A broadband random noise source with a high supersonic-to-noise ratio

Abstract

This invention discloses a broadband random noise source with a high noise-to-noise ratio, belonging to the field of microwave and millimeter-wave vacuum device technology. The broadband random noise source includes a dielectric-loaded gyrocopter and a Bragg filter. By increasing the axial length of the dielectric-loaded circuit in the dielectric-loaded gyrocopter, a broadband noise floor signal is generated. A Bragg filter is placed between the collection stage and the output window to reflect and filter the broadband noise floor signal, resulting in a high-flatness, wide-spectrum random noise signal. This invention utilizes the high power, high frequency, and wide bandwidth characteristics of the gyrocopter in amplifying microwaves to generate a high-power noise signal. Simultaneously, the Bragg filter filters and equalizes the noise floor signal, thereby achieving a high-power, wide-spectrum, and high-flatness random noise signal output, effectively improving the output power of the generated noise signal.

Description

Technical Field

[0001] This invention belongs to the field of microwave and millimeter-wave vacuum device technology, specifically relating to a random noise source with high noise ratio and broadband characteristics based on a gyro traveling wave tube. Background Technology

[0002] A noise source is an instrument that artificially generates noise with a flat power spectrum and randomly varying amplitude within a specific frequency range. It has wide applications in system noise figure measurement, noisy radar systems, target detection and imaging, electromagnetic interference, and secure communication. Currently, noise generation mainly employs three technical approaches: thermodynamics, electronics, and photonics. Commonly used noise sources include hot / cold load noise sources, active cold noise sources, gas discharge noise sources, saturated vacuum diode noise sources, solid-state noise sources, and photonic noise sources. However, these noise sources are insufficient to meet the higher power and efficiency requirements of radar and long-distance communication.

[0003] Gyrotron traveling wave tubes (GWTs) based on the electron gyrotron pulsation mechanism can achieve high-power, wide-bandwidth, and high-frequency microwave amplification in the hundreds of kW range, making them a promising broadband high-power noise source. However, in traditional GWTs, the noise floor signal gain is usually low in order to maintain a high signal-to-noise ratio. Summary of the Invention

[0004] The technical problem this invention aims to solve is that traditional noise sources have low power, making it difficult to meet the noise power requirements of noisy radar and long-distance communication. To address this problem, this invention proposes a high-power broadband random noise source. This noise source utilizes a dielectric-loaded gyrotron traveling wave tube to generate an extremely wide-spectrum noise floor signal, which is then reflected and filtered by a Bragg filter to finally generate a high-power, high-flatness, and wide-spectrum random noise signal.

[0005] The technical solution adopted in this invention is as follows:

[0006] A broadband random noise source with a high noise-to-noise ratio is characterized by comprising: a dielectric-loaded gyrotron traveling wave tube and a Bragg filter.

[0007] The dielectric-loaded gyroscopic traveling wave tube generates a wide-spectrum noise floor signal by increasing the axial length of the dielectric loading circuit.

[0008] The Bragg filter is positioned between the collector stage and the output window of the dielectric-loaded gyrotron traveling wave tube to reflect and filter the broadband noise floor signal, thereby obtaining a high-flatness, broadband random noise signal.

[0009] Furthermore, when the dielectric-loaded gyrotron traveling wave tube operates in the Ku band, the axial length of the dielectric loading circuit ranges from 400mm to 600mm.

[0010] Furthermore, the Bragg filter includes a main waveguide and a non-periodic cylindrical grating structure loaded on the main waveguide to achieve better passband transmission and lower stopband transmission.

[0011] Furthermore, the Bragg filter is connected to the collector stage via a first tapered waveguide and to the output window via a second tapered waveguide.

[0012] Furthermore, the radius R1 of the main waveguide is (1~1.3)R0, where R0 is the waveguide radius of the dielectric loading circuit; the purpose of setting the radius of the main waveguide within this range is to cut off microwave transmission in the low-frequency stopband.

[0013] Furthermore, the lengths and radii of each tooth structure in the non-periodic cylindrical tooth structure along the axial direction are not exactly the same, and the radius of all tooth structures is in the range of (1~1.5)R1.

[0014] Furthermore, the first and second graded waveguides satisfy Chebyshev curves to achieve low-reflection microwave transmission.

[0015] The working principle of this invention is as follows:

[0016] This invention presents a novel broadband random noise source with a high super-noise ratio (SNR), using a dielectric-loaded gyrotron traveling-wave tube (GWT) as its main structure. In the absence of an input microwave signal, the gyrotron beam emitted by the magnetron-injected electron gun undergoes pre-grouping in an elongated lossy dielectric-loaded circuit, exciting a broadband noise floor signal. Then, in a nonlinear beam-wave interaction circuit, the pre-grouped electron beam amplifies the noise floor signal with high-power microwaves. The amplified broadband noise floor signal is then a high-power, low SNR flatness broadband noise signal. When this noise signal enters the Bragg filter, microwaves of a specific wavelength (i.e., the noise signal within the required frequency band) are transmitted through the output window for microwave output, while microwaves of other wavelengths are reflected back to the lossy dielectric-loaded circuit and absorbed by the attenuating ceramic. Therefore, the noise floor signal generated by the dielectric-loaded gyrotron traveling-wave tube can be filtered and balanced to a certain extent by the Bragg filter, resulting in a broadband, high-power, and high-flatness random noise output. Compared with existing technologies, this invention has the following main advantages:

[0017] This invention realizes a novel broadband random noise source with a high noise-to-noise ratio. Utilizing the high power, high frequency, and wide bandwidth characteristics of microwave amplification via a gyrocopter, it can amplify the noise floor signal to generate a high-power noise signal. Simultaneously, a Bragg filter structure is applied to filter and power equalize this noise floor signal, thereby achieving a high-power, wide-spectrum, and highly flat random noise signal output, effectively improving the output power of noise signals generated by existing technologies.

[0018] In this invention, the Bragg filter is integrated into the dielectric-loaded gyrotron traveling wave tube, making the overall system more compact and integrated. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a broadband random noise source with a high supersonic noise ratio in the embodiment.

[0020] Figure 2 This is a three-dimensional vacuum simulation model diagram of the Bragg filter in the embodiment.

[0021] Figure 3 This is a schematic longitudinal cross-sectional view of the Bragg filter in the embodiment.

[0022] Figure 4 The transmission coefficient and reflection coefficient of the Bragg filter obtained from simulation using CST high-frequency simulation software are shown in the example.

[0023] Figure 5 The output signal of the noise source of this invention is obtained from simulation using CST 3D particle studio simulation software in an example embodiment.

[0024] Figure 6 The super-noise ratio is the noise signal generated by the noise source of this invention, obtained from simulation using CST 3D particle studio simulation software in the example embodiment.

[0025] Explanation of reference numerals in the attached figures: 1 is the magnetron injection electron gun, 2 is the electron beam channel, 3 is the compensation magnetic field coil, 4 is the loss medium loading circuit, 5 is the superconducting magnet, 6 is the nonlinear beam-wave interaction circuit, 7 is the electron beam, 8 is the collector stage, 9 is the first tapered waveguide, 10 is the Bragg filter, 11 is the second tapered waveguide, and 12 is the output window. Detailed Implementation

[0026] The technical solution of the present invention will be further described in detail below with reference to a design example and accompanying drawings of a high super noise ratio broadband random noise source operating in the Ku band.

[0027] like Figure 1 As shown, a broadband random noise source with a high super-noise ratio in this embodiment includes: a dielectric-loaded cyclotron traveling wave tube and a Bragg filter.

[0028] The dielectric-loaded gyroscopic traveling wave tube operates in a circular waveguide TE mode. 11The operating frequency band is Ku-band (12.4GHz-18GHz), the operating voltage is 60kV, the operating current is 10A, and the magnetic field amplitude is 0.6T. This dielectric-loaded gyrotron traveling wave tube includes a magnetron-injected electron gun, an electron injection channel, a compensating magnetic field coil, a lossy dielectric loading circuit, a superconducting magnet, a nonlinear injection-wave interaction circuit, a first graded waveguide, a second graded waveguide, a collector stage, and an output window. In other words, compared to a conventional gyrotron traveling wave tube, the dielectric-loaded gyrotron traveling wave tube of this invention only increases the axial length of the lossy dielectric loading circuit and adds a Bragg filter between the collector stage and the output window; therefore, other structural details are omitted.

[0029] In this embodiment, the dielectric in the lossy dielectric loading circuit is a decaying ceramic BeO-TiO2(ε) r =9, tanδ=0.5), possessing good electrical conductivity and heat dissipation characteristics; the ceramic thickness is 1.3mm, which can withstand the working TE 11 The mode achieves a loss of 6.14 dB / cm to suppress its oscillation; the axial length of the loss medium loading circuit is 500 mm (approximately 1.5 to 3 times that of the conventional scheme), which allows the cyclotron electron beam to pre-cluster in the extended loss medium loading circuit and excite a broadband noise floor signal to achieve a sufficiently high noise amplification gain.

[0030] The Bragg filter is positioned between the collector stage and the output window of the dielectric-loaded gyrotron traveling wave tube, and is connected to the collector stage via a first tapered waveguide and to the output window via a second tapered waveguide. The Bragg filter is used to reflect and filter broadband noise floor signals to obtain high flatness and broadband random noise signals.

[0031] like Figure 2 As shown, the Bragg filter includes a main waveguide and 11 non-periodic cylindrical grating structures loaded on the main waveguide to achieve better passband transmission and lower stopband transmission. Figure 3The diagram shows a longitudinal cross-section of the Bragg filter structure, where the radius of the main waveguide is R1 = 7.6 mm. After optimization, the radii of the cylindrical grating structure are: R2 = 10.655 mm, R3 = 11.064 mm, R4 = 10.789 mm, R5 = 10.288 mm, R6 = 10.631 mm, R7 = 10.755 mm, R8 = 10.148 mm, R9 = 9.833 mm, R10 = 10.519 mm, R11 = 10.767 mm, R12 = 10.476 mm; the thicknesses of the cylindrical grating structure are: L1 = 1.997 mm, L2 = 2.214 mm, L3 = 1.927 mm, L4 = 1.916 mm. The diameters of the cylindrical grating structures are as follows: L5 = 2.993 mm, L6 = 1.980 mm, L7 = 2.141 mm, L8 = 2.254 mm, L9 = 2.268 mm, L10 = 2.120 mm, L11 = 2.108 mm; the spacing between the cylindrical grating structures is as follows: D1 = 2.515 mm, D2 = 2.061 mm, D3 = 1.516 mm, D4 = 3.089 mm, D5 = 4.496 mm, D6 = 4.626 mm, D7 = 1.257 mm, D8 = 3.947 mm, D9 = 4.957 mm, D10 = 3.286 mm.

[0032] Figure 4 The figure shows the transmission coefficient and reflection coefficient of the Bragg filter obtained from CST high-frequency simulation software. As can be seen from this figure, the optimized Bragg filter exhibits better performance in the 11.7–18 GHz range for TE... 11 The transmission rate is greater than -0.3dB, and the reflection rate is less than -15dB. The transmission rate within the stopband is less than -20dB, and even less than -30dB in the 18.5–22GHz range.

[0033] Figure 5 The image shows the output signal of the noise source of this invention obtained from simulation using CST 3D particle studio simulation software. In a gyrotron traveling wave tube, the working TE... 11 The mode is circular polarization. The figure only shows the TE in one polarization direction. 11 The mode output signal, another TE in its vertical polarization direction 11 The output power of the modes is consistent with this. Their average power, when integrated and accumulated, reaches 28.81kW, which meets the high power requirements of this design.

[0034] Figure 6The figure shows the super-noise ratio (SNR) of the noise signal generated by the noise source of this invention, obtained from simulation using CST 3D particle studio simulation software. The SNR can reach 80 dB, and it is relatively flat in the range of 11.7–18 GHz, with a flatness of approximately ±20 dB. This noise source has a high SNR and good flatness, meeting the high SNR and high flatness requirements of this design.

[0035] The above description is merely a specific implementation of the present invention applied to a Ku-band cyclotron traveling wave tube. The present invention is also applicable to other frequency bands operating in TE mode. 11 mode or TE 01 The mode of the gyroscopic traveling wave tube.

Claims

1. A broadband random noise source with a high supersonic-to-noise ratio, characterized in that, include: Dielectric-loaded gyroscopic traveling wave tube, Bragg filter; The dielectric-loaded gyrotron traveling wave tube generates a broadband noise floor signal by increasing the axial length of the dielectric loading circuit. The Bragg filter is connected to the collector stage through a first tapered waveguide and to the output window through a second tapered waveguide to perform reflection filtering on the broadband noise floor signal, thereby obtaining a high-flatness, broadband random noise signal. The Bragg filter includes a main waveguide and a non-periodic cylindrical grating structure loaded on the main waveguide. The first and second graded waveguides satisfy Chebyshev curves.

2. A broadband random noise source with a high supersonic-to-noise ratio as described in claim 1, characterized in that, When the dielectric-loaded gyrotron traveling wave tube operates in the Ku band, the axial length of the dielectric loading circuit ranges from 400 mm to 600 mm.

3. A broadband random noise source with a high supersonic-to-noise ratio as described in claim 2, characterized in that, The radius R1 of the main waveguide is (1~1.3)R0, where R0 is the waveguide radius of the dielectric loading circuit.

4. A broadband random noise source with a high supersonic-to-noise ratio as described in claim 3, characterized in that, The lengths and radii of the various teeth in the non-periodic cylindrical tooth structure along the axial direction are not exactly the same, and the radius of all the teeth is in the range of (1~1.5)R1.

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