WO2020113671A1 - System and method for detecting electromagnetic characteristic of object by using terahertz electromagnetic wave - Google Patents
System and method for detecting electromagnetic characteristic of object by using terahertz electromagnetic wave Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
- G01N21/3586—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation by Terahertz time domain spectroscopy [THz-TDS]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2617—Measuring dielectric properties, e.g. constants
Definitions
- the invention relates to the field of electromagnetic detection, in particular to a system and method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves.
- the use of electromagnetic waves to detect the dielectric constant of objects the frequency band of electromagnetic waves used is generally below 6GHz, and the size of the measured object needs to be used when using, the use of electromagnetic waves
- an accurate object thickness is required.
- the size of the object used cannot be too small; the object is detected using light waves, and the content of the object is determined by the absorption rate of light waves of different wavelengths.
- the object needs to be transparent for the detection; use NMR and other methods to excite the object to emit electromagnetic waves, obtain the internal structure of the object by detecting the electromagnetic wave, and use the NMR method to detect the device is very complicated, and because of the presence of the magnetic field coil, the device is bulky; use X Rays or other high-energy rays detect the internal structure of the object.
- the equipment is complicated when using X-ray detection. At the same time, considering the relationship between human radiation, these devices must be equipped with relatively bulky radiation protection devices.
- the technical problem to be solved by the present invention is to provide a system and method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, which can detect the electromagnetic characteristics of an object using terahertz electromagnetic waves, realize non-destructive detection, have high accuracy, and have good effects.
- the present invention provides a system for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, including:
- a signal source which can generate the same transmission signal and reference signal, and the transmission signal and the reference signal are terahertz electromagnetic wave signals;
- a signal transmitting unit which is located on the side of the object to be measured, the transmitting signal transmits electromagnetic waves toward the object to be measured through the signal transmitting unit, and the signal transmitting unit is a phased array antenna;
- a signal receiving unit which is located on the other side of the measured object, and the signal receiving unit receives the electromagnetic wave emitted by the phased array antenna;
- the signal comparison unit compares the electromagnetic wave signal received by the signal receiving unit with the reference signal to obtain the amplitude ratio and the phase difference ratio of the two, thereby obtaining the electromagnetic characteristics of the object to be measured.
- the signal source is a terahertz frequency sweep signal source.
- the frequency sweep signal range of the terahertz frequency sweep signal source is 100 GHz to 1 THz.
- a power distributor is connected to the signal source, and the signal source is divided into two channels of the same output signal by the power distributor, and the two channels of the same output signal are a transmission signal and a reference signal.
- the signal receiving unit includes a first receiving antenna and a second receiving antenna, and the first receiving antenna and the second receiving antenna are at equal vertical distances from the phased array antenna plane;
- the connection of the array antenna is perpendicular to the phased array antenna surface, and the connection between the second receiving antenna and the phased array antenna is at an angle of ⁇ with the phased array antenna surface, where -90° ⁇ 90°, and ⁇ ⁇ 0.
- the invention also discloses a method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves. Based on the above system for detecting the electromagnetic characteristics of an object, the method includes the following steps:
- Step 1 The signal source works and sends out a reference signal and a transmission signal
- Step 2 No object to be measured is placed between the phased array antenna and the signal receiving unit, and the transmission direction of the phased array antenna is adjusted so that the main lobe of the phased array antenna faces the first receiving antenna.
- the unit obtains the amplitude ratio R 1, f of the received signal of the first receiving antenna and the reference signal and the phase difference value Adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the second receiving antenna, and obtain the amplitude ratio R 2 of the received signal of the second receiving antenna and the reference signal through the signal comparison unit f and phase difference
- Step 3 Place the measured object between the phased array antenna and the signal receiving unit, adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the first receiving antenna, and pass the signal comparison unit Obtain the amplitude ratio of the received signal of the first receiving antenna to the reference signal R'1 , f and the phase difference Adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the second receiving antenna, and obtain the amplitude ratio R′ 2 of the received signal of the second receiving antenna and the reference signal through the signal comparison unit ,f and phase difference
- Step 4 Through the amplitude ratio and phase difference ratio obtained in Step 2 and Step 3, calculate the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band.
- the "calculation to obtain the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band” specifically includes solving the following equation to obtain the frequency loss characteristic and the measured object in the transmitted signal frequency band Frequency-dielectric constant characteristics:
- ⁇ f is the loss coefficient of the measured object
- ⁇ f is the dielectric constant of the measured object
- L is the thickness of the measured object
- A( ⁇ f ,l,f) is the antenna shaping factor
- f is the transmitted signal
- ⁇ 0 is the dielectric constant in vacuum
- ⁇ 0 is the permeability in vacuum.
- a system using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has beneficial effects: the use of a phased array antenna in the present invention can realize multi-angle directional beam transmission; the present invention uses a signal comparison unit to receive The electromagnetic wave signal is compared with the reference signal to obtain the amplitude ratio and the phase difference ratio, and then the electromagnetic characteristics of the measured object can be obtained, and the accuracy is high; the size of the terahertz product in the present invention is small and the portability is strong.
- the method of using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has the beneficial effect of adopting a method of considering both amplitude and phase, and taking advantage of the characteristics of terahertz electromagnetic waves with good directivity.
- Direction measurement increase measurement accuracy, and achieve non-destructive detection;
- the present invention uses a phased array antenna as a signal transmission unit, by adjusting the phased array antenna to change the direction of electromagnetic wave emission, measured electromagnetic wave attenuation in different directions and phase delay , And then calculate the electromagnetic wave absorption characteristics and dielectric constant characteristics of the object in the terahertz frequency band.
- Figure 1 is a schematic diagram of the principle of the present invention
- FIG. 2 is a schematic diagram of the structure of the present invention.
- the reference numbers in the figure indicate: 1. Signal source; 2. Signal transmitting unit; 3. First receiving antenna; 4. Second receiving antenna; 5. Object to be measured; 6. Signal comparison unit.
- the present invention discloses a system for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, including:
- Signal source 1 which can generate the same transmission signal and reference signal, the transmission signal and the reference signal are terahertz electromagnetic wave signals;
- the signal transmitting unit 2 is located on the side of the measured object 5, and the transmitted signal transmits electromagnetic waves toward the measured object through the signal transmitting unit, and the signal transmitting unit is a phased array antenna;
- a signal receiving unit which is located on the other side of the measured object 5, the signal receiving unit receives the electromagnetic wave emitted by the phased array antenna;
- the signal comparison unit 6 compares the electromagnetic wave signal received by the signal receiving unit with the reference signal to obtain the amplitude ratio and the phase difference ratio of the two, and then obtains the electromagnetic characteristics of the measured object.
- the signal source is a terahertz frequency sweep signal source.
- the sweep signal range of the terahertz sweep signal source is 100GHz to 1THz.
- a power distributor is connected to the signal source, and the signal source is divided into two channels of the same output signal by the power distributor, and the two channels of the same output signal are the transmission signal and the reference signal.
- the signal receiving unit includes a first receiving antenna 3 and a second receiving antenna 4, the first receiving antenna 3 and the second receiving antenna 4 are equal to the vertical distance of the phased array antenna plane; the connection between the first receiving antenna and the phased array antenna is The phased array antenna plane is vertical, and the connection between the second receiving antenna and the phased array antenna forms an angle of ⁇ with the phased array antenna plane, where -90° ⁇ 90°, and ⁇ 0.
- the present invention also provides a method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves. Based on the system for detecting the electromagnetic characteristics of an object, the method includes the following steps:
- Step 1 The signal source 1 works and sends out the reference signal and the transmission signal;
- Step 2 No object is placed between the phased array antenna and the signal receiving unit, adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the first receiving antenna 3, and obtain the first The amplitude ratio R 1, f and phase difference of the received signal and reference signal of a receiving antenna Adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the second receiving antenna 4 and obtain the amplitude ratio R 2, f and phase of the received signal of the second receiving antenna and the reference signal through the signal comparison unit Difference
- Step 3 Place the measured object 5 between the phased array antenna and the signal receiving unit, adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna faces the first receiving antenna 3, and obtain the first The amplitude ratio R′ 1, f and phase difference of the received signal and reference signal of a receiving antenna Adjust the transmission direction of the phased array antenna so that the main lobe of the phased array antenna is directed toward the second receiving antenna 4, and the amplitude comparison ratio R′ 2, f of the received signal of the second receiving antenna and the reference signal is obtained by the signal comparison unit Phase difference
- Step 4 Through the amplitude ratio and phase difference ratio obtained in Step 2 and Step 3, calculate the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band.
- calculating the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band specifically includes solving the following equation to obtain the frequency loss characteristic and frequency of the measured object in the transmitted signal frequency band- Dielectric constant characteristics:
- ⁇ f is the loss coefficient of the measured object
- ⁇ f is the dielectric constant of the measured object
- L is the thickness of the measured object
- A( ⁇ f ,l,f) is the antenna shaping factor
- f is the transmitted signal
- ⁇ 0 is the dielectric constant in vacuum
- ⁇ 0 is the permeability in vacuum.
- A( ⁇ f ,l,f) is the antenna shaping factor, which is different according to the antenna design, and this factor will also change with the frequency.
- the shape factor cannot be expressed by a simple formula, and can only be finally determined according to the antenna design.
- the terahertz electromagnetic wave is used for detection.
- the terahertz electromagnetic wave frequency band is between the light wave and the wireless electromagnetic wave. Therefore, it has the characteristics of wide light wave frequency band, good orientation, small components, and strong electromagnetic wave penetration.
- the use of electromagnetic waves in this frequency band is basically harmless to the human body, so the terahertz equipment can be made portable.
- the invention can detect the absorption characteristic of the object to the electromagnetic wave of the terahertz frequency band and the size of the dielectric constant in the frequency band without damage to the object or contact. At the same time, if the electromagnetic wave absorption characteristics and dielectric constant characteristics of an object in the terahertz frequency band are known.
- This method provides a new method for detecting objects. At the same time, it uses the characteristics of terahertz electromagnetic waves with high directivity and high frequency, which can reduce the size of the detection device and provide the possibility for the subsequent development of portable devices.
- Transmitting antenna can adopt phased array or other forms to realize multi-angle directional beam transmission; the amplitude difference and phase difference are analyzed at the same time when the received signal is compared with the transmitted signal; including the calibration phase and the test phase, the calibration process is the measurement process without the measured object ,
- the calibrated data can be used when calculating the characteristics of the object; using terahertz electromagnetic waves to measure the characteristics of the object, mainly the frequency loss characteristics and dielectric constant-frequency characteristics of the object in the transmitted signal frequency band, such as the magnetic permeability and vacuum permeability of the object Different, then the magnetic permeability can also be measured using this method.
- the above only lists the measurement of the beam in two directions.
- the actual beam can change multiple directions to measure multiple times, so as to obtain more accurate measurement results, or obtain more object characteristics, such as the internal distribution of the object.
- This method only describes how to measure the characteristics of an object. In practical applications, when the characteristics of a specific object are known, this method can also detect whether the specific object exists in the measured object, and the content of the specific object in the measured object .
- the design of the transmitting antenna enables the beam to be directionally transmitted. On the one hand, it can enhance the strength of the electromagnetic wave in a specific direction and increase the test accuracy. On the other hand, it can also simplify the design of the signal source and the signal transmission path. According to the characteristics of an object, a specific object may have a significant difference in loss coefficient or dielectric constant from adjacent frequencies at certain frequency points, and these frequency points may be used as characteristic points when the method is used to identify the specific object.
- the method of using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has the beneficial effect of adopting a method of considering both amplitude and phase, and taking advantage of the characteristics of terahertz electromagnetic waves with good directivity, and using multiple Direction measurement, increase measurement accuracy, and achieve non-destructive detection;
- the present invention uses a phased array antenna as a signal transmission unit, by adjusting the phased array antenna to change the direction of electromagnetic wave emission, measured electromagnetic wave attenuation in different directions and phase delay , And then calculate the electromagnetic wave absorption characteristics and dielectric constant characteristics of the object in the terahertz frequency band.
- the present invention can also use the method to test the existence of the specific substance and the content of the substance in the test object after determining the characteristics of a specific substance, and then use the characteristics of good directivity of the terahertz electromagnetic wave. The distribution of the specific substance in the object under test is measured.
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Abstract
Description
本发明涉及电磁检测领域，具体涉及一种使用太赫兹电磁波检测物体的电磁特性的系统及方法。The invention relates to the field of electromagnetic detection, in particular to a system and method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves.
目前对物体的电磁特性进行无损检测的方法主要有以下几种：使用电磁波对物体介电常数进行检测，所使用电磁波频段一般在6GHz以下，而且使用时需要对被测物尺寸有要求，使用电磁波检测物体介电常数时需要有准确的物体厚度，同时由于电磁波频段较低，因此所使用物体尺寸不能过小；使用光波对物体进行检测，通过对不同波长光波的吸收率测定物体含量，使用光波进行检测时需要物体透明；使用核磁共振等方法激发物体发出电磁波，通过检测电磁波获得物体内部结构，使用核磁共振方法进行检测时设备非常复杂，而且由于磁场线圈的存在，导致设备体积庞大；使用X射线或其它高能射线对物体内部结构进行检测，使用X射线检测时设备复杂，同时考虑到人体辐射的关系，导致这些设备都必须配备比较笨重的辐射防护装置。At present, there are mainly the following methods for non-destructive detection of the electromagnetic characteristics of objects: the use of electromagnetic waves to detect the dielectric constant of objects, the frequency band of electromagnetic waves used is generally below 6GHz, and the size of the measured object needs to be used when using, the use of electromagnetic waves When measuring the dielectric constant of an object, an accurate object thickness is required. At the same time, due to the low frequency of electromagnetic waves, the size of the object used cannot be too small; the object is detected using light waves, and the content of the object is determined by the absorption rate of light waves of different wavelengths. The object needs to be transparent for the detection; use NMR and other methods to excite the object to emit electromagnetic waves, obtain the internal structure of the object by detecting the electromagnetic wave, and use the NMR method to detect the device is very complicated, and because of the presence of the magnetic field coil, the device is bulky; use X Rays or other high-energy rays detect the internal structure of the object. The equipment is complicated when using X-ray detection. At the same time, considering the relationship between human radiation, these devices must be equipped with relatively bulky radiation protection devices.
发明内容Summary of the invention
本发明要解决的技术问题是提供一种使用太赫兹电磁波检测物体的电磁特性的系统及方法，其能够使用太赫兹电磁波检测物体的电磁特性，实现无损检测，精度高，效果好。The technical problem to be solved by the present invention is to provide a system and method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, which can detect the electromagnetic characteristics of an object using terahertz electromagnetic waves, realize non-destructive detection, have high accuracy, and have good effects.
为了解决上述技术问题，本发明提供了一种使用太赫兹电磁波检测物体的电磁特性的系统，包括：In order to solve the above technical problems, the present invention provides a system for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, including:
信号源，其能够产生相同的发射信号和参考信号，所述发射信号与参考信号为太赫兹电磁波信号；A signal source, which can generate the same transmission signal and reference signal, and the transmission signal and the reference signal are terahertz electromagnetic wave signals;
信号发射单元，其位于被测物体一侧，所述发射信号通过信号发射单元朝被测物体发射电磁波，所述信号发射单元为相控阵天线；A signal transmitting unit, which is located on the side of the object to be measured, the transmitting signal transmits electromagnetic waves toward the object to be measured through the signal transmitting unit, and the signal transmitting unit is a phased array antenna;
信号接收单元，其位于被测物体另一侧，所述信号接收单元接收所述相控阵天线发出的电磁波；A signal receiving unit, which is located on the other side of the measured object, and the signal receiving unit receives the electromagnetic wave emitted by the phased array antenna;
信号比较单元，其将所述信号接收单元接收的电磁波信号与所述参考信号进行比对，得到两者的幅值比和相位差比，进而获得被测物体的电磁特性。The signal comparison unit compares the electromagnetic wave signal received by the signal receiving unit with the reference signal to obtain the amplitude ratio and the phase difference ratio of the two, thereby obtaining the electromagnetic characteristics of the object to be measured.
作为优选的，所述信号源为太赫兹扫频信号源。Preferably, the signal source is a terahertz frequency sweep signal source.
作为优选的，所述太赫兹扫频信号源的扫频信号范围为100GHz至1THz。Preferably, the frequency sweep signal range of the terahertz frequency sweep signal source is 100 GHz to 1 THz.
作为优选的，所述信号源上连接有功率分配器，所述信号源经功率分配器分成两路相同的输出信号，所述两路相同的输出信号为发射信号和参考信号。Preferably, a power distributor is connected to the signal source, and the signal source is divided into two channels of the same output signal by the power distributor, and the two channels of the same output signal are a transmission signal and a reference signal.
作为优选的，所述信号接收单元包括第一接收天线和第二接收天线，所述第一接收天线和第二接收天线与相控阵天线面垂直距离相等；所述第一接收天线与相控阵天线的连线与相控阵天线面垂直，所述第二接收天线与相控阵天线的连线与相控阵天线面成θ角度，其中，-90°＜θ＜90°，且θ≠0。Preferably, the signal receiving unit includes a first receiving antenna and a second receiving antenna, and the first receiving antenna and the second receiving antenna are at equal vertical distances from the phased array antenna plane; The connection of the array antenna is perpendicular to the phased array antenna surface, and the connection between the second receiving antenna and the phased array antenna is at an angle of θ with the phased array antenna surface, where -90°<θ<90°, and θ ≠0.
本发明还公开了一种使用太赫兹电磁波检测物体的电磁特性的方法，基于上述的检测物体的电磁特性的系统，包括以下步骤：The invention also discloses a method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves. Based on the above system for detecting the electromagnetic characteristics of an object, the method includes the following steps:
步骤一、所述信号源工作，发出参考信号和发射信号；Step 1: The signal source works and sends out a reference signal and a transmission signal;
步骤二、在相控阵天线和信号接收单元间不放置被测物体，调整所述相控阵天线的发射方向，使所述相控阵天线的天线主瓣朝向第一接收天线，通过信号比较单元获得第一接收天线的接收信号与参考信号的幅值比值R
1,f与相位差 值
步骤三、在相控阵天线和信号接收单元间放置被测物体，调整所述相控阵天线的发射方向，使所述相控阵天线的天线主瓣朝向第一接收天线，通过信号比较单元获得第一接收天线的接收信号与参考信号的幅值比值R’
1,f与相位差值
步骤四、通过步骤二和步骤三所获得的幅值比值和相位差比值，计算获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性。Step 4: Through the amplitude ratio and phase difference ratio obtained in Step 2 and Step 3, calculate the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band.
作为优选的，所述“计算获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性”，具体包括求解下列方程式，获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性：Preferably, the "calculation to obtain the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band" specifically includes solving the following equation to obtain the frequency loss characteristic and the measured object in the transmitted signal frequency band Frequency-dielectric constant characteristics:
其中，ρ f为被测物的损耗系数,ε f为被测物的介电常数，L为被测物的厚度，A(ε f,l,f)为天线赋形因子，f为发射信号的频率，ε 0为真空中的介电常数，μ 0为真空里的磁导率。 Where ρ f is the loss coefficient of the measured object, ε f is the dielectric constant of the measured object, L is the thickness of the measured object, A(ε f ,l,f) is the antenna shaping factor, and f is the transmitted signal , Ε 0 is the dielectric constant in vacuum, μ 0 is the permeability in vacuum.
本发明中，使用太赫兹电磁波检测物体的电磁特性的系统，其有益效果：本发明中相控阵天线的使用，可实现波束多角度定向发射；本发明通过信号比较单元将信号接收单元接收的电磁波信号与参考信号进行比对，获得幅值比和相位差比，进而可获得被测物体的电磁特性，精度高；本发明中太赫兹产品尺寸小，便携性强。In the present invention, a system using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has beneficial effects: the use of a phased array antenna in the present invention can realize multi-angle directional beam transmission; the present invention uses a signal comparison unit to receive The electromagnetic wave signal is compared with the reference signal to obtain the amplitude ratio and the phase difference ratio, and then the electromagnetic characteristics of the measured object can be obtained, and the accuracy is high; the size of the terahertz product in the present invention is small and the portability is strong.
本发明中，使用太赫兹电磁波检测物体的电磁特性的方法，其有益效果在于：采用幅度与相位共同考虑的方法，同时利用太赫兹电磁波方向性好的特点，在对物体性质测量时采用多个方向测量，增加测量精度，且实现无损检测；本发明采用相控阵天线作为信号发射单元，通过调节相控阵天线以改变电磁波的发射方向，测得不同方向下的电磁波衰减情况以及相位延迟情况，进而计算得到物体在太赫兹频段中的电磁波吸收特性以及介电常数特性。In the present invention, the method of using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has the beneficial effect of adopting a method of considering both amplitude and phase, and taking advantage of the characteristics of terahertz electromagnetic waves with good directivity. Direction measurement, increase measurement accuracy, and achieve non-destructive detection; the present invention uses a phased array antenna as a signal transmission unit, by adjusting the phased array antenna to change the direction of electromagnetic wave emission, measured electromagnetic wave attenuation in different directions and phase delay , And then calculate the electromagnetic wave absorption characteristics and dielectric constant characteristics of the object in the terahertz frequency band.
图1是本发明的原理示意图；Figure 1 is a schematic diagram of the principle of the present invention;
图2是本发明的结构示意图。2 is a schematic diagram of the structure of the present invention.
图中标号说明：1、信号源；2、信号发射单元；3、第一接收天线；4、第二接收天线；5、被测物体，6、信号比较单元。The reference numbers in the figure indicate: 1. Signal source; 2. Signal transmitting unit; 3. First receiving antenna; 4. Second receiving antenna; 5. Object to be measured; 6. Signal comparison unit.
下面结合附图和具体实施例对本发明作进一步说明，以使本领域的技术人员可以更好地理解本发明并能予以实施，但所举实施例不作为对本发明的限定。The present invention will be further described below with reference to the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the illustrated embodiments are not intended to limit the present invention.
参照图1-图2所示，本发明的公开了一种使用太赫兹电磁波检测物体的电磁特性的系统，包括：Referring to FIGS. 1-2, the present invention discloses a system for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves, including:
信号源1，其能够产生相同的发射信号和参考信号，发射信号与参考信号为太赫兹电磁波信号；Signal source 1, which can generate the same transmission signal and reference signal, the transmission signal and the reference signal are terahertz electromagnetic wave signals;
信号发射单元2，其位于被测物体5一侧，发射信号通过信号发射单元朝被测物体发射电磁波，信号发射单元为相控阵天线；The signal transmitting unit 2 is located on the side of the measured object 5, and the transmitted signal transmits electromagnetic waves toward the measured object through the signal transmitting unit, and the signal transmitting unit is a phased array antenna;
信号接收单元，其位于被测物体5另一侧，信号接收单元接收相控阵天线发出的电磁波；A signal receiving unit, which is located on the other side of the measured object 5, the signal receiving unit receives the electromagnetic wave emitted by the phased array antenna;
信号比较单元6，其将信号接收单元接收的电磁波信号与参考信号进行比对，得到两者的幅值比和相位差比，进而获得被测物体的电磁特性。The signal comparison unit 6 compares the electromagnetic wave signal received by the signal receiving unit with the reference signal to obtain the amplitude ratio and the phase difference ratio of the two, and then obtains the electromagnetic characteristics of the measured object.
其中，信号源为太赫兹扫频信号源。太赫兹扫频信号源的扫频信号范围为100GHz至1THz。Among them, the signal source is a terahertz frequency sweep signal source. The sweep signal range of the terahertz sweep signal source is 100GHz to 1THz.
在信号源上连接有功率分配器，信号源经功率分配器分成两路相同的输出信号，两路相同的输出信号为发射信号和参考信号。A power distributor is connected to the signal source, and the signal source is divided into two channels of the same output signal by the power distributor, and the two channels of the same output signal are the transmission signal and the reference signal.
信号接收单元包括第一接收天线3和第二接收天线4，第一接收天线3和第二接收天线4与相控阵天线面垂直距离相等；第一接收天线与相控阵天线的连线与相控阵天线面垂直，第二接收天线与相控阵天线的连线与相控阵天线面成θ角度，其中，-90°＜θ＜90°，且θ≠0。The signal receiving unit includes a first receiving antenna 3 and a second receiving antenna 4, the first receiving antenna 3 and the second receiving antenna 4 are equal to the vertical distance of the phased array antenna plane; the connection between the first receiving antenna and the phased array antenna is The phased array antenna plane is vertical, and the connection between the second receiving antenna and the phased array antenna forms an angle of θ with the phased array antenna plane, where -90°<θ<90°, and θ≠0.
本发明还一种使用太赫兹电磁波检测物体的电磁特性的方法，基于上述的检测物体的电磁特性的系统，包括以下步骤：The present invention also provides a method for detecting the electromagnetic characteristics of an object using terahertz electromagnetic waves. Based on the system for detecting the electromagnetic characteristics of an object, the method includes the following steps:
步骤一、信号源1工作，发出参考信号和发射信号；Step 1: The signal source 1 works and sends out the reference signal and the transmission signal;
步骤二、在相控阵天线和信号接收单元间不放置被测物体，调整相控阵天线的发射方向，使相控阵天线的天线主瓣朝向第一接收天线3，通过信号比较单元获得第一接收天线的接收信号与参考信号的幅值比值R
1,f与相位差值
步骤三、在相控阵天线和信号接收单元间放置被测物体5，调整相控阵天线的发射方向，使相控阵天线的天线主瓣朝向第一接收天线3，通过信号比较单元获得第一接收天线的接收信号与参考信号的幅值比值R’
1,f与相位差值
步骤四、通过步骤二和步骤三所获得的幅值比值和相位差比值，计算获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性。Step 4: Through the amplitude ratio and phase difference ratio obtained in Step 2 and Step 3, calculate the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band.
作为优选的，“计算获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性”，具体包括求解下列方程式，获得被测物体在发射信号频段内的频率损耗特性和频率-介电常数特性：Preferably, "calculating the frequency loss characteristic and frequency-dielectric constant characteristic of the measured object in the transmitted signal frequency band" specifically includes solving the following equation to obtain the frequency loss characteristic and frequency of the measured object in the transmitted signal frequency band- Dielectric constant characteristics:
其中，ρ f为被测物的损耗系数,ε f为被测物的介电常数，L为被测物的厚度，A(ε f,l,f)为天线赋形因子，f为发射信号的频率，ε 0为真空中的介电常数，μ 0为真空里的磁导率。 Where ρ f is the loss coefficient of the measured object, ε f is the dielectric constant of the measured object, L is the thickness of the measured object, A(ε f ,l,f) is the antenna shaping factor, and f is the transmitted signal , Ε 0 is the dielectric constant in vacuum, μ 0 is the permeability in vacuum.
其中，A(ε f,l,f)是天线赋形因子，根据天线设计有所不同，这一因子随着频率变化也会变化。同时考虑到由于介电常数的存在，电磁波在被测物中存在一定的折射现象，这一现象的影响也在该赋形因子中表现出来。因此该赋形因 子无法通过简单的公式表示，只能根据天线设计来最后确定。 Among them, A(ε f ,l,f) is the antenna shaping factor, which is different according to the antenna design, and this factor will also change with the frequency. At the same time, considering that due to the existence of dielectric constant, there is a certain refraction phenomenon of electromagnetic waves in the measured object, and the influence of this phenomenon is also manifested in this shaping factor. Therefore, the shape factor cannot be expressed by a simple formula, and can only be finally determined according to the antenna design.
本发明中使用太赫兹的电磁波做检测，太赫兹电磁波频段介于光波和无线电磁波之间，因此既具有光波频段宽、定向性好、元器件小的特点，也具有电磁波穿透力强的特点，同时使用该频段电磁波对人体基本无害，因此可将太赫兹设备做成便携化。In the invention, the terahertz electromagnetic wave is used for detection. The terahertz electromagnetic wave frequency band is between the light wave and the wireless electromagnetic wave. Therefore, it has the characteristics of wide light wave frequency band, good orientation, small components, and strong electromagnetic wave penetration. At the same time, the use of electromagnetic waves in this frequency band is basically harmless to the human body, so the terahertz equipment can be made portable.
本发明可以在对物体无损害、无接触的情况下检测物体对太赫兹频段电磁波的吸收特性以及在该频段内介电常数的大小。同时如果已知某物体在太赫兹频段中的电磁波吸收特性和介电常数特性。该方法提供了一种对物体进行检测的新方法，同时利用太赫兹电磁波定向性强、频率高的特点，可以减小检测设备的尺寸，为后续向便携式设备发展提供可能。The invention can detect the absorption characteristic of the object to the electromagnetic wave of the terahertz frequency band and the size of the dielectric constant in the frequency band without damage to the object or contact. At the same time, if the electromagnetic wave absorption characteristics and dielectric constant characteristics of an object in the terahertz frequency band are known. This method provides a new method for detecting objects. At the same time, it uses the characteristics of terahertz electromagnetic waves with high directivity and high frequency, which can reduce the size of the detection device and provide the possibility for the subsequent development of portable devices.
发射天线可采用相控阵或其它形式，实现波束多角度定向发射；接收信号与发射信号比较时同时分析幅度差与相位差；包括校准阶段与测试阶段，校准过程为无被测物体的测量过程，校准的数据在计算物体特性时可以使用；使用太赫兹电磁波测量物体特性，主要为物体在发射信号频段的频率损耗特性和介电常数-频率特性，如该物体磁导率与真空磁导率不同，那么使用本方法也可对磁导率进行测量。上文只列出波束在两个方向上的测量，实际波束可改变多个方向多次测量，这样得到更精确的测量结果，或者获得更多的物体特性，比如物体内部分布等。该方法只描述了如何测量物体特性，实际应用中在已知某特定物体特性时，采用该方法也能检测该特定物体是否存在于被测物体中，以及该特定物体在被测物体中的含量。发射天线设计使波束能定向发射，这样一方面可以增强电磁波在特定方向的强度，增加测试精度，另一方面也可简化信号源以及信号传输通路设计。根据物体特性，特定物体可能在某些频率点损耗系数或介电常数与邻近频率有显著差异，这些频率点可作为在使用该方法识别该特定物体时的特征点。Transmitting antenna can adopt phased array or other forms to realize multi-angle directional beam transmission; the amplitude difference and phase difference are analyzed at the same time when the received signal is compared with the transmitted signal; including the calibration phase and the test phase, the calibration process is the measurement process without the measured object , The calibrated data can be used when calculating the characteristics of the object; using terahertz electromagnetic waves to measure the characteristics of the object, mainly the frequency loss characteristics and dielectric constant-frequency characteristics of the object in the transmitted signal frequency band, such as the magnetic permeability and vacuum permeability of the object Different, then the magnetic permeability can also be measured using this method. The above only lists the measurement of the beam in two directions. The actual beam can change multiple directions to measure multiple times, so as to obtain more accurate measurement results, or obtain more object characteristics, such as the internal distribution of the object. This method only describes how to measure the characteristics of an object. In practical applications, when the characteristics of a specific object are known, this method can also detect whether the specific object exists in the measured object, and the content of the specific object in the measured object . The design of the transmitting antenna enables the beam to be directionally transmitted. On the one hand, it can enhance the strength of the electromagnetic wave in a specific direction and increase the test accuracy. On the other hand, it can also simplify the design of the signal source and the signal transmission path. According to the characteristics of an object, a specific object may have a significant difference in loss coefficient or dielectric constant from adjacent frequencies at certain frequency points, and these frequency points may be used as characteristic points when the method is used to identify the specific object.
本发明中，使用太赫兹电磁波检测物体的电磁特性的方法，其有益效果在于：采用幅度与相位共同考虑的方法，同时利用太赫兹电磁波方向性好的特点， 在对物体性质测量时采用多个方向测量，增加测量精度，且实现无损检测；本发明采用相控阵天线作为信号发射单元，通过调节相控阵天线以改变电磁波的发射方向，测得不同方向下的电磁波衰减情况以及相位延迟情况，进而计算得到物体在太赫兹频段中的电磁波吸收特性以及介电常数特性。此外，本发明也可通过在确定某一特定物质的特性后，通过该方法测试被检物中是否有该特定物质的存在以及该物质的含量，进而利用太赫兹电磁波定向性好的特点，可以对该特定物质在被检物体中的分布情况进行测定。In the present invention, the method of using terahertz electromagnetic waves to detect the electromagnetic characteristics of an object has the beneficial effect of adopting a method of considering both amplitude and phase, and taking advantage of the characteristics of terahertz electromagnetic waves with good directivity, and using multiple Direction measurement, increase measurement accuracy, and achieve non-destructive detection; the present invention uses a phased array antenna as a signal transmission unit, by adjusting the phased array antenna to change the direction of electromagnetic wave emission, measured electromagnetic wave attenuation in different directions and phase delay , And then calculate the electromagnetic wave absorption characteristics and dielectric constant characteristics of the object in the terahertz frequency band. In addition, the present invention can also use the method to test the existence of the specific substance and the content of the substance in the test object after determining the characteristics of a specific substance, and then use the characteristics of good directivity of the terahertz electromagnetic wave. The distribution of the specific substance in the object under test is measured.
以上所述实施例仅是为充分说明本发明而所举的较佳的实施例，本发明的保护范围不限于此。本技术领域的技术人员在本发明基础上所作的等同替代或变换，均在本发明的保护范围之内。本发明的保护范围以权利要求书为准。The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.
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