Parallel microstrip line design method for framing camera

Abstract

The invention discloses a parallel microstrip line structure with a patch on the end face of a dielectric substrate. The parallel microstrip line structure comprises a coaxial feed port, a multi-section gradient microstrip patch and the dielectric substrate. The antenna is characterized in that the microstrip patches are a plurality of metal conductor sheets, and each microstrip patch passes through a coaxial feed port; each micro-strip patch adopts a bilaterally symmetrical structure, and the structures of the micro-strip patches are the same; and the size of each patch is adjusted, so that the impedance of the whole microstrip patch is matched with the impedance of the coaxial feed port. By the adoption of the microstrip line structure, impedance matching can be achieved in a wide frequency band range, meanwhile, crosstalk between the channels is small, it can be guaranteed that the channels work in a traveling wave state at low insertion loss and low crosstalk, and the microstrip line structure has obvious application value in the field of framing cameras.

Description

Technical Field

[0001] This invention relates to the field of optical ultrafast imaging, and in particular to a traveling wave framing camera based on a microchannel plate. Background Technology

[0002] Since the 1950s and 60s, countries around the world have attached great importance to the development of laser nuclear fusion, especially inertial confinement fusion experiments. Laser nuclear fusion has three main advantages: 1. It can provide efficient and clean energy: using hydrogen as fuel, it produces light elements such as nitrogen. 2. It is not affected by the environment: inertial confinement fusion experiments are conducted in a reaction chamber, unaffected by the environment, making it safer. 3. It can create "cleaner" nuclear weapons: using a laser as an ignition source to trigger a hydrogen bomb explosion produces fewer radioactive fission products.

[0003] Research on framing cameras began during World War II, and their rapid development was driven by the need for nuclear weapons research. With the development of image converters, framing cameras have gone through four stages: shutter-type framing cameras, scanning framing cameras, cathode-gated framing cameras, and traveling-wave-gated framing cameras.

[0004] The basic principle of a shutter-type framing camera is that when a continuous rectangular positive pulse is applied to the control electrode, photoelectrons can pass through and strike the fluorescent screen to achieve imaging. When a negative pulse is applied to the control electrode, photoelectrons cannot pass through. By applying different pulse voltages to the control electrode, framing effects can be achieved. A scanning framing camera adds a shutter, aperture, and deflector plate to the original structure to achieve framing. When a shutter voltage is applied, electrons emitted from the cathode disperse at a certain angle. When a reverse voltage is applied, electrons emitted from the same position on the cathode plate converge. The deflector plate's role is to image electrons emitted at different times at different positions. The main characteristic of a cathode-gated framing camera is the use of a microchannel plate as an electron multiplier, offering advantages such as low gating voltage requirements, high time resolution, strong anti-interference capabilities, and high gain. A typical example of this stage is the nanosecond-level high-resolution framing camera.

[0005] With breakthroughs in microchannel plates and picosecond high-voltage pulse technology, traveling wave gating framing cameras have developed rapidly and become the mainstream research direction, with advantages such as high temporal resolution and a large number of images. Summary of the Invention

[0006] The purpose of this invention is to design a pulse gating transmission line for use in traveling wave gating framing cameras.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A multi-parallel microstrip line includes: a coaxial feed port, a multi-segment gradient microstrip patch, and a dielectric substrate (equivalent to a microchannel plate).

[0009] The coaxial port serves as a power supply port and is in contact with the microstrip line.

[0010] The microstrip line mainly consists of three parts: a thin sheet of metal conductor, a dielectric substrate, and a ground plane.

[0011] The number of segments and the width of each segment of the multi-segment gradient microstrip patch are related to the impedance of the coaxial port. Preferably, the Chebyshev method is used to calculate the size and impedance of each segment to achieve impedance matching.

[0012] The present invention uses the above structure to achieve impedance transformation, which has the following advantages: it fully guarantees the bandwidth of each microstrip line, significantly reduces reflection and improves signal transmission efficiency, reduces the mutual influence between microstrip lines, and enables each microstrip line to work synchronously or asynchronously.

[0013] The present invention can also use a microstrip line as a photocathode. When the microstrip patch is Au and the incident light irradiates the photocathode, the microstrip line can perform electron gating emission under the action of an external gating signal. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0015] Figure 1 This is a top view (perspective view) of the present invention.

[0016] Figure 2 This is a top view showing a detailed view of the microstrip patch of the present invention.

[0017] Figure 3 This indicates the distribution of the electric field in the microstrip line of the present invention in the transverse direction.

[0018] Figure 4 This represents the reflection coefficient of port 1 in this invention.

[0019] Figure 5 This represents the transmission coefficient of port 1 in this invention.

[0020] Figure 6 This indicates the crosstalk of port 1 in the other ports of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be fully and clearly described below with reference to the accompanying drawings to illustrate the technical solutions of the embodiments of the present invention. The described embodiments are not all examples, but only some examples. Based on the examples in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] A microstrip line structure, in a specific example, selects four microstrip patches with an operating frequency in the range of 1.1 GHz to 5.8 GHz. Each microstrip patch (1) is located on the end face of a dielectric substrate (2) and is fed through a coaxial port (3), such as... Figure 1 As shown. When the characteristic impedance of the coaxial port is 50 ohms, the characteristic impedance of the microstrip patch connected to the coaxial port is also 50 ohms. The inner diameter of the coaxial line is 0.94 mm, and the outer diameter is 4.66 mm. The dielectric substrate is a homogeneous dielectric with a relative permittivity of 3.6 and a conductivity of 0.05 S / m. When the microstrip lines are placed parallel to each other, the center-to-center spacing between adjacent lines is 14 mm.

[0023] In specific examples, such as Figure 2 The microstrip patches are symmetrically distributed from left to right. Given that the diameter of the microchannel plate is usually around 100 mm, the size of the dielectric substrate is set to 144 mm × 50 mm. For ease of engineering, the length of each patch segment can be set to be the same, and only the width variation and impedance matching of each segment are considered. For the 9-strip patch, patch segment (4) is the center segment, and patch segments (5-9) have the same length. The parameters of each segment are obtained using the Chebyshev method, as shown in Table 1.

[0024]

[0025] In a specific example, the electric field distribution of a microstrip line in the transverse direction is as follows: Figure 3 As shown, the electric fields on the four parallel microstrip lines are relatively uniform with little difference. In a static field environment, the coupling between adjacent microstrip lines is very small and can be almost ignored.

[0026] In a specific example, using port 1 as the input port, the reflection characteristics of the microstrip line are as follows: Figure 4 As shown. The passband is 1.1 GHz to 5.8 GHz, S 11 It is basically less than −20 dB.

[0027] In a specific example, using port 1 as the input port, the transmission characteristics of the microstrip line are as follows: Figure 5 As shown. In the range of 1 GHz to 6 GHz, S 21 All values ​​are greater than -0.6 dB, indicating low loss and ensuring that the gating pulse can pass smoothly through the microstrip line.

[0028] In a specific example, using port 1 as the input port, the crosstalk between ports is as follows: Figure 6 As shown, when the center-to-center spacing between adjacent microstrip lines is 14 mm, S 31 With S 41 All values ​​are less than -20 dB, meaning that less than one percent of the signal will propagate to adjacent microstrip lines or even further microstrip lines, indicating low inter-line crosstalk.

Claims

1. A parallel microstrip line structure patched on the end face of a dielectric substrate, comprising a coaxial feed port, a multi-segment graded microstrip patch, and a dielectric substrate, wherein the microstrip patch is a thin sheet of metal conductor. Its characteristic is that... The microstrip patch consists of multiple thin metal conductor strips, each fed through a coaxial feed port. Each microstrip patch has a symmetrical structure, and all microstrip patches have the same structure. The dimensions of each patch are adjusted so that the impedance of the entire microstrip patch matches the impedance of the coaxial feed port.

2. The microstrip line structure as described in claim 1, characterized in that, The characteristic impedance of the coaxial port portion is not limited to 50 ohms.

3. The microstrip line structure as described in claim 1, characterized in that, The multi-segment gradient microstrip patch section has microstrip patches that are parallel to each other. By controlling the distance between each microstrip patch, crosstalk between ports is reduced.

4. The microstrip line structure as described in claim 1, characterized in that, The dielectric substrate portion can be equivalent to a microchannel plate (a uniform dielectric with a relative permittivity of 3.6 and a conductivity of 0.05 S / m) in practical use, but is not limited to this.

5. The microstrip line structure as described in claim 1, characterized in that, The microstrip patch portion can be made of precious metals such as gold and silver or other highly conductive metals.

6. The microstrip line structure as described in claim 1, characterized in that, The number of segments and the width of each segment of the multi-segment gradient microstrip patch are related to the impedance of the coaxial port.

Images