A composite time-varying antenna structure for a confined space and a wideband impedance matching method thereof

Abstract

The application discloses a composite time-varying antenna structure for a limited space and a wideband impedance matching method thereof, which sequentially comprises a spiral slow wave main radiation structure, a high-voltage time-varying cutoff node and an orthogonal umbrella-shaped charge storage structure. The spiral slow wave main radiation structure is used for introducing distributed inductance to realize slow wave delay and inductance pre-compensation. The physical extension plane of the orthogonal umbrella-shaped charge storage structure is perpendicular to the vertical polarization direction of the spiral slow wave main radiation structure. The high-voltage time-varying cutoff node is connected in series at the physical junction of the spiral slow wave main radiation structure and the orthogonal umbrella-shaped charge storage structure, and is used for executing high-frequency on-off action within a set time domain window to cut off the current conduction loop on the antenna. The application effectively solves the problem of solid-state switch transient overvoltage breakdown, greatly improves the reliability of high-power work, eliminates the problems of sharp-end discharge and arc ablation, significantly reduces the active power loss, simultaneously suppresses the horizontal polarization parasitic radiation, and greatly optimizes the main polarization purity and spatial isolation.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a physical configuration and broadband impedance matching method for a nonlinear time-varying small antenna suitable for confined physical spaces such as underground, underwater, airborne, or portable devices. Background Technology

[0002] Electrically small antenna systems based on nonlinear time-varying networks (such as direct antenna modulation or time-domain reflection suppression techniques) typically use classic linear straight wires as the antenna body. A high-speed switch is connected in series at a specific physical node of the wire. Before the electromagnetic wave undergoes total reflection at its origin and returns to the feed end, the conducted current is interrupted, thus eliminating the inherent static capacitive reactance of the short antenna in the time domain. In practical applications, the single end wire behind the switch can be bent (e.g., placed in an inverted L-shape) to reduce radiated interference caused by the oscillation of the trapped charge.

[0003] Although the above antenna structure theoretically has the potential to broaden the bandwidth, in the practical application of high-power transmission within a limited physical space, this straight conductor and single-bend architecture have the following inherent physical and system-level limitations:

[0004] First, the lack of distributed reactance leads to transient overvoltage breakdown in solid-state switches: In electrically small sizes, the equivalent input impedance of a linear straight conductor exhibits extremely low radiation resistance and large capacitive reactance, with very low distributed inductance. When a high-power pulse is injected and truncated at its peak, the lack of sufficient inductance for energy buffering causes the high current change rate generated by the high-speed pulse to induce a high-amplitude inductive surge on the system's stray inductance. Simultaneously, the equivalent self-capacitance at the physical end of the straight conductor is extremely small, according to the electrostatic field equation... A large amount of trapped charge Q accumulates within the confined capacitance boundary, instantly establishing an extremely high residual potential. The superposition of these two transient high voltages can easily exceed the rated withstand voltage limit of a single wide-bandgap semiconductor switch, leading to thermal runaway and hardware damage to the device junction.

[0005] Second, asymmetric single bends cause tip discharge and parasitic radiation: In existing technologies, straight conductors with bent ends or inverted L-shaped placement exhibit an asymmetric structure in physical topology. First, a single bend cannot provide sufficient effective plate area to expand the distributed capacitance. The high electric field at the charge accumulation point easily reaches the air dielectric breakdown threshold, inducing corona discharge or even arc erosion at sharp angles or points, resulting in active power loss. Second, the intercepted high-energy charges undergo high-frequency reciprocating oscillations within the asymmetric straight conductor, which is equivalent to a horizontal alternating current dipole in electrodynamics, thus radiating horizontally polarized electromagnetic waves into free space. This parasitic radiation increases out-of-band interference and severely degrades the main polarization purity and spatial isolation of the time-varying antenna system. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a composite time-varying antenna structure for confined spaces and its broadband impedance matching method.

[0007] The objective of this invention is achieved through the following technical solution: a composite time-varying antenna structure for confined spaces, comprising, in sequence, a spiral slow-wave main radiating structure, a high-voltage time-varying truncation node, and an orthogonal umbrella-shaped charge storage structure. The spiral slow-wave main radiating structure is used to introduce distributed inductance to achieve slow-wave delay and inductive reactance pre-compensation. The physical extension plane of the orthogonal umbrella-shaped charge storage structure is orthogonal to the vertical polarization direction of the spiral slow-wave main radiating structure. The high-voltage time-varying truncation node is connected in series at the physical boundary between the spiral slow-wave main radiating structure and the orthogonal umbrella-shaped charge storage structure, and is used to perform high-frequency switching actions within a set time-domain window to cut off the current conduction loop on the antenna.

[0008] Preferably, the high-voltage time-varying cutoff node uses a wide-bandgap semiconductor switching device, and the equivalent output capacitance of the high-voltage time-varying cutoff node in the off state is less than 50pF.

[0009] Preferably, the wide bandgap semiconductor switching device is a gallium nitride high electron mobility transistor or a MOSFET array.

[0010] Preferably, the spiral slow-wave main radiation structure is a spiral coil.

[0011] As a preferred method, the pitch, outer diameter of the helix, and cross-sectional area of ​​the conductor of the helical coil structure are determined by inversely solving the problem based on the center frequency of the target operating frequency band and the physical dimensions of the confined space.

[0012] Preferably, the outer diameter D of the spiral coil and the height H of the spiral coil are determined by the physical dimensions of the confined space; Cross-sectional area of ​​the conductor of the helical coil The determination is based on the following formula: ; in, For the maximum safe current density, This represents the peak current of a high-power pulse. The inductance L1 of the spiral coil satisfies the following formula: ; In the above formula, The high-frequency oscillation frequency is generated within the orthogonal umbrella-shaped charge storage structure after the high-voltage time-varying cutoff node is turned off; The equivalent output capacitance of the high-voltage time-varying cutoff node in the off state; Based on the above formula, the minimum buffer inductance that the spiral coil structure must possess is determined. ; The total number of turns N of the helical coil is calculated using the following formula; ; In the above formula, The vacuum permeability; Calculate the pitch of the helical coil based on the total number of turns N and the height H of the helical coil. .

[0013] Preferably, the orthogonal umbrella-shaped charge storage structure includes multiple horizontal line antennas, which are evenly distributed in a centrally symmetrical manner with the central hub as the center.

[0014] A broadband impedance matching method for a composite time-varying antenna structure in confined spaces includes the following specific steps: Step 1: Envelope Modulation and High-Frequency Pulse Injection of Communication Signal: The system's built-in envelope modulator generates a series of extremely narrow high-frequency carrier pulse sequences; the high-frequency carrier pulse sequences are envelope-modulated with the low-frequency / baseband communication signal to be transmitted to generate a series of Gaussian pulse sequences whose amplitude varies with the signal envelope, and then injected into the near-end feed port of the antenna via a power amplifier. Step 2: Static inductive pre-tuning compensation; Utilizing the distributed inductance of the spiral slow-wave main radiating structure itself, the inherent capacitive impedance of the electrically small antenna system is neutralized in advance under passive static conditions, and the initial natural resonant frequency of the antenna is lowered to near the target operating frequency band, so as to reduce the voltage standing wave ratio at the feed output. Step 3: Slow Wave Time-Domain Delay and Precise Truncation in Dynamic Window: After the Gaussian pulse sequence is injected into the spiral slow wave main radiation structure, the slow wave effect of the spiral slow wave main radiation structure is used to reduce the rising phase velocity of the electromagnetic wave, thereby extending the transmission time of the pulse to the high-voltage time-varying truncation node; within this delay window, the digital delay trigger outputs the trigger level according to the pre-calculated phase velocity. At the nanosecond instant when the peak of the pulse group just crosses the high-voltage time-varying truncation node and the electromagnetic wave front has not yet touched the physical end of the antenna and is reflected, the reverse bias voltage is applied through the driving circuit to control the high-voltage time-varying truncation node to disconnect and enter a high-impedance state, thereby achieving unidirectional energy isolation; Step 4: Multi-pole current shunting expansion and dynamic voltage reduction protection: After the cutoff occurs, the unidirectional pulse charge is physically isolated in the orthogonal umbrella-shaped charge storage area, and then evenly shunted through the central hub to multiple horizontal line antennas of the orthogonal umbrella-shaped charge storage structure; by utilizing the capacitor pool effect of the orthogonal umbrella-shaped charge storage structure, the peak residual voltage at both ends of the high-voltage time-varying cutoff node is reduced, and the local electric field strength at the end of the horizontal line antenna is reduced to within the safe threshold of air ionization breakdown; Step 5: Purification through internal oscillation dissipation and radiation vector cancellation.

[0015] Preferably, in step five, the high-voltage charge that is truncated and stored in the orthogonal umbrella-shaped charge storage structure undergoes total reflection at the end of the horizontal line antenna and generates an internal high-frequency oscillating current. By utilizing the centrally symmetrical structure of multiple horizontal line antennas, the far-field radiated electromagnetic waves generated by the synchronously oscillating transient alternating current are vector-antiphase canceled out, thereby cutting off the horizontally polarized parasitic broadband radiation path and achieving noise-free and efficient signal transmission.

[0016] Preferably, the high-frequency carrier pulse sequence is a nanosecond-level extremely narrow pulse sequence.

[0017] The beneficial effects of this invention are: 1. Completely solves the problem of transient overvoltage breakdown in solid-state switches, significantly improving the reliability of high-power operation.

[0018] The spiral slow-wave main radiation structure introduces sufficient distributed inductance, which not only neutralizes the inherent large capacitive reactance of the electrically small antenna through passive static reactance pre-compensation, but also forms an energy buffer for the high current change rate of high-power nanosecond pulses, suppressing inductive surges induced by stray inductance in the system, thus reducing the cause of transient high voltage at the source. The orthogonal umbrella-shaped charge storage structure forms a multi-pole capacitor pool effect, significantly expanding the equivalent plate area for charge storage, avoiding the ultra-high residual potential caused by the small self-capacitance at the end of traditional straight wires. At the same time, the pulse charge is evenly distributed through the central hub, reducing the peak residual voltage at both ends of the high-voltage time-varying cutoff node to within the rated withstand voltage range of the semiconductor switch. The synergistic effect of dual voltage reduction protection completely eliminates junction thermal runaway and hardware breakdown damage to the wide-bandgap semiconductor switch caused by transient overvoltage, enabling the antenna to stably adapt to high-power pulse transmission conditions.

[0019] 2. Eliminates tip discharge and arc erosion, significantly reducing active power loss.

[0020] Traditional single-bend asymmetric structures suffer from insufficient effective electrode area, leading to corona and arcing at charge accumulation points where the electric field easily exceeds the air dielectric threshold. The orthogonal umbrella-shaped multi-symmetrical horizontal line antenna of this invention greatly increases the physical space and equivalent capacitance for charge storage, reducing the local electric field strength in the charge accumulation area to below the air ionization breakdown safety threshold. This eliminates the problems of tip discharge and arc erosion from a physical perspective, avoids active power loss caused by discharge, and improves the antenna's energy conversion efficiency.

[0021] 3. Suppresses horizontal polarization parasitic radiation, significantly optimizing the purity and spatial isolation of the main polarization.

[0022] The physical extension plane of the orthogonal umbrella-shaped charge storage structure is orthogonal to the vertical polarization direction of the spiral slow-wave main radiation structure, and adopts a centrally symmetric multi-line topology. The high-frequency oscillating current generated by the stored charge in the horizontal line antenna after truncation will achieve vector anti-phase cancellation of its far-field radiated electromagnetic waves due to the structural symmetry, directly cutting off the parasitic radiation path of the equivalent horizontal alternating current dipole of the traditional asymmetric structure. Ultimately, it eliminates out-of-band interference of horizontal polarization, ensures the purity of the antenna's main polarization, significantly improves the spatial isolation of the time-varying antenna system, and avoids the noise degradation of the communication link caused by parasitic radiation.

[0023] 4. Achieve broadband and efficient impedance matching for electrically small antennas, adapting to deployment in confined spaces.

[0024] The slow-wave delay effect of the spiral slow-wave structure reduces the phase velocity of electromagnetic waves and extends the pulse transmission time. Combined with nanosecond-level precise time-domain truncation, it cuts off the current loop before the electromagnetic wave is reflected, completely eliminating the static capacitive reactance of short antennas in the time domain and breaking through the inherent bottleneck of narrow bandwidth of electrically small antennas. The static inductive reactance pre-tuning pulls the antenna's natural resonant frequency to the target operating frequency band, significantly reducing the voltage standing wave ratio at the feed end and achieving broadband impedance matching. The spiral + orthogonal umbrella composite structure is a compact design that can achieve high-power, broadband, and low-interference radiation performance within a limited physical space, solving the engineering contradiction of traditional antennas' inability to balance space occupation and electrical performance.

[0025] 5. It has extremely high engineering robustness.

[0026] The time margin provided by the slow wave effect enables existing nanosecond-level switching control systems to easily achieve high-frequency continuous closed-loop control. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the composite time-varying antenna structure of the present invention.

[0028] In the figure: 1. Spiral slow wave main radiation structure, 2. High voltage time-varying truncation node, 3. Orthogonal umbrella-shaped charge storage structure. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0030] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, the above terms should not be construed as limiting this invention.

[0031] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0032] like Figure 1 As shown, a composite time-varying antenna structure for confined spaces includes, in sequence, a spiral slow-wave main radiating structure 1, a high-voltage time-varying truncation node 2, and an orthogonal umbrella-shaped charge storage structure 3. The spiral slow-wave main radiating structure 1 is used to introduce distributed inductance to achieve slow-wave delay and inductive reactance pre-compensation. The physical extension plane of the orthogonal umbrella-shaped charge storage structure 3 is orthogonal to the vertical polarization direction of the spiral slow-wave main radiating structure 1. The high-voltage time-varying truncation node 2 is connected in series at the physical boundary between the spiral slow-wave main radiating structure 1 and the orthogonal umbrella-shaped charge storage structure 3, and is used to perform high-frequency switching actions within a set time domain window to cut off the current conduction loop on the antenna.

[0033] The composite time-varying antenna structure of the present invention is strictly divided into three core functional areas from bottom to top: the spiral slow wave main radiation area (spiral slow wave main radiation structure 1), the high voltage time-varying truncation node 2, and the orthogonal umbrella-shaped charge storage area (orthogonal umbrella-shaped charge storage structure 3).

[0034] Among them, the spiral slow-wave main radiating structure 1, as the main radiating part of the antenna, abandons the linear straight wire used in traditional electrically small antennas (referring to antennas whose maximum physical size is much smaller than the operating wavelength), and adopts a three-dimensional spiral coil. This spiral coil extends spirally along the direction perpendicular to the main axis. This spiral coil introduces a large physical distributed inductance within a limited space, significantly changing the dispersion characteristics of the antenna, and laying the physical foundation for subsequent slow-wave delay and inductive reactance pre-compensation.

[0035] The pitch, outer diameter of the helix, and cross-sectional area of ​​the conductor in the helical coil structure are determined by inverse calculation based on the center frequency of the target operating frequency band and the physical dimensions of the confined space. Specifically, The outer diameter D of the helical coil and the height H of the helical coil are determined by the physical dimensions of the confined space; Cross-sectional area of ​​the conductor of the helical coil The determination is based on the following formula: ; in, For the maximum safe current density, This represents the peak current of a high-power pulse. The inductance L1 of the spiral coil satisfies the following formula: ; In the above formula, The high-frequency oscillation frequency is generated within the orthogonal umbrella-shaped charge storage structure after the high-voltage time-varying cutoff node is turned off; The equivalent output capacitance of the high-voltage time-varying cutoff node in the off state; Based on the above formula, the minimum buffer inductance that the spiral coil structure must possess is determined. ; The total number of turns N of the helical coil is calculated using the following formula; ; The magnetic permeability of free space, also known as the magnetic field constant, has a value of 4π × 10⁻⁶. -7 N / A² (Henry / meter).

[0036] Calculate the pitch of the helical coil based on the total number of turns N and the height H of the helical coil. Among them, the pitch of the helical coil The calculation formula is as follows: .

[0037] Due to the complex parasitic capacitance to ground and inter-turn mutual inductance effects existing in the actual physical space, to further improve the reliability and effectiveness of the helical coil, the theoretical initial values ​​driven by the above method can be imported into a three-dimensional full-wave electromagnetic simulation software (such as HFSS or CST) and a circuit simulator (SPICE) for joint simulation. The helical pitch p, helical outer diameter D, conductor cross-sectional area S, and coil number N are used as joint optimization variables to simulate the real high-frequency pulse injection and high-current instantaneous cutoff capture process in the simulation environment. Through iterative optimization, the final combination of structural parameters that satisfies the constraints of limited space size, meets the requirements of high-voltage time-varying cutoff node state cutoff protection, and optimizes antenna radiation efficiency is determined.

[0038] The high-voltage time-varying cutoff node 2, serving as the core execution unit for nonlinear time-domain chopping, is connected in series at the physical boundary between the spiral slow-wave main radiation structure 1 and the orthogonal umbrella-shaped charge storage structure 3. The high-voltage time-varying cutoff node 2 employs a wide-bandgap semiconductor switching device with extremely low parasitic junction capacitance and extremely high withstand voltage threshold. Excessive parasitic capacitance after the wide-bandgap semiconductor switching device is turned off can cause high-frequency signal components to leak directly through capacitive impedance, leading to cutoff failure. Therefore, to achieve isolation of high-frequency signal components, a device with extremely low parasitic capacitance parameters should be used. In this application, the equivalent output capacitance of the high-voltage time-varying cutoff node 2 in the off state is less than 50 pF.

[0039] The high-voltage time-varying cutoff node 2 is controlled by an external high-speed gate drive circuit. It is responsible for performing high-frequency physical closing and opening actions within a set extremely narrow time window (nanosecond level) to forcibly cut off the current conduction loop on the antenna.

[0040] Wide bandgap semiconductor switching devices can be made using gallium nitride high electron mobility transistors or MOSFET arrays.

[0041] The orthogonal umbrella-shaped charge storage structure 3 is located above the high-voltage time-varying cutoff node 2. The orthogonal umbrella-shaped charge storage structure 3 includes multiple horizontal line antennas, which are centrally symmetrically and uniformly distributed around the central hub. Its overall shape resembles an umbrella frame or a symmetrical multi-pole disk. In three-dimensional space, the physical extension plane of this orthogonal umbrella-shaped charge storage structure 3 maintains a strictly orthogonal relationship with the vertical polarization direction of the spiral slow-wave main radiation structure 1. The free ends of the horizontal antennas are all treated with smooth, large-curvature chamfers, or equipped with high-voltage anti-corona spheres to avoid tip discharge.

[0042] The composite time-varying antenna structure of the present invention has the following working mechanism: 1. Delay and Inductive Reactance Pre-compensation Mechanism: When a high-power excitation pulse is injected into the spiral slow-wave main radiation structure from the bottom feed terminal, the spiral coil structure will introduce a large distributed inductance. and distributed capacitance According to transmission line theory and the electromagnetic wave phase velocity formula: ; Axial propagation phase velocity of electromagnetic waves within the spiral slow-wave main radiation structure Significantly reduced to the speed of light in a vacuum This significantly extends the rise time of the pulse from the bottom to the top within a confined space of extremely short absolute physical length. This physical modification provides a generous and engineerable action time window for the high-voltage time-varying cutoff node.

[0043] 2. Charge cutoff and isolation mechanism: After the pulse wave enters the orthogonal umbrella-shaped charge storage structure through the high-voltage time-varying cutoff node at the front end of the spiral slow wave main radiation structure, the control system drives the high-voltage time-varying cutoff node (semiconductor switching device) to quickly disconnect at the nanosecond instant when the current wave peak just arrives and before the end reflection occurs, through the time delay network. The channel of the semiconductor switching device instantly presents an extremely high resistance state. This action forcibly cuts off the current loop at the physical level, and electrically transforms the orthogonal umbrella-shaped charge storage structure at the top into an isolated charge storage area, fundamentally blocking the path of high-energy reflected wave charge to flow back to the spiral slow wave main radiation structure and the feed end, thereby eliminating the reverse standing wave.

[0044] 3. Multi-stage current shunting and hardware voltage reduction protection mechanism: The total pulse charge Q flowing unidirectionally into the storage area is uniformly guided to multiple horizontal antennas via the central node. This is based on fundamental principles of electrostatics. (V is voltage; C is capacitance) Because the orthogonal umbrella-shaped charge storage structure greatly expands the metal surface area within the confined three-dimensional space through multiple horizontal antennas, it provides a large spatial distributed capacitance. Under the condition that the total amount of injected charge remains constant at the moment of cutoff, the rapidly increasing spatial capacitance directly causes a cliff-like drop in the transient peak residual charge at both ends of the switching node. This mechanism prevents the physical risk of the switch being broken down due to voltage backflow overvoltage. At the same time, the charge is dispersed to multiple end tips, which greatly reduces the surface charge density of a single tip, forcing the local spatial electric field strength down to within the safe threshold of air breakdown, thus avoiding corona discharge.

[0045] 4. The mechanism of cancellation between internal oscillations and far-field radiation vectors: The high-energy charges physically trapped undergo total internal reflection at the end of the horizontal antenna with an open orthogonal umbrella-shaped charge storage structure, forming a high-frequency oscillating dissipative current inside. Due to the strict geometric symmetry of this orthogonal umbrella-shaped charge storage structure, the transient currents oscillating synchronously outward or inward within it constitute multiple current elements with completely opposite directions in space. According to far-field electromagnetic radiation theory, the vector sum of the spatial radiated electric and magnetic fields generated by these symmetrically opposite current elements in the far-field region strictly approaches zero; this spatial vector anti-phase cancellation mechanism ensures that the energy of the trapped charges is mainly dissipated in the form of non-radiative losses such as ohmic heat inside the conductor, thereby completely cutting off the parasitic broadband radiation path in the horizontal polarization direction and ensuring the purity of the vertical main polarization signal.

[0046] A broadband impedance matching method for a composite time-varying antenna structure in confined spaces includes the following specific steps: Step 1: Envelope Modulation and High-Frequency Pulse Injection of Communication Signal: The system's built-in envelope modulator generates a series of extremely narrow high-frequency carrier pulse sequences; these high-frequency carrier pulse sequences are nanosecond-level extremely narrow pulse sequences; the high-frequency carrier pulse sequences are envelope-modulated with the low-frequency / baseband communication signal to be transmitted to generate a series of Gaussian pulse sequences whose amplitude varies with the signal envelope, and then injected into the near-end feed port of the antenna via a power amplifier; Step 2: Static inductive pre-tuning compensation; Utilizing the distributed inductance of the spiral slow wave main radiation structure 1 itself, the inherent capacitive impedance of the electrically small antenna system is neutralized in advance under passive static conditions, and the initial natural resonant frequency of the antenna is lowered to near the target operating frequency band, so as to reduce the voltage standing wave ratio at the feed output end. Step 3: Slow Wave Time-Domain Delay and Precise Truncation in Dynamic Window: After the Gaussian pulse sequence is injected into the spiral slow wave main radiation structure 1, the slow wave effect of the spiral slow wave main radiation structure 1 is used to reduce the rising phase velocity of the electromagnetic wave, thereby extending the transmission time of the pulse to the high-voltage time-varying truncation node 2; within this delay window, the digital delay trigger outputs the trigger level according to the pre-calculated phase velocity. At the nanosecond instant when the peak of the pulse group just crosses the high-voltage time-varying truncation node 2 and the electromagnetic wave front has not yet touched the physical end of the antenna and is reflected, the reverse bias voltage is applied through the driving circuit to make the high-voltage time-varying truncation node 2 disconnect and be in a high-impedance state, thereby achieving unidirectional energy isolation; Step 4: Multi-pole current shunting expansion and dynamic voltage reduction protection: After the cutoff occurs, the unidirectional pulse charge is physically isolated in the orthogonal umbrella-shaped charge storage area, and is evenly shunted to multiple horizontal line antennas of the orthogonal umbrella-shaped charge storage structure 3 through the central hub; by utilizing the capacitor pool effect of the orthogonal umbrella-shaped charge storage structure 3, the peak residual voltage at both ends of the high-voltage time-varying cutoff node 2 is reduced, and the local electric field strength at the end of the horizontal line antenna is reduced to within the safe threshold of air ionization breakdown; Step 5: Internal Oscillation Dissipation and Radiation Vector Cancellation Purification: The high-voltage charge, which is truncated and stored in the orthogonal umbrella-shaped charge storage structure 3, undergoes total reflection at the end of the horizontal line antenna and generates an internal high-frequency oscillating current. By utilizing the centrally symmetrical structure of multiple horizontal line antennas, the far-field radiated electromagnetic waves generated by the synchronously oscillating transient alternating current undergo vector anti-phase cancellation, thereby cutting off the parasitic broadband radiation path of horizontal polarization and realizing noiseless and efficient signal transmission.

[0047] The present invention has the following effects: I. Effectively solves the problem of transient overvoltage breakdown in solid-state switches, significantly improving the reliability of high-power operation.

[0048] The spiral slow-wave main radiation structure introduces sufficient distributed inductance, which not only neutralizes the inherent large capacitive reactance of the electrically small antenna through passive static reactance pre-compensation, but also forms an energy buffer for the high current change rate of high-power nanosecond pulses, suppressing inductive surges induced by stray inductance in the system, thus reducing the cause of transient high voltage at the source. The orthogonal umbrella-shaped charge storage structure forms a multi-pole capacitor pool effect, significantly expanding the equivalent plate area for charge storage, avoiding the ultra-high residual potential caused by the small self-capacitance at the end of traditional straight wires. At the same time, the pulse charge is evenly distributed through the central hub, reducing the peak residual voltage at both ends of the high-voltage time-varying cutoff node to within the rated withstand voltage range of the semiconductor switch. The synergistic effect of dual voltage reduction protection completely eliminates junction thermal runaway and hardware breakdown damage to the wide-bandgap semiconductor switch caused by transient overvoltage, enabling the antenna to stably adapt to high-power pulse transmission conditions.

[0049] Second, it eliminates tip discharge and arc erosion, significantly reducing active power loss.

[0050] Traditional single-bend asymmetric structures suffer from insufficient effective electrode area, leading to corona and arcing at charge accumulation points where the electric field easily exceeds the air dielectric threshold. The orthogonal umbrella-shaped multi-symmetrical horizontal line antenna of this invention greatly increases the physical space and equivalent capacitance for charge storage, reducing the local electric field strength in the charge accumulation area to below the air ionization breakdown safety threshold. This eliminates the problems of tip discharge and arc erosion from a physical perspective, avoids active power loss caused by discharge, and improves the antenna's energy conversion efficiency.

[0051] Third, it suppresses horizontal polarization parasitic radiation and significantly optimizes the purity and spatial isolation of the main polarization.

[0052] The physical extension plane of the orthogonal umbrella-shaped charge storage structure is orthogonal to the vertical polarization direction of the spiral slow-wave main radiation structure, and adopts a centrally symmetric multi-line topology. The high-frequency oscillating current generated by the stored charge in the horizontal line antenna after truncation will achieve vector anti-phase cancellation of its far-field radiated electromagnetic waves due to the structural symmetry, directly cutting off the parasitic radiation path of the equivalent horizontal alternating current dipole of the traditional asymmetric structure. Ultimately, it eliminates out-of-band interference of horizontal polarization, ensures the purity of the antenna's main polarization, significantly improves the spatial isolation of the time-varying antenna system, and avoids the noise degradation of the communication link caused by parasitic radiation.

[0053] IV. Achieve broadband and efficient impedance matching for electrically small antennas, adapting to deployment in confined spaces.

[0054] The slow-wave delay effect of the spiral slow-wave structure reduces the phase velocity of electromagnetic waves and extends the pulse transmission time. Combined with nanosecond-level precise time-domain truncation, it cuts off the current loop before the electromagnetic wave is reflected, completely eliminating the static capacitive reactance of short antennas in the time domain and breaking through the inherent bottleneck of narrow bandwidth of electrically small antennas. The static inductive reactance pre-tuning pulls the antenna's natural resonant frequency to the target operating frequency band, significantly reducing the voltage standing wave ratio at the feed end and achieving broadband impedance matching. The spiral + orthogonal umbrella composite structure is a compact design that can achieve high-power, broadband, and low-interference radiation performance within a limited physical space, solving the engineering contradiction of traditional antennas' inability to balance space occupation and electrical performance.

[0055] Fifth, it has extremely high engineering robustness.

[0056] The time margin provided by the slow wave effect enables existing nanosecond-level switching control systems to easily achieve high-frequency continuous closed-loop control.

[0057] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces, characterized in that, The composite time-varying antenna structure for confined spaces sequentially includes a spiral slow-wave main radiating structure, a high-voltage time-varying truncation node, and an orthogonal umbrella-shaped charge storage structure. The spiral slow-wave main radiating structure is used to introduce distributed inductance to achieve slow-wave delay and inductive reactance pre-compensation. The physical extension plane of the orthogonal umbrella-shaped charge storage structure is orthogonal to the vertical polarization direction of the spiral slow-wave main radiating structure. The high-voltage time-varying truncation node is connected in series at the physical boundary between the spiral slow-wave main radiating structure and the orthogonal umbrella-shaped charge storage structure, and is used to perform high-frequency switching actions within a set time window to cut off the current conduction loop on the antenna. The broadband impedance matching method for the composite time-varying antenna structure oriented towards confined spaces includes the following specific steps: Step 1: Envelope Modulation and High-Frequency Pulse Injection of Communication Signal: The system's built-in envelope modulator generates a series of extremely narrow high-frequency carrier pulse sequences; the high-frequency carrier pulse sequences are envelope-modulated with the low-frequency / baseband communication signal to be transmitted to generate a series of Gaussian pulse sequences whose amplitude varies with the signal envelope, and then injected into the near-end feed port of the antenna via a power amplifier. Step 2: Static inductive pre-tuning compensation; Utilizing the distributed inductance of the spiral slow-wave main radiating structure itself, the inherent capacitive impedance of the electrically small antenna system is neutralized in advance under passive static conditions, and the initial natural resonant frequency of the antenna is lowered to near the target operating frequency band, so as to reduce the voltage standing wave ratio at the feed output. Step 3: Slow wave time-domain delay and precise truncation of dynamic window: After the Gaussian pulse sequence is injected into the spiral slow wave main radiation structure, the slow wave effect of the spiral slow wave main radiation structure is used to reduce the rise phase velocity of the electromagnetic wave, so as to extend the transmission time of the pulse to the high voltage time-varying truncation node. Within this time window, the digital delay trigger outputs a trigger level based on the pre-calculated phase velocity. At the nanosecond instant when the peak of the pulse group just crosses the high-voltage time-varying cutoff node and the electromagnetic wave front has not yet touched the physical end of the antenna and is reflected, the driving circuit applies a reverse bias voltage to make the high-voltage time-varying cutoff node open and in a high-impedance state, thereby achieving unidirectional energy isolation. Step 4: Multi-pole current shunting expansion and dynamic voltage reduction protection: After the cutoff occurs, the unidirectional pulse charge is physically isolated in the orthogonal umbrella-shaped charge storage area, and then evenly shunted through the central hub to multiple horizontal line antennas of the orthogonal umbrella-shaped charge storage structure; by utilizing the capacitor pool effect of the orthogonal umbrella-shaped charge storage structure, the peak residual voltage at both ends of the high-voltage time-varying cutoff node is reduced, and the local electric field strength at the end of the horizontal line antenna is reduced to within the safe threshold of air ionization breakdown; Step 5: Purification through internal oscillation dissipation and radiation vector cancellation.

2. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 1, characterized in that, The high-voltage time-varying cutoff node uses a wide bandgap semiconductor switching device, and the equivalent output capacitance of the high-voltage time-varying cutoff node in the off state is less than 50pF.

3. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 2, characterized in that, The wide bandgap semiconductor switching device employs gallium nitride high electron mobility transistors or MOSFET arrays.

4. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 1, characterized in that, The spiral slow-wave main radiation structure uses a spiral coil.

5. A broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 4, characterized in that, The pitch, outer diameter of the helix, and cross-sectional area of ​​the conductor are determined by inversely solving the problem based on the center frequency of the target operating frequency band and the physical dimensions of the confined space.

6. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 5, characterized in that, The outer diameter D of the helical coil and the height H of the helical coil are determined by the physical dimensions of the confined space; Cross-sectional area of ​​the conductor of the helical coil The determination is based on the following formula: ； in, For the maximum safe current density, This represents the peak current of a high-power pulse. The inductance L1 of the spiral coil satisfies the following formula: ； In the above formula, The high-frequency oscillation frequency is generated within the orthogonal umbrella-shaped charge storage structure after the high-voltage time-varying cutoff node is turned off; The equivalent output capacitance of the high-voltage time-varying cutoff node in the off state; Based on the above formula, the minimum buffer inductance that the spiral coil structure must possess is determined. ; The total number of turns N of the helical coil is calculated using the following formula; ； In the above formula, Permeability of free space; Calculate the pitch of the helical coil based on the total number of turns N and the height H of the helical coil. .

7. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 1, characterized in that, The orthogonal umbrella-shaped charge storage structure includes multiple horizontal line antennas, which are evenly distributed in a centrally symmetrical manner with the central hub as the center.

8. The broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 1, characterized in that, In step five, the high-voltage charge that is truncated and stored in the orthogonal umbrella-shaped charge storage structure undergoes total reflection at the end of the horizontal line antenna and generates an internal high-frequency oscillating current. By utilizing the centrally symmetrical structure of multiple horizontal line antennas, the far-field radiated electromagnetic waves generated by the synchronously oscillating transient alternating current are vector-antiphase canceled out, thereby cutting off the horizontally polarized parasitic broadband radiation path and achieving noise-free and efficient signal transmission.

9. A broadband impedance matching method for a composite time-varying antenna structure oriented towards confined spaces according to claim 1, characterized in that, The high-frequency carrier pulse sequence is a nanosecond-level extremely narrow pulse sequence.

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