CN116130912B - Power transmission system - Google Patents
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- CN116130912B CN116130912B CN202310402420.1A CN202310402420A CN116130912B CN 116130912 B CN116130912 B CN 116130912B CN 202310402420 A CN202310402420 A CN 202310402420A CN 116130912 B CN116130912 B CN 116130912B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P3/00—Waveguides; Transmission lines of the waveguide type
- H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
- H01P3/06—Coaxial lines
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P3/00—Waveguides; Transmission lines of the waveguide type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/19—Conjugate devices, i.e. devices having at least one port decoupled from one other port of the junction type
- H01P5/20—Magic-T junctions
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a power transmission system, which comprises a three-branch impedance matching system, a conjugate-T branch and a 30-50 ohm impedance converter, wherein the three-branch impedance matching system, the conjugate-T branch and the 30-50 ohm impedance converter are sequentially arranged on a transmission line; the three-section impedance matching system is arranged on a transmission line close to the transmitter end and is used for solving the problems of overlarge wave reflected power and overlarge standing wave voltage caused by inherent impedance mismatch between the transmitter and the antenna; the conjugate-T branch utilizes two arm branches and a conjugate T structure to divide one signal of the transmission line into two signals; the distance between the first signal transmission line where the first signal output end is positioned and the second signal transmission line where the second signal output end is positioned is half of the wavelength of the ion cyclotron wave; the first signal transmission line and the second signal transmission line are respectively connected with a 30 ohm-50 impedance converter. The scheme is less sensitive to impedance disturbance response when the input impedance of the transmission line is larger, so that the overall impedance disturbance tolerance of the system is enhanced.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a power transmission system.
Background
The ion cyclotron heating is realized by radiating electromagnetic waves of ion cyclotron frequency into plasma, transmitting wave energy to ions through the interaction of the wave and the ions, and slowing down the ions. It has proven to be very effective for ion heating, and most large and medium-sized tokamaks currently use megawatt-level ion cyclotron heating systems to heat the plasma.
The inventors found in the course of studying the related art that, during the heating of the ion cyclotron wave, a cutoff layer exists between the wave and the plasma, and the thickness of the cutoff layer depends on the plasma boundary parameters, which are mainly affected by the boundary density. The boundary parameter change of the plasma can cause the coupling state of the ion cyclotron to change, and the load impedance of the ion cyclotron antenna changes in real time from the perspective of the ion cyclotron system.
The load resistance of the ion cyclotron antenna in a tokamak device is typically low and changes rapidly. This rapid change can lead to mismatch between the transmitter and antenna impedance, and thus to excessive reflected power in the transmission line network, and excessive transmission line voltage, ultimately affecting the high power operation of the ion cyclotron heating system. Therefore, how to realize stable high-power operation of the system under the condition that the antenna impedance is greatly disturbed is a problem to be solved.
Disclosure of Invention
The present invention is directed to at least solving the technical problems of the prior art, and for this purpose, a first aspect of the present invention proposes a power transmission system for stably feeding transmitter power into an antenna, the system comprising a transmission line connecting a transmitter end and an antenna end, and a three-node impedance matching system, a conjugate-T-node and an impedance converter of 30-50 ohms mounted on the transmission line in this order from the transmitter end;
the three-section impedance matching system is used for realizing antenna impedance matching and is arranged on a transmission line close to the transmitter end;
the conjugate-T branch utilizes two arm branches and one T branch to divide one path of signal of the transmission line into two paths of signals, a first arm branch of the two arm branches is a signal input end of the conjugate-T branch, a second arm branch is a first signal output end of the conjugate-T branch, and the T branch is a second signal output end of the conjugate-T branch; the distance between the first signal transmission line where the first signal output end is positioned and the second signal transmission line where the second signal output end is positioned is half of the wavelength of the ion cyclotron wave, and the distance is used for ensuring that the current directions of the antennas are consistent;
the first signal transmission line and the second signal transmission line are respectively connected with a 30 ohm-50 impedance converter, and the impedance converters are used for improving the input impedance of the transmission lines; the input end of the impedance converter is connected with a coaxial transmission line with characteristic impedance of 50 ohms, and the output end of the impedance converter is connected with the antenna.
Optionally, the impedance converter includes a first portion as the input end, a second portion located in the middle section, and a third portion as the output end, where the first portion is a coaxial transmission line with a characteristic impedance of 30 ohms, the second portion is a 30 ohms-50 ohms impedance conversion portion, and the third portion is a coaxial transmission line with a characteristic impedance of 50 ohms; the second portion effects a change in impedance by changing the outer diameter of the coaxial transmission line.
Optionally, if the distances from the T point of the conjugate-T branch to the antenna of the two paths of signals of the conjugate-T branch are a first distance and a second distance, respectively, the sum of the first distance and the second distance is an integer multiple of 1/2 wavelength of the ion cyclotron.
Optionally, the three-branch impedance matching system comprises three coaxial transmission branches, three short circuit branches corresponding to the three coaxial transmission branches, a voltage and current probe and a directional coupler;
the three coaxial transmission branches are sequentially arranged on a transmission line between the transmitting end and the conjugate-T branch, and the directional coupler is arranged on the transmission line between the transmitting end and the first coaxial transmission branch; the voltage and current probe is arranged on a transmission line between the third coaxial transmission branch joint and the conjugate-T branch joint;
the three short circuit branch joints comprise silicone oil, and the electrical length of the corresponding coaxial transmission branch joint is adjusted by changing the liquid level height of the silicone oil; the voltage and current probe is used for measuring the voltage and current of the probe position, and the directional coupler is used for testing reflected power.
Optionally, the impedance converter is selected by:
when the voltage and current probe position is the minimum impedance point of the transmission line impedance distribution
When determining input impedance
And power reflection coefficient->
A relationship graph between the two;
giving three nodes matching multiple characteristic impedances, changing only
Determining the power reflection coefficient +.>
Is a trend of change in (2);
according to the change trend of the reflection coefficients corresponding to the characteristic impedances, determining the impedance characteristic which can make the system impedance have the strongest tolerance; the impedance is characterized in that: the larger the impedance, the more resistant the impedance change of the system;
and determining an impedance converter according to the impedance characteristics.
Optionally, when the voltage-current probe is installed on a transmission line between a third coaxial transmission branch and the conjugate-T branch, the method for determining the input impedance and the power reflection coefficient of the position of the voltage-current probe is as follows:
acquiring the first electrical lengths of the three coaxial transmission branches, the second electrical lengths of the three short circuit branches and the voltage and current of the probe positions measured by the voltage and current probes;
determining an input voltage and current from the first electrical length, the second electrical length, the voltage and current;
and determining the input impedance and the power reflection coefficient of the upper end of the third coaxial transmission branch according to the voltage and the current of the upper end of the third coaxial transmission branch.
Optionally, the assembly position of the T-branch in the conjugated-T-branch is determined by the following method:
respectively acquiring the lengths of the two arm branches and the port impedance of the two arm branches;
determining the input impedance of the T branch joint according to the lengths of the two arm branch joints and the port impedance;
determining the voltage standing wave ratio of the arm branch joint according to the characteristic impedance of the arm branch joint, the port impedance electrical lengths of the two arm branch joints and the input impedance of the T branch joint;
determining a relation diagram of the voltage standing wave ratio and the lengths of the two arm branches according to the port impedance of the two arm branches;
and determining the assembling position of the T-branch joint according to the relation diagram.
Optionally, the assembly position is a maximum point of voltage standing wave ratio distribution on the arm support node.
Optionally, the length value of the T-branch in the conjugated-T-branch is determined by the following method:
representing the transmission line current voltage as a first function of the antenna current voltage according to the characteristic impedance distribution characteristics of the impedance converter;
under the condition that the characteristic impedance of the transmission line is not changed, determining an input impedance expression of the minimum voltage standing wave ratio point of the transmission line according to the characteristic impedance of the transmission line and the current voltage of the transmission line;
converting the input impedance expression into a second function of the length of the transmission line, the length of the T-branch, the antenna current voltage;
determining a relationship graph between a minimum impedance point and the transmission line length according to the second function;
and determining a target length value of the T branch which can increase the impedance of the transmission line most according to the relation diagram, and taking the target length value as the length value of the T branch.
Optionally, the impedance converters are respectively installed at the maximum points of voltage standing wave ratio distribution on the first signal transmission line and the second signal transmission line.
The embodiment of the invention has the following beneficial effects:
the power transmission system provided by the embodiment of the invention comprises a transmission line for connecting a transmitter end and an antenna end, and a three-node impedance matching system, a conjugate-T node and a 30-50 ohm impedance converter which are sequentially arranged on the transmission line from the transmitter end; the three-section impedance matching system is used for realizing antenna impedance matching and is arranged on a transmission line close to the transmitter end; the conjugate-T branch utilizes two arm branches and one T branch to divide one path of signal of the transmission line into two paths of signals, a first arm branch of the two arm branches is a signal input end of the conjugate-T branch, a second arm branch is a first signal output end of the conjugate-T branch, and the T branch is a second signal output end of the conjugate-T branch; the distance between the first signal transmission line where the first signal output end is positioned and the second signal transmission line where the second signal output end is positioned is half of the wavelength of the ion cyclotron wave, and the distance is used for ensuring that the current directions of the antennas are consistent; the first signal transmission line and the second signal transmission line are respectively connected with a 30 ohm-50 impedance converter, and the impedance converters are used for improving the input impedance of the transmission lines; the input end of the impedance converter is connected with a coaxial transmission line with characteristic impedance of 50 ohms, and the output end of the impedance converter is connected with the antenna. The input impedance of the transmission line is improved by introducing the conjugate-T branch and the impedance converter, and the three-branch impedance matching system in the system is insensitive to impedance disturbance response when the input impedance of the transmission line is larger, so that the overall impedance disturbance tolerance of the system is enhanced.
Drawings
Fig. 1 is a schematic diagram of a power transmission system according to an embodiment of the present invention;
FIG. 2 is a detailed schematic diagram of a three-node impedance matching system according to an embodiment of the present invention;
FIG. 3 is a graph showing the relationship between the position impedance and the power reflection coefficient of the voltage and current probe according to the embodiment of the present invention;
FIG. 4 is a schematic diagram of details of a conjugated-T branch according to an embodiment of the present invention;
FIG. 5 is a graph showing the relationship between the voltage standing wave ratio and the lengths of two arm joints according to the embodiment of the present invention;
fig. 6 is a schematic diagram of an impedance converter according to an embodiment of the present invention;
fig. 7 is a graph showing a relationship between a minimum impedance point and the length of the transmission line according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first" and "second" are used below for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present disclosure, unless otherwise indicated, the meaning of "a plurality" is two or more. In addition, the use of "based on" or "according to" is intended to be open and inclusive in that a process, step, calculation, or other action "based on" or "according to" one or more of the stated conditions or values may in practice be based on additional conditions or beyond the stated values.
Fig. 1 is a schematic diagram of a power transmission system according to an embodiment of the present invention.
As shown in fig. 1, the system comprises a transmission line connecting a transmitter end and an antenna end, and a three-node impedance matching system, a conjugate-T node and a 30 ohm-50 ohm impedance converter which are sequentially installed on the transmission line from the transmitter end.
The whole system is used for stably feeding the power of the transmitter into the antenna, wherein the input end is the transmitter end, and the output end is the antenna end.
The power transmission system comprises a transmission line for connecting a transmitter end and an antenna end, and a three-node impedance matching system, a conjugate-T node and a 30 ohm-50 ohm impedance converter which are sequentially arranged on the transmission line from the transmitter end;
the three-section impedance matching system is used for realizing antenna impedance matching and improving the heating power of the ion cyclotron heating system. In particular on the transmission line close to the transmitter end. The three-section impedance matching system is used for solving the problems of overlarge wave reflected power and overlarge standing wave voltage caused by inherent impedance mismatch between a transmitter and an antenna.
The conjugate-T branch utilizes two arm branches and one T branch to divide one signal of a transmission line into two signals, a first arm branch of the two arm branches is a signal input end of the conjugate-T branch, a second arm branch is a first signal output end of the conjugate-T branch, and the T branch is a second signal output end of the conjugate-T branch; the distance between the first signal transmission line where the first signal output end is positioned and the second signal transmission line where the second signal output end is positioned is half of the wavelength of the ion cyclotron wave, so that the current direction of the antenna is consistent;
the first signal transmission line and the second signal transmission line are respectively connected with a 30 ohm-50 impedance converter, and the impedance converters are used for improving the input impedance of the transmission lines; the input end of the impedance converter is connected with a coaxial transmission line with characteristic impedance of 50 ohms, and the output end of the impedance converter is connected with an antenna.
In one possible implementation manner, the impedance converter includes a first portion as the input end, a second portion located in a middle section, and a third portion as the output end, where the first portion is a coaxial transmission line with a characteristic impedance of 30 ohms, the second portion is a 30 ohm-50 ohm impedance conversion portion, and the third portion is a coaxial transmission line with a characteristic impedance of 50 ohms; the second portion effects a change in impedance by changing the outer diameter of the coaxial transmission line.
Specifically, the impedance converter is a power transmission device capable of improving input impedance, and mainly has three parts of impedance, wherein a first part close to an antenna is a coaxial transmission line with characteristic impedance of 30 ohms, a middle part is an impedance conversion part with characteristic impedance of 30 ohms-50 ohms, and a third part is a coaxial transmission line with characteristic impedance of 50 ohms. For the impedance converting section, the impedance change is achieved by changing the outer conductor diameter of the coaxial transmission line without changing the inner conductor diameter of the coaxial transmission line. The design can increase the input impedance of the coaxial transmission line by 0.6 times.
In one possible implementation, if the distances from the T point of the conjugate-T branch to the antenna of the two signals of the conjugate-T branch are a first distance and a second distance, respectively, then the sum of the first distance and the second distance is an integer multiple of 1/2 wavelength of the ion cyclotron.
Specifically, the conjugated T-branch consists of three branches divided into two. The conjugate-T branch is arranged between the three-branch impedance matching system and the impedance converter, and the input end and the output end are coaxial transmission lines with characteristic impedance of 50 ohms and are used for improving the input impedance and reducing the voltage standing wave ratio of the transmission lines.
If we set the distance between the T point and the antenna as L1 and L2, and set the length of L1+L2 as
Wherein n is a positive integer, ">
Is the wavelength of the ion cyclotron. Then the conjugate structural design of the T-branch is realized. The design can improve the input impedance of the coaxial transmission line by 1 time.
The two arm joints have different lengths
Mainly for adjusting the phase of the antenna +.>
Exactly one period of the input impedance change, therefore here +.>
And does not cause a change in the input impedance of the transmission line. The T point is also required to be arranged at the maximum point of the voltage standing wave ratio distribution of the transmission line, so that the input impedance of the transmission line can be doubled, and meanwhile, the disturbance of the input impedance caused by the change of the antenna impedance can be reduced.
In one possible implementation manner, the three-branch impedance matching system comprises three coaxial transmission branches, three short-circuit branches corresponding to the three coaxial transmission branches, a voltage and current probe and a directional coupler;
the three coaxial transmission branches are sequentially arranged on a transmission line between the transmitting end and the conjugate-T branch, and the directional coupler is arranged on the transmission line between the transmitting end and the first coaxial transmission branch; the voltage and current probe is arranged on a transmission line between the third coaxial transmission branch joint and the conjugate-T branch joint; the three short circuit branch joints comprise silicone oil, and the electrical length of the corresponding coaxial transmission branch joint is adjusted by changing the liquid level height of the silicone oil; the voltage and current probe is used for measuring the voltage and current of the probe position, and the directional coupler is used for testing reflected power.
Specifically, the three-branch impedance matching system is connected behind the conjugate-T branch and is used for realizing antenna impedance matching. One of the features of the three nodes with the greatest impedance matching is that the larger the input impedance of the transmission line is, the less sensitive the transmission system is to the impedance disturbance response, namely the stronger the impedance disturbance tolerance of the system is.
Fig. 2 is a detailed schematic diagram of a three-node impedance matching system according to an embodiment of the present invention.
Three coaxial transmission stubs are shown in fig. 2: branch 1, branch 2, branch 3, three short-circuited branches represented by three arrows, and voltage-current probes, directional coupler.
The three short circuit branch joints comprise silicone oil, and the electrical length of the corresponding coaxial transmission branch joint is adjusted by changing the liquid level height of the silicone oil; the voltage current probe is used to measure the voltage and current at the probe location and the directional coupler is used to test the reflected power.
The three-section impedance matching system can solve the problem of overlarge reflection of the transmission system and improve the output power of the ion cyclotron system. An important feature of a three-segment dispenser is that the greater the input impedance, the greater its impedance tolerance. The impedance tolerance referred to herein means: the ion cyclotron reflected power does not change much when a large disturbance occurs in the input impedance.
In one possible embodiment, the impedance converter is selected by:
step 101, when the voltage and current probe position is the minimum impedance point of the transmission line impedance distribution
When determining the input impedance +.>
And power reflection coefficient->
A graph of the relationship between the two.
As shown in fig. 2, it is assumed that the electrical lengths corresponding to the three coaxial transmission branches are respectively
The corresponding electrical lengths of the three short circuit branch joints are +.>
Voltage and current at the probe position measured by the voltage and current probe is +.>
. Based on transmission line theory, the input impedance at any point on the transmission line can be calculated given the voltage current at that point on the transmission line and the electrical length of the transmission line.
Let us assume that the current probe position is the minimum impedance point of the transmission line impedance distribution
The impedance of the voltage and current probe position can be drawn>
And power reflection coefficient->
The relationship diagram, namely the characteristic parameter curve of the three-node matching system, is obtained as shown in fig. 3.
FIG. 3 is a graph showing the relationship between the position impedance and the power reflection coefficient of the voltage and current probe according to the embodiment of the present invention.
Step 102, matching a plurality of characteristic impedances to the three nodes, and only changing
Determining the power reflection coefficient +.>
Is a trend of change in (c).
The different curves in FIG. 3 represent the matching of a characteristic impedance at three nodes
) In the case of (2) only change +.>
In the case of (2) reflection coefficient->
Is a trend of change in (c).
Step 103, determining the impedance characteristic which can make the system impedance have the strongest tolerance according to the change trend of a plurality of reflection coefficients corresponding to the plurality of characteristic impedances; the impedance is characterized in that: the greater the impedance, the more resistant the system to impedance variation.
As can be seen from fig. 3, when the impedance is larger, the power reflection change caused by the impedance disturbance is less sensitive, which means that the impedance change tolerance of the system is stronger, that is, the impedance characteristic that the impedance tolerance of the system is strongest is: the greater the impedance, the more resistant the system to impedance variation.
Step 104, determining an impedance converter according to the impedance characteristics.
Typically, the impedance of the antenna is only 3 to 8 ohms, so the input impedance of the three-node matching system is improved by optimizing the design. The invention improves the input impedance of the transmission line by introducing a conjugate-T junction and a 30 ohm-50 impedance transformer.
In one possible implementation, when the voltage-current probe is installed on the transmission line between the third coaxial transmission branch and the conjugate-T branch, the method for determining the input impedance and the power reflection coefficient in step 101 is as follows:
step 201, obtaining a first electrical length of the three coaxial transmission branches, a second electrical length of the three short-circuit branches, and a voltage and a current of a probe position measured by the voltage and current probe.
Assume that the electrical lengths corresponding to the three coaxial transmission branches are respectively
The corresponding electrical lengths of the three short circuit branch joints are +.>
Voltage and current at the probe position measured by the voltage and current probe is +.>
。
Step 202, determining input voltage and current according to the first electrical length, the second electrical length, the voltage and current.
Based on transmission line theory, the input impedance at any point on the transmission line can be calculated given the voltage current at that point on the transmission line and the electrical length of the transmission line. Thus, the input voltage and current at the top of Stub3
Can be expressed as
Is specifically represented by formula (1):
(1)
wherein,,
is the characteristic impedance.
And 203, determining the input impedance and the power reflection coefficient of the upper end of the third coaxial transmission branch according to the voltage and the current of the upper end of the third coaxial transmission branch.
Setting up
. Calculating the voltage and current of the upper end of Stub3>
The input impedance +.>
And power reflection coefficient->
. The specific expression is as follows:
wherein V is 1 、I 1 Respectively represent the voltage and the current of the upper end of stub3, Z 0 =50Ω。
In one possible embodiment, the fitting position of the T-branch of the conjugate-T-branch is determined by the following method:
step 301, respectively obtaining the lengths of the two arm branches and the port impedance of the two arm branches.
Fig. 4 is a detailed schematic diagram of a conjugate-T branch according to an embodiment of the present invention.
As shown in FIG. 4, the length of the two arm joints obtained is set to be
，/>
Two arm supportsThe port impedance of the node is +.>
And->
。
Given the known port impedance and leg length, the input impedance of another port can be calculated. The specific equation expression is as follows:
(3)
wherein,,
is the characteristic impedance of the transmission line. />
，/>
For transmission lines->
And->
Electrical length of->
Is the impedance of the T point, < >>
And->
Is->
，/>
Is provided).
Step 303, determining the voltage standing wave ratio of the arm branch according to the characteristic impedance of the arm branch, the port impedance electrical lengths of the two arm branches and the input impedance of the T branch.
According to
The voltage standing wave ratio can be calculated, and the equation is as follows:
step 304, determining a relation diagram of the voltage standing wave ratio and the lengths of the two arm branches according to the port impedance of the two arm branches.
At a known position
And->
In impedance, standing wave ratio +.>
Expressed as->
，/>
Is a function of (2).
Fig. 5 is a graph of a relationship between a voltage standing wave ratio and lengths of two arm branches according to an embodiment of the present invention.
In fig. 5, it is assumed that
=/>
=/>
Shows the voltage standing wave ratio and +.>
，/>
I.e. the characteristic relationship of the T-branch.
And 305, determining the assembling position of the T-branch joint according to the relation diagram.
The dotted line in FIG. 5 corresponds to the conjugated-T structure, satisfying
+/>
The sum of the lengths is->
。
The scheme selects the midpoint of the dotted line as the final T-branch joint assembly position. The point is the maximum point of the voltage standing wave ratio distribution of the arm support.
The reason for selecting this is: first, the voltage standing wave ratio change rate is the lowest, for
Has minimal impact on (i); second, this impedance doubles the port impedance, which has a good effect on improving the system impedance disturbance tolerance.
In one possible embodiment, the length value of the T-branch of the conjugated-T-branch is determined by the following method:
step 401, representing the transmission line current voltage as a first function of the antenna current voltage according to the characteristic impedance distribution characteristics of the impedance converter.
Fig. 6 is a schematic diagram of an impedance converter according to an embodiment of the invention.
As shown in fig. 6, L represents the transmission line length,
represents->
Impedance conversion branch length, < >>
Representative of
Impedance transformation branch and->
The total length of the branch.
According to the theory of transmission lines, we can
Expressed as->
The specific expression of the function of (2) is as follows:
wherein,,
//>
representation->
The dot length of the transmission line.
Step 402, under the assumption that the characteristic impedance of the transmission line is unchanged, determining an input impedance expression of the minimum voltage standing wave ratio point of the transmission line according to the characteristic impedance of the transmission line and the current voltage of the transmission line.
For transmission line current voltage
,/>
We divide a transmission line of 30-50 ohms into n segments of length d, d ≪ +.>
,/>
=n*d，/>
For the electrical length of each segment. We assume that in each section of transmission line, its characteristic impedance (labeled
N=1, 2,3 …) remains unchanged. Input impedance of minimum voltage standing wave ratio point +.>
Can be expressed as:
(6)
wherein,,
，/>
。
step 403, converting the input impedance expression into a second function of the length of the transmission line, the length of the T-branch, and the antenna current voltage.
Thus, the first and second substrates are bonded together,
can be expressed as +.>
,/>
And->
Is a second function of (1), here->
。
Step 404, determining a relation diagram between a minimum impedance point and the transmission line length according to the second function.
Assume that
In->
At the time, draw +.>
And L.
Fig. 7 is a graph showing a relationship between a minimum impedance point and the length of the transmission line according to an embodiment of the present invention.
And step 405, determining a target length value of the T branch which can increase the impedance of the transmission line most according to the relation diagram, and taking the target length value as the length value of the T branch.
As can be seen in FIG. 7, in
The impedance can be increased by a factor of 1.6. At the same time can be seen
Impedance transformation branch length->
For->
The influence of (c) is very small. For the engineering feasibility and physical rationality, the solution selects +.>
Length of->
。
Furthermore, as can be seen from FIG. 7, R as L increases for the case without 30-50Ω transmission line min Without any change.
In one possible implementation, the impedance converter is mounted at a maximum point of voltage standing wave ratio distribution on the first signal transmission line and the second signal transmission line, respectively.
The impedance converter installation position needs the maximum point of the voltage standing wave ratio on the signal transmission line, and only then can maximally improve the input impedance of the transmission line.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.
Claims (10)
1. A power transmission system for stably feeding transmitter power into an antenna, said system comprising a transmission line connecting a transmitter end and an antenna end, and a three-node impedance matching system, a conjugate-T-node, and a 30 ohm-50 ohm impedance transformer mounted on said transmission line in order from said transmitter end;
the three-section impedance matching system is used for realizing antenna impedance matching and is arranged on a transmission line close to the transmitter end;
the conjugate-T branch utilizes two arm branches and one T branch to divide one path of signal of the transmission line into two paths of signals, a first arm branch of the two arm branches is a signal input end of the conjugate-T branch, a second arm branch is a first signal output end of the conjugate-T branch, and the T branch is a second signal output end of the conjugate-T branch; the distance between the first signal transmission line where the first signal output end is positioned and the second signal transmission line where the second signal output end is positioned is half of the wavelength of the ion cyclotron wave, and the distance is used for ensuring that the current directions of the antennas are consistent;
the first signal transmission line and the second signal transmission line are respectively connected with the impedance converter, and the impedance converter is used for improving the input impedance of the transmission line; the input end of the impedance converter is connected with a coaxial transmission line with characteristic impedance of 50 ohms, and the output end of the impedance converter is connected with the antenna.
2. The system of claim 1, wherein the impedance transformer comprises a first portion as the input, a second portion at a middle section, the first portion being a coaxial transmission line having a characteristic impedance of 30 ohms, the second portion being a 30 ohm-50 ohm impedance transforming portion, and a third portion as the output, the third portion being a coaxial transmission line having a characteristic impedance of 50 ohms; the second portion effects a change in impedance by changing the outer diameter of the coaxial transmission line.
3. The system of claim 1, wherein if the distances of the two signals of the conjugate-T leg from the T point of the conjugate-T leg to the antenna are a first distance and a second distance, respectively, then the sum of the first distance and the second distance is an integer multiple of 1/2 wavelength of the ion cyclotron.
4. The system of claim 1, wherein the three-leg impedance matching system comprises three coaxial transmission legs, three short-circuit legs corresponding to the three coaxial transmission legs, and a voltage-current probe, a directional coupler;
the three coaxial transmission branches are sequentially arranged on a transmission line between the transmitter end and the conjugate-T branch, and the directional coupler is arranged on the transmission line between the transmitter end and the first coaxial transmission branch; the voltage and current probe is arranged on a transmission line between the third coaxial transmission branch joint and the conjugate-T branch joint;
the three short circuit branch joints comprise silicone oil, and the electrical length of the corresponding coaxial transmission branch joint is adjusted by changing the liquid level height of the silicone oil; the voltage and current probe is used for measuring the voltage and current of the probe position, and the directional coupler is used for testing reflected power.
5. The system of claim 4, wherein the impedance converter is selected by:
when the voltage and current probe position is the minimum impedance point of the transmission line impedance distribution
When determining the input impedance +.>
And power reflection coefficient->
A relationship graph between the two;
giving three nodes matching multiple characteristic impedances, changing only
Determining the power reflection coefficient in the relation diagram
Is a trend of change in (2);
according to the change trend of the reflection coefficients corresponding to the characteristic impedances, determining the impedance characteristic which can make the system impedance have the strongest tolerance; the impedance is characterized in that: the larger the impedance, the more resistant the impedance change of the system;
and determining an impedance converter according to the impedance characteristics.
6. The system of claim 5, wherein when said voltage-current probe is installed on a transmission line between a third one of said coaxial transmission branches and said conjugate-T branch, the input impedance and power reflection coefficient of said voltage-current probe position are determined as follows:
acquiring the first electrical lengths of the three coaxial transmission branches, the second electrical lengths of the three short circuit branches and the voltage and current of the probe positions measured by the voltage and current probes;
determining an input voltage and current from the first electrical length, the second electrical length, the voltage and current;
and determining the input impedance and the power reflection coefficient of the upper end of the third coaxial transmission branch according to the voltage and the current of the upper end of the third coaxial transmission branch.
7. The system of claim 1, wherein the fitting position of a T-branch of the conjugated-T-branch is determined by:
respectively acquiring the lengths of the two arm branches and the port impedance of the two arm branches;
determining the input impedance of the T branch joint according to the lengths of the two arm branch joints and the port impedance;
determining the voltage standing wave ratio of the arm branch joint according to the characteristic impedance of the arm branch joint, the port impedance electrical lengths of the two arm branch joints and the input impedance of the T branch joint;
determining a relation diagram of the voltage standing wave ratio and the lengths of the two arm branches according to the port impedance of the two arm branches;
and determining the assembling position of the T-branch joint according to the relation diagram.
8. The system of claim 7, wherein the mounting location is a maximum point of a voltage standing wave ratio distribution on the arm stub.
9. The system of claim 1, wherein the length value of a T-branch of the conjugated-T-branch is determined by:
representing the transmission line current voltage as a first function of the antenna current voltage according to the characteristic impedance distribution characteristics of the impedance converter;
under the condition that the characteristic impedance of the transmission line is not changed, determining an input impedance expression of the minimum voltage standing wave ratio point of the transmission line according to the characteristic impedance of the transmission line and the current voltage of the transmission line;
converting the input impedance expression into a second function of the length of the transmission line, the length of the T-branch, the antenna current voltage;
determining a relationship graph between a minimum impedance point and the transmission line length according to the second function;
and determining a target length value of the T branch which can increase the impedance of the transmission line most according to the relation diagram, and taking the target length value as the length value of the T branch.
10. The system of claim 1, wherein the impedance converter is mounted at a maximum point of a voltage standing wave ratio distribution on the first signal transmission line and the second signal transmission line, respectively.
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