A beam position detector calibration system

Abstract

The present invention discloses a beam position detector calibration system, which is characterized by comprising a coaxial cable, a conical emitter, a Goubau line, a conical receiver, an absorption load, a moving platform and a signal recording subsystem; wherein, one end of the coaxial cable is connected to the top end of the conical emitter for inputting the signal generated by a signal source into the conical emitter; the end of the conical emitter is connected to one end of the Goubau line for gradually transitioning the TEM wave input by the coaxial cable into a TM-mode surface wave and inputting the TM-mode surface wave into the Goubau line for transmission; the other end of the Goubau line is connected to the end of the conical receiver for inputting the input TM-mode surface wave into the conical receiver; the top end of the conical receiver is connected to the absorption load for inputting the received signal into the absorption load; and the moving platform is used for carrying an object to be calibrated to move along the Goubau line.

Description

Technical Field

[0001] The present invention belongs to the technical field of particle accelerators and relates to a novel beam position detector calibration system. Background Art

[0002] A beam position monitor (BPM) is the "eye" of a particle accelerator, which is used to observe the position of the beam in the pipeline, achieve precise control of the beam position, and thus ensure normal operation. When the beam passes through the BPM, a voltage signal U with a certain amplitude will be generated on the output electrode welded to the pipeline. As Figure 1 shown, the signal is inversely proportional to the distance d between the beam and the electrode. By comparing the signals relative to the electrode, the beam position can be obtained, that is, there is:

[0003]

[0004] where x is the position of the beam, the coefficient k is also called the sensitivity of the BPM, and δ is the offset of the geometric center relative to the electrical center caused by various reasons for the two electrodes, such as electrode differences, pipeline symmetry, etc. Generally, after the BPM is manufactured and before it is installed on the accelerator, it is necessary to calibrate the sensitivity k and offset δ of the BPM. On the one hand, it is to evaluate the accuracy of mechanical processing. On the other hand, by determining the calibration coefficient k, the electronics can calculate the correct position.

[0005] In addition, the applicable range of formula (1), that is, the relationship between the signal intensity and the position is proportional, is only valid when the beam is close to the center of the pipeline. This range is called the linear region. The role of calibration is also to obtain the relationship between the beam position outside the linear region and U1, U2, and determine the higher-order calibration coefficients.

[0006] The goal of the BPM calibration system is to generate an electromagnetic wave that simulates the beam. This electromagnetic wave needs to be precise and stable, and its position can be changed within a certain range according to experimental requirements. Figure 2 It is a schematic diagram of the basic composition of the calibration system. The signal generated by the signal source to simulate the beam propagates and is emitted outward through the coaxial cable and the transmitter. The signal recording system measures U1 and U2. The moving platform system drives the BPM to move through the synchronous motor to achieve the change of the beam position (in some systems, it drives the transmitter and the wire passing through the BPM to move), and the receiver absorbs the electromagnetic wave signal to reduce reflection.

[0007] For a calibration system, on the one hand, it is necessary to realize the relative position change between the antenna (the part passing through the component to be calibrated between the transmitter and the receiver) and the component under test. On the other hand, it is necessary to record the response of the component under test to this position change through a signal recording system. The requirement for positioning accuracy becomes gradually stricter with the measurement requirements of the component under test BPM. Since the system composed of the transmitter and the antenna can simulate the beam current well, this calibration system can also be used for calibrating other beam measurement components to obtain the characteristic information of components such as the beam current detector Current Transformer CT.

[0008] The single-wire antenna used in a general BPM calibration system is that the inner conductor of the coaxial cable is connected with a section of metal wire as the antenna. To ensure the accuracy of the antenna relative to the position of the BPM, usually a thicker rigid metal wire is used. The typical outer diameter of the inner conductor is between 4 and 10 mm, so as to ensure sufficient mechanical strength.

[0009] The signal generated by the signal source is amplified and then transmitted through the coaxial cable in the form of TEM wave, and then radiated outward in the form of plane wave through the antenna to simulate the beam current.

[0010] The disadvantages of the existing calibration systems are mainly in the following aspects:

[0011] 1. The accuracy of the system is poor. To have sufficient mechanical strength, usually the inner conductor has a large size. For a BPM with a small pipe diameter or other devices to be tested (Device Under Test, DUT), its positioning accuracy is poor. Even if a material with a smaller inner conductor (metal wire) is used, its vibration and parallelism with the axis of the BPM will have a great impact on the calibration accuracy. For the fourth-generation light source of advanced accelerators, the inner diameter of the pipeline has been reduced to the level of 20 mm, and the requirement for calibration accuracy has also reached the micron level.

[0012] 2. The signal emission efficiency is not high. The characteristic impedance of the coaxial cable is 50Ω, and the characteristic impedance of the plane wave in free space is 377Ω. The impedance mismatch and the jump-like change result in most of the power being reflected. Multiple reflections will also introduce additional reading errors.

[0013] 3. The system has a narrow scope of application. Usually, the BPM calibration system can only be used for BPM measurement. The difficulty for other DUTs is that different DUTs need to measure different response frequency ranges. Generally, the operating frequency of the electron accelerator BPM is 500MHz, and the operating frequency of the ion accelerator BPM is also in the order of 100MHz. On the one hand, structural optimization is usually aimed at a certain frequency, so it is difficult to apply it to the calibration of equipment with a large difference in operating frequency. For example, for different CTs, the frequency range of interest is from kHz to MHz, or even GHz (FCT), so the BPM calibration system cannot be used for CT calibration. In addition, for a 100MHz signal, the wavelength in a vacuum is λ0=3m, so it is difficult to make the size of the transmitting device small, which is not conducive to the experiment. Summary of the invention

[0014] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a new beam position detector calibration system. The present invention can simulate the beam of the accelerator to calibrate the BPM and obtain the calibration coefficient and offset of the BPM. It is characterized by being able to improve the emission efficiency of the signal (electromagnetic wave) and using smaller-sized components to obtain more accurate calibration results. It is particularly suitable for the calibration of the accelerator BPM with a thinner pipeline. At the same time, the calibration system can also be used for the tail field impedance measurement of the accelerator components, and has a wider and higher application value. The goal of the present invention is to optimize the electromagnetic wave transmitting device, make the transition of the characteristic impedance smoother, improve the input matching state of the signal source to the transmitting system, that is, reduce S 11 , and also increases the transmission, the loss of the smaller signal on the antenna increases S 21 .

[0015] The present invention realizes the gradual change of the characteristic impedance of the coaxial 50Ω to 300Ω through a conical transmitter, thereby increasing the transmission efficiency and reducing the reflection of the signal. The conical receiver is connected to a matching load to minimize the interference of the reflected signal on the system; the present invention uses a Gaobou wire with a size of 100μm to replace the mm-level transmitting antenna or metal bare wire to simulate the beam, which ensures that the electric field is concentrated in a local area very close to the wire, reduces the dependence on the boundary conditions, and reduces the size of the transmitting device; the combination of the conical transmitter receiver and the Gaobou wire can be used not only for BPM calibration, but also for the calibration of other beam detectors such as CT, and can also be used for tail field impedance research.

[0016] The technical solution of the present invention is:

[0017] A beam position detector calibration system, characterized in that it includes a coaxial line, a conical transmitter, a Gaobou line, a conical receiver, an absorbing load, a mobile platform and a signal recording subsystem; wherein,

[0018] One end of the coaxial cable is connected to the top end of the conical emitter for inputting the signal generated by the signal source into the conical emitter. The signal generated by the signal source is transmitted in the coaxial cable in the form of TEM wave.

[0019] The end of the conical emitter is connected to one end of the Goubau line for gradually transitioning the TEM wave input from the coaxial cable into a TM mode surface wave and inputting it into the Goubau line for transmission.

[0020] The other end of the Goubau line is connected to the end of the conical receiver for inputting the input TM mode surface wave into the conical receiver.

[0021] The top end of the conical receiver is connected to the absorption load for inputting the received signal into the absorption load.

[0022] The moving platform is used to carry the object to be calibrated and move along the Goubau line.

[0023] The signal recording subsystem is used to record the response when the position of the object to be calibrated changes relative to the Goubau line.

[0024] Further, the structures of the conical emitter and the conical receiver are the same.

[0025] Further, the coaxial cable is an N-type coaxial cable. An N-type connector matching the coaxial cable is provided at the top end of the conical emitter. The inner conductor at the end of the conical emitter is connected to the Goubau line. The inner conductor at the end of the conical receiver is connected to the Goubau line.

[0026] Further, the outer conductor inner radius r of the conical emitter 22 changes according to r 12 +0.67*L0, where 0 ≤ L0 ≤ 300, and the outer conductor inner radius r of the inner conductor 21 is r 22 / e Z / 60 ; where r 12 is the outer conductor inner radius of the coaxial cable, and Z is the characteristic impedance of the conical emitter, which gradually transitions from 50Ω at the entrance to 300Ω at the exit within the 300mm long conical emitter.

[0027] Further, the longitudinal length of the conical emitter along the signal propagation direction is 300mm, and the relative dielectric constant of the material between the inner conductor and the outer conductor is 1.

[0028] Further, the Klopfenstein progressive method is used to optimize the impedance of the conical emitter to determine the characteristic impedance Z.

[0029] Furthermore, the ratio of the end diameter of the conical emitter to the longitudinal length L2 along the signal propagation direction is 0.4 to 1.

[0030] Furthermore, 2r / L2 = 0.67; where r is the end radius of the conical emitter and L2 is the longitudinal length.

[0031] Furthermore, the absorption load is a standard N-type connector matching load.

[0032] Furthermore, the radius of the copper enameled wire of the Goubau line is 0.28 mm, the thickness of the dielectric layer is 0.02 mm, the dielectric constant of the dielectric layer is 3.5, and the length is 1500 mm.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. It is superior to the traditional coaxial cable in terms of structure. The device itself has a simple structure and does not require a complex matching network.

[0035] 2. It has good impedance matching in the high-frequency band, allowing signals in the GHz range to propagate along the transmitting device without significant power loss.

[0036] 3. The size of the wire used to simulate the beam current is on the order of μm, causing less interference to the boundary conditions.

[0037] 4. It has a wide range of applications. It can not only be used for BPM calibration, but also simulate the response measurement of various CTs for shorter beam lengths (higher frequencies) and the wakefield impedance study of vacuum components.

[0038] The conical emitter in the present invention can achieve good impedance matching, allowing signals in the GHz range to propagate along a single wire without significant power loss.

[0039] The present invention reduces the size of the 100 MHz electromagnetic wave transmitting device to the order of 100 mm, with a very compact structure.

[0040] The present invention has a wide range of applications. It can be applied to the calibration of different beam current detectors in accelerators and the wakefield study of various vacuum components on various accelerators. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the principle of measuring the beam current position by BPM.

[0042] Figure 2 It is a schematic diagram of the basic composition of the BPM calibration system.

[0043] Figure 3 It is a schematic diagram of the Goubau line surface wave calibration system.

[0044] Figure 4 For the internal electromagnetic field distribution of the conical coaxial line structure transmitter at a signal frequency of 1 GHz;

[0045] (A) is the electric field distribution, and (B) is the magnetic field distribution.

[0046] Figure 5 For the electromagnetic field emission at different frequencies;

[0047] (A) is at a signal frequency of 1 GHz, and (B) is at a signal frequency of 100 MHz.

[0048] Figure 6

[0049] Figure 7 For the frequency domain response of the Klopfenstein tapered impedance matching type conical transmitter;

[0050] Figure 8 For the S parameters of the Gaobou line system;

[0051] Figure 9 For the input end Smith chart;

[0052] Figure 10 For the optimized calibration system mechanical model diagram;

[0053] Figure 11 For the calibration results of the BPM designed for HEPS within the range of ±6 mm; Specific implementation mode

[0054] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0055] The present invention intends to use a single-wire transmission line utilizing surface electromagnetic waves proposed by George Goubau in 1950 to simulate the accelerator beam current to complete the calibration experiment of the BPM.

[0056] Figure 3 As shown, assume there is a metal wire with a radius of a (Gaobou-line, abbreviated as G-line), and its surface is coated with a dielectric material with a thickness of d = b - a. After adding the coating, the outer radius of the wire is b. Cylindrical coordinates are adopted and it is assumed that the system has a periodic structure in the z direction. Inside the dielectric, the electromagnetic field distribution is given jointly by the Bessel function J n (x) and the Neumann function Y n (x). Inside the dielectric material, that is, a ≤ r ≤ b, there is:

[0057] ​

[0058]

[0059] E z = iA[J0(γ d r) + mY0(γ d r)]e -i(ωt-lz) (4 - 1c)

[0060] where A is the amplitude factor of the electromagnetic field, m is a function determined by the boundary conditions, r is the distance from the center of the metal wire, Er and Ez are the radial and longitudinal components of the electric field respectively, and B Φ is the axial component of the magnetic field. Equations (4 - 1a) to (4 - 1c) give the solutions of the electromagnetic field in terms of the frequency ω and the propagation constant l, and there is a relationship between them and the material parameters:

[0061]

[0062] where the subscript d represents the dielectric material, used to distinguish from the subscript 0 in vacuum or air. So the relative permittivity ∈ r = ∈ d / ∈0, and the permeability μ of the non - magnetic material d is equal to the vacuum permeability μ0 = 4π×10 -7 T·m / A, k0 = ω / c, l is the propagation constant of the guided wave, also known as the longitudinal wavenumber of the wave, and γ d and k d are the three - dimensional spatial wavenumber and the transverse two - dimensional wavenumber in the dielectric material respectively. In the free space (air) outside the wire, we similarly define:

[0063]

[0064]

[0065] Because on the interfaces between the conductor and the dielectric material and between the dielectric material and air, is continuous. Inside the ideal wire, applying E z = 0 at r = a to formula (4 - 1c), we get m = -J0(γ d a) / Y0(γ d a). Outside the wire where r ≥ b in air, the solution in cylindrical coordinates is given by the Hankel function of the first kind of order 0, H0 (1) and the Hankel function of the first kind of order 1, H1 (1) as follows:

[0066]

[0067] Applying the ratio obtained from Equation (4 - 5) at r = b to Equations (4 - 1a) to (4 - 1c), we have:

[0068]

[0069] Where a useful approximation of the Bessel function is adopted. The condition for its validity is that the phase velocity of the surface wave is close to the speed of light c. When the thickness of the dielectric material is much smaller than the wire radius d << a, or when the thickness and radius are much smaller than the electromagnetic wave wavelength The phase velocity is close to the speed of light. In the G - line BPM calibration system, both of the above two conditions are satisfied.

[0070] Solving Equations (4 - 4) and (4 - 6) will yield the surface wave parameters γ0 in air with frequency ω as the independent variable and the surface wave parameters γ in the medium with frequency ω as the independent variable d , and then the numerical solutions B φ ~E r ~H1 (1) (γ0r) in free space can be obtained through software. The difference between the electric field distribution and the electromagnetic field of the beam current for calibration can be completely ignored.

[0071] 1.1. Implementation Scheme of Quasi - Beam - Current Electromagnetic Field with Low Reflection and High Transmission

[0072] To emit the surface wave of the required mode with higher efficiency, a special type of horn or cone, called a transmitter, needs to be built, as Figure 3 shown. The electromagnetic field of an ordinary metal wire extends from the center to a relatively long distance according to the law of 1 / r. Especially when emitting low - frequency electromagnetic waves, a transmitter with a relatively large physical size is required. For Goubau lines, the electromagnetic wave exists in the form of a surface wave. After the electric field drops to a certain distance according to 1 / r, it drops exponentially. The energy of the electromagnetic field is concentrated near the surface of the Goubau line. The surface wave propagates in a very small area near r. Thus, a smaller - sized transmitter can be used to emit waves with high efficiency.

[0073] Specific to the BPM transmitter, in order to better achieve impedance matching, the output impedance of the signal source, the ordinary N-type or SMA-type connectors, and the characteristic impedance of the coaxial cable are all 50 Ω. The impedance of the Goubau line is determined by its structure and the frequency of the transmitted signal. Generally, the impedance of a 100-μm-level Goubau line in the GHz frequency range is on the order of 100 Ω. In the present invention, the characteristic impedance of the tapered transmitter end is set to 300 Ω, and the Klopfenstein taper method can be used to achieve the transition from the starting segment of 50 Ω to 300 Ω. The radius r of the tapered transmitter end is 100 mm, and the total length (height) L2 is 300 mm. According to experience, the ratio of the diameter to the length is generally taken between 0.4 and 1, and we select 2r / L2 = 0.67. A larger cone angle is likely to generate higher-order modes in the horn, which is not conducive to signal transmission. Finally, the main mechanical parameters of the taper are designed as shown in Table 1.

[0074] Table 1 shows the basic parameters of the electromagnetic field transmission system

[0075]

[0076]

[0077] * Where Z is the characteristic impedance required by the Klopfenstein taper method at L0 in the z direction (L0 is the longitudinal distance from the starting end of the tapered transmitter, and the value range is 0 ≤ L0 ≤ L2 = 300). For specific values, see the description of impedance matching in 1.1.2.

[0078] During the calibration process, the signal source is connected to the coaxial cable. The starting segment of the tapered transmitter is designed with the dimensions of a standard N-type connector for the coaxial cable, and the inner conductor at the end of the transmitter is directly connected to the Gaobou line. The starting segment of the receiver is connected to the end of the Gaobou line, and the absorption load connected to the end of the receiver is a standard N-type connector matching load, which is used to reduce multiple reflections of the signal.

[0079] 1.1.1. Electromagnetic field transmission

[0080] The signal is generated by the signal source and transmitted in the coaxial cable in the form of a TEM wave. Starting from the tapered transmitter, it gradually transitions to the TM mode of a single wire of the Gaobou line. The surface wave of this mode is transmitted on the Goubau line and can be used to simulate the beam current. Its electric field lines are all perpendicular to the wire surface, similar to the electric field generated by a relativistic beam current, as Figure 4 shown.

[0081] For the transmitter, its physical size needs to match the frequency of the transmitted signal. For 100 MHz, 500 MHz, 1 GHz, and 10 GHz in free space ε rThe wavelengths of the = 1 plane waves are 3m, 0.6m, 0.3m, and 0.03m respectively, while in the polyurethane with a relative dielectric constant of ε r = 3.5 (the main component of the outer layer of the enameled wire), the wavelengths are 1.6m, 0.32m, 0.16m, and 0.016m. It can be seen that the physical size of the transmitting device required for the emission of lower-frequency electromagnetic waves is larger. Figure 5 It shows the emission of signals with different frequencies by the entire transmission system. From it, the radial electromagnetic distribution of the electromagnetic fields at 1GHz and 0.1GHz can be seen when the Gaobo wire length is 600mm for a typical transmitting device. It can be seen that the electromagnetic wave with a longer wavelength of 0.1GHz cannot be transmitted to the receiving end. The specific transmission and reflection situations are shown in Table 2.

[0082] Table 2 shows the transmission of signals with different frequencies by Gaobou wires of different lengths.

[0083]

[0084]

[0085] 1.1.2. Impedance Matching

[0086] For better impedance matching and to reduce signal reflection, within a longitudinal length of 300mm, the Klopfenstein progressive method is used to achieve the transition from an initial 50Ω to 300Ω. The variation of the specific characteristic impedance with the longitudinal position is as Figure 6 shown, where position 0 is the starting point of the conical transmitter.

[0087] After optimizing the characteristic impedance of the conical transmitter using the Klopfenstein method, the frequency-domain response of the transmitter is as Figure 7 shown. When designing, it is required that the reflection at 500MHz, the frequency at which the BPM electronics operates, is small, and the reflection coefficient does not exceed 0.1 within the entire frequency band range of 0.5 - 5GHz. A smaller reflection and a smoother transition require more longitudinal matching space. The current design can already meet most BPM calibration experiments.

[0088] To comprehensively consider the signal transmission characteristics of the entire system, that is, including the conical transmitter, Gaobou-wire, and conical receiver, the scattering parameters (S parameters) of the system were calculated using the microwave studio (MWS) of the finite element electromagnetic simulation software Computer Simulation Technology (CST). The results are as Figure 8As shown, it can be seen that the reflection coefficients are all around -15 dB, while the transmission coefficients are all around -3 dB. Most of the signal power has successfully been transmitted from the input end of the coaxial cable to the matching load. According to the reflection coefficient S11, the input impedance as seen from the input port is as Figure 9 shown. From this, we can clearly see the impedance matching process. The input impedance rapidly changes from 1000 Ω to near a well-matched 50 Ω. At 500 MHz, the real part and the imaginary part are 50.7 Ω and 1.5 Ω respectively.

[0089] 1.2. Specific Applications of the Present Invention in Engineering

[0090] The present invention is designed for calibrating the beam position detector. The moving platform adopts the HST-XYZ(SG) series produced by Sigma Koki Co., Ltd. of Japan, with a repeat positioning accuracy of 0.5 μm and a minimum step size of 2 μm, enabling two-dimensional movement in the horizontal directions x and y (the beam direction and the Gaobou line propagation direction are the z direction). The signal source uses a KEYSIGHT MXG Analog Signal Generator NS181B (9 kHz to 6 GHz), and the measurement of the BPM probe signal uses Libera Brilliance+ electronics. The entire system is as Figure 10 shown.

[0091] We calibrate the button-type BPM of the HEPS storage ring of the high-energy light source. The radius r of the button electrode is 4 mm, the height h is 2 mm, the gap g between it and the pipe is 0.3 mm, and the pipe radius R is 11 mm. The signal source outputs a 500 MHz point-frequency signal of 0 dBm. After being amplified by a 20 dB amplifier, it emits electromagnetic waves through a coaxial cable and a conical emitter. Its energy is mainly concentrated near the Gaobou line. The electronics reads the signal amplitude induced on the probe. The signal coupled on the probe only accounts for a very small part of the emitted electromagnetic waves, and the remaining electromagnetic field is absorbed by the absorption load after passing through the conical receiver. The first step of calibration is to control the movement of the stepper motor so that the signal amplitudes on the four electrodes are equal, and this position is set as the coordinate origin. The second step is to move within the range of x = ±6 mm and y = ±6 mm with a step size of 1 mm centered on the original position. The electronics reads the signal amplitudes on the four electrodes and calculates the difference and ratio mentioned above. For two electrodes, it is (U1 - U2) / (U1 + U2), and for four electrodes, it is (U a +U c -U b -U d ) / (U a +U b -U c -U d ). The obtained calibration Mapping diagram is as Figure 11As shown, according to the calculation result of CST, the sensitivity coefficients Kx = Ky = 9.35 mm of this BPM, while the calibrated results of the system are kx = 9.261 mm and ky = 9.264 mm. Considering factors such as processing errors, the relative error of (9.35 - 9.26) / 9.35 = 0.96% is acceptable.

[0092] This application is not limited to the embodiments detailed in the present invention. Those skilled in the art can make various modifications to it, but as long as these modifications do not deviate from the spirit and intention of the present invention, they are still within the protection scope of the present invention.

Claims

1. A beam position detector calibration system, characterized in that, It includes a coaxial cable, a conical emitter, a Gaobou line, a conical receiver, an absorption load, a moving platform, and a signal recording subsystem; among them, One end of the coaxial cable is connected to the top end of the conical emitter, and is used to input the signal generated by the signal source into the conical emitter; the signal generated by the signal source is transmitted in the coaxial cable in the form of a TEM wave; The end of the conical emitter is connected to one end of the Gaobou line, and is used to gradually transition the TEM wave input from the coaxial cable to the TM mode of the single wire of the Gaobou line and input it into the Gaobou line to transmit the surface wave of the TM mode; The other end of the Gaobou line is connected to the end of the conical receiver, and is used to input the surface wave of the TM mode input into the conical receiver; The top end of the conical receiver is connected to the absorption load, and is used to input the received signal into the absorption load; The moving platform is used to carry the object to be calibrated and move along the Gaobou line; The signal recording subsystem is used to record the response when the position of the object to be calibrated changes relative to the Gaobou line.

2. The system according to claim 1, wherein The structures of the conical emitter and the conical receiver are the same.

3. The system according to claim 1 or 2, characterized in that, The coaxial cable is an N-type coaxial cable, and an N-type connector matching the coaxial cable is provided at the top end of the conical emitter. The inner conductor at the end of the conical emitter is connected to the Gaobou line; the inner conductor at the end of the conical receiver is connected to the Gaobou line.

4. The system according to claim 1, wherein The outer conductor inner radius r of the conical emitter 22 is r 12 + 0.67 * L0, and the inner conductor outer radius r 21 is r 22 / e Z / 60 ; where r 12 is the outer conductor inner radius of the coaxial cable, Z is the characteristic impedance at L0 of the conical emitter, and L0 is the longitudinal distance from the starting end of the conical emitter.

5. The system according to claim 4, wherein The longitudinal length of the conical emitter along the signal propagation direction is 300 mm, and the relative dielectric constant of the material between the inner conductor and the outer conductor is 1.

6. The system according to claim 4, wherein The impedance of the conical emitter is optimized by the progressive method to determine the characteristic impedance Z.

7. The system according to claim 1, wherein The ratio of the end diameter of the conical emitter to the longitudinal length L2 along the signal propagation direction is 0.4 - 1.

8. The system according to claim 7, characterized in that 2r / L2 = 0.67; where r is the end radius of the conical emitter and L2 is the longitudinal length.

9. The system according to claim 1, wherein The absorption load is a standard N-type connector matching load.

10. The system according to claim 1, wherein The radius of the copper enameled wire of the Gaobou line is 0.28 mm, the thickness of the dielectric layer is 0.02 mm, the dielectric constant of the dielectric layer is 3.5, and the length is 1500 mm.

Images