Incident field full waveform measurement method of horizontal polarization spherical radiation wave based on magnetic field

Abstract

The invention discloses a magnetic field-based incident field full waveform measurement method for horizontal polarization spherical radiation waves, and solves the problem that the full waveform of an electromagnetic pulse incident field of the existing horizontal polarization spherical radiation waves is difficult to measure. Appropriate magnetic field measuring points and polarization directions are selected based on a simple and scientific principle, the problem that full waveforms of an incident field are difficult to obtain due to the fact that a ground reflection field is superposed to the incident field is ingeniously solved, and the incident field waveforms generated by a horizontal polarization electromagnetic pulse simulation device can be completely measured. The method has important application value in the field of high-altitude electromagnetic pulse (HEMP).

Description

Technical Field

[0001] The invention relates to an electromagnetic field incident waveform measurement method, in particular to an incident field full waveform measurement method of a horizontally polarized spherical radiation wave based on a magnetic field. Background Art

[0002] High-altitude electromagnetic pulse (HEMP) has high field strength, wide frequency range and wide coverage area, posing a threat to electronic and electrical equipment and systems. At present, the electromagnetic pulse field environment mainly adopts the electric field peak of 50kV / m, front edge of 2.5ns and half-width of 23ns specified in IEC6100-2-9, and the corresponding high-altitude electromagnetic pulse simulator is also built in accordance with this standard. The incident field waveform of the HEMP simulator is an important parameter for judging the performance indicators of the simulator, and is also an important basis for conducting experiments under the simulator.

[0003] The horizontally polarized spherical radiation wave simulator is a typical simulator. At present, the measurement of its incident field mainly adopts the electric field measurement method. However, due to the influence of ground reflection, the electric field incident from the simulator is superimposed on the electric field reflected from the ground, which makes it difficult to measure the incident field. The current common practice is to select electric field measurement points that are relatively far from the ground, so that there is a large time difference between the incident field and the ground reflection field, so that key parameters such as the front edge and half width of the incident field can be read. However, in actual operation, the height of the electric field measurement point selection is limited. Even if the key parameters of the waveform can be measured by the above means, it is still impossible to separate the reflected field from the incident field. In particular, the second half of the waveform is significantly affected by the reflection and the complete waveform of the incident field cannot be obtained.

[0004] How to fully obtain the incident field waveform of the horizontally polarized spherical radiated electromagnetic pulse affected by ground reflection is still a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the problem that it is difficult to measure the full waveform of the incident field of the existing horizontally polarized spherical radiation wave electromagnetic pulse, the present invention provides a method for measuring the full waveform of the incident field of the horizontally polarized spherical radiation wave based on a magnetic field.

[0006] The inventive concept of the present invention:

[0007] In the horizontally polarized electromagnetic pulse environment of spherical radiation, in theory, the incident electric field waveform of the electromagnetic pulse is consistent with the incident magnetic field waveform, the amplitude ratio of the electric field and the magnetic field is approximately equal to the free space wave impedance, and the same waveform is also presented in each region. However, due to the influence of the ground reflection field, the arrival time of the reflected wave of the field at different positions in space is inconsistent. For the electric field, the polarization directions of the incident field and the reflected field are both in the horizontal direction, so the traditional incident field measurement method based on the electric field can only maximize the time difference between the incident field and the reflected field, and obtain the incident field waveform with a relatively long time scale as much as possible. However, for the magnetic field, the polarization directions of the incident field and the reflected field present different angles in different regions. This feature is used in the present invention to form the principle of selecting the measuring point and the polarization direction, so that the polarization directions of the incident magnetic field and the reflected magnetic field are orthogonal. At this time, the magnetic field of the reflected field is zero in the polarization direction of the incident magnetic field. By reasonably placing the magnetic field sensor, only the magnetic field component in the magnetic field direction of the incident field is measured, and the magnetic field can be guaranteed not to be affected by the reflected field.

[0008] In order to achieve the above purpose and complete the above invention concept, the present invention adopts the following technical solutions:

[0009] A method for measuring the full waveform of an incident field of a horizontally polarized spherical radiation wave based on a magnetic field is special in that it comprises the following steps:

[0010] Step 1, determine the radiation source center point O of the horizontally polarized spherical radiation wave, the projection point O' of the radiation source center point O on the ground, and the polarization direction of the electromagnetic field;

[0011] Step 2, select the measuring point M so that the line segment OO'=O'M;

[0012] Step 3: Set up a magnetic field measuring device at the measuring point M, and adjust the direction of the magnetic field measuring device so that its polarization direction is parallel to the plane OO'M and perpendicular to the line segment OM;

[0013] Step 4: The incident magnetic field is measured by the magnetic field measuring device, and the obtained incident magnetic field waveform is the full waveform of the incident field of the horizontally polarized spherical radiation wave.

[0014] Furthermore, step 4 is specifically as follows:

[0015] The incident magnetic field is measured by the magnetic field measuring device, and the measured electromagnetic field signal is converted into a pick-up electrical signal, which is then converted into an optical signal and transmitted to a remote device via an optical fiber. The remote device then converts the optical signal into an electrical signal, thereby obtaining an incident magnetic field waveform, i.e., the full waveform of the incident field of the horizontally polarized spherical radiation wave, which is displayed and stored by an oscilloscope.

[0016] Furthermore, in step 3 and step 4, the magnetic field measuring device is a measuring device based on optical fiber transmission.

[0017] Furthermore, in step 3 and step 4, the magnetic field measuring device is a magnetic field sensor.

[0018] Furthermore, in step 3 and step 4, the magnetic field measuring device is a magnetic field detector.

[0019] Beneficial effects of the present invention:

[0020] 1. The method for measuring the full waveform of the incident field of the horizontally polarized spherical radiation wave based on the magnetic field provided by the present invention utilizes the consistent characteristics of the electromagnetic field waveform, uses the existing mature measurement technology, selects appropriate magnetic field measuring points and polarization directions based on simple principles, and cleverly avoids the problem of difficulty in obtaining the full waveform of the incident field caused by the superposition of the ground reflection field to the incident field. The incident field waveform generated by the horizontally polarized electromagnetic pulse simulation device can be fully measured, and has important application value in the field of high altitude electromagnetic pulse (HEMP).

[0021] 2. The method for measuring the full waveform of the incident field of the horizontally polarized spherical radiation wave based on the magnetic field provided by the present invention has a large margin for measuring point selection and can conveniently realize the measurement of the incident field of the horizontally polarized spherical wave.

[0022] 3. The magnetic field measuring equipment selected by the present invention is a measuring equipment based on optical fiber transmission, and the measuring signal is transmitted through optical fiber, which can effectively avoid the distortion of the measured field caused by cable transmission signal, and obtain the complete incident magnetic field waveform that is not distorted by ground reflection and cable interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of an embodiment of a method for measuring the full waveform of an incident field of a horizontally polarized spherical radiation wave based on a magnetic field according to the present invention;

[0024] Figure 2 It is a schematic diagram of the installation position of the magnetic field measuring device and the magnetic field direction of the incident field in step 2 of the incident field measurement method based on the magnetic field in an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of the incident field and the reflected field of horizontally polarized spherical radiation in an embodiment of the present invention;

[0026] Figure 4 4 is a diagram showing the relationship between the incident field waveform, the reflected field waveform and the measured waveform in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] An embodiment of the present invention provides a method for measuring the full waveform of the incident field of a horizontally polarized spherical radiation wave based on a magnetic field. The method is mainly aimed at the horizontally polarized spherical wave electromagnetic radiation environment near the ground, especially the electromagnetic pulse environment, and is mainly used for the incident field measurement of a horizontally polarized electromagnetic pulse simulation device. In the horizontally polarized spherical wave electromagnetic radiation environment near the ground, the measurement of the incident field in this environment is achieved by measuring the magnetic field. The influence of ground reflection on the waveform characteristics can be effectively avoided.

[0029] like Figure 1 As shown, the specific steps include:

[0030] Step 1, determine the radiation source center O of the horizontally polarized spherical radiation wave, the ground projection point O' of the radiation source center and the polarization direction of the electromagnetic field;

[0031] Step 2: Figure 2 As shown, select the measuring point M so that OO'=O'M;

[0032] Step 3: Set up a magnetic field measuring device at the measuring point M and adjust the direction of the magnetic field measuring device so that its polarization direction is parallel to the plane OO'M and perpendicular to the line segment OM; the magnetic field measuring device can be a magnetic field sensor or a magnetic field detector.

[0033] Step 4: Measure the incident magnetic field through the installed magnetic field sensor. The magnetic field measuring equipment converts the electromagnetic signal of the spatial magnetic field into a pick-up electrical signal, and then converts the electrical signal into an optical signal. The optical signal is then transmitted to the remote device through an optical fiber. The remote device then converts the optical signal into an electrical signal. Finally, the electrical signal is displayed and stored through an oscilloscope to obtain the incident magnetic field waveform, which is the full waveform of the incident field of the horizontally polarized spherical radiation wave.

[0034] like Figure 3 As shown, the horizontally polarized incident wave and reflected wave under spherical radiation are as follows Figure 2 As shown. Where E and E' are the incident electric field and reflected electric field respectively; H and H' are the incident magnetic field and reflected magnetic field respectively; k and k' are the incident wave vector and reflected wave vector respectively; h1 and h2 are the distance from the center point O of the radiation source to the ground and the distance from the measuring point M to the ground respectively, that is, OO'=h1, MM'=h2, l is the distance from the projection point O' of the center point O of the radiation source on the ground to the projection point M' of the measuring point M on the ground, that is, O'M'=l.

[0035] It can be seen that the incident electric field E and the reflected electric field E' are both horizontally polarized but in opposite directions, and the incident magnetic field H and the reflected magnetic field H' are coplanar with the wave vector but have different polarization directions. m is the superposition of the incident electric field E and the reflected electric field E'. The measured magnetic field H m is the superposition of the incident magnetic field H and the reflected magnetic field H', then:

[0036]

[0037] Since there is a time difference between the incident wave and the reflected wave arriving at the measuring point M, and the ground reflection can be approximated as a plane reflection in the ground medium, the amplitude relationship between the incident electric field E and the reflected electric field E' can be approximated as:

[0038] E'(t)=ηE(t+Δt) (3)

[0039] H'(t)=ηH(t+Δt) (4)

[0040] Among them, η represents the ground reflectivity, and Δt is the time difference between the incident wave and the reflected wave reaching the measuring point M, that is, the clear time.

[0041]

[0042] Where c is the speed of light, the coordinates of the measuring point M are (x, y, z), and the origin of the coordinate system is the projection point O' of the center point O of the radiation source on the ground.

[0043] Assume the coordinates of the measuring point M are (x, y, z), then:

[0044] l 2 =x 2 +y 2 (6)

[0045]

[0046] If the magnetic field component in the direction of the incident magnetic field H is measured, the measured magnetic field H m for:

[0047]

[0048] in, is the unit vector of the magnetic field.

[0049] when:

[0050]

[0051] That is, when the incident magnetic field H and the reflected magnetic field H' (polarization direction) are perpendicular to each other, then:

[0052]

[0053] Wherein, θ is the angle between the polarization direction of the incident magnetic field H and the horizontal plane where the measuring point M is located, θ≤π / 2, and θ' is the angle between the polarization direction of the reflected magnetic field H' and the horizontal plane where the measuring point M is located, θ'≤π / 2.

[0054] and then:

[0055]

[0056] At this time, the measured magnetic field component is exactly consistent with the incident magnetic field H.

[0057] Known:

[0058]

[0059] To meet:

[0060]

[0061] Then we have:

[0062]

[0063] Arranged:

[0064]

[0065] The right side of the equal sign in the above formula (16) It is equal to the distance from the projection point O' of the center point O of the radiation source on the ground to the measuring point M.

[0066] Therefore, if Figure 3 As shown, the full waveform measurement of the incident field can be achieved by measuring the magnetic field, as long as the distance from the projection point O' of the center of the radiation source on the ground to the center point O of the radiation source is equal to the distance from the selected measuring point M to the projection point O' of the center of the radiation source on the ground, that is, O'O = O'M, and the polarization direction of the magnetic field sensor is consistent with the incident magnetic field.

[0067] like Figure 4 As shown, it can be seen that: according to the above method, under the corresponding conditions, the measured magnetic field waveform is consistent with the incident field waveform. This method solves the problem of missing complete information of the incident field during the test under the HEMP simulation device.

[0068] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for measuring the full waveform of the incident field of a horizontally polarized spherical radiation wave based on a magnetic field, characterized in that: The following steps are involved: Step 1, determine the radiation source center point O of the horizontally polarized spherical radiation wave, the projection point O' of the radiation source center point O on the ground, and the polarization direction of the electromagnetic field; Step 2, select the measuring point M so that the line segment OO'=O'M; Step 3: Set up a magnetic field measuring device at the measuring point M, and adjust the direction of the magnetic field measuring device so that its polarization direction is parallel to the plane OO'M and perpendicular to the line segment OM; Step 4: The incident magnetic field is measured by the magnetic field measuring device, and the obtained incident magnetic field waveform is the full waveform of the incident field of the horizontally polarized spherical radiation wave.

2. The incident field full waveform measurement method of horizontally polarized spherical radiation wave based on magnetic field according to claim 1 is characterized in that: Step 4 is as follows: The incident magnetic field is measured by the magnetic field measuring device, and the measured electromagnetic field signal is converted into a pick-up electrical signal, which is then converted into an optical signal and transmitted to a remote device via an optical fiber. The remote device then converts the optical signal into an electrical signal, thereby obtaining an incident magnetic field waveform, i.e., the full waveform of the incident field of the horizontally polarized spherical radiation wave, which is displayed and stored by an oscilloscope.

3. The incident field full waveform measurement method of the horizontally polarized spherical radiation wave based on the magnetic field according to claim 1 or 2, characterized in that: In step 3 and step 4, the magnetic field measuring device is a measuring device based on optical fiber transmission.

4. The method for measuring the incident field full waveform of the horizontally polarized spherical radiation wave based on the magnetic field according to claim 3 is characterized in that: In step 3 and step 4, the magnetic field measuring device is a magnetic field sensor.

5. The method for measuring the incident field full waveform of the horizontally polarized spherical radiation wave based on the magnetic field according to claim 3 is characterized in that: In step 3 and step 4, the magnetic field measuring device is a magnetic field detector.

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