Compact electromagnetic vector sensor for radiation source parameter estimation

Abstract

The invention discloses a compact electromagnetic vector sensor for radiation source parameter estimation, which comprises a first electromagnetic induction unit, a second electromagnetic induction unit and a third electromagnetic induction unit, and the structural characteristics and the electrical characteristics of the first electromagnetic induction unit, the second electromagnetic induction unit and the third electromagnetic induction unit are completely the same. The first electromagnetic induction unit, the second electromagnetic induction unit and the third electromagnetic induction unit are distributed in a pairwise orthogonal mode. The compact electromagnetic vector sensor for radiation source parameter estimation disclosed by the invention has the beneficial effects that the compact electromagnetic vector sensor is simple and compact in structure and easy to process and manufacture; electromagnetic field measurement characteristics of six dimensions are basically equivalent, and analytical calculation is easy to perform; meanwhile, complete electromagnetic wave measurement information is given, and the direction of arrival and polarization parameters can be estimated at the same time.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic sensors, specifically relating to a compact electromagnetic vector sensor for radiation source parameter estimation. Background Technology

[0002] A complete plane electromagnetic wave contains electric and magnetic field vectors, which can be decomposed into six-dimensional field components in Cartesian coordinates. Conventional electric field scalar sensors, such as dipole antennas, can only measure the electric field components projected onto their axes; conventional magnetic field scalar sensors, such as current loops, have similar limitations. Due to the incomplete measurement of field components, scalar sensors cannot acquire complete information about electromagnetic waves. They often require arraying, sacrificing spatial expansion and an increased number of array elements to improve the accuracy of the angle of arrival (ALO) parameter estimation. Even then, scalar arrays still cannot capture the polarization characteristics of the signal.

[0003] In recent years, some incomplete electromagnetic vector sensors have gradually begun to be used, the most typical being the triorthogonal current loop antenna, which can simultaneously measure the three Cartesian components of the magnetic field and is commonly used in electromagnetic compatibility testing. However, the measurement dimensions of such vector sensors are still incomplete, making it difficult to simultaneously estimate the signal's angle of arrival and polarization parameters.

[0004] In summary, due to the scarcity of compact six-dimensional electromagnetic vector sensors, there are many limitations to the ability to estimate parameters of plane electromagnetic waves. Summary of the Invention

[0005] In view of the current state of the technology and to overcome the above-mentioned defects, the present invention provides a compact electromagnetic vector sensor for radiation source parameter estimation.

[0006] This invention employs the following technical solution: a compact electromagnetic vector sensor for radiation source parameter estimation, comprising a first electromagnetic induction unit, a second electromagnetic induction unit, and a third electromagnetic induction unit. The first, second, and third electromagnetic induction units have identical structural and electrical characteristics, and are orthogonally distributed in pairs.

[0007] The first electromagnetic induction unit includes a coaxial hollow first outer radiator and a second outer radiator spaced apart. The first outer radiator is provided with a first through-hole, and the second outer radiator is provided with a second through-hole. The width of the first through-hole and the width of the second through-hole are equal and aligned along the same axis.

[0008] A gap between the first and second external radiators is left;

[0009] The first and second external radiators are simultaneously coupled to the electric field feeding circuit.

[0010] The compact electromagnetic vector sensor for radiation source parameter estimation disclosed in this invention has the following advantages:

[0011] 1. The structure is simple and compact, and easy to process and manufacture.

[0012] The electromagnetic field measurement characteristics in 2.6 dimensions are basically the same, making analytical calculations easy.

[0013] 3. At the same time, complete electromagnetic wave measurement information is provided, and the angle of arrival and polarization parameters can be estimated simultaneously. As the preferred technical solution of the above technical solution, the first external radiator and the second external radiator respectively contain magnetic elements.

[0014] As a preferred technical solution to the above technical solutions, the magnetic element consists of a ferrite rod and a multilayer ferrite rod coil surrounding the ferrite rod. The multilayer ferrite rod coil is led out and further electrically connected to the magnetic field feeding circuit.

[0015] As a preferred technical solution to the above technical solutions, both the first external radiator and the second external radiator are cylindrical structures.

[0016] As a preferred technical solution to the above technical solutions, the cross-sections of both the first and second outer radiators are polygonal.

[0017] As a preferred technical solution to the above technical solutions, the electric field feeding circuit is specifically implemented as a passive circuit. The passive circuit includes a first coil and a second coil, and transmits the induced electric field to the feeding terminal and then to the receiver via a coaxial cable.

[0018] As a preferred technical solution to the above technical solutions, the electric field feeding circuit is specifically implemented as an active circuit. The active circuit uses a differential amplifier to connect the induced electric field to the receiver through the feeding terminal.

[0019] As a preferred technical solution of the above technical solution, the magnetic field feeding circuit includes an upper multi-layer primary coil surrounding the upper half of the ferrite rod and a lower multi-layer primary coil surrounding the lower half of the ferrite rod. The upper multi-layer primary coil is used to sense the magnetic field received by the upper gap, and the lower multi-layer primary coil is used to sense the magnetic field received by the lower gap.

[0020] As a preferred technical solution to the above technical solutions, the energy collected by the upper multi-layer primary coil and the lower multi-layer primary coil is transferred to the secondary coil by inductive coupling, and then sent to the receiver through the feed terminal and grounded by the grounding wire.

[0021] The compact electromagnetic vector sensor for radiation source parameter estimation disclosed in this invention has the following advantages:

[0022] 1. The structure is simple and compact, and easy to process and manufacture.

[0023] The electromagnetic field measurement characteristics in 2.6 dimensions are basically the same, making analytical calculations easy.

[0024] 3. It also provides complete electromagnetic wave measurement information, and can simultaneously estimate the angle of arrival and polarization parameters. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the combined structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of a single electromagnetic induction unit of the present invention.

[0027] Figure 3A and Figure 3B These are typical structural schematic diagrams of the electric field feeding circuit of the present invention.

[0028] Figure 4A and Figure 4B These are typical structural schematic diagrams of the magnetic field feeding circuit of the present invention.

[0029] Figure 5A , Figure 5B , Figure 5C and Figure 5D The figures shown are simulation diagrams of the mutual ambiguity function of the present invention under different spacing conditions.

[0030] Figure 6A and Figure 6B These are simulation diagrams of the guidance vector correlation spectrum of the present invention under different spacing conditions for a specified incident orientation.

[0031] The reference numerals in the attached figures include: 21a-first external radiator; 21b-second external radiator; 22a-first through-slot; 22b-second through-slot; 23-external radiator gap; 24-electric field feeding circuit; 25-magnetic element; 25a-ferrite rod; 25b-multilayer ferrite rod coil; 26-magnetic field feeding circuit; 27-coaxial cable; 31-first coil; 32-second coil; 33-feeding terminal; 41-upper slot; 42-upper multilayer primary coil; 43-lower slot; 44-lower multilayer primary coil; 45-secondary coil; 46-feeding terminal; 47-grounding wire; 100-first electromagnetic induction unit; 200-second electromagnetic induction unit; 300-third electromagnetic induction unit. Detailed Implementation

[0032] This invention discloses a compact electromagnetic vector sensor for radiation source parameter estimation. The following description, in conjunction with a preferred embodiment (Embodiment 1), is shown in the accompanying drawings. Figures 1 to 6BThe specific embodiments of the present invention will be further described below.

[0033] Example 1.

[0034] like Figure 1 The diagram shows a schematic representation of the structure of this embodiment. The compact electromagnetic vector sensor for radiation source parameter estimation includes a first electromagnetic induction unit 100, a second electromagnetic induction unit 200, and a third electromagnetic induction unit 300. The first electromagnetic induction unit 100, the second electromagnetic induction unit 200, and the third electromagnetic induction unit 300 have identical structural and electrical characteristics, and are orthogonally distributed in pairs.

[0035] The electromagnetic field energy flux density of the incident electromagnetic wave is used The electric field vector is represented by... The magnetic field vector is represented by... Let's establish a Cartesian coordinate system. The angle between the incident wave and the Z-axis is the elevation angle (denoted by θ), and the angle between the projection of the incident wave onto the XOY plane and the X-axis is the azimuth angle (denoted by φ). A typical analytical solution method, based on Poynting's theorem, is used when the electric field vector is known. and magnetic field vector The electromagnetic field energy flux density can be obtained using the vector cross product. See equation (1).

[0036]

[0037] Electromagnetic field energy flux density The direction is consistent with the direction of wave propagation, and it is decomposed into three components, namely S... x S y S z By analyzing the electromagnetic field energy flux density Perform vector decomposition, then analyze the electromagnetic field energy flux density. By performing trigonometric function transformations on the three vector components, the pitch angle θ and azimuth angle φ can be derived, as shown in equations (2) and (3).

[0038]

[0039] Please note that the above derivation is used to explain the electric field vector as a measured value. Magnetic field vector The relationship between the elevation angle θ and the azimuth angle φ, which are the values ​​of interest. In practical applications, the analytical solution method mentioned above is not the only option; other methods such as correlation lookup table method and spectral estimation method can be used for direction finding estimation.

[0040] The following details how to measure the electric field vector. Magnetic field vector Given that the first electromagnetic induction unit 100, the second electromagnetic induction unit 200, and the third electromagnetic induction unit 300 have identical structural and electrical characteristics, differing only in orientation, we will describe any one of the electromagnetic induction units without loss of generality. For example... Figure 2 The diagram shows a schematic of the electromagnetic induction unit relative to the Z-axis. The first electromagnetic induction unit 100 (the second electromagnetic induction unit 200 and the third electromagnetic induction unit 300 are similar) includes a spaced-apart coaxial hollow first outer radiator 21a and a second outer radiator 21b. The first outer radiator 21a has a first through-slit 22a, and the second outer radiator 22b has a second through-slit 22b. The widths of the first through-slit 22a and the second through-slit 22b are equal and aligned along the same axis. A gap 23 is left between the first outer radiator 21a and the second outer radiator 21b. The first outer radiator 21a and the second outer radiator 21b are simultaneously coupled to the electric field feeding circuit 24.

[0041] As previously described, both the first external radiator 21a and the second external radiator 21b are hollow. Each of the first external radiator 21a and the second external radiator 21b contains a magnetic element 25. In a typical embodiment, the magnetic element 25 consists of a ferrite rod 25a and a multilayer ferrite rod coil 25b surrounding the ferrite rod 25a. The multilayer ferrite rod coil 25b can be led out and further electrically connected to the magnetic field feeding circuit 26.

[0042] The electromagnetic induction unit can acquire the electric and magnetic fields projected along a certain axis and convert them into radio frequency signals.

[0043] The mechanism of conversion to radio frequency signals is explained in detail below. When the total length L1 of the first external radiator 21a and the second external radiator 21b is less than λ (λ represents the wavelength of the electromagnetic wave, generally L1 < 0.1λ), it can be considered as a short electric dipole antenna, which can sense the electric field projected along the axis of the short electric dipole (Z-axis in this figure). This electric field is coupled to the electric field feeding circuit 24 through the gap 23 between the external radiators to be converted into a radio frequency signal, and then transmitted to the receiver (not shown in the figure) via the coaxial cable 27. When the total length L2 of the first external radiator 21a and the second external radiator 21b is less than λ (λ represents the wavelength of the electromagnetic wave, generally L2 < 0.1λ), it can be considered as a short magnetic dipole antenna, which can sense the magnetic field projected along the axis of the short magnetic dipole (Z-axis in this figure) and be coupled to the magnetic element 25 to be converted into a radio frequency signal. The multilayer ferrite rod coil 25b is led out to the magnetic field feeding circuit 26, and then transmitted to the receiver (not shown in the figure) via the coaxial cable 27.

[0044] In this embodiment, both the first outer radiator 21a and the second outer radiator 21b are cylindrical structures, but are not limited to this shape. Provided that they are hollow cylinders, the cross-sections of the first outer radiator 21a and the second outer radiator 21b can be polygonal (e.g., square).

[0045] Furthermore, a typical implementation example of the electric field feeding circuit 24 is shown below. Figure 3A and Figure 3B Optionally, the electric field feeding circuit 24 can be a passive or active circuit. Figure 3A As an example of a passive circuit implementation, the passive circuit includes a first coil 31 and a second coil 32, and transmits the induced electric field to a feed terminal 33, and then to a receiver (not shown) via a coaxial cable 27. The use of coaxial cable 27 for transmission is taken into consideration. Optionally, a balun is added to implement unbalanced-to-balanced conversion. Optionally, a broadband impedance matching circuit can be added in series to achieve broadband operation. Figure 3B As an example of an active circuit implementation, a differential amplifier is used to connect the induced electric field to a receiver (not shown in the figure) via feed terminal 33.

[0046] Furthermore, a typical implementation example of the magnetic field feeding circuit 26 is shown below. Figure 4A and Figure 4B . Figure 4A One embodiment is shown, in which an upper multilayer primary coil 42 surrounds the upper half of the ferrite rod 25a to sense the magnetic field received by the upper slot 41; and a lower multilayer primary coil 44 surrounds the lower half of the ferrite rod 25a to sense the magnetic field received by the lower slot 43. The energy collected by the upper multilayer primary coil 42 and the lower multilayer primary coil 44 is transferred to the secondary coil 45 via inductive coupling, and then sent to the receiver through the feed terminal 46 and grounded by the ground wire 47. Figure 4B Another embodiment is shown, the basic principles and Figure 4A Similarly, the induction method of the secondary coil 45 differs slightly from that of the upper multi-layer primary coil 42 and the lower multi-layer primary coil 44. It is particularly important to note that the winding direction (clockwise or counterclockwise) of the upper multi-layer primary coil 42 and the lower multi-layer primary coil 44, and the wiring order of the upper multi-layer primary coil 42 and the lower multi-layer primary coil 44 with the secondary coil 45, can be changed according to the application scenario. However, the principle that must be followed is that the induced energy should accumulate in the secondary coil 45, rather than cancel out.

[0047] Example 2.

[0048] Example 2 further illustrates the selection of the main dimensions of the compact electromagnetic vector sensor used for radiation source parameter estimation in Example 1.

[0049] Determining the size of a compact electromagnetic vector sensor used for radiation source parameter estimation requires both theoretical calculations and precise analysis of radiation characteristics using electromagnetic simulation software. This embodiment describes the sensor size, which has a significant impact on radiation characteristics.

[0050] In Example 1, the length of the radiator is described as follows:

[0051] Condition 1: The total length L1 of the first external radiator 21a and the second external radiator 21b is less than λ (λ represents the wavelength of the electromagnetic wave, and is generally taken as L1 < 0.1λ).

[0052] Condition 2: The width of the first penetrating slit 22a and the total length of the second penetrating slit 22b, L2 << λ (λ represents the wavelength of the electromagnetic wave, and is generally taken as L2 < 0.1λ).

[0053] Without loss of generality, we will first describe the electric dipole oriented along the Z-axis. In the far-field environment, when condition 1 is satisfied, in the transmitting state, the current distribution of the first external radiator 21a and the second external radiator 21b is approximately constant, and the electric field satisfies equation (4).

[0054]

[0055] According to the reciprocity theorem, in the receiving state, the positions of the electric field and current in equation (4) are interchanged, and E is considered. θ sin(θ) = E z The induced current I along the Z-axis towards the electric dipole Z_Edipole With E z Linear dependence, i.e., I Z_Edipole ∝E z Magnetic dipoles exhibit similar characteristics. In a far-field environment, when condition 2 is satisfied, the induced current I along the Z-axis towards the magnetic dipole... Z_Hdipole With H z Linear dependence, i.e., I Z_Hdipole ∝H z Based on this, for three pairwise orthogonal electromagnetic induction units, six induced currents can be obtained, which are respectively related to E. x E y E z H x H y H z Linear correlation. This results in two technical effects of Example 2: it facilitates direct analytical calculation (based on the aforementioned equation (1)); the measured value is independent of the wavelength of the incident wave (insensitive to frequency).

[0056] It is worth noting that the two conditions mentioned above limit the sensor's sensitivity (i.e., limit the antenna gain). The conversion efficiency of electromagnetic wave energy is closely related to the relative length (l / λ) of the sensor. In some other applications, it is desirable to further improve the system's receiving sensitivity (i.e., increase the antenna gain), which requires overcoming the limitations of conditions 1 and 2.

[0057] Taking the Z-axis oriented electric dipole as an example, in the far-field environment, when L1 is further increased during the transmission state, it is necessary to integrate the antenna current, and the electric field can be approximately expressed by equation (5).

[0058]

[0059] According to the reciprocity theorem, in the receiving state, the positions of the electric field and current in equation (5) are interchanged, and E is considered. θ sin(θ) = E z The induced current along the Z-axis toward the electric dipole can be written as equation (6).

[0060]

[0061] As can be seen, the induced current I of the electric dipole Z_Edipole Not only with E z It is related to the pitch angle θ and the relative length L1 / λ (i.e., it is related to the frequency). The induced current of a magnetic dipole has similar characteristics. In this application scenario, it is very difficult to directly perform analytical calculation of the angle of arrival. An alternative solution is to measure the array response of electromagnetic waves incident at various frequencies and azimuth angles, create tables and store them as reference values, and determine the azimuth angle of incident waves at different frequencies by searching for correlation peaks.

[0062] Example 3.

[0063] Example 3 further illustrates the arrangement of the compact electromagnetic vector sensor used for radiation source parameter estimation in Example 1.

[0064] like Figure 1 As shown, the first electromagnetic induction unit 100, the second electromagnetic induction unit 200, and the third electromagnetic induction unit 300 are orthogonal to each other, but their geometric centers do not overlap. Let the distance from the geometric center of each electromagnetic induction unit to the origin be d. When d << λ (generally d < 0.1λ), the spatial phase difference of the electromagnetic wave surface arriving at each array element can be approximately ignored, and it can be approximately considered that each electromagnetic induction unit measures the same wave surface. Under this premise, analytical calculation can be performed directly (based on the aforementioned equations (1), (2), and (3)).

[0065] It is worth noting that when the distance d from the geometric center of the electromagnetic induction unit to the origin increases further, the above approximate calculation method will lead to an increase in error. Array modeling based on the signal receiving model is required, as shown in equation (7):

[0066] X = (A s ⊙A p )·S+N (7);

[0067] In equation (7), X∈C 6 This is called the sensor output signal vector, and its physical meaning is 6 measured values ​​[I] X_Edipole ,I Y_Edipole ,I Z_Edipole ,I X_Hdipole ,I Y_Hdipole ,I Z_Hdipole ] T A s ∈C 6 , is called the spatial steering vector, and is related to the spatial position of the sensor, as shown in equation (8): A p ∈C 6 , known as the normalized polarization angle domain steering vector, can be represented as [e x ,e y ,e z ,h x ,h y ,h z ] T S is the complex envelope of the incident signal; N∈C 6 This is called the sensor noise vector, and its physical meaning is six independent white Gaussian noises with zero mean; the symbol ⊙ represents the Hadamard product, A s ⊙A p The value is the array steering vector;

[0068]

[0069] In equation (8), It is the wave vector of the incident signal (related to the azimuth and elevation angles of the incident signal); λ is the position vector of the geometric center of the m-th unit; λ is the wavelength of the incident signal.

[0070] As can be seen, due to the spatial steering vector A s The existence of this means that directly performing a vector cross product on the sensor output signal vector X, which is used as a measurement value, is not equivalent to performing a vector cross product on the electric field and the magnetic field. Based on this, it is impossible to obtain the electromagnetic field energy flux density and perform subsequent angle of arrival calculations.

[0071] In this application scenario (d≥0.1λ), similar to Example 2, an optional solution is to measure the array response of electromagnetic waves incident at various frequency points and azimuth angles, create a table and store it as a reference value, and determine the azimuth angle of incident waves at different frequencies by searching for relevant peaks.

[0072] It is worth noting that the distance from the geometric center of the element to the origin should not be too large, because changes in distance will amplify the variation in the array steering vector, meaning that electromagnetic waves incident at different angles may have two similar array steering vectors. Based on this, the risk of ambiguity increases with increasing distance when calculating the incident angle.

[0073] In this embodiment, the mutual ambiguity function of the sensor is simulated for different d / λ values ​​(a larger value indicates better anti-ambiguity performance). See Figures 5A to 5D As shown, Figure 5A Corresponding to d / λ = 0.1, Figure 5B Corresponding to d / λ = 0.2, Figure 5C Corresponding to d / λ = 0.25, Figure 5D This corresponds to d / λ = 0.3. In the figure, the angular coordinates represent the true incident azimuth angle, the radial axis represents the true incident elevation angle, and a higher color temperature value indicates a lower risk of blurring. It can be seen that as d / λ increases, the risk of blurring gradually increases. Figure 5C In the data, two regions have a higher risk of ambiguity: Region A: φ∈[225°-10°, 225°+10°], θ∈[75°-15°, 75°+15°]; Region B: φ∈[45°-10°, 45°+10°], θ∈[75°-15°, 75°+15°]. Figure 5D In the middle, the blurred area further spread.

[0074] To further enable those skilled in the art to understand the physical meaning of the mutual ambiguity function, Figure 6A and Figure 6B For a given incident angle (φ=225°, θ=90°), the steering vector correlation spectrum is displayed in the form of a color temperature diagram. Figure 6A Corresponding to d / λ = 0.25, Figure 6B The corresponding d / λ = 0.3. Figure 6A and Figure 6B In this diagram, angular coordinates represent azimuth angles, the radial axis represents elevation angles, and lower color temperature values ​​indicate stronger correlations. When the array spacing d / λ = 0.25, for signals incident at φ = 225° and θ = 90°, strong correlations exist not only at the true incident azimuth but also at φ = 45° and θ = 90° (an undesirable correlation). As the array spacing continues to increase to d / λ = 0.3, this correlation between the false and true incident azimuths becomes increasingly stronger, leading to blurring.

[0075] In summary, for this embodiment, it is recommended that the array spacing d / λ should not exceed 0.25.

[0076] Example 4.

[0077] Building upon Example 1, Example 4 can be used not only to estimate the angle of arrival (AHA) but also to estimate the polarization characteristics of electromagnetic waves, obtaining the polarization auxiliary angle γ and the polarization phase difference η. Example 4 provides the calculation process for the analytical solution.

[0078] The electric field vector of electromagnetic waves under far-field conditions Always located at the electromagnetic field energy flux density In a vertical plane (also known as a wavefront). Electric field vector. Within the wavefront, it can be decomposed into a perpendicular vector of the electric field. and the horizontal component of the electric field A spherical coordinate system is established in this way. The conversion formula between the spherical coordinate system and the Cartesian coordinate system is expressed as in equation (9):

[0079] As mentioned above, the measured value in Example 4 is consistent with E. x E y E z H x H y H z Related. The perpendicular vector of the electric field is obtained according to equation (9). and the horizontal component of the electric field After the value of E (for E) r Without needing to solve for its value of 0), the complete information of the electric field within the wavefront is obtained. The polarization auxiliary angle γ and polarization phase difference η are solved according to equations (10) and (11), respectively.

[0080]

[0081] In practical applications, the analytical solution methods described above are not the only options; analytical solutions can also be performed based on magnetic field measurements. Alternatively, methods such as correlation lookup tables and spectral estimation can be used to estimate polarization characteristics.

[0082] It is worth mentioning that the proof E involved in this invention patent application r Technical features such as the specific process with a value of 0 should be regarded as prior art. The specific structure, working principle, and possible control methods and spatial arrangement of these technical features can be conventionally selected in the field and should not be regarded as the inventive point of this invention. This invention will not elaborate further.

[0083] For those skilled in the art, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A compact electromagnetic vector sensor for radiation source parameter estimation, characterized in that, It includes a first electromagnetic induction unit, a second electromagnetic induction unit, and a third electromagnetic induction unit. The first, second, and third electromagnetic induction units have identical structural and electrical characteristics. The first, second, and third electromagnetic induction units are orthogonally distributed in pairs, wherein: The first electromagnetic induction unit includes a coaxial hollow first outer radiator and a second outer radiator spaced apart. The first outer radiator is provided with a first through-hole, and the second outer radiator is provided with a second through-hole. The width of the first through-hole and the width of the second through-hole are equal and aligned along the same axis. A gap between the first and second external radiators is left; The first and second external radiators are simultaneously coupled to the electric field feeding circuit.

2. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 1, characterized in that, The first and second external radiators each contain magnetic elements.

3. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 2, characterized in that, The magnetic element consists of a ferrite rod and a multi-layer ferrite rod coil wrapped around the ferrite rod. The multi-layer ferrite rod coil is led out and further electrically connected to the magnetic field feeding circuit.

4. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 1, characterized in that, Both the first and second external radiators are cylindrical structures.

5. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 1, characterized in that, The cross-sections of both the first and second external radiators are polygonal.

6. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 1, characterized in that, The electric field feeding circuit is specifically implemented as a passive circuit, which includes a first coil and a second coil. It transmits the induced electric field to the feeding terminal and then to the receiver via a coaxial cable.

7. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 1, characterized in that, The electric field feeding circuit is specifically implemented as an active circuit. The active circuit uses a differential amplifier to connect the induced electric field to the receiver through the feeding terminal.

8. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 3, characterized in that, The magnetic field feeding circuit includes an upper multi-layer primary coil surrounding the upper half of the ferrite rod and a lower multi-layer primary coil surrounding the lower half of the ferrite rod. The upper multi-layer primary coil is used to sense the magnetic field received by the upper slit, and the lower multi-layer primary coil is used to sense the magnetic field received by the lower slit.

9. The compact electromagnetic vector sensor for radiation source parameter estimation according to claim 8, characterized in that, The energy collected by the upper and lower multi-layer primary coils is transferred to the secondary coils via inductive coupling, and then sent to the receiver through the feed terminal and grounded by the grounding wire.

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