A high-power microwave signal generation and transmission device and system

Abstract

The application relates to the technical field of signal transmission, and particularly discloses a high-power microwave signal generation and transmission device and system. The device comprises a coaxial transmission line, the coaxial transmission line comprises coaxially arranged outer and inner conductors and a composite material filled between the outer and inner conductors; the composite material comprises a ferroelectric material with a nonlinear dielectric constant and a ferromagnetic material with a nonlinear magnetic permeability; positioning rings are respectively fixed on the axial two ends of the coaxial transmission line; the composite material is used for steepening a waveform based on the nonlinear dielectric constant to realize a pulse forming function when a pulse signal is transmitted in a forward direction, and is used for collimating magnetic moments in the ferromagnetic material based on a transient pulse magnetic field of an initial injected pulse; and the composite material is also used for driving the magnetic moments to coherently precess based on a reflected magnetic field generated by a reflected signal when the pulse signal is reflected and transmitted in a reverse direction, so that a microwave signal is generated without an external bias magnetic field. Through the application, the hardware architecture of a high-power microwave source is simplified.

Description

Technical Field

[0001] This application belongs to the field of signal transmission technology, specifically relating to the field of high-power microwave signal transmission technology based on nonlinear transmission lines, and more specifically, relating to a high-power microwave signal generation and transmission device and system. Background Technology

[0002] High-power microwaves (HPMs) refer to strong electromagnetic pulse radiation with peak power exceeding 100 megawatts and frequencies ranging from 300 MHz to 300 GHz. They have broad application prospects in fields such as radar detection, electronic warfare, plasma heating, industrial processing, and medical treatment. With the development of solid-state devices and new materials technologies, solid-state HPM sources based on nonlinear transmission lines (NLTLs) are gradually becoming an important development direction for HPM source technology due to their advantages such as compact structure, no need for a vacuum environment, and repetitive frequency operation.

[0003] Existing NLTL-type HPM sources are mainly divided into two categories: one is the gyromagnetic NLTL based on the nonlinear permeability of ferromagnetic materials. Its working principle relies on the precession of the magnetic moment of the ferromagnetic material around an effective magnetic field to generate microwave oscillations, which usually requires the application of an external bias magnetic field to maintain coherent precession; the other is the ferroelectric NLTL based on the nonlinear dielectric constant of ferroelectric materials. It utilizes the characteristic that the dielectric constant of the material changes with the electric field near the Curie temperature to achieve waveform modulation. Both types of NLTLs require an independent high-voltage pulse modulator (such as a Marx generator, pulse forming network, or pulse forming line) to provide a fast-rising-edge (rise time less than 5 nanoseconds) driving pulse to excite the nonlinear response of the material.

[0004] However, existing NLTL-type HPM sources face the following shortcomings in practical applications: First, the independent pulse modulator not only increases the size, weight, and cost of the system, but also introduces additional control complexity; second, the dependence of vortex NLTLs on external bias magnetic fields requires the system to be equipped with auxiliary devices such as permanent magnets or electromagnetic coils, further limiting the system's compactness and portability; in addition, the typical length of traditional NLTLs is about 1 meter, and the overall size is relatively large, making it difficult to meet the urgent needs of portable HPM applications for miniaturization and lightweighting. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a high-power microwave signal generation and transmission device and system, which aims to solve the problems of high system complexity, large size, and difficulty in portability caused by the need to separately configure pulse modulators and external bias magnetic fields in existing high-power microwave source systems, and to realize the multiplexing of pulse forming and microwave generation functions and microwave oscillation without external bias magnetic fields.

[0006] The first aspect of this application relates to a high-power microwave signal generation and transmission device, comprising: a coaxial transmission line, the coaxial transmission line including an outer conductor and an inner conductor arranged coaxially, and a composite material filled between the outer conductor and the inner conductor; the composite material including a ferroelectric material having a nonlinear dielectric constant and a ferromagnetic material having a nonlinear permeability; positioning rings respectively nested and fixed at both ends of the axial direction of the coaxial transmission line for maintaining the coaxial state of the outer conductor and the inner conductor; the composite material is used to steepen the waveform based on the nonlinear dielectric constant to achieve pulse formation function when the pulse signal is transmitted in the forward direction, and to collimate the magnetic moment in the ferromagnetic material based on the transient pulse magnetic field of the initially injected pulse; and is also used to drive the magnetic moment to coherently precess based on the reflected magnetic field generated by the reflected signal when the pulse signal is reflected and transmitted in the reverse direction, so as to generate a microwave signal in the absence of an external bias magnetic field.

[0007] This application utilizes a composite material containing both ferroelectric and ferromagnetic materials between the inner and outer conductors of a coaxial transmission line. Leveraging the dual nonlinear characteristics of the composite material's nonlinear dielectric constant and nonlinear permeability, the same transmission line can be used as a pulse forming line to steepen the waveform during forward pulse transmission and as a microwave generator to drive coherent precession of the magnetic moment to produce microwave oscillations during reverse reflection transmission. This achieves the multiplexing of pulse forming and microwave generation functions. Since the transient magnetic field of the initial injected pulse has already collimated the magnetic moment, the reflected signal can drive the magnetic moment to coherently precess and generate strong microwave oscillations without the need for an external bias magnetic field, eliminating dependence on an external bias magnetic field system, thus significantly simplifying the system architecture and reducing the device size.

[0008] In some embodiments, the composite material further includes a polymer matrix, wherein the ferroelectric material and the ferromagnetic material are dispersed and mixed in the polymer matrix; wherein the polymer matrix is ​​polydimethylsiloxane, the ferroelectric material is barium strontium titanate, and the ferromagnetic material is nickel-zinc ferrite.

[0009] This solution uses polydimethylsiloxane (PDMS) as the polymer matrix, and disperses barium strontium titanate (BST) and nickel zinc ferrite (NZF) in it to form a uniform composite material. The PDMS matrix has good insulation, flexibility and easy molding characteristics, which can effectively support and fix ferroelectric and ferromagnetic particles, ensuring that the composite material maintains a stable microstructure and electromagnetic properties after infusion and curing, while facilitating filling and molding in the coaxial cavity.

[0010] In some embodiments, the doping volume percentage of barium strontium titanate is 10%-15% and the doping volume percentage of nickel-zinc ferrite is 5%-25%, based on the total volume of the composite material.

[0011] This scheme precisely controls the doping ratio of barium strontium titanate to nickel-zinc ferrite, ensuring sufficient nonlinear dielectric strength to achieve effective pulse steepening while maintaining the magnetic moment density of the ferromagnetic component to support strong coherent precession. This ratio range avoids the increase in magnetic loss caused by excessive ferroelectric phase or the weakening of dielectric nonlinearity caused by excessive ferromagnetic phase, which is beneficial to balancing pulse formation efficiency and microwave output power.

[0012] In some embodiments, both the outer conductor and the inner conductor are made of low-loss metallic materials; the outer conductor is a tubular structure and the inner conductor is a rod-shaped structure; the ratio of the inner diameter of the outer conductor to the outer diameter of the inner conductor is determined based on the dielectric constant and permeability of the composite material, so that the characteristic impedance of the device matches the load impedance connected to the output terminal.

[0013] This solution effectively reduces ohmic losses during transmission and improves energy transmission efficiency by using low-loss metal materials for the outer and inner conductors. At the same time, by precisely designing the ratio of the inner diameter of the outer conductor to the outer diameter of the inner conductor based on the equivalent dielectric constant and equivalent permeability of the composite material, the characteristic impedance of the coaxial transmission line is matched with the impedance of the load at the back end, reducing signal reflection loss and ensuring that the steepened pulse energy is efficiently transferred to the load end and excites the subsequent microwave oscillation process.

[0014] In some embodiments, the positioning ring is made of aluminum; the positioning ring has a central through hole, and the end of the inner conductor passes through the central through hole; the positioning ring covers the end opening of the outer conductor, and the end face of the positioning ring abuts against the end face of the outer conductor to close the gap between the outer conductor and the inner conductor and define a cavity for accommodating the composite material.

[0015] This solution utilizes aluminum to fabricate the positioning ring. Aluminum has low density, good conductivity, and is easy to machine, ensuring both the structural strength and coaxial positioning accuracy of the positioning ring while reducing the overall weight of the device. Through the precise fit of the aluminum positioning ring, the relative positions of the inner and outer conductors are reliably fixed during the composite material infusion and curing process, ensuring coaxiality throughout the process. At the same time, its end-face abutment design forms a sealed cavity to prevent leakage of uncured material, ensuring the uniformity of the transmission line geometry and the consistency of electrical performance, laying a structural foundation for subsequent stable pulse propagation and microwave generation.

[0016] The second aspect of this application relates to a high-power microwave signal generation and transmission system, comprising: a high-power microwave signal generation and transmission device as described above, a power supply interface, an impedance mismatch structure, an output switch, and an impedance matching structure. The power supply interface is used to connect an external DC voltage to charge the device. The impedance mismatch structure is connected in series between the power supply interface and the input terminal of the inner conductor of the device, used to form a signal reflection boundary at the input terminal of the inner conductor. The output switch is connected in series at the output terminal of the inner conductor, used to release a pulse signal when a conduction condition is met. The input terminal of the impedance matching structure is connected to the output terminal of the output switch, and its output terminal is connected to an outer conductor, which is connected to the ground terminal of the power supply interface. The impedance matching structure is used to absorb output energy and suppress signal reflection at the output terminal.

[0017] This system provides a DC charging voltage to the coaxial transmission line via a power supply interface. When the output switch is turned on, the electrical energy stored in the device is released in the form of a fast-rising-edge pulse. This pulse propagates along the coaxial transmission line from the output switch side towards the inner conductor input end and is reflected at the high-impedance boundary formed by the impedance mismatch structure. After returning to the coaxial transmission line, the reflected pulse acts on the composite material, driving the magnetic moment in the ferromagnetic material to undergo coherent precession and generate a microwave signal. The impedance matching structure located after the output switch forms a discharge circuit, absorbs the pulse energy released by the output switch, and suppresses signal reflection at that end. Thus, the coaxial transmission line can achieve pulse formation during the initial pulse propagation stage and microwave excitation during the reflected pulse action stage.

[0018] In some embodiments, the impedance mismatch structure is a current-limiting resistor; the impedance value of the current-limiting resistor is greater than the characteristic impedance of the device, used to limit the incoming DC current to form the signal boundary condition that generates the reflected magnetic field at the input end of the inner conductor.

[0019] This scheme uses a current-limiting resistor with an impedance value greater than the characteristic impedance of the transmission line as an impedance mismatch structure. On the one hand, it limits the magnitude of the DC charging current and protects the DC power supply from overcurrent impact. On the other hand, this high-impedance node forms an approximate open-circuit reflection boundary when the pulse signal arrives, causing the voltage pulse to be almost completely reflected back to the transmission line. This establishes a reflected electromagnetic field on the transmission line that is sufficient to drive the precession of the magnetic moment of the ferromagnetic material, thus achieving the dual function of reflection boundary construction and circuit safety protection.

[0020] In some embodiments, the output switch is a gas spark gap switch; the gas spark gap switch is used to turn on when the charging voltage on the inner conductor reaches a set threshold, so as to cut off the slowly rising charging voltage and convert it into a voltage pulse with a fast leading edge on the nanosecond level, and release the voltage pulse to the impedance matching structure.

[0021] This solution employs a gas spark gap switch as the output switch, utilizing the rapid response characteristics of gas breakdown (nanosecond-level rise time). When the inner conductor charging voltage reaches a set threshold, it instantaneously conducts, releasing the electrostatic energy stored on the transmission line in the form of a high-voltage pulse with an extremely fast leading edge (approximately 2ns rise time). This steepening process further enhances the nonlinear response efficiency of the composite material and provides a high-quality incident pulse for subsequent reflection excitation. The switch's self-triggering characteristic allows it to respond to the charging state without external synchronization control, simplifying system timing design. Simultaneously, its high-voltage tolerance supports higher charging voltages, directly increasing the output microwave power.

[0022] In some embodiments, the impedance matching structure is a resistive load; the impedance value of the resistive load is matched with the characteristic impedance of the device.

[0023] This solution employs a resistive load that matches the characteristic impedance of the transmission line as an impedance matching structure. This ensures that the pulse energy output from the spark gap switch is fully absorbed by the load without secondary reflection, guaranteeing the purity of the output waveform. A pure output waveform not only facilitates accurate characterization of the device's performance but also provides a foundation for subsequent signal coupling and utilization in practical applications, ensuring high-quality transmission and utilization of microwave signals and enhancing the system's practicality and reliability.

[0024] In some embodiments, the system further includes a measurement component comprising a voltage divider, a coaxial cable, and an oscilloscope; the input of the voltage divider is connected to the output of the inner conductor for extracting an output voltage signal at a preset ratio; a first end of the coaxial cable is connected to the output of the voltage divider, and a second end of the coaxial cable is connected to the oscilloscope; the oscilloscope is used to receive and display the output voltage signal; wherein the length of the coaxial cable is configured to prevent reflected signals caused by the measurement from interfering with the original signal.

[0025] This solution introduces a time delay through a coaxial cable of a specific length, causing the reflected signal that may be generated in the measurement circuit to be further away from the original signal window in time, thereby achieving high-precision voltage monitoring without affecting the integrity of the main signal; the voltage divider attenuates the high-voltage signal proportionally to adapt to the oscilloscope range, and the entire measurement link ensures both equipment safety and the authenticity and repeatability of experimental data.

[0026] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) This application combines ferroelectric and ferromagnetic materials in a coaxial transmission line, enabling a single structure to simultaneously perform the dual functions of pulse formation and microwave generation, eliminating the need for a separate high-voltage pulse modulator module in traditional systems; at the same time, it utilizes the forward pulse transient magnetic field to pre-collimate the magnetic moment, and drives the magnetic moment coherent precession by the reverse magnetic field formed by the reflection from the input end, replacing the external bias magnetic field system, thereby simplifying the hardware architecture of the high-power microwave source, reducing the size and weight of the device, and making it suitable for portable application scenarios.

[0027] (2) This application achieves synergistic optimization of pulse steepening efficiency and microwave oscillation intensity by precisely designing the ratio of ferroelectric and ferromagnetic components in the composite material and the geometric dimensions of the transmission line; the reasonable configuration of impedance matching and mismatch structure not only ensures efficient absorption of output energy, but also constructs an effective reflection boundary at the input end to excite coherent precession, thereby obtaining microwave output with a longer duration and higher power even without external field assistance, improving energy utilization and overall system performance.

[0028] (3) This application adopts a working mode of DC charging combined with gas spark gap switch self-triggering, which avoids the timing synchronization problem of complex high voltage modulator, simplifies the design of input connector and peripheral control circuit; the measurement component isolates reflected interference through delay cable, ensuring accurate acquisition of high voltage pulse signal, providing a reliable means for system debugging and performance verification, and enhancing the feasibility of engineering implementation and the credibility of test data. Attached Figure Description

[0029] Figure 1 This is a longitudinal cross-sectional structural schematic diagram of the high-power microwave signal generation and transmission device according to an embodiment of this application; Figure 2 This is a schematic diagram of the circuit principle of a high-power microwave signal generation and transmission system according to an embodiment of this application.

[0030] Among them, 100 is a high-power microwave signal generation and transmission device; 110 is a coaxial transmission line; 120 is a positioning ring; 111 is an outer conductor; 112 is a composite material; 113 is an inner conductor; 210 is a power supply interface; 220 is an impedance mismatch structure; 230 is an output switch; and 240 is an impedance matching structure. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In the description of this application, it should be understood that the terms "center", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] The embodiments of this application are described below with reference to the accompanying drawings. Figure 1 As shown, this embodiment provides a high-power microwave signal generation and transmission device 100. The device includes a coaxial transmission line 110 and a positioning ring 120. The coaxial transmission line 110 includes an outer conductor 111 and an inner conductor 113 arranged coaxially, and a composite material 112 filling the space between the outer conductor 111 and the inner conductor 113. Specifically, the outer conductor 111 has a tubular structure, and the inner conductor 113 has a rod-like structure. The two are arranged rotationally symmetrically about a central axis, and the composite material 112 is tightly filled in the annular gap formed by the two, constituting a complete coaxial transmission line structure. This three-layer concentric layout allows the composite material 112 to not only serve as an insulating support medium but also as the core medium region for electromagnetic wave propagation and energy conversion.

[0034] The composite material 112 comprises a ferroelectric material having a nonlinear dielectric constant and a ferromagnetic material having a nonlinear magnetic permeability. In this embodiment, the composite material 112 is configured to perform different electromagnetic physical responses during the forward and reverse transmission of pulse signals, thereby achieving functional multiplexing of pulse formation and microwave generation.

[0035] The first stage of the physical process (forward transmission): When the nanosecond-level high-voltage pulse signal propagates forward along the coaxial transmission line, the composite material 112 exhibits two parallel physical effects.

[0036] 1) The waveform is steepened based on the nonlinear dielectric constant to achieve pulse generation. Specifically, the dielectric constant of ferroelectric materials exhibits a significant electric field dependence, decreasing with increasing applied electric field strength. This is based on the formula for the propagation speed of electromagnetic waves in a medium. (in The speed of light in a vacuum. The relative permittivity, The decrease in dielectric constant (relative permeability) directly leads to an increase in the local propagation speed of electromagnetic waves. Therefore, when a pulse signal propagates in composite material 112, the portion of the pulse waveform with higher electric field amplitude (i.e., the wave crest region) has a lower dielectric constant and a faster propagation speed, while the portion with lower electric field amplitude (i.e., the wave tail region) has a higher dielectric constant and a slower propagation speed. As the transmission distance increases, the wave crest continuously catches up with the wave tail, and the wavefront is continuously compressed and gradually becomes steeper, eventually shaping the slowly varying input pulse into a nanosecond-level fast-rising-edge pulse. This nonlinear waveform compression process is essentially a redistribution of the pulse's own energy in the time domain, rather than a result of external modulation.

[0037] 2) Simultaneously, the transient pulsed magnetic field generated by the initial injected pulse collimates the magnetic moments in the ferromagnetic material. Collimation here refers to the process by which the magnetic moments, originally randomly oriented due to thermal disturbance within the ferromagnetic material, align neatly along the transmission line axis under the influence of the transient strong magnetic field. This is not the concept of parallel beams in optics, but rather the establishment of an ordered initial state of magnetic moments for subsequent microwave radiation. The physical process is as follows: When the pulsed current flows along the inner conductor 113, according to Ampere's circuital law, a ring-shaped transient magnetic field is generated around the inner conductor 113 in the composite material 112 surrounding the inner conductor 113. The field strength of this transient magnetic field is much higher than the anisotropic field of the ferromagnetic material, exerting a strong orientation torque on the magnetic moments, forcing them to overcome thermal disturbance and anisotropic barriers, aligning along the direction of the transient magnetic field (i.e., the circumferential direction of the transmission line). Because the pulse duration is extremely short (on the order of nanoseconds), the alignment of the magnetic moments is a transient response rather than steady-state magnetization. After the pulse passes, the magnetic moments relax to the easy magnetization direction along the transmission line axis due to the magnetic anisotropy of the material, but still maintain a macroscopically ordered alignment. This process fully utilizes the magnetic field energy carried by the pulse itself, without the need for an additional static bias magnetic field.

[0038] The second stage of the physical process (reverse transmission): When the pulse signal is reflected at the system input (or a set boundary) to form a reverse-transmitted electromagnetic wave, the composite material 112 enters the microwave excitation stage. At this time, the reflected magnetic field generated by the reflected signal drives the magnetic moment to undergo coherent precession, so as to generate a microwave signal in the absence of an external bias magnetic field.

[0039] Specifically, the physical process of coherent precession is as follows: when the reverse magnetic field carried by the reflected signal acts on the collimated magnetic moment, the reverse magnetic field exerts a torque on the magnetic moment ( ,in It is the magnetic moment vector. The reflected magnetic field vector forces the magnetic moments to deviate from their collimated equilibrium positions and precess around the effective magnetic field direction (determined by the vector superposition of the material's anisotropic field, demagnetizing field, and reflected magnetic field). Since all magnetic moments are collimated to a highly consistent initial state during the forward propagation phase, they precess synchronously at the same Larmor frequency under the excitation of the reflected magnetic field, forming macroscopic coherent oscillations. This collective synchronous precession couples the magnetic moment oscillation energy into the electromagnetic field mode of the transmission line through the electromagnetic induction effect described by Maxwell's equations, forming a microwave oscillation signal in the GHz band. The radiation frequency is jointly determined by the effective magnetic field strength and the gyromagnetic ratio of the ferromagnetic material. Because the magnetic moments are pre-collimated during the forward propagation phase, the reflected magnetic field during reverse propagation can directly trigger high-intensity coherent oscillations, eliminating the need for the external bias magnetic field system required by traditional gyromagnetic devices, simplifying the device structure and reducing weight.

[0040] Positioning rings 120 are nested and fixed at both ends of the coaxial transmission line to maintain the coaxial state of the outer conductor 111 and the inner conductor 113. In high-frequency / high-power microwave transmission, conductor eccentricity can cause severe distortion of the local electric field, easily inducing partial discharge (breakdown) of the dielectric, and also exciting parasitic electromagnetic waves in non-TEM (Transverse Electromagnetic) modes. Positioning rings 120 provide mechanical rigidity, ensuring the axial consistency of the effective impedance within the transmission line.

[0041] For example, the positioning ring 120 can be made of a metal material such as aluminum, with a through hole in the center for the inner conductor 113 to pass through, and its outer edge precisely fitting the inner wall of the outer conductor 111. The positioning rings 120 at both ends ensure that the inner and outer conductors do not shift relative to each other during the pouring and curing process of the composite material 112, maintaining the uniformity of the transmission line geometry, thereby ensuring the consistency of characteristic impedance and the purity of the electromagnetic wave transmission mode, and avoiding the risk of parasitic mode interference or local breakdown caused by structural eccentricity.

[0042] In some embodiments, composite material 112 further includes a polymer matrix, in which ferroelectric and ferromagnetic materials are dispersed and mixed.

[0043] Specifically, polydimethylsiloxane (PDMS) is selected as the polymer matrix. The selection of PDMS is based on multiple considerations: First, PDMS has excellent dielectric strength and bulk resistivity, and can withstand the strong electric field (several kV / mm to tens of kV / mm) under high voltage pulses without electrical treeing aging or intrinsic breakdown; Second, its room temperature curing characteristics and suitable rheological viscosity allow the functional particles to achieve high uniformity mixing through ultrasonic dispersion and vacuum degassing processes before curing, avoiding electric field stress concentration caused by particle agglomeration; Third, its highly elastic network structure after curing can effectively absorb the electrostrictive stress caused by high voltage pulses, improving the mechanical fatigue life of the device.

[0044] Barium strontium titanate (BST) was chosen as the ferroelectric material. BST is a typical ferroelectric material with a perovskite structure. By adjusting the molar ratio of barium to strontium, the Curie temperature of the material can be controlled to near room temperature. At room temperature, BST is located in the boundary region between the ferroelectric and paraelectric phases, exhibiting extremely high relative permittivity and significant electric field tunability. More importantly, a properly proportioned BST exhibits a small hysteresis loop area in the quasi-paraelectric state, resulting in low dielectric loss during rapid charge and discharge, which contributes to lossless steepening of the pulse leading edge.

[0045] Nickel-zinc ferrite (NZF) was selected as the ferromagnetic material. NZF belongs to the spinel-type soft magnetic ferrite. Under high-power pulsed environments, metallic magnetic materials (such as permalloy) will generate huge eddy current losses due to the skin effect, leading to heat generation and even device failure. As an oxide ceramic magnetic material, NZF has extremely high resistivity, which can effectively suppress high-frequency eddy currents. At the same time, its suitable saturation magnetization and gyromagnetic ratio ensure that it can provide a sufficiently strong precessing magnetic moment and form a microwave oscillation signal in the required frequency band when excited by transient magnetic fields.

[0046] Furthermore, based on the total volume of the composite material 112, the doping volume percentage of barium strontium titanate is 10%-15%, and the doping volume percentage of nickel-zinc ferrite is 5%-25%. This ratio balances pulse steepening effect and microwave oscillation response. For example, in a preferred embodiment, the doping volume percentage of barium strontium titanate is 15%, and the doping volume percentage of nickel-zinc ferrite is 10%. In this case, the composite material 112 can ensure sufficient nonlinear dielectric strength to shape the input pulse into a nanosecond-level fast leading edge, while maintaining a suitable magnetic moment density to support high-intensity coherent precession, thus facilitating a balance between pulse steepening response and microwave oscillation response.

[0047] The physical basis for this parameter range lies in establishing a balance threshold between the nonlinear dielectric constant and the magnetic moment density. When the doping volume percentage of barium strontium titanate is less than 10%, the overall nonlinear dielectric effect of the composite material 112 is significantly weakened, resulting in insufficient steepening of the pulse waveform and a slower rise time. Consequently, the driving energy for subsequent coherent precession of the excitation magnetic moment is reduced, and the microwave output power decreases significantly. Conversely, when the doping volume percentage of barium strontium titanate is higher than 15%, excessive ferroelectric particles tend to agglomerate in the polymer matrix. This not only increases dielectric loss leading to heat transfer but also crowds out the distribution space of the ferromagnetic material, disrupting the uniformity of the two-phase interface.

[0048] Similarly, when the doping volume percentage of nickel-zinc ferrite is less than 5%, the number of effective magnetic moments per unit volume is insufficient to form macroscopically observable strong coherent radiation. However, when the doping volume percentage of nickel-zinc ferrite is higher than 25%, the spacing between magnetic particles decreases, potentially exceeding the percolation threshold to form conductive pathways, reducing the overall withstand voltage level of the material. Simultaneously, the increase in the magnetic damping coefficient accelerates microwave energy attenuation. Therefore, the above ratio is a feasible operating range optimized based on multiphysics coupling effects.

[0049] In some embodiments, both the outer conductor 111 and the inner conductor 113 are made of low-loss metal materials; the outer conductor 111 is a tubular structure and the inner conductor 113 is a rod-shaped structure. The ratio of the inner diameter of the outer conductor 111 to the outer diameter of the inner conductor 113 is determined based on the dielectric constant and permeability of the composite material 112, so that the characteristic impedance of the device 100 matches the load impedance connected to the output terminal.

[0050] Specifically, the low-loss metal material can be selected from metals with high conductivity and low high-frequency loss, such as brass, oxygen-free copper, or aluminum. Brass has excellent conductivity and surface finish. Under the high-frequency skin effect, it can reduce the ohmic loss of electromagnetic waves propagating along the inner wall of the conductor to a low level. In this embodiment, brass is preferred to balance conductivity and machinability.

[0051] The inner diameter of outer conductor 111 ( ) and the outer diameter of the inner conductor 113 ( The ratio is not arbitrarily set, but is based on the macroscopic dielectric constant and permeability of the composite material 112 for characteristic impedance matching design. The theoretical characteristic impedance of the coaxial transmission line is given by the following formula: ; in, These are the vacuum permittivity and permeability, respectively. Here, represents the relative permittivity and relative permeability of the composite material. To prevent unnecessary energy reflection (voltage standing wave ratio approaching 1) when the device 100 is connected to an external load, it is necessary to ensure that... It approaches the load impedance (e.g., 10Ω). Due to the introduction of BST, The impedance is relatively high, and to maintain a specific impedance value, it needs to be precisely set through machining. The ratio. This configuration enables the output microwave energy to cross the dielectric interface and be injected into subsequent load or antenna systems with maximum efficiency.

[0052] This design method, which uses the electromagnetic parameters of the material to deduce the geometric dimensions, ensures that the pulse signal is fully absorbed at the interface between the transmission line and the load without energy reflection. This avoids waveform distortion and power loss caused by impedance mismatch, thereby ensuring the stability and output efficiency of the microwave signal.

[0053] In one embodiment, the outer conductor 111 is a 1-inch brass tube with an inner diameter of 0.75 inches. The inner conductor 113 is a 0.5-inch diameter brass rod, such that the characteristic impedance of the coaxial transmission line is 10Ω.

[0054] In terms of mechanical packaging, the positioning ring 120 is made of aluminum; the positioning ring 120 has a central through hole, and the end of the inner conductor 113 passes through the central through hole; the positioning ring 120 covers the end opening of the outer conductor 111, and the end face of the positioning ring 120 abuts against the end face of the outer conductor 111 to close the gap between the outer conductor 111 and the inner conductor 113 and define a cavity for accommodating the composite material 112.

[0055] Combination Figure 1 As shown, the aluminum positioning ring 120 not only has the advantages of being lightweight and easy to process, but also possesses excellent non-magnetic characteristics, avoiding interference with the magnetic field distribution inside the transmission line. The diameter of the central perforation is precisely matched with the outer diameter of the inner conductor 113, so that the inner conductor 113 is firmly fixed on the central axis of the outer conductor 111; the end face of the positioning ring 120 facing the inside of the transmission line is tightly fitted with the end section of the outer conductor 111, forming an axially closed annular cavity, which is the injection space for the composite material 112.

[0056] This structural design provides dual protection in the manufacturing process: Firstly, during the preparation stage, the liquid PDMS and powder mixture is injected into the cavity. The end face of the aluminum positioning ring effectively prevents the overflow of viscous materials; during the curing and cross-linking stage, it resists the volume shrinkage caused by internal material stress, thus defining a geometrically stable composite dielectric layer. This design ensures the continuity of the electromagnetic boundary from the input to the output. Secondly, it forcibly maintains the strict coaxiality of the inner and outer conductors along the entire length. Maintaining coaxiality is crucial for high-power microwave devices; any slight eccentricity can cause fluctuations in the characteristic impedance of the transmission line along the axial direction, leading to local electric field concentration, parasitic mode excitation, or even high-voltage breakdown.

[0057] Based on the above embodiments, such as Figure 2 As shown, this embodiment provides a high-power microwave signal generation and transmission system. The system includes a high-power microwave signal generation and transmission device 100 as described in the preceding embodiments, a power supply interface 210, an impedance mismatch structure 220, an output switch 230, and an impedance matching structure 240. These functional modules are connected according to a specific electrical topology, collectively forming a complete working link that can autonomously complete the process from DC charging to microwave output without the need for an external modulator and bias magnetic field.

[0058] The power supply interface 210 is used to connect an external DC voltage to charge the device 100. Specifically, the power supply interface physically connects to the positive output terminal of a high-voltage DC power supply, and its function is to convert external electrical energy into electric field energy stored in the composite material 112 inside the device 100. During the charging phase, the high-voltage DC power output from the high-voltage DC power supply is applied to the inner conductor 113 of the device 100 through this interface, putting the coaxial transmission line in a high-energy ready state.

[0059] Impedance mismatch structure 220 is connected in series between power supply interface 210 and the input terminal of inner conductor 113 of device 100 to form a signal reflection boundary at the input terminal of inner conductor 113. Specifically, the impedance mismatch structure is implemented as a current-limiting resistor, one end of which is connected to a high-voltage DC power supply, and the other end is connected to the input terminal of inner conductor 113 of device 100. The signal reflection boundary referred to here is the physical interface where electromagnetic wave signals transmitted to this point undergo total or partial reflection due to a significant discontinuous change in impedance along the transmission path. Since the resistance of the current-limiting resistor is much larger than the characteristic impedance of device 100, when a forward-transmitted pulse signal reaches this interface, it will be forcibly reflected back into the coaxial transmission line. It is this reflected signal that generates the reverse magnetic field required to drive the coherent precession of the magnetic moment of the ferromagnetic material. Simultaneously, the current-limiting resistor also plays an auxiliary role in limiting DC current and protecting power supply safety during the charging phase.

[0060] Output switch 230 is connected in series at the output terminal of inner conductor 113 and is used to release a pulse signal when the conduction condition is met. When the charging voltage of device 100 rises to the self-breakdown threshold of output switch 230, the switch turns on instantaneously, cutting off the originally slowly rising charging voltage and converting it into a steepened pulse with a fast leading edge on the nanosecond scale, which is then released outward. This self-triggering method eliminates the need for complex external synchronization control circuitry, simplifying timing design.

[0061] The input terminal of the impedance matching structure 240 is connected to the output terminal of the output switch 230, and its output terminal is connected to the outer conductor 111. The outer conductor 111 is connected to the ground terminal of the power supply interface 210. The impedance matching structure 240 is used to absorb output energy and suppress signal reflection at the output terminal. In this embodiment, the impedance matching structure 240 is specifically a resistive load, and its resistance is designed to be equal to the characteristic impedance of the device 100. When the steepened pulse signal reaches the resistive load through the gas spark gap switch, the energy is completely absorbed and converted into heat energy or other forms of output, avoiding secondary reflection interference caused by terminal impedance mismatch. In addition, the outer conductor 111 is connected to the negative terminal (GND) of the high-voltage DC power supply through a wire, forming a complete current loop, ensuring the uniformity and stability of the system reference potential. Through the coordinated cooperation of the above modules, the system successfully realizes the multiplexing of pulse formation and microwave generation functions, significantly reducing the size and complexity of the high-power microwave source.

[0062] In some implementations, the impedance mismatch structure 220 is a current-limiting resistor; the impedance value of the current-limiting resistor is greater than the characteristic impedance of the device 100, and it is used to limit the incoming DC current to form a signal boundary condition at the input terminal of the inner conductor 113 that generates a reflected magnetic field.

[0063] Specifically, the selection of the current-limiting resistor value needs to comprehensively consider the steady-state characteristics of the charging circuit and the transient response of the pulse transmission process. In this embodiment, the characteristic impedance of device 100 is designed to be 10Ω, while the resistance value of the current-limiting resistor is preferably 5MΩ. This resistance value is much larger than the characteristic impedance of device 100, and its physical significance lies in constructing a significant impedance discontinuity interface. During the charging phase, the high resistance value of 5MΩ can effectively limit the steady-state current output by the high-voltage DC power supply, preventing power supply overload or transmission line overheating; during the pulse transmission phase, for nanosecond-level fast-rising-edge pulse signals, the 5MΩ current-limiting resistor presents an approximately open-circuit state relative to the 10Ω transmission line impedance, causing the pulse signal transmitted to the input terminal in the forward direction to undergo almost total reflection. It is this strong reflection effect that establishes a sufficiently strong reverse magnetic field inside device 100. This reverse magnetic field is the key excitation source that drives the magnetic moment of the composite material 112 ferromagnetic material to undergo coherent precession and radiate microwaves.

[0064] In some embodiments, the output switch 230 is a gas spark gap switch; the gas spark gap switch is used to turn on when the charging voltage of the inner conductor 113 reaches a set threshold, so as to cut off the slowly rising charging voltage and convert it into a voltage pulse with a fast leading edge on the nanosecond level, and release the voltage pulse to the impedance matching structure 240.

[0065] Specifically, the conduction threshold of the gas spark gap switch is determined by both the electrode spacing and the filling gas pressure, and is set to a safe operating voltage slightly below the device's insulation withstand limit. When the charging voltage rises to this threshold, the electric field strength within the switch gap exceeds the gas breakdown field strength, triggering avalanche ionization and forming a low-resistivity plasma channel, thus completing the switch from the insulating state to the conducting state in a very short time. This rapid breakdown characteristic can truncate the originally slowly rising charging voltage, transforming it into a steep voltage pulse with a rise time of approximately 2 ns. This steepening process is crucial because the nonlinear dielectric effect and nonlinear permeability effect of the composite material 112 are both significantly field strength dependent. Only pulses with sufficiently fast rise times and high peak field strengths can effectively excite the nonlinear response of the material, thereby achieving waveform compression and microwave generation. Furthermore, the self-triggering characteristic of the gas spark gap switch allows it to respond to the charging state without external synchronization control circuitry, simplifying the timing design complexity of the system.

[0066] In some embodiments, the impedance matching structure 240 is a resistive load; the impedance value of the resistive load is matched with the characteristic impedance of the device 100.

[0067] Specifically, the resistive load, as the system's terminal energy absorption unit, is precisely designed with a resistance equal to the characteristic impedance of device 100, for example, both being 10Ω. This impedance matching ensures that the pulse signal output after being steepened by the gas spark gap switch can be completely absorbed by the resistive load, preventing secondary reflection signals caused by terminal impedance mismatch from flowing back into device 100. If terminal reflection exists, the returned signal will be superimposed on the ongoing microwave oscillation process, leading to output waveform distortion, decreased spectral purity, and even uncontrollable parasitic oscillations. Therefore, precise impedance matching is not only a guarantee of efficient energy transmission but also a prerequisite for maintaining system stability and output signal quality. In practical applications, resistive loads often use non-inductive high-power resistors to reduce the negative impact of their own parasitic inductance on the high-frequency pulse response.

[0068] In some embodiments, the system further includes a measurement component comprising a voltage divider, a coaxial cable, and an oscilloscope; the input of the voltage divider is connected to the output of the inner conductor 113 for extracting the output voltage signal at a preset ratio; a first end of the coaxial cable is connected to the output of the voltage divider, and a second end of the coaxial cable is connected to the oscilloscope; the oscilloscope is used to receive and display the output voltage signal; wherein the length of the coaxial cable is configured to prevent reflected signals caused by the measurement from interfering with the original signal.

[0069] Specifically, a voltage divider, either resistive or capacitive, can be used to attenuate the high-voltage pulse signal (tens of kilovolts) to a low-voltage range that is safe for oscilloscope measurement. The coaxial cable is preferably a standard RG58 RF cable, configurable to a length of 10 feet (approximately 3.05 meters). This specific length is chosen based on the time delay calculated from the propagation speed of electromagnetic waves in the cable (approximately 66% of the speed of light). Due to the unavoidable slight impedance mismatch at the measurement port, a reflected signal will be generated in the cable. By setting the cable length to 10 feet, the round-trip time of this reflected signal far exceeds the duration of the original pulse signal (e.g., on the order of 10 ns), thus completely separating the measured reflected signal from the original signal window in the time domain. In this way, the waveform of the original signal captured by the oscilloscope is the true waveform unaffected by the measurement loop, ensuring the accuracy and reliability of the experimental data. It should be understood that the specific length of the coaxial cable can be adjusted according to the actual pulse width and measurement requirements, as long as the reflected signal avoids the original signal observation window in time.

[0070] To further verify the practicality and reproducibility of the aforementioned high-power microwave signal generation and transmission system, this embodiment is based on Figure 2 The system architecture shown, combined with specific experimental test data, provides a detailed explanation of the dynamic response characteristics of this system during high-power microwave signal generation and transmission. The application verification process of this system mainly includes the following steps: In step S1, the high-voltage DC power supply charges the device 100 through the power supply interface 210. The high-voltage DC power supply (e.g., Glassman high-voltage source model EJ40P15) outputs a DC high voltage with a set voltage of 40kV, which is applied to the inner conductor 113 of the device 100 via a current-limiting resistor. During this process, the current-limiting resistor not only limits the steady-state current of the charging circuit to protect the power supply safety, but also establishes a high-impedance signal reflection boundary at the input end of the inner conductor 113, pre-setting the necessary boundary conditions for microwave excitation in the subsequent reverse transmission stage. As the charging process proceeds, the composite material 112 inside the device 100 gradually establishes a high-intensity electric field energy storage state.

[0071] In step S2, the gas spark gap switch self-breaks down and releases a steepening pulse when the conduction condition is met. When the charging voltage on the inner conductor 113 of device 100 rises to the self-breakdown threshold of the gas spark gap switch, the switch gap instantaneously conducts, cutting off the originally slowly rising DC voltage and converting it into a fast-rising-edge voltage pulse with a rise time of approximately 2ns. This steepening process is a prerequisite for exciting the nonlinear effect of the composite material 112; only a pulse with a sufficiently fast rise time can effectively drive the change in the dielectric constant of the ferroelectric material and the magnetic moment response of the ferromagnetic material. Due to the self-triggering method, the system can accurately respond to the charging state without the need for an external synchronous control circuit, significantly simplifying the timing design complexity.

[0072] In step S3, the pulse propagates towards the input end within the coaxial transmission line and is reflected at the current-limiting resistor to excite microwave oscillation. After the output switch is turned on, the electrical energy stored in device 100 is released in the form of a fast-rising-edge pulse; this pulse enters device 100 from the output switch side and propagates along the coaxial transmission line towards the input end of the inner conductor 113. During this initial propagation phase, the barium strontium titanate in the composite material 112 steepens the waveform based on its nonlinear dielectric constant, and the transient pulse magnetic field of the initially injected pulse collimates the magnetic moment in the nickel-zinc ferrite. After the pulse reaches the input end of the inner conductor 113, it is reflected at the high-impedance boundary formed by the current-limiting resistor; the reflected pulse returns to the transmission line and generates a reflected magnetic field, which drives the collimated magnetic moment to undergo coherent precession to generate a microwave signal. The resistive load connected to the output switch forms a discharge circuit, which is used to absorb the pulse energy released by the output switch and suppress signal reflection at that end.

[0073] Meanwhile, the pulse signal transmitted forward to the input terminal is strongly reflected upon encountering the signal reflection boundary formed by the current-limiting resistor. The reverse magnetic field generated by the reflected signal drives the collimated magnetic moment to undergo coherent precession, thereby generating a microwave signal without an external bias magnetic field. Experimental observations show that the duration of the RF pulse output by this system is approximately 10 ns, which is significantly longer than the typical output pulse width of 2 ns to 7 ns for traditional gyromagnetic nonlinear transmission lines. This means that higher energy can be delivered to the target at the same repetition frequency.

[0074] In step S4, the measurement component captures and displays a clean output waveform. To accurately characterize system performance, the output voltage signal is proportionally attenuated by a voltage divider and then transmitted to an oscilloscope for display via a 10-foot RG58 coaxial cable. This specific length of coaxial cable introduces sufficient time delay to ensure that any minute reflections that may exist in the measurement loop completely bypass the observation window of the original signal in the time domain. This ensures that the waveform captured by the oscilloscope accurately reflects the output characteristics of device 100 without being affected by measurement interference. The measured waveform verifies that the system can stably generate microwave oscillations in the GHz band during a single discharge process, and the waveform quality is good.

[0075] The application verification process described above demonstrates that the high-power microwave signal generation and transmission system provided in this application exhibits significant technical advantages in actual operation. First, the system requires only a 20-inch transmission line to achieve effective pulse formation and microwave generation, a significant reduction in size compared to the typically 1-meter length of traditional nonlinear transmission lines, making it more suitable for portable platforms. Second, the entire operation relies entirely on DC charging and a self-triggered switch, eliminating the need for expensive and bulky high-voltage pulse modulators and external bias magnetic field systems, thus simplifying the hardware architecture and connection design. Finally, the longer RF pulse duration and stable output waveform prove the rationality of the composite material ratio and impedance matching design, verifying the feasibility and superiority of this technical solution in engineering applications. It should be understood that the above experimental parameters (such as 40kV charging voltage, 20-inch length, 10ns pulse width, etc.) are merely illustrative and can be adjusted within a reasonable range according to specific needs in practical applications. As long as the working principles and system design principles disclosed in this application are followed, the expected technical effects can be achieved.

[0076] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-power microwave signal generation and transmission device, characterized in that, include: A coaxial transmission line comprising an outer conductor and an inner conductor arranged coaxially, and a composite material filling the space between the outer conductor and the inner conductor; the composite material comprising a ferroelectric material having a nonlinear dielectric constant and a ferromagnetic material having a nonlinear permeability; Positioning rings, respectively nested and fixed at both ends of the coaxial transmission line, are used to maintain the coaxial state of the outer conductor and the inner conductor; The composite material is used to steepen the waveform based on the nonlinear dielectric constant during the forward transmission of the pulse signal to achieve the pulse forming function, and to collimate the magnetic moment in the ferromagnetic material based on the transient pulse magnetic field of the initial injected pulse. It is also used to drive the magnetic moment to coherently precess based on the reflected magnetic field generated by the reflected signal when the pulse signal is reflected and transmitted in the opposite direction, so as to generate a microwave signal in the absence of an external bias magnetic field.

2. The apparatus according to claim 1, characterized in that, The composite material further includes a polymer matrix, wherein the ferroelectric material and the ferromagnetic material are dispersed and mixed in the polymer matrix; The polymer matrix is ​​polydimethylsiloxane, the ferroelectric material is barium strontium titanate, and the ferromagnetic material is nickel-zinc ferrite.

3. The apparatus according to claim 2, characterized in that, Based on the total volume of the composite material, the doping volume percentage of barium strontium titanate is 10%-15%, and the doping volume percentage of nickel-zinc ferrite is 5%-25%.

4. The apparatus according to claim 1, characterized in that, Both the outer conductor and the inner conductor are made of low-loss metallic materials; The outer conductor is a tubular structure, and the inner conductor is a rod-shaped structure. The ratio of the inner diameter of the outer conductor to the outer diameter of the inner conductor is determined based on the dielectric constant and permeability of the composite material, so as to match the characteristic impedance of the device with the load impedance connected to the output terminal.

5. The apparatus according to claim 1, characterized in that, The positioning ring is made of aluminum; the positioning ring has a central through hole, and the end of the inner conductor passes through the central through hole; The positioning ring covers the end opening of the outer conductor, and the end face of the positioning ring abuts against the end face of the outer conductor to close the gap between the outer conductor and the inner conductor and define a cavity for accommodating the composite material.

6. A high-power microwave signal generation and transmission system, characterized in that, include: The high-power microwave signal generation and transmission apparatus as described in any one of claims 1 to 5; A power supply interface is provided for connecting an external DC voltage to charge the device. An impedance mismatch structure is connected in series between the power supply interface and the input terminal of the inner conductor of the device to form a signal reflection boundary at the input terminal of the inner conductor. An output switch, connected in series at the output terminal of the inner conductor, is used to release a pulse signal when the conduction condition is met; An impedance matching structure is provided, wherein its input terminal is connected to the output terminal of the output switch, its output terminal is connected to the outer conductor, and the outer conductor is connected to the ground terminal of the power supply interface. The impedance matching structure is used to absorb output energy and suppress signal reflection at the output terminal.

7. The system according to claim 6, characterized in that, The impedance mismatch structure is a current-limiting resistor; the impedance value of the current-limiting resistor is greater than the characteristic impedance of the device, and it is used to limit the incoming DC current in order to form the signal boundary condition that generates the reflected magnetic field at the input end of the inner conductor.

8. The system according to claim 6, characterized in that, The output switch is a gas spark gap switch; The gas spark gap switch is used to turn on when the charging voltage on the inner conductor reaches a set threshold, so as to cut off the slowly rising charging voltage and convert it into a voltage pulse with a fast leading edge on the nanosecond level, and release the voltage pulse to the impedance matching structure.

9. The system according to claim 6, characterized in that, The impedance matching structure is a resistive load; the impedance value of the resistive load is matched with the characteristic impedance of the device.

10. The system according to claim 6, characterized in that, The system also includes a measurement component, which includes a voltage divider, a coaxial cable, and an oscilloscope. The input terminal of the voltage divider is connected to the output terminal of the inner conductor, and is used to extract the output voltage signal according to a preset ratio; The first end of the coaxial cable is connected to the output end of the voltage divider, and the second end of the coaxial cable is connected to the oscilloscope. The oscilloscope is used to receive and display the output voltage signal; wherein the length of the coaxial cable is configured to prevent reflected signals caused by the measurement from interfering with the original signal.

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