CN106770374B - Wave-absorbing material reflection measurement device and method - Google Patents
Wave-absorbing material reflection measurement device and method Download PDFInfo
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Abstract
The invention provides a wave-absorbing material reflection measuring device, which comprises a transmitting antenna, a receiving antenna, an arch frame, a time domain pulse generator, a time domain pulse receiver and a good conductor plate, wherein the transmitting antenna is connected with the receiving antenna through a cable; the receiving antenna and the transmitting antenna are symmetrically arranged on the arch frame, the positions of the transmitting antenna and the receiving antenna and the normal direction of the mouth surface are adjustable, and the time domain pulse generator generates time domain pulses to excite the transmitting antenna; and the time domain pulse receiver receives time domain signals, and wave-absorbing materials are laid on one surface of the good conductor plate facing the transmitting antenna and the receiving antenna to form a wave-absorbing material plate. The measuring method comprises the following steps: the included angle between the normal of the receiving and transmitting antenna aperture surface and the normal of the wave-absorbing material plate to be measured is equal; sending out a time domain pulse signal and receiving a time domain receiving signal waveform; and selecting a time domain reflection signal of the detected wave-absorbing material by using the time window to perform time-frequency domain processing to obtain a wave-absorbing material frequency domain reflection waveform. The invention reduces the test error caused by data time-frequency domain transformation.
Description
Technical Field
The application relates to the technical field of electromagnetic fields, in particular to a device and a method for measuring a wave absorbing material.
Background
In recent years, with the rapid development of the electromagnetic compatibility measurement technology and the antenna measurement technology, the demands for the electromagnetic compatibility darkroom and the antenna measurement darkroom are increasing. In order to reduce multipath reflection in the electromagnetic compatibility measurement and antenna measurement processes, radio frequency wave absorbing materials are attached to the inner walls and ceilings or all wall surfaces of the electromagnetic compatibility darkroom and the antenna darkroom. The radio frequency wave-absorbing material can absorb and attenuate radio frequency electromagnetic waves projected on the surface of the material, and convert the electromagnetic energy into heat energy to be dissipated or eliminate the electromagnetic waves due to interference. As the performance of the radio frequency wave-absorbing material directly influences the performance of the electromagnetic compatibility darkroom and the antenna darkroom, the performance of the used radio frequency wave-absorbing material needs to be tested and evaluated in the construction process of the darkroom in order to ensure that the field performance of the darkroom and the measurement environment meet the actual use requirements. The absorption and attenuation performance of the radio frequency wave-absorbing material to the electromagnetic waves is represented by the reflectivity of the radio frequency wave-absorbing material, so that before the radio frequency wave-absorbing material leaves a factory, a wave-absorbing material manufacturer can measure the reflectivity of the radio frequency wave-absorbing material. In the existing method for measuring the reflectivity of the radio frequency wave-absorbing material, a frequency domain curve needs to be converted into a time domain curve in the data processing process, and after direct coupling signals between transmitting and receiving antennas and other environment reflection signals are filtered by using the time domain gate function of a vector network analyzer, the time domain curve is converted into the frequency domain curve. In the data processing process, enough frequency points need to be collected in the frequency domain scanning process to obtain accurate time domain information, and meanwhile, truncation errors of conversion also exist in the two time-frequency conversion processes, so that the measurement result of the reflectivity of the radio frequency wave-absorbing material can be influenced.
Disclosure of Invention
The invention provides a device and a method for measuring reflection of a wave-absorbing material, which can reduce test errors caused by time-frequency domain transformation of data.
The embodiment of the application provides a wave-absorbing material reflection measuring device, which comprises a transmitting antenna, a receiving antenna, an arch frame, a time domain pulse generator, a time domain pulse receiver and a good conductor plate, wherein the receiving antenna is arranged on the top of the arch frame; the arch of the arch frame surrounds the center of the good conductor plate, and the plane of the arch is vertical to the plane of the good conductor plate; the receiving antenna and the transmitting antenna are symmetrically arranged on an arch frame, and the positions of the transmitting antenna and the receiving antenna on the arch frame are adjustable; the normal direction of the transmitting antenna aperture surface is adjustable; the normal direction of the aperture surface of the receiving antenna is adjustable; the output end of the time domain pulse generator is connected with the transmitting antenna and is used for generating time domain pulses and exciting the transmitting antenna; the input end of the time domain pulse receiver is connected with the receiving antenna and used for receiving time domain signals; the transmitting antenna is used for emitting electromagnetic waves to the good conductor plate; the receiving antenna is used for receiving the electromagnetic wave reflected by the good conductor plate; the good conductor plate is used for reflecting electromagnetic waves; and one surface of the good conductor plate facing the transmitting antenna and the receiving antenna is also used for paving a wave-absorbing material to manufacture a wave-absorbing material plate.
Preferably, the good conductor plate or the wave-absorbing material plate can translate back and forth along the normal direction of the good conductor plate or the wave-absorbing material plate.
The embodiment of the application also provides a wave-absorbing material reflection measurement method, which is used for any device in the application and comprises the following steps:
symmetrically placing the transmitting antenna and the receiving antenna on an arch frame, so that a first included angle is formed between the normal of the mouth surface of the receiving antenna and the normal of the measured wave-absorbing material plate, a second included angle is formed between the normal of the mouth surface of the transmitting antenna and the normal of the measured wave-absorbing material plate, and the first included angle and the second included angle are equal;
generating a time domain pulse signal by using a time domain pulse generator, exciting a transmitting antenna to emit electromagnetic waves to a measured wave-absorbing material plate, and enabling reflected electromagnetic waves to enter a time domain pulse receiver through a receiving antenna to obtain a received signal waveform;
selecting a time domain reflection signal of the wave-absorbing material to be detected from the received signal waveform by using a time window;
and carrying out time-frequency domain processing on the wave-absorbing material time domain reflection signal to obtain a wave-absorbing material frequency domain reflection waveform.
Further, the method of the present application further comprises the steps of:
replacing the wave-absorbing material plate with a good conductor plate;
generating a time domain pulse signal by using a time domain pulse generator, exciting a transmitting antenna to emit electromagnetic waves to a good conductor plate to be tested, and reflecting the electromagnetic waves to enter a time domain pulse receiver through a receiving antenna to obtain a received signal waveform;
selecting a good conductor plate time domain reflection signal to be tested from the received signal waveform by using a time window;
and performing time-frequency domain processing on the good conductor plate time domain reflection signal to obtain a good conductor plate frequency domain reflection waveform.
Further, the method of the present application further comprises the steps of: and calculating the reflectivity of the detected wave-absorbing material by using the wave-absorbing material frequency domain reflection waveform and the good conductor plate frequency domain reflection waveform.
Preferably, in the method of the present invention, the positions of the transmitting antenna and the receiving antenna on the arch are changed, the first angle and the second angle are changed, and the steps are repeated.
Preferably, in the method of the present invention, the rise time of the time domain pulse signal is less than 19.4 ps.
Preferably, in the method of the present invention, the transmission wire and the reception antenna are linearly polarized antennas; the steps are repeated in both cases of horizontal polarization and vertical polarization, respectively.
Preferably, in the method of the present invention, the wave-absorbing material plate or the good conductor plate is moved back and forth along a normal direction of the wave-absorbing material plate or the good conductor plate, and the steps are repeated.
Preferably, the time-frequency domain processing method is to use a kaiser window to weight a time window, and then perform fast fourier transform to obtain the wave-absorbing material frequency domain waveform or the good conductor plate frequency domain waveform.
The embodiment of the application adopts at least one technical scheme which can achieve the following beneficial effects: the device and the method for measuring the reflection of the wave-absorbing material can overcome the defects of a method for testing a vector network analyzer, do not need the vector network analyzer, utilize the combination of a time domain pulse generator and pulse receiving equipment according to the definition of the reflectivity of the radio frequency wave-absorbing material, and obtain the reflection signal of the radio frequency wave-absorbing material by the pulse receiving equipment receiving the time domain signals with different arrival times through the transmitting and receiving processes of the time domain pulse signals, thereby avoiding the conversion process from a frequency domain curve to a time domain curve in the method, effectively reducing the truncation error in the time frequency conversion process and improving the accuracy of the measurement result of the reflectivity of the radio frequency wave-absorbing material.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a schematic diagram of a conventional vector network analyzer measurement device;
FIG. 2 is a schematic view of a measurement receiving curve of a conventional vector network analyzer;
FIG. 2a is curve 1 (frequency domain);
FIG. 2b is curve 2 (curve 1 transformed to the time domain);
FIG. 2c is plot 3 (plot 2 is time-domain gated);
FIG. 2d is curve 4 (curve 3 transformed to the frequency domain);
FIG. 3 is a schematic view of a reflection measurement apparatus for a wave-absorbing material according to the present invention;
FIG. 4 is a flow chart of steps of a reflection measurement method of a wave-absorbing material according to the present invention;
FIG. 5 is a schematic diagram of a time-domain received signal waveform of the measurement method of the present invention;
FIG. 5a is a diagram illustrating an actual received signal waveform and a time window selection;
fig. 5b shows the transformation of the time-window selected time-domain signal into a frequency-domain waveform.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The reflectivity of the radio frequency wave-absorbing material is characterized by the reflection loss of different wave-absorbing materials to electromagnetic waves with different frequencies, and is defined as the ratio of the reflection power of the electromagnetic waves from the same direction to the measured radio frequency wave-absorbing material and the reflection power of the electromagnetic waves from the same mirror surface direction to the same power density on the good conductor metal flat plate with the same size under the condition of given wavelength and polarization. According to the definition of the reflectivity of the radio frequency wave-absorbing material, when the reflectivity of the material is measured, two times of measurement are needed, one time is to measure the signal of the electromagnetic wave reflected by the measured radio frequency wave-absorbing material, and the other time is to measure the signal of the electromagnetic wave reflected by the good conductor metal plate with the same size, which comprises the following steps:
Γ＝20log(E1/E0) Equation 1
The transform in dB is expressed as follows:
Γ(dB)＝E1(dB)-E0(dB) formula2
Wherein: gamma-the reflectivity of the radio frequency wave-absorbing material to be detected; e1-signals reflected by the radio frequency wave absorbing material to be detected; e0-signal reflected by the good conductor metal plate.
The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a conventional vector network analyzer measuring device. The device comprises an arch frame device, a transmitting antenna, a receiving antenna, a vector network analyzer, a control computer and the like. The output end of the vector network analyzer is connected with the transmitting antenna, and the excited signal is reflected by the tested radio frequency wave-absorbing material or the good conductor metal plate, then is received by the receiving antenna and is sent to the input end of the vector network analyzer connected with the receiving antenna; the transmitting antenna and the receiving antenna can independently move on the arch frame and point to the circle center; the ratio of the reflection signal of the tested radio frequency wave-absorbing material to the reflection signal of the good conductor metal plate is the reflectivity of the tested radio frequency wave-absorbing material.
Fig. 2 is a schematic diagram of a receiving curve of a measurement method of a conventional vector network analyzer. The signals received by the receiving antenna comprise not only the wave-absorbing material and the reflected signals of the metal plate, but also direct coupling signals between the transmitting antenna and the receiving antenna, reflected signals of the arch frame and the surrounding environment, and the like. The frequency domain curve received by the input end of the vector network analyzer is required to be transformed to the time domain, the reflected signal of the wave-absorbing material to be detected is separated by adopting the time domain gate function of the vector network analyzer according to different arrival times of the received time domain signal, and then the time domain signal processed by the time domain gate is transformed to the frequency domain. Typical application data processing process diagrams are shown in fig. 2 a-d. FIG. 2a is curve 1 (frequency domain); FIG. 2b is curve 2 (curve 1 transformed to the time domain); FIG. 2c is plot 3 (plot 2 is time-domain gated); fig. 2d is curve 4 (curve 3 transformed into the frequency domain).
FIG. 3 is a schematic view of a reflection measurement device of a wave-absorbing material of the present invention. The embodiment of the application provides a wave-absorbing material reflection measuring device, which comprises a transmitting antenna 1, a receiving antenna 2, an arch frame 3, a time domain pulse generator 4, a time domain pulse receiver 5 and a good conductor plate 6; the arch of the arch frame surrounds the center of the good conductor plate, and the plane of the arch is vertical to the plane of the good conductor plate; the receiving antenna and the transmitting antenna are symmetrically arranged on an arch frame, and the positions of the transmitting antenna and the receiving antenna on the arch frame are adjustable; the normal direction of the transmitting antenna aperture surface is adjustable; the normal direction of the aperture surface of the receiving antenna is adjustable; the output end of the time domain pulse generator is connected with the transmitting antenna and is used for generating time domain pulses and exciting the transmitting antenna; the input end of the time domain pulse receiver is connected with the receiving antenna and used for receiving time domain signals; the transmitting antenna is used for emitting electromagnetic waves to the good conductor plate; the receiving antenna is used for receiving the electromagnetic wave reflected by the good conductor plate; the good conductor plate is used for reflecting electromagnetic waves; and one surface of the good conductor plate facing the transmitting antenna and the receiving antenna is also used for paving a wave-absorbing material 7 to manufacture a wave-absorbing material plate.
Preferably, the good conductor plate or the wave-absorbing material plate can translate back and forth along the normal direction of the good conductor plate or the wave-absorbing material plate.
When the device works, firstly, the receiving antenna and the transmitting antenna are aligned to the surface of a measured radio frequency wave-absorbing material, a time domain pulse generator generates a time domain pulse signal, electromagnetic waves are radiated to the space through the transmitting antenna, and the time domain pulse signal is received by the receiving antenna and enters a time domain pulse receiver after being reflected by the measured radio frequency wave-absorbing material or a good conductor metal plate. Optimally, the computer 8 is used for controlling the receiving and sending of the time domain pulse signals to obtain the reflection signals of the radio frequency wave-absorbing material to be detected or the good conductor metal plate, and further the reflectivity of the wave-absorbing material to be detected is obtained.
FIG. 4 is a flow chart of the steps of the method for measuring reflection of a wave-absorbing material of the present invention. The embodiment of the application also provides a wave-absorbing material reflection measurement method, which is used for any device in the application and comprises the following steps:
And step 40, performing time-frequency domain processing on the wave-absorbing material time domain reflection signal to obtain a wave-absorbing material frequency domain reflection waveform.
Further, the method of the present application further comprises the steps of:
50, replacing the wave-absorbing material plate with a good conductor plate;
and 80, performing time-frequency domain processing on the good conductor plate time domain reflection signal to obtain a good conductor plate frequency domain reflection waveform.
Further, the method of the present application may further comprise the steps of:
and 90, calculating the reflectivity of the detected wave-absorbing material by using the wave-absorbing material frequency domain reflection waveform and the good conductor plate frequency domain reflection waveform.
Preferably, in the method of the present invention, the positions of the transmitting antenna and the receiving antenna on the arch frame are changed, the first included angle a1 and the second included angle a2 are changed, and the steps 10 to 90 are repeated.
Preferably, in the method of the present invention, the transmission wire and the reception antenna are linearly polarized antennas; the steps 10 to 90 are repeated in both cases of horizontal polarization and vertical polarization, respectively. It should be noted that, because the representation of the reflectivity of the radio frequency wave-absorbing material is generally divided into two situations of vertical polarization and horizontal polarization, when the time domain measurement of the reflectivity of the radio frequency wave-absorbing material is performed in this scheme, a linear polarization antenna needs to be used to perform measurement under two situations of vertical polarization and horizontal polarization respectively.
Fig. 5 is a schematic diagram of a time-domain received signal waveform of the measurement method of the present invention. In the process of obtaining the measured radio frequency wave-absorbing material or good conductor metal plate reflection signal, the required wave-absorbing material plate time domain reflection signal or good conductor plate time domain reflection signal needs to be separated from the receiving and transmitting antenna direct coupling signal, the arch frame and the surrounding environment reflection signal. Since the measuring signal used by the invention is a time domain pulse signal, the signal sent by the receiving antenna to the pulse receiving equipment is a time domain signal. Because the time of each part of the multipath time domain signal reaching the receiving antenna is different, the signal can be separated according to the time sequence, thereby obtaining the wave-absorbing material of the tested equipment or the reflection signal of the good conductor metal plate. After the reflection signal of the measured radio frequency wave-absorbing material and the reflection signal of the good conductor metal plate are obtained according to the measurement process, the reflection measurement result is usually expressed in a frequency spectrum curve mode, therefore, the time domain reflection signal needs to be converted to the frequency domain, the reflection rate gamma of the measured radio frequency wave-absorbing material is obtained by calculation according to the formula 2, the data processing flow chart is shown in fig. 5, and fig. 5a is a schematic diagram for selecting the waveform and the time window of the actual received signal; fig. 5b shows the transformation of the time-window selected time-domain signal into a frequency-domain waveform. The method comprises the steps of sequentially obtaining an ambient reflection signal r1, a wave-absorbing material time domain reflection signal r2 and an ambient multiple reflection signal r3, and extracting the wave-absorbing material time domain reflection signal from the received time domain signal by setting a time window W.
Preferably, in the method of the present invention, the rise time of the time domain pulse signal is less than 19.4 ps. It should be noted that, because the radio frequency wave-absorbing material is applied to the electromagnetic compatible darkroom, and the using frequency range of the electromagnetic compatible darkroom wave-absorbing material is 30 MHz-18 GHz, the radio frequency wave-absorbing material is applied to the electromagnetic compatible darkroom, the frequency range of the electromagnetic compatible darkroom wave-absorbing material is 30 MHz-18 GHzIn order to measure the reflectivity of the radio frequency wave-absorbing material at the frequency of 18GHz, the time domain pulse signal used in the measurement can cover the frequency of 18GHz when converted into the frequency domain. According to the relation BW between the rise time of the time domain pulse and the covered frequency bandwidth being 0.35/trIt can be seen that in order to cover the frequency range of 18GHz, the scheme requires the use of the rise time trA time domain pulse signal of less than 19.4 ps. Wherein BW represents frequency bandwidth in GHz, trRepresenting the pulse rise time in ns.
Preferably, in the method of the present invention, the wave-absorbing material plate or the good conductor plate is moved back and forth along a normal direction of the wave-absorbing material plate or the good conductor plate, and the steps 10 to 90 are repeated. It should be noted that, as shown in fig. 5, the signals received by the time-domain pulse receiving device include signals directly coupled by the transceiver antenna, reflected signals of the radio frequency wave-absorbing material or the metal plate to be tested, and other stray reflected signals. In the selection process of the time domain gate, the distance between the detected material or the metal plate and the receiving antenna changes due to the fact that the detected radio frequency wave-absorbing material or the metal plate moves up and down, so that in signals received by the time domain pulse receiving equipment, the arrival time of the reflected signal part of the detected material or the metal plate changes along with the change of the distance, in a received signal curve shown in fig. 5, signals in a square frame range move left and right on a time axis, and the width of the time domain gate can be determined according to the reflected signals of the detected material or the metal plate moving left and right, and is within the square frame range shown in fig. 5.
Preferably, the time-frequency domain processing method is to use a kaiser window to weight a time window, and then perform fast fourier transform to obtain the wave-absorbing material frequency domain waveform or the good conductor plate frequency domain waveform. It should be noted that, in the time-frequency domain conversion process, an appropriate time window function needs to be selected for transformation. In the transformation process, firstly, a rectangular window function is selected to intercept a time domain signal waveform; the direct FFT is equivalent to the conversion after adding a rectangular window to the whole time domain signal, and the energy of a side lobe in the frequency spectrum component of the rectangular window function is larger, so that larger interference is introduced to the frequency spectrum component of the time domain signal waveform, the kaiser window has maximum side lobe suppression, and the interference introduced to the frequency spectrum component of the time domain signal waveform is minimum, so the kaiser window is added to the whole time domain signal.
Therefore, according to the definition of the reflectivity of the radio frequency wave-absorbing material, the method utilizes the combination of the time domain pulse generator and the pulse receiving equipment, and obtains the reflected signal of the radio frequency wave-absorbing material by the pulse receiving equipment receiving the time domain signals with different arrival times through the transmitting and receiving processes of the time domain pulse signals, thereby avoiding the conversion process from the frequency domain curve to the time domain curve, effectively reducing the truncation error in the time frequency conversion process and improving the accuracy of the measurement result of the reflectivity of the radio frequency wave-absorbing material.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (5)
1. A wave-absorbing material reflection measuring device is characterized by comprising a transmitting antenna, a receiving antenna, an arch frame, a time domain pulse generator, a time domain pulse receiver, a good conductor plate, a wave-absorbing material plate and a computer;
the arch of the arch frame surrounds the center of the good conductor plate, and the plane of the arch is vertical to the plane of the good conductor plate;
the receiving antenna and the transmitting antenna are symmetrically arranged on an arch frame, and the positions of the transmitting antenna and the receiving antenna on the arch frame are adjustable;
the normal direction of the transmitting antenna aperture surface is adjustable; the normal direction of the aperture surface of the receiving antenna is adjustable;
the output end of the time domain pulse generator is connected with the transmitting antenna and is used for generating time domain pulses and exciting the transmitting antenna; the rise time of the time domain pulse signal is less than 19.4 ps;
the input end of the time domain pulse receiver is connected with the receiving antenna and used for receiving a time domain signal to obtain a received signal waveform;
the transmitting antenna is used for transmitting electromagnetic waves to the good conductor plate or the wave-absorbing material plate;
the receiving antenna is used for receiving the electromagnetic waves reflected by the good conductor plate or the wave-absorbing material plate;
the good conductor plate is used for reflecting electromagnetic waves;
one surface of the good conductor plate, which faces the transmitting antenna and the receiving antenna, is also used for paving a wave-absorbing material to manufacture a wave-absorbing material plate;
the computer is used for controlling the receiving and sending of the time domain pulse signals to obtain the reflection signals of the measured radio frequency wave-absorbing material or the good conductor metal plate, and further obtain the reflectivity of the measured wave-absorbing material:
sending electromagnetic waves to a wave-absorbing material plate to be detected, and selecting a time domain reflection signal of the wave-absorbing material to be detected from the received signal waveform by using a time window;
performing time-frequency domain processing on the wave-absorbing material time-domain reflection signal to obtain a wave-absorbing material frequency-domain reflection waveform;
sending electromagnetic waves to the good conductor plate to be tested, and selecting a time domain reflection signal of the good conductor plate to be tested from the received signal waveform by using a time window;
performing time-frequency domain processing on the good conductor plate time domain reflection signal to obtain a good conductor plate frequency domain reflection waveform;
calculating the reflectivity of the detected wave-absorbing material by using the wave-absorbing material frequency domain reflection waveform and the good conductor plate frequency domain reflection waveform;
the time-frequency domain processing is to use a Kaiser window to weight a time window and then carry out fast Fourier transform to obtain the wave-absorbing material frequency domain waveform or the good conductor plate frequency domain waveform;
the transmitting wire and the receiving antenna are linearly polarized antennas, and measurement is performed under two conditions of vertical polarization and horizontal polarization respectively.
2. The reflection measurement device of claim 1, wherein,
the good conductor plate or the wave-absorbing material plate can move back and forth along the normal direction of the good conductor plate or the wave-absorbing material plate.
3. A wave-absorbing material reflection measurement method is characterized by comprising the following steps:
symmetrically placing the transmitting antenna and the receiving antenna on an arch frame, so that a first included angle is formed between the normal of the mouth surface of the receiving antenna and the normal of the measured wave-absorbing material plate, a second included angle is formed between the normal of the mouth surface of the transmitting antenna and the normal of the measured wave-absorbing material plate, and the first included angle and the second included angle are equal;
generating a time domain pulse signal by using a time domain pulse generator, wherein the rise time of the time domain pulse signal is less than 19.4 ps; exciting the transmitting antenna to send out electromagnetic waves to the measured wave absorbing material plate, and reflecting the electromagnetic waves to enter a time domain pulse receiver through the receiving antenna to obtain a received signal waveform;
selecting a time domain reflection signal of the wave-absorbing material to be detected from the received signal waveform by using a time window;
performing time-frequency domain processing on the wave-absorbing material time-domain reflection signal to obtain a wave-absorbing material frequency-domain reflection waveform;
replacing the wave-absorbing material plate with a good conductor plate;
generating a time domain pulse signal by using a time domain pulse generator, exciting a transmitting antenna to emit electromagnetic waves to a good conductor plate to be tested, and reflecting the electromagnetic waves to enter a time domain pulse receiver through a receiving antenna to obtain a received signal waveform;
selecting a good conductor plate time domain reflection signal to be tested from the received signal waveform by using a time window;
performing time-frequency domain processing on the good conductor plate time domain reflection signal to obtain a good conductor plate frequency domain reflection waveform;
calculating the reflectivity of the detected wave-absorbing material by using the wave-absorbing material frequency domain reflection waveform and the good conductor plate frequency domain reflection waveform;
the time-frequency domain processing is to use a Kaiser window to weight a time window and then carry out fast Fourier transform to obtain the wave-absorbing material frequency domain waveform or the good conductor plate frequency domain waveform;
the transmitting wire and the receiving antenna are linearly polarized antennas, and measurement is performed under two conditions of vertical polarization and horizontal polarization respectively.
4. The method for measuring reflection of a wave-absorbing material according to claim 3, further comprising the steps of:
and changing the positions of the transmitting antenna and the receiving antenna on the arch frame, changing the first included angle and the second included angle, and repeating the steps.
5. The reflection measurement method of wave-absorbing material according to claim 3,
and moving the wave absorbing material plate or the good conductor plate back and forth along the normal direction of the wave absorbing material plate or the good conductor plate, and repeating the steps.
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