Short-wave high-power mismatched load with adjustable reflection coefficient

Abstract

The application discloses a short-wave high-power mismatched load with adjustable reflection coefficient, which comprises a variable resistor, a step phase shifter and a cooling and heat dissipation system, the variable resistor generates a required reflection coefficient amplitude, the step phase shifter with discrete variable phase shifts the reflection coefficient to a required reflection phase, the step phase shifter is composed of a plurality of phase shift networks in series, the delay of each unit is designed according to a logarithmic frequency division principle, the ratio between the delays of adjacent units is the same as the frequency ratio, the number of phase shift units can be greatly reduced, the variable resistor is installed on a cold plate and is cooled by the cooling system, and the variable resistor can work safely and stably on several kilowatt power levels. Through the above manner, the application can realize discrete variable reflection coefficient in a short-wave full frequency band, including amplitude and phase, and is used for the anti-mismatch performance test of a short-wave high-power active component.

Description

Technical Field

[0001] This invention relates to the field of radio frequency high-power circuit technology, and in particular to a shortwave high-power mismatched load with adjustable reflection coefficient. Background Technology

[0002] Load mismatch tolerance is a key technical performance of high-power radio frequency equipment, and it is especially important for broadband systems with operating bandwidths of several octaves. Optimizing the VSWR of broadband antenna systems is difficult, and the VSWR often reaches 2.0 or higher when space is limited. However, the bandwidth of circulators, as isolation devices, is limited and cannot meet the requirements of broadband use. Therefore, such equipment will face serious load mismatch problems when operating.

[0003] Impedance deviation caused by harsh load conditions will reduce the performance of power amplifier circuits. High reflection will increase the risk of overvoltage, overcurrent and overheating of high-power devices. Working in a mismatched state for a long time will not only reduce the reliability of devices, but more seriously, it will lead to breakdown discharge or burnout. Necessary technical methods should be adopted in the product design and development stage to avoid this. For this reason, a high-power mismatched load with an adjustable reflection coefficient is needed for the research and development of anti-mismatch technology for related equipment and the final testing of products.

[0004] This demand is particularly urgent in shortwave communication, beyond-line-of-sight detection, and countermeasures. The shortwave band ranges from 1.6MHz to 30MHz, exceeding four octaves, with the longest wavelength approaching 200m. Within acceptable spatial dimensions, it is difficult to achieve well-matched broadband antennas. Especially when operating in arrays, the mutual coupling between array elements generates equivalent reflected waves, further deteriorating load characteristics. A VSWR of 2.5 or even 3.0 or higher can easily occur across the entire band, and the reflected wave phase is randomly distributed within the 0-360° range. Furthermore, circulator-type isolation devices cannot currently be used to improve the load VSWR in the shortwave band. These load conditions pose severe challenges to the design of high-power shortwave amplifiers, filters, antenna tuners, synthesizers, and other components. There is an urgent need for high-power mismatched loads with adjustable reflection amplitude and phase for research and development in related technologies.

[0005] Existing mismatch load technologies cannot meet the usage requirements of the shortwave high-power field. Existing mismatch load technologies can be divided into two categories: one is a scheme that uses a mechanical motion mechanism to continuously adjust the reflection coefficient; the other is a method that designs several loads with fixed reflection coefficients according to usage requirements and makes them discretely adjustable by switching them.

[0006] For example, the methods disclosed in Chinese patents with publication numbers CN202759003U, CN201812914U, and CN101576592A all employ mechanical structures to continuously adjust the reflection coefficient. Among them, the methods disclosed in patents CN202759003U and CN201812914U adjust the reflection coefficient by changing the spatial coupling or cavity resonant impedance. The required physical structure size is wavelength-dependent, making it impractical for engineering implementation in the shortwave band, and the working bandwidth of both is difficult to reach four octaves. The method disclosed in patent CN101576592A adjusts the resistance value of the resistive load through a sliding contact structure, and then changes the phase of the reflection coefficient by sliding the length of the coaxial line. This can achieve continuous adjustment of the amplitude and phase of the reflection coefficient, and in principle, the bandwidth is unlimited. However, the power capacity that the sliding contact structure can pass through is limited. The power carrying capacity of this solution is 100W, which cannot meet the needs of applications with several kilowatts.

[0007] In addition, a common problem with mechanically continuously adjustable systems is that the mechanical structure has dimensional errors and backlash, which cannot guarantee the accuracy after repeated adjustments and long-term use. Furthermore, the mapping relationship between the mechanical adjustment dimensions and electrical characteristics also needs to be calibrated, which makes use and maintenance inconvenient. Moreover, the mechanical motion structure has poor reliability under high-power electromagnetic load conditions, which limits its power capacity.

[0008] The methods disclosed in Chinese patents with publication numbers CN219915791U, CN219266374U, CN211829153U, and CN108767386A are discrete switching schemes with fixed standing wave ratios. Their common feature is that they use a load with a fixed resistance value to generate several discrete standing wave ratios required. The advantage is that they can achieve a large power capacity and there is no error caused by mechanical structure. The disadvantage is that they have no phase adjustment capability.

[0009] The method disclosed in Chinese Patent Publication No. CN112769499A generates discrete load VSWRs by setting different attenuators, and adjusts the reflected phase by changing the reactance of the inductor and capacitor network. The solution does not involve the specific implementation of the adjustable capacitor. If the capacitor is mechanically adjusted, continuous phase adjustment can be achieved, but it also faces problems such as mechanical structure size error and backlash error, as well as power capacity limitation, and the working bandwidth is limited. If a discrete capacitor switching method is used, the distributed parameters of the switching switch will affect the capacitor accuracy, and the correction of the capacitor value is frequency-dependent, making calibration work complicated, especially when the working bandwidth is wide and there are many discrete phase points, making engineering implementation more difficult.

[0010] Another commonly used solution in engineering is as follows: Figure 1As shown, a resistive load 01 with a fixed VSWR, plus discrete phase delay line groups 02, can achieve discrete adjustment of amplitude and phase. Each phase delay line group includes a switching network 021 and N (N is the number of phase division points) transmission lines 022. Adjacent transmission lines are separated by frequency... The upper phase difference is the phase step value. If the mismatched load is divided into the operating frequency band as follows: If there are discrete frequency points, then a total of [number] are needed. One phase delay line group 02. Although this method is simple to implement, and the power capacity is determined only by the load and the delay line, there are no mechanical structural error problems. However, the system requires The number of transmission lines, i.e., the number of transmission lines, is "number of frequency points × number of phase points". Under conditions of wide operating bandwidth and fine phase stepping, the number of operating frequency points... and delay line digital The number of delay lines required is large, resulting in high system size and complexity, which is not conducive to engineering implementation and application.

[0011] In summary, existing mismatch load technologies with adjustable reflection coefficients cannot meet the mismatch resistance requirements of shortwave high-power components in terms of accuracy, complexity, power capacity, and operating bandwidth. Based on these defects and shortcomings, it is necessary to improve the existing technology and design a shortwave high-power mismatch load with adjustable reflection coefficients. Summary of the Invention

[0012] The main technical problem solved by this invention is to provide a shortwave high-power mismatched load with adjustable reflection coefficient. It uses a discrete step adjustment method to adjust the amplitude and phase of the reflection coefficient of the mismatched load, avoiding errors and power capacity limitations caused by moving mechanical structures. It solves the problem of excessively large and complex phase shifting networks when using large bandwidth and small phase step size, reduces the size of the equipment, and lowers the difficulty of engineering implementation and maintenance.

[0013] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide a shortwave high-power mismatch load with adjustable reflection coefficient, including a variable resistor, a stepper phase shifter with phase coverage of 0°~360°, and a cooling system. The stepper phase shifter includes two terminals, wherein the first terminal serves as the input terminal of a shortwave high-power mismatched load with adjustable reflection coefficient, and the second terminal is connected to the first terminal of the variable resistor, and the second terminal of the variable resistor is grounded. The variable resistor has One or 2 A settable discrete value, The number of amplitude values ​​for the discrete reflection coefficient, where each or each pair of resistance values ​​corresponds to a scattering coefficient amplitude, and the amplitude value of the reflection coefficient to be achieved is specified. Set the resistance value of the variable resistor. ; The variable resistor is mounted on the cold plate of the cooling system. The refrigerant flowing in the cooling system comes into contact with the cold plate to exchange heat, carrying away the heat loss generated by the variable resistor. The stepper phase shifter is configured as follows: Assume a shortwave high-power mismatched load with adjustable reflection coefficient operating frequency The range is ,in The lowest frequency, The highest frequency is divided equally on the logarithmic frequency. share, , Given natural numbers, the frequency multiples are obtained. The working discrete frequency points are The delay ratios between each network section within the step phase shifter are set according to frequency multiples, and the phase shift characteristics of networks at adjacent frequencies exhibit self-similarity; Delay of the section There are two adjustable values, 0 and , , The phase step corresponds to the transmission delay; The stepping phase shifter is composed of The Mth linear phase network is cascaded together. Each linear phase network has two terminals. The phase delay in the operating frequency band is linearly related to the frequency. The first signal terminal of each linear phase network is connected to the second signal terminal of the next linear phase network, and so on. The first signal terminal of the Mth linear phase network serves as the first terminal of the stepper phase shifter, and the second signal terminal of the first linear phase network serves as the second terminal of the stepper phase shifter.

[0014] Preferably, the variable resistor has When there are configurable discrete values, for a given operating frequency The required amplitude value of the reflection coefficient Phase is hour, Set the resistance value of the variable resistor to 1. , , The characteristic impedance is set to 50Ω or 75Ω. Number of segments in a linear phase network , Indicates rounding up. This refers to the phase step requirement for the reflection coefficient. The unit is degrees; Section 1 Delay Quantities of Linear Phase Networks have One adjustable value, For natural numbers greater than 1, , represented as ;in , , The unit is degrees. ; Set the delay of each section of the linear phase network in the stepper phase shifter as follows: S1): Calculate delay and its impact Normalization yields ; S2): Let ,set up For the front Step to The remaining residual value after approximation, the initial value of the iteration is taken as... ; S3): Calculation Judgment: If , then let the first The delay of the linear phase network is , Otherwise, let the first The delay of the linear phase network is 0; S4): ,if If the result is positive, return to step S3); otherwise, execute step S5. When the iteration reaches the second section of the linear phase network, execute step S5. S5): If S> Let the delay of the linear phase network in the second section be... , Otherwise, set the delay of the linear phase network in the second section to 0. S6): Calculation , This indicates rounding down, setting the delay of the first linear phase network to [value]. .

[0015] Preferably, the variable resistor has 2 The number of nodes in the linear phase network when a settable discrete value is obtained. , Indicates rounding up. This refers to the phase step requirement for the reflection coefficient. The unit is degrees; Section 1 Delay Quantities of Linear Phase Networks have One adjustable value, For natural numbers greater than 1, , represented as ;in , , The unit is degrees. .

[0016] Preferably, for a given operating frequency The required amplitude of the reflection coefficient is Phase is ( When calculating, first calculate Judgment: If Then the resistance value of the variable resistor is set to... Otherwise, set the resistance value of the variable resistor to [value missing]. And make , Characteristic impedance; The delay of each section of the linear phase network in the step phase shifter is set according to the following steps: S1): Calculate the delay and its impact Normalization yields ; S2): Let ,set up For the front Step to The remaining residual value after approximation, the initial value of the iteration is taken as... ; S3): Calculation Judgment: If Then let the first The delay of the linear phase network is , Otherwise, let the first The delay of the linear phase network is 0; S4): ,if If the result is positive, return to step S3); otherwise, execute step S5). When the iteration reaches the second section of the linear phase network, execute step S5. S5): If S> Let the delay of the linear phase network in the second section be... , Otherwise, set the delay of the linear phase network in the second section to 0. S6): Calculation , This indicates rounding down, setting the delay of the first linear phase network to [value]. .

[0017] Preferably, the variable resistor includes a single-pole K-throw switch and K high-power radio frequency resistors. The common terminal of the single-pole K-throw switch serves as the input terminal of the variable resistor. Each branch terminal of the single-pole K-throw switch is connected to one end of a high-power radio frequency resistor. The other end of each high-power radio frequency resistor is grounded. The position of the single-pole K-throw switch is determined by the amplitude of the reflection coefficient. When the amplitude of the reflection coefficient is... hour, The single-pole K-throw switch is connected to the first Each branch has a resistance value of [value missing]. .

[0018] Preferably, the variable resistor includes a single-pole K-throw switch, K single-pole double-throw switches, and 2K high-power radio frequency resistors; the common terminal of the single-pole K-throw switch serves as the input terminal of the variable resistor, each branch terminal of the single-pole K-throw switch is connected to the common terminal of a single-pole double-throw switch, the two branch terminals of each single-pole double-throw switch are respectively connected to one end of a high-power radio frequency resistor, and the other end of the high-power radio frequency resistor is grounded; The position of the single-pole K-throw switch is determined by the amplitude of the reflection coefficient. When the amplitude of the reflection coefficient is... hour, The single-pole K-throw switch is connected to the first The branch road, the first The high-power radio frequency resistor is connected to one branch terminal of the single-pole double-throw switch. One end of the high-power radio frequency resistor is connected to the other branch terminal. One end; No. The position of a single-pole double-throw switch is determined by the phase of the reflection coefficient. satisfy At that time, the first A single-pole double-throw switch connection When the reflection coefficient phase satisfy At that time, the first A single-pole double-throw switch connection .

[0019] Preferably, the first linear phase network of the stepper phase shifter includes two single-pole P-throw switches and P transmission lines (e.g., microstrip lines or coaxial lines); the common terminal of the first single-pole P-throw switch serves as the input terminal of the first linear phase network, and each branch terminal of the single-pole P-throw switch is connected to one end of a transmission line; each branch terminal of the second single-pole P-throw switch is connected to the other end of the P transmission lines, and the common terminal of the second single-pole P-throw switch serves as the output terminal of the first linear phase network. The transmission line delay connected to the first branch of the single-pole P-throw switch is denoted as . , No. The transmission line delay connected to each branch is... , .

[0020] Preferably, the first step phase shifter The linear phase network comprises two single-pole double-throw (SPDT) switches and two transmission lines (e.g., microstrip lines or coaxial lines); the common terminal of the first SPDT switch serves as the... The input terminal of the linear phase network is connected to the first single-pole double-throw (SPDT) switch. Each branch terminal of the first SPDT switch is connected to one end of a transmission line. Each branch terminal of the second SPDT switch is connected to the other end of two transmission lines. The common terminal of the first SPDT switch serves as the input terminal of the linear phase network. The output of the linear phase network; The transmission line delay connected to the first branch of the single-pole double-throw switch is denoted as . The transmission line delay configuration for the second branch is as follows: ; The position of the single-pole double-throw switch is determined by the first... The required delay for the linear phase network is determined. When the required delay is 0, the single-pole double-throw switch is located in the first branch; when the required delay is... At that time, the single-pole double-throw switch is located in the second branch.

[0021] Preferably, the first step phase shifter The linear phase network consists of two single-pole double-throw (SPDT) switches, a transmission line (e.g., a microstrip line or coaxial line), and a low-pass two-port lumped parameter network composed of inductors and capacitors; the common terminal of the first SPDT switch serves as the... The input terminal of the linear phase network is connected to the transmission line. The first branch terminal of the single-pole double-throw switch is connected to one end of the transmission line, and the second branch terminal is connected to one end of the low-pass two-port lumped parameter network composed of inductors and capacitors. The first branch terminal of the second single-pole double-throw switch is connected to the other end of the transmission line, and the second branch terminal is connected to the other end of the low-pass two-port lumped parameter network composed of inductors and capacitors. The common terminal of the single-pole double-throw switch serves as the input terminal of the first... The output of the linear phase network; The delay of the transmission line is denoted as The low-pass two-port lumped parameter network composed of inductors and capacitors has a frequency band of... Internal transmission delay configuration is And the insertion loss is 0dB; The position of the single-pole double-throw switch is determined by the first... The required delay for the linear phase network is determined. When the required delay is 0, the single-pole double-throw switch is located in the first branch; when the required delay is... At that time, the single-pole double-throw switch is located in the second branch.

[0022] Preferably, the cooling system uses coolant as the refrigerant and includes a liquid cooling plate, a water pump, a water tank, a heat exchanger, a pressure gauge, and a flow meter. The liquid cooling plate has a pipe inside for the refrigerant to flow. One end of the pipe serves as an inlet connected to the outlet of the water pump, and the other end serves as an outlet connected to the inlet of the heat exchanger. A variable resistor is installed on the surface of the liquid cooling plate directly above the pipe, and the heat dissipation flange of the variable resistor is in close contact with the surface of the liquid cooling plate. The inlet of the water pump is connected to the outlet of the water tank; the inlet of the water tank is connected to the outlet of the heat exchanger; a pressure gauge is installed on the outlet pipe of the water pump, and a flow meter is connected in series at the outlet of the liquid cooling plate.

[0023] Compared with the prior art, the beneficial effects of the present invention are: The amplitude and phase of the reflection coefficient are discretely adjustable, avoiding the errors and power capacity limitations caused by mechanical motion structures in continuous adjustment schemes. The amplitude of the reflection coefficient is generated by a variable resistor, and the required phase of the reflection coefficient is generated by a stepper phase shifter, which has the advantages of wide bandwidth and large power capacity. At the same time, the design of the stepper phase shifter adopts a multi-section series approach, dividing the working frequency band into logarithmic equal parts. The delay ratio between each section of the network in the stepper phase shifter is set according to the frequency ratio. The phase shift characteristics of adjacent frequency networks have self-similarity, thereby reducing the number of sections of the phase shifting network to "number of frequency points + number of phase points". This solves the problem of excessively large and complex phase shifting networks when the bandwidth is large and the phase step is small, reducing the size of the equipment and reducing the difficulty of engineering implementation and maintenance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a traditional scheme using a phase-shifting network and a mismatch resistor.

[0025] Figure 2 This is a block diagram of a shortwave high-power mismatched load with adjustable reflection coefficient.

[0026] Figure 3 This is a schematic diagram of the variable resistor in Example 1.

[0027] Figure 4 This is a block diagram of a stepper phase shifter.

[0028] Figure 5 This is a schematic diagram of the phase frequency response of a linear phase system.

[0029] Figure 6 This is a schematic diagram of the linear phase network in the first section.

[0030] Figure 7 For the first A schematic diagram of one implementation principle of a linear phase network.

[0031] Figure 8 This is a schematic diagram of a low-pass, two-port lumped parameter network using a "Π" structure.

[0032] Figure 9 This is a schematic diagram of a low-pass, two-port lumped parameter network using a "T"-shaped structure.

[0033] Figure 10 The phase frequency response curve of a low-pass two-port lumped parameter network with a "Π" structure to achieve a 180° phase shift.

[0034] Figure 11 Delay frequency response curves of a low-pass two-port lumped parameter network with a "Π" structure to achieve a 180° phase shift.

[0035] Figure 12 The frequency response curve of reflection loss of a low-pass two-port lumped parameter network with a "Π" structure to achieve a 180° phase shift.

[0036] Figure 13 This is a schematic diagram of the variable resistor in Example 2.

[0037] Figure 14 This diagram illustrates the effect of using two different resistance values ​​to produce the same reflection coefficient amplitude.

[0038] Figure 15 This is a block diagram of a cooling system for a shortwave high-power mismatched load with adjustable reflection coefficient. Detailed Implementation

[0039] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0040] Please see Figures 2 to 15 The embodiments of the present invention include: A shortwave high-power mismatch load with adjustable reflection coefficient includes a variable resistor 21, a stepper phase shifter 22, and a cooling system 23, such as... Figure 2 As shown.

[0041] The phase shifter 22 covers a phase range of 0° to 360°. The phase shifter 22 includes two terminals, wherein the first terminal serves as the input terminal for a shortwave high-power mismatched load with adjustable reflection coefficient, and the second terminal is connected to the first terminal of the variable resistor 21. The second terminal of the variable resistor 21 is grounded. The variable resistor 21 is mounted on the cold plate of the cooling system 23. The refrigerant flowing in the cooling system 23 contacts the cold plate for heat exchange, carrying away the heat dissipation generated by the variable resistor 21.

[0042] By changing the resistance value of variable resistor 21 The required reflection coefficient amplitude can be achieved within a bandwidth of several octaves. The two satisfy , This is the characteristic impedance, typically taken as 50Ω or 75Ω.

[0043] The reflection coefficient generated by the variable resistor 21 is phase-shifted by the step phase shifter 22 to generate the required reflection coefficient phase. The step phase shifter 22 needs to generate the corresponding phase delay by stepping the phase at all operating frequencies.

[0044] The variable resistor 21 will eventually absorb part of the incident wave and generate heat loss. The cooling system 23 will exchange heat with the variable resistor 21 and transfer the heat to the ambient atmosphere.

[0045] Example 1: The variable resistor 21 is as follows Figure 3 As shown, it consists of a single-pole K-throw switch 31 and K high-power radio frequency resistors 32, which are denoted as follows: The common terminal 311 of the single-pole K-throw switch 31 serves as the input terminal of the variable resistor. Each branch terminal 312 of the single-pole K-throw switch 31 is connected to one end of a high-power radio frequency resistor, i.e., the first... The terminals of each branch circuit and Connection; the other end of the high-power RF resistor is grounded, and in this embodiment, K=5. The corresponding reflection coefficients are 0.333, 0.428, 0.5, 0.557 and 0.6 for 100Ω, 125Ω, 150Ω, 165Ω and 200Ω respectively, which are converted to VSWRs of 2.0, 2.5, 3.0, 3.5 and 4.0.

[0046] The step phase shifter 22 is as follows Figure 4As shown, it consists of M cascaded linear phase networks. Each linear phase network has two signal terminals. The first signal terminal of each linear phase network is connected to the second signal terminal of the next linear phase network, and so on. Specifically, the first signal terminal 441 of the Mth linear phase network 44 serves as the first terminal of the stepper phase shifter, the second signal terminal 411 of the first linear phase network 41 serves as the second terminal of the stepper phase shifter, the first signal terminal 412 of the first linear phase network 41 is connected to the second signal terminal 421 of the second linear phase network 42, and so on. The first signal terminal of the linear phase network and the second The second signal terminal 431 of the linear phase network 43 is connected, the... The first signal terminal 432 of the linear phase network 43 and the second... Connect the second signal terminal of the linear phase network, and so on.

[0047] The characteristics of a linear phase network satisfy the following: the signal transmission phase difference between the second signal terminal and the first signal terminal. With angular frequency A linear relationship with a negative slope, such as Figure 5 As shown, the slope of line 51 is the delay of this linear phase network. ,Right now .

[0048] The number of sections M in the linear phase-shifting network and the delay design of each section are as follows: Logarithmically divide the operating frequency band: Let the operating frequency of a shortwave high-power mismatched load with adjustable reflection coefficient be... The range is ,in The lowest frequency, The highest frequency is divided equally on the logarithmic frequency. Equal parts ( (where is a natural number), to obtain the frequency multiplier. Then the working discrete frequency points are .

[0049] Logarithmic frequency division can meet the testing requirements of broadband RF systems because broadband RF systems have frequency response flatness requirements and will not exhibit extremely narrow-band resonance. This can be achieved by adjusting the number of frequency points. This allows adjustment of the relative step size between frequency points; for example, in the 2MHz~30MHz frequency band, a step size can be selected. At that time, the obtained operating frequency sequence was 2.0MHz, 2.4MHz, 2.88MHz, ..., MHz,..., 25MHz, and 30MHz, totaling 15 frequency points, the maximum frequency step is between 25MHz and 30MHz, but the relative step always remains 20% unchanged.

[0050] Let the step requirement for reflection coefficient phase adjustment be , and the phase adjustment range is 0° to 360°, then the phase shifting step of the stepped phase shifter 22 is , and the phase shifting range is 0° to 180°. If phase shifting is performed in uniform equal divisions, at one frequency point, types of phase shifting networks are required, where denotes rounding up. For the frequency points, phase shifting networks are required. For example, if and the number L of frequency points is set to 15, is set to 10°, then 540 phase shifting networks are required, which results in excessively high complexity.

[0051] To reduce the complexity of the phase shifting network, with reference to the idea of representing integers by binary decomposition, Q is decomposed based on the frequency multiplication factor to obtain , that is , the coefficient takes a value of 0 or 1, and the value of the natural number N ensures that for all , , that is , from which is obtained.

[0052] It can be proved that when , , that is, the represented by decomposition based on and the original have an error between - and 0. To reduce the error, a discrete value is added on the basis of (where is a natural number not greater than 10, ), so that the final error is controlled within .

[0053] According to the above principle, a linear phase network is first designed at the highest frequency point : set stages of linear phase networks, each stage can generate two optional phase values of 0 and (0<n<N), and the number N of stages satisfies , denotes rounding up. Due to the rounding operation in , the final phase step For ease of frequency expansion, the phase step is converted into propagation delay: , The phase shift generated by the cascaded N linear phase networks is the sum of the phases of each network segment, thus achieving... To reduce error, an additional linear phase network is added before the aforementioned N-section linear phase network to generate the total phase. The nth phase value, the nth Each phase value is The corresponding delay is This way, a total of N+1 linear phase-shifting network sections satisfy the highest frequency point. The phase step adjustment requirement.

[0054] When the frequency decreases by one step... At frequency points, thanks to the characteristics of linear phase, The linear phase network corresponding to each frequency point in The phase change generated at the frequency point Note that sections 3 through N+1 are in The non-zero phase value of the frequency point is Simply add a linear phase network section and label it as the N+2th section, then... Frequency generation If the phase is non-zero, then it is still possible to achieve the following: Approximation of the basis, principle and With similar frequency points, the N+2th section of the network is in The phase shift generated at the frequency point is The corresponding delay is It can be seen that the linear phase networks in sections 2 to N+1 are "similar" to those in sections 3 to N+2, with a similarity ratio equal to the frequency multiple. .

[0055] Similarly, for each frequency decrease, an additional linear phase network section is needed, with a delay equal to that of the previous section. Times, to achieve Coverage of each frequency point needs to be achieved Adding N+2 sections of linear phase network at frequency point The number of nodes in the network, ultimately resulting in a total number of linear phase networks. According to this design principle, if The number of frequency points L is set to 15. If we take 10°, the total number of linear phase networks decreases from 540 to 28.

[0056] Based on the above principles, refer to Figure 4In this embodiment, each section of the linear phase network is designed with a control terminal to control the selection of the delay of each section of the linear phase network.

[0057] The first section, linear phase network 41, has... ( For natural numbers greater than 1, usually The network delay can be selected via control terminal 413 with several adjustable values. .

[0058] The delay of any section (section m) of the linear phase network 43 in sections 2 to M has two adjustable values: {0, ...} }, selected via the control terminal 433 of the linear phase network 43 (section m).

[0059] When the implementation needs to be at the operating frequency ( The phase of the generated reflection coefficient is ( When ), the control codes of the control terminals of each section of the linear phase network. The following iterative algorithm is used to generate it: Step 1: Calculate delay and its impact Normalization yields Because the linear phase network produces a phase lag, the original reflection coefficient phase is converted to a negative value; Step 2: Let , This step sets the initial values ​​for the iteration; Step 3: Calculation Judgment: If Then let the phase encoding That is, the first The delay of the section is , Otherwise, let That is, the first The delay of the section is 0, here For the front Step to The remaining residual value after approximation is such that there are currently 1 to m network sections available to approximate this residual value, and the maximum normalized delay generated by 1 to m-1 network sections is... If residual value Compare If it is large, then the m-th section must be used to generate it. The delay amount; otherwise, the residual can be approximated by a network of 1 to m-1 sections, and the delay of the m-th section can be ignored and set to 0; Step 4: Let ,if If the result is positive, return to step 3; otherwise, proceed to step 5. When the iteration reaches the second section of the linear phase network, proceed to step 5. Step 5: If S> Then let The second section describes the delay of the linear phase network. , Otherwise, The second section has a linear phase network delay of 0. Step 6: Calculation , This indicates rounding down, setting the delay of the first linear phase network to [value]. .

[0060] The specific implementation principle of the first section, Linear Phase Network 41, is as follows: Figure 6 As shown, it includes two single-pole P-throw switches S11 and S12 and P radio frequency transmission lines 64. The common terminal of the single-pole P-throw switch S11 serves as the first signal terminal of the first section of the linear phase network, and the P branches are sequentially connected to one end of the P radio frequency transmission lines 64. The P branches of the single-pole P-throw switch S12 are sequentially connected to the other end of the P radio frequency transmission lines 64, and the common terminal serves as the second signal terminal of the first section of the linear phase network. The control terminals of the single-pole P-throw switches S11 and S12 are connected in parallel as the control terminal 63 of the first section of the linear phase network. The digital p (p=1,2,…,P) input to the control terminal determines that the common terminal of S11 and S12 is connected to the p-th branch.

[0061] The radio frequency transmission line 64 can be a coaxial cable or a microstrip line. There is no strict limitation on the delay of the first branch transmission line 641 connected to S11 and S12; it should be as short as possible while facilitating structural connections. Once the length is determined, its delay is... It means that if... For reference, the delay of the first branch transmission line 641 is "0", and it is connected to the first branch transmission line 641 in S11 and S12. The delay of each branch transmission line 642 is Compared with the first branch transmission line 641, the delay difference of the second to P branches is as follows: Increment at equal intervals.

[0062] No. Specific implementations of linear phase networks, for example Figure 7As shown, it includes two single-pole double-throw (SpD) switches Sm1 and Sm2, and two radio frequency (RF) transmission lines, a first branch RF transmission line 74 and a second branch RF transmission line 75. The common terminal 71 of SpD switch Sm1 serves as the first signal terminal of the m-th linear phase network, and its two branches are respectively connected to one end of the two RF transmission lines. The two branches of SpD switch Sm2 are respectively connected to the other end of the two RF transmission lines. The common terminal 72 of SpD switch Sm2 serves as the second signal terminal of the m-th linear phase network. The control terminals of SpD switches Sm1 and Sm2 are connected in parallel as the control terminal 73 of the m-th linear phase network. The control word Cm input to this control terminal is 0 or 1, which determines whether the common terminal of Sm1 and Sm2 is connected to the first or second branch.

[0063] The delay of the first branch RF transmission line 74 is denoted as The delay design of the second branch RF transmission line 75 is then... If with For reference, the delay of the m-th linear phase network is "0" when the first branch is connected, and the delay when the second branch is connected is... .

[0064] No. Another implementation principle of the linear phase network is as follows: Figure 8 As shown, with Figure 7 The illustrated embodiment differs in that the RF transmission line 75 located in the second branch of the single-pole double-throw switches Sm1 and Sm2 is replaced with a low-pass dual-port lumped-parameter network 81, whose transmission delay over the operating frequency range is configured as follows: And the insertion loss is close to 0dB, where Figure 8 The low-pass two-port lumped parameter network 81 shown is a "Π" shaped structure. There are R series inductors connected in series, and each inductor has a capacitor connected to ground at both ends. There are a total of R+1 capacitors. The value of the natural number R is related to the operating bandwidth and the delay. Figure 9 The low-to-medium throughput dual-port lumped parameter network adopts a "T"-shaped structure. A total of R+1 inductors are connected in series, with a capacitor connected to ground at every connection point between two inductors. These are denoted as R+1, R+2, R+3, R+4, R+5, R+6, R+7, R+8, R+9, R+1 ... Common R capacitor.

[0065] Using a low-pass two-port lumped parameter network, large delays can be achieved at lower frequencies with a compact size. For example, using... Figure 8 The "Π" structure low-pass two-port lumped parameter network 81 shown has R=4 and inductance... When all values ​​are set to 199.5nH, and capacitors C1=C5=40.5pF and C2=C3=C4=83pF, it can produce the following in the frequency band of 2MHz~30MHz: Figure 10 The transmission phase characteristics shown in the figure indicate that the network has a phase of -180° at 30MHz. A linear fit is applied to the transmission phase curve in the figure, and the correlation coefficient R = 0.9999 is obtained, which shows that the linearity is very ideal. Figure 11 The delay frequency response of the "Π" structure low-pass two-port lumped parameter network 81 has an average delay of 16.7 ns across the entire frequency band and a flatness within 1.4 ns. Achieving a delay of 16.7 ns using an air-medium transmission line would require a line length of 5.0 m. However, using a lumped element network with 5 capacitors and 4 inductors can significantly reduce the size of the linear phase-shifting network. Figure 12 The reflection loss characteristics of the "Π" structure low-pass two-port lumped parameter network 81 are shown. The reflection is less than -40dB across the entire frequency band, and the resulting power loss is negligible.

[0066] In this embodiment, the single-pole multi-throw switches in each section of the linear phase-shifting network are implemented using high-power vacuum relays.

[0067] Example 2: Variable resistor 21 Figure 13 As shown, it includes one single-pole K-throw switch S and K single-pole double-throw switches. and 2K high-power RF resistors .

[0068] The common terminal 101 of the single-pole K-throw switch S serves as the input terminal of the variable resistor. Each branch terminal is connected to the common terminal of a single-pole double-throw switch, for example, the first... The terminals of branch 102 are connected to the single-pole double-throw switch. The common terminal is connected, and the two branch terminals of each single-pole double-throw switch are respectively connected to one end of a high-power RF resistor, for example, a single-pole double-throw switch. The first branch and the high-power RF resistor One end is connected, and the second branch is connected to a high-power RF resistor. One end is connected, and the other end of all high-power RF resistors is grounded.

[0069] The control terminal 103 of the single-pole K-throw switch S serves as the first control terminal of the variable resistor, used to set the conducting branch of the single-pole K-throw switch S. The number of the conducting branch is determined by the amplitude of the required reflection coefficient. ( ) Decision, namely the first The amplitude value of the reflection coefficient corresponding to each branch .

[0070] Single-pole double-throw switch The resistance values ​​connected to the two branches are determined by the amplitude of the reflection coefficient. and its phase Decision: Single-pole double-throw switch Branch 1 connection ,and Branch 2 connection ,and .

[0071] All single-pole double-throw switches The control terminals are connected in parallel, serving as the second control terminal 104 of the variable resistor, determined by the phase of the reflection coefficient. Control switching, when When, connect to the first branch; when At that time, connect to the second branch.

[0072] Figure 14 Instructions to use two resistors and The reason for the same amplitude of reflection coefficient is that the radius of the reflection coefficient circle 111 in the figure is... , At point 112, corresponding to a phase of 0°, after the phase shifter generates a phase shift, the phase angle of the reflection coefficient decreases. The reflection coefficient moves clockwise along the direction of arrow 113, and the phase shifter generates a phase shift of -180° to 0°, thus covering the lower half of the reflection coefficient circle 111. When the reflection coefficient is located in the upper half of the circle, a resistor is used. , The corresponding reflection coefficient is located at Figure 14 Point 114 in the diagram, after connecting the phase shifter, shifts the reflection coefficient along the direction shown by arrow 115. A phase shift of -180° to 0° can cover the upper half of the reflection coefficient circle 111. and Two resistance values ​​produce the same reflection coefficient, which can reduce the phase shift range of the step phase shifter by half, thereby reducing the number of sections in the linear phase shifting network.

[0073] In Embodiment 2 of the present invention, since the maximum phase shift required by the step phase shifter is reduced to 180° instead of 360° in Embodiment 1, the required number of linear phase shifting network sections is reduced. , This indicates rounding up. The number of frequency points L is set to 15. If we take 10°, then the number of segments in the linear phase network is M=24, which is 4 fewer segments than in Example 1.

[0074] The phase step size in Example 2 is , The unit is degrees. .

[0075] When the implementation needs to be at the operating frequency ( The phase of the generated reflection coefficient is ( When ), the control codes of the control terminals of each section of the linear phase network. Compared with Example 1, the generation method modifies step 1 as follows: Step 1: Judgment: If Then the selector resistance value of the variable resistor control terminal 104 is set to... Otherwise, set the selector resistance value of the variable resistor control terminal 104 to [value missing]. And make Calculate delay and its impact Normalization yields .

[0076] Steps 2 through 6 are the same as in Example 1.

[0077] In this embodiment of the invention, the high-power radio frequency resistors in the variable resistor are connected in multiple series and parallel to ensure sufficient power capacity. For example, to generate a reflection coefficient with a VSWR of 2.5, the embodiment uses four 125Ω resistors with a power capacity of 800W. First, they are connected in series in pairs to obtain two 250Ω resistors, and then the two 250Ω resistors are connected in parallel to obtain a 125Ω resistance value, which also has a power capacity of 3200W.

[0078] Both embodiments of the present invention employ a liquid cooling system to heat the high-power radio frequency resistor. The cooling system is as follows: Figure 15 As shown, multiple high-power radio frequency resistors 121 are mounted on the surface of the liquid cooling plate 122 to conduct the heat generated by the absorbed radio frequency power to the liquid cooling plate. The liquid cooling plate has a pipe 123 inside, which passes under the high-power radio frequency resistors 121.

[0079] The coolant is drawn from the water tank 125 by the water pump 124, pressurized, and sent into the pipe 123 of the liquid cooling plate. During the flow through the pipe 123, it exchanges heat with the liquid cooling plate 122. After leaving the liquid cooling plate 122, the heated coolant enters the air-cooled heat exchanger 126, where it exchanges the heat carried by the coolant into the atmosphere. The coolant, after being cooled by the air-cooled heat exchanger 126, flows back to the water tank 125, completing the cycle.

[0080] To ensure the safe and reliable operation of the cooling system, this embodiment is equipped with a pressure gauge 127 at the output port of the water pump to monitor whether the pressure in the liquid circuit is normal, and a flow meter 128 is also installed at the outlet of the liquid cooling plate to monitor the flow rate of the coolant.

[0081] This invention discloses a shortwave high-power mismatched load with adjustable reflection coefficient. It uses a resistive mismatched load to generate discrete reflection coefficient amplitudes and a stepping phase shifter to generate discrete phases. This avoids the problems of large structural accuracy errors, narrow bandwidth, small power capacity, and poor reliability of continuously adjustable mismatched loads. The stepping phase shifter is designed as a series connection of multiple phase shifting networks and uses a logarithmic frequency division method. The delay ratio between adjacent units is the same as the frequency ratio, which greatly reduces the number of phase shifting units and thus reduces the implementation complexity.

[0082] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A shortwave high-power mismatched load with adjustable reflection coefficient, characterized in that: Includes variable resistors, stepper phase shifters with phase coverage of 0°~360°, and a cooling system; The stepper phase shifter includes two terminals, wherein the first terminal serves as the input terminal of a shortwave high-power mismatched load with adjustable reflection coefficient, and the second terminal is connected to the first terminal of the variable resistor, and the second terminal of the variable resistor is grounded. The variable resistor has One or 2 A settable discrete value, The number of amplitude values ​​for the discrete reflection coefficient, where each or each pair of resistance values ​​corresponds to a scattering coefficient amplitude, and the amplitude value of the reflection coefficient to be achieved is specified. Set the resistance value of the variable resistor. ; The variable resistor is mounted on the cold plate of the cooling system. The refrigerant flowing in the cooling system comes into contact with the cold plate to exchange heat, carrying away the heat loss generated by the variable resistor. The stepper phase shifter is configured as follows: Assume the operating frequency of a shortwave high-power mismatched load with adjustable reflection coefficient. The range is ,in The lowest frequency, The highest frequency is divided equally on the logarithmic frequency. share, , Given natural numbers, the frequency multiples are obtained. The working discrete frequency points are The delay ratios between each network section within the step phase shifter are set according to frequency multiples, and the phase shift characteristics of networks at adjacent frequencies exhibit self-similarity; Delay of the section There are two adjustable values, 0 and , ; The phase step corresponds to the transmission delay; The stepping phase shifter is composed of The Mth linear phase network is cascaded together. Each linear phase network has two terminals. The phase delay in the operating frequency band is linearly related to the frequency. The first signal terminal of each linear phase network is connected to the second signal terminal of the next linear phase network, and so on. The first signal terminal of the Mth linear phase network serves as the first terminal of the stepper phase shifter, and the second signal terminal of the first linear phase network serves as the second terminal of the stepper phase shifter.

2. The shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The variable resistor has When there are configurable discrete values, for a given operating frequency The required amplitude value of the reflection coefficient Phase is hour, Set the resistance value of the variable resistor to 1. , , The characteristic impedance is set to 50Ω or 75Ω. Number of segments in a linear phase network , Indicates rounding up. This refers to the phase step requirement for the reflection coefficient. The unit is degrees; Section 1 Delay Quantities of Linear Phase Networks have One adjustable value, For natural numbers greater than 1, , represented as ;in , , The unit is degrees. ; Set the delay of each section of the linear phase network in the stepper phase shifter as follows: S1): Calculate delay and its impact Normalization yields ; S2): Let ,set up For the front Step to The remaining residual value after approximation, the initial value of the iteration is taken as... ; S3): Calculation Judgment: If , then let the first The delay of the linear phase network is , Otherwise, let the first The delay of the linear phase network is 0; S4): ,if If the result is positive, return to step S3); otherwise, execute step S5. When the iteration reaches the second section of the linear phase network, execute step S5. S5): If S> Let the delay of the linear phase network in the second section be... , ; Otherwise, set the delay of the linear phase network in the second section to 0; S6): Calculation , This indicates rounding down, setting the delay of the first linear phase network to [value]. .

3. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The variable resistor has 2 The number of nodes in the linear phase network when a settable discrete value is obtained. , Indicates rounding up. This refers to the phase step requirement for the reflection coefficient. The unit is degrees; Section 1 Delay Quantities of Linear Phase Networks have One adjustable value, For natural numbers greater than 1, , represented as ;in , , The unit is degrees. .

4. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 3, characterized in that: For a given operating frequency The required amplitude of the reflection coefficient is Phase is hour, First calculate Judgment: If Then the resistance value of the variable resistor is set to... Otherwise, set the resistance value of the variable resistor to [value missing]. And make , Characteristic impedance; The delay of each section of the linear phase network in the step phase shifter is set according to the following steps: S1): Calculate the delay and its impact Normalization yields ; S2): Let ,set up For the front Step to The remaining residual value after approximation, the initial value of the iteration is taken as... ; S3): Calculation Judgment: If Then let the first The delay of the linear phase network is , Otherwise, let the first The delay of the linear phase network is 0; S4): ,if If the result is positive, return to step S3); otherwise, execute step S5). When the iteration reaches the second section of the linear phase network, execute step S5. S5): If S> Let the delay of the linear phase network in the second section be... , Otherwise, set the delay of the linear phase network in the second section to 0. S6): Calculation , This indicates rounding down, setting the delay of the first linear phase network to [value]. .

5. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 2, characterized in that: The variable resistor includes a single-pole K-throw switch and K high-power radio frequency resistors. The common terminal of the single-pole K-throw switch serves as the input terminal of the variable resistor. Each branch terminal of the single-pole K-throw switch is connected to one end of a high-power radio frequency resistor. The other end of each high-power radio frequency resistor is grounded. The position of the single-pole K-throw switch is determined by the amplitude of the reflection coefficient. When the amplitude of the reflection coefficient is... hour, The single-pole K-throw switch is connected to the first Each branch has a resistance value of [value missing]. .

6. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 3, characterized in that: The variable resistor includes a single-pole K-throw switch, K single-pole double-throw switches, and 2K high-power radio frequency resistors; the common terminal of the single-pole K-throw switch serves as the input terminal of the variable resistor, each branch terminal of the single-pole K-throw switch is connected to the common terminal of a single-pole double-throw switch, and the two branch terminals of each single-pole double-throw switch are respectively connected to one end of a high-power radio frequency resistor, and the other end of the high-power radio frequency resistor is grounded; The position of the single-pole K-throw switch is determined by the amplitude of the reflection coefficient. When the amplitude of the reflection coefficient is... hour, The single-pole K-throw switch is connected to the first The branch road, the first The high-power radio frequency resistor is connected to one branch terminal of the single-pole double-throw switch. One end of the high-power radio frequency resistor is connected to the other branch terminal. One end; No. The position of a single-pole double-throw switch is determined by the phase of the reflection coefficient. satisfy At that time, the first A single-pole double-throw switch connection When the reflection coefficient phase satisfy At that time, the first A single-pole double-throw switch connection .

7. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The first linear phase network of the stepper phase shifter includes two single-pole P-throw switches and P transmission lines; the common terminal of the first single-pole P-throw switch serves as the input terminal of the first linear phase network, and each branch terminal of the single-pole P-throw switch is connected to one end of a transmission line; each branch terminal of the second single-pole P-throw switch is connected to the other end of the P transmission lines, and the common terminal of the second single-pole P-throw switch serves as the output terminal of the first linear phase network. The transmission line delay connected to the first branch of the single-pole P-throw switch is denoted as . , No. The transmission line delay connected to each branch is... , .

8. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The first step phase shifter The linear phase network consists of two single-pole double-throw (SPDT) switches and two transmission lines; the common terminal of the first SPDT switch serves as the... The input terminal of the linear phase network is connected to the first single-pole double-throw (SPDT) switch. Each branch terminal of the first SPDT switch is connected to one end of a transmission line. Each branch terminal of the second SPDT switch is connected to the other end of two transmission lines. The common terminal of the first SPDT switch serves as the input terminal of the linear phase network. The output of the linear phase network; The transmission line delay connected to the first branch of the single-pole double-throw switch is denoted as . The transmission line delay configuration for the second branch is as follows: ; The position of the single-pole double-throw switch is determined by the first... The required delay for the linear phase network is determined. When the required delay is 0, the single-pole double-throw switch is located in the first branch; when the required delay is... At that time, the single-pole double-throw switch is located in the second branch.

9. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The first step phase shifter The linear phase network consists of two single-pole double-throw (SPDT) switches, a transmission line, and a low-pass two-port lumped-parameter network composed of inductors and capacitors; the common terminal of the first SPDT switch serves as the... The input terminal of the linear phase network is connected to the transmission line. The first branch terminal of the single-pole double-throw switch is connected to one end of the transmission line, and the second branch terminal is connected to one end of the low-pass two-port lumped parameter network composed of inductors and capacitors. The first branch terminal of the second single-pole double-throw switch is connected to the other end of the transmission line, and the second branch terminal is connected to the other end of the low-pass two-port lumped parameter network composed of inductors and capacitors. The common terminal of the single-pole double-throw switch serves as the input terminal of the first... The output of the linear phase network; The delay of the transmission line is denoted as The low-pass two-port lumped parameter network composed of inductors and capacitors has a frequency band of... Internal transmission delay configuration is ; The position of the single-pole double-throw switch is determined by the first... The required delay for the linear phase network is determined. When the required delay is 0, the single-pole double-throw switch is located in the first branch; when the required delay is... At that time, the single-pole double-throw switch is located in the second branch.

10. A shortwave high-power mismatched load with adjustable reflection coefficient according to claim 1, characterized in that: The cooling system uses coolant as the refrigerant and includes a liquid cooling plate, a water pump, a water tank, a heat exchanger, a pressure gauge, and a flow meter. The liquid cooling plate has a pipe inside for the refrigerant to flow. One end of the pipe serves as an inlet connected to the outlet of the water pump, and the other end serves as an outlet connected to the inlet of the heat exchanger. A variable resistor is installed on the surface of the liquid cooling plate directly above the pipe, and the heat dissipation flange of the variable resistor is in close contact with the surface of the liquid cooling plate. The inlet of the water pump is connected to the outlet of the water tank; the inlet of the water tank is connected to the outlet of the heat exchanger; a pressure gauge is installed on the outlet pipe of the water pump, and a flow meter is connected in series at the outlet of the liquid cooling plate.

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