatus according to any one of?   The plurality of receiving antennas are arranged in a matrix in the vertical and horizontal directions or arranged in a vertical row on the electromagnetic wave arrival side surface of a vertically extending frame. The electromagnetic field measuring apparatus described in 1.   The electromagnetic field measuring apparatus according to claim 7, wherein the plurality of receiving antennas are movable in a direction orthogonal to an arrival direction of electromagnetic waves.   The plurality of receiving antennas are arranged in a line on the surface of the arc-shaped frame on the electromagnetic wave arrival side, and receive electromagnetic waves from an object to be measured that is rotatably installed at the center of the arc-shaped frame. The electromagnetic field measuring apparatus according to claim 1, wherein the electromagnetic field measuring apparatus is characterized.   The electromagnetic field measuring apparatus according to claim 9, wherein the plurality of receiving antennas are movable in the same direction as an arrival direction of electromagnetic waves.   The electromagnetic wave receiving body for reducing the electromagnetic wave reflected by the electromagnetic wave arrival side surface of the frame is provided on the electromagnetic wave arrival side surface of the frame in which the plurality of receiving antennas are disposed. The electromagnetic field measurement apparatus according to any one of 7 to 10.   The electromagnetic field measuring apparatus according to any one of claims 1 to 6, wherein the plurality of receiving antennas are arranged inwardly on six inner surfaces of a cubic room.   The electromagnetic wave according to any one of claims 1 to 6, wherein the plurality of receiving antennas are arranged inwardly on an inner surface of a spherical anechoic chamber for measuring electromagnetic field strength. Field measuring device.

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