JPS6115629Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is used for connecting railway lines or railway lines and equipment. This invention uses impedance matching,
This invention relates to an impedance conversion transformer inserted for purposes such as reducing induced noise.

[Conventional technology]

A conventional impedance conversion transformer is shown in Figure 1a.
As shown in the figure, the input winding 2 and the output winding 3 are wound around a magnetic core 1 forming a closed magnetic path. The equivalent circuit of such a conventional transformer can be expressed as shown in FIG. 1b. For example, by setting the ratio of the number of turns of input side winding 2 to the number of turns of output side winding 3 to √10075, the input impedance is 100Ω,
A transformer with an output impedance of 75Ω can be obtained.

[Problem that the invention attempts to solve]

However, such conventional transformers have the disadvantage that a broadband transformer cannot be obtained. This is because if the number of input/output turns is reduced, the impedance will not be sufficient and the mid-low frequency characteristics will deteriorate, while if the number of turns is increased, the high frequency characteristics will deteriorate due to leakage inductance and stray capacitance. .

The present invention is intended to solve this problem, and aims to provide an impedance conversion transformer with significantly improved high frequency characteristics and a wider band.

[Means for solving problems]

The present invention includes first to fifth coaxial type lines, and the first coaxial type line has its input side internal conductor connected to one end of the input terminal, and its output side internal conductor connected to one end of the output terminal. The second coaxial type line has its input side internal conductor connected to the input side external conductor of the first coaxial type line, its output side internal conductor is connected to one end of the output terminal, and its output side external conductor is connected to the input side external conductor of the first coaxial type line. The conductor is connected to the output side outer conductor of the first coaxial type line, the input side inner conductor of the third coaxial type line is connected to one end of the input terminal, and the output side inner conductor is connected to the output side inner conductor of the third coaxial type line. The fourth coaxial line is connected to the output external conductor of the coaxial line, and the input internal conductor of the fourth coaxial line is connected to the input external conductor of the third coaxial line, and the output internal conductor of the fourth coaxial line is connected to the input external conductor of the third coaxial line. The input internal conductor of the fifth coaxial line is connected to the input external conductor of the fourth coaxial line, and the output internal conductor of the fifth coaxial line is connected to the input external conductor of the fourth coaxial line. It is connected to the output-side inner conductor of the fourth coaxial line, and the input-side outer conductor of the second coaxial line and the input-side outer conductor of the fifth coaxial line are connected to the other end of the input terminal. , the output side external conductor of the third coaxial line, the output terminal external conductor of the fourth coaxial line, and the output terminal external conductor of the fifth coaxial line are connected to the other end of the output terminal, and at least The first to fourth coaxial lines are surrounded by a magnetic material.

[Effect]

The impedance conversion transformer of the present invention uses five coaxial lines with good characteristics as coils, matches the impedance to the load at both the input end and the output end, and also maintains the voltage-current relationship between the input and output ends of each coil. Since they are connected in combination without disturbance, excellent characteristics can be obtained and high frequency characteristics can be significantly improved.

Note that a conversion transformer similar to the present invention can also be constructed using balanced pair lines instead of coaxial lines.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective view showing the first embodiment of the present invention. That is, a coaxial line having a characteristic impedance of about 60Ω is inserted through a hole 4 formed in a core 5 made of a magnetic material such as ferrite to form a so-called double line coil. Five such double line type coils are stacked. In the figure, the left side of each line is the input end, and the right side is the output end. and,
On the input side, the input ends of the first line 6 and the second line 7 are connected in series and connected to input terminals 13 and 22. That is, the input terminal 13 is connected to the center conductor 11 of the line 6, and the outer conductor 14 of the line 6 is connected to the second
is connected to the center conductor 12 of the line 7 , and the outer conductor 15 of the line 7 is connected to the input terminal 22 . Also, the third
~The input ends of the fifth lines 8 to 10 are connected in series and connected between the input terminals 13 and 22. That is, the input terminal 13 is connected to the center conductor 16 of the third line 8, the outer conductor 20 of the line 8 is connected to the center conductor 17 of the fourth line 9, and the outer conductor 18 of the line 9 is connected to the center conductor 16 of the third line 8.
is connected to the center conductor 19 of the line 10 , and the center conductor 21 of the line 10 is connected to the input terminal 22 .

Next, on the output side (right side in the figure), the output ends of the third to fifth lines 8 to 10 are connected in parallel to the circuit in which the output ends of the first line 6 and the second line 7 are connected in parallel. Connect the circuits in series to output terminals 25 and 3.
Connect between 4. That is, the output terminal 25 is connected to the center conductors 23 and 30 of the coaxial lines 6 and 7, the center conductors 29 and 31 of the lines 6 and 7 are connected in common, and the center conductors 24 and 2 of the lines 8, 9, and 10 are connected.
7, 28, and connect the center conductors 26, 32, 33 of the lines 8, 9, 10 in common to output terminal 34.
Connect to.

With the above configuration, the impedance ratio of the input terminals 13, 22 and the output terminals 25, 34 is approximately 75.
Ω: Obtain an impedance conversion transformer of 50Ω.

Next, the operation of this embodiment will be explained. 6th
The figure is an equivalent circuit diagram of the transformer of this embodiment. First, a so-called double line coil in which a coaxial line 6 is inserted through a core 5 made of a magnetic material forms a transformer with an impedance ratio of 1:1. and,
This double line type transformer is a balanced/unbalanced conversion transformer with excellent characteristics. This means that the current that flows into the center conductor 11 and flows out to the center conductor 23 is always equal to the current that flows back from the center conductor 29 to the center conductor 14. Since the core 5 exhibits a large inductance and blocks the current that attempts to flow back to the input side external conductor, the load connected between the line output side external conductor 29 and the center conductor 23 is unbalanced even if it is a balanced type. This is because there is no problem with the type.

Similarly, the input power supply connected between the input side external conductor 14 and the center conductor 11 does not matter whether it is balanced or unbalanced. That is, an unbalanced power supply can be connected to the input side, and a balanced load can be connected to the output side. That is, it has characteristics close to a 1:1 ideal transformer. The same applies to the coaxial lines 7 to 10.

Therefore, the output terminals 13 of the transformer of FIG.
When input voltage E is applied between 22 and 22, the voltage applied to each coaxial input is assumed to be terminated with a characteristic impedance on the output side _. ). That is, the input voltages E ₆ and E 7 of the lines 6 and ₇ are E ₆ = E ₇ = E/2, or the input terminal voltages E ₈ to E ₁₀ of the lines 8 to 10 are E ₈ = E ₉ = E ₁₀ = It is E/3. The input currents I ₆ to I ₁₀ of each line are I ₆ = I ₇ = E/2Z ₀ I ₈ = I ₉ = I ₁₀ = E/3Z ₀ . Since the current I flowing from the input terminals 13 and 22 is 5E/6Z ₀ , the input impedance of the transformer is E/I=6Z ₀ /5 (1). Then, the input voltage at the output end of each line,
Since the current appears as it is, the voltage at the output terminal
E ₆ ′ to E ₁₀ ′ and current I ₆ ′ to I ₁₀ ′ are E ₆ ′=E ₇ ′=E/2 E ₈ ′=E ₉ ′=E ₁₀ ′=E/3 I ₆ ′=I ₇ ′=E/2Z ₀ I ₈ ′=I ₉ ′=I ₁₀ ′=E/3Z ₀ . And the voltage between output terminals 25 and 34
E' is: E'=E/2+E/3=5E/6 Also, the current flowing to the output terminals 25 and 26 is I'=E/Z ₀ Therefore, the impedance between the output terminals 25 and 26 is: E'/I'=5Z ₀ /6 ...(2) Considering equations (1) and (2), the input impedance is set to 6Z ₀ /5, and the distance between output terminals 25 and 34 is 5Z ₀ /
If the line is terminated with an impedance of 6, the voltage and current will be matched, and the voltage-current relationship of each line will be as described above. In other words, each line is equivalent to being terminated with a characteristic impedance Z ₀ , and the first assumption holds true. In other words, this transformer is 6Z ₀ /5:5Z ₀ /
6, that is, the impedance ratio (6/5) ² :1
It can be used as a transformer. This impedance ratio is approximately 75Ω:50Ω. At medium and low frequencies, this transformer operates as a 72Ω:52Ω transformer, with almost no relation to the characteristic impedance Z ₀ of the line mentioned above, but at high frequencies, Z ₀ must be set to √72×52. . That is, if the above transformer is formed using a line with a characteristic impedance of about 60Ω, a transformer with a characteristic impedance of about 72Ω:50Ω can be obtained. Also,
For example, if you use a line with a characteristic impedance of 87Ω, you will get a 104Ω:73Ω transformer.

Figure 3 a and b show a characteristic impedance of approximately 60
A transformer with the configuration shown in Figure 2 is formed using a coaxial line of Ω and a ferrite core, and approximately 75Ω: 50
The actual measured values of mismatch attenuation and operating attenuation when using a Ω transformer are shown. In each figure, the horizontal axis indicates frequency, and the vertical axis indicates mismatch attenuation and operational attenuation, respectively. In each figure, the dotted lines indicate the characteristics when the conventional transformer of FIG. 1a is formed using a core made of the same material. As is clear from these figures, when designing for low frequency characteristics, there is a significant difference in high frequency characteristics, and it is understood that the present invention is effective. Note that the low-frequency characteristics can be improved by increasing the core size.

FIG. 4 is a perspective view showing a second embodiment of the present invention. In this case, the fifth coaxial line 10 does not pass through the core 5. The input terminal 22 and the output terminal 34 are grounded. In this way, the input end 21 and the output end 3 of the coaxial line 10
3 are both grounded, there is no need to surround the coaxial line 10 with a magnetic material. That is, the sixth
In the equivalent circuit diagram shown in the figure, the winding ends 21 and 33 are short-circuited. At this time, no current flows back through the external conductor due to stray capacitance or the like. This case has the advantage of requiring fewer cores.

FIG. 5 is a perspective view showing a third embodiment of the present invention. Each line is not surrounded by a separate core, but five insertion holes 4 are bored in a common core, and each coaxial type line 6 to 10 is inserted into each insertion hole. In this case, since only one core is required, there is an advantage that the structure is simple and strong.

[Effect of idea]

As described above, in this invention, five lines are used, and the line connection combinations at the input end and the output end are different, while keeping the voltage-current ratio of each line equal to the characteristic impedance. Therefore, an impedance conversion transformer with a wide band can be obtained without deteriorating high frequency characteristics.

[Brief explanation of the drawing]

FIGS. 1a and 1b are a perspective view and an equivalent circuit diagram showing an example of a conventional impedance conversion transformer. FIG. 2 is a perspective view showing the first embodiment of the present invention. FIG. 3 is a diagram showing an example of the characteristics of a transformer according to an embodiment of the present invention. FIG. 4 is a diagram showing a second embodiment of the present invention. FIG. 5 is a diagram showing a third embodiment of the present invention. FIG. 6 is an equivalent circuit diagram of the first embodiment of the present invention. 1, 5...Magnetic core, 2...Input winding, 3
... Output winding, 4 ... Hole drilled in the core, 6 to 1
0...Coaxial line, 11, 12, 16, 17, 1
9... Center conductor on the input side, 14, 15, 18, 2
0, 21... Input side external conductor, 13, 22...
Transformer input terminals, 23, 24, 27, 28, 3
0... Center conductor on the output side, 26, 29, 31, 3
2, 33... Output side external conductor, 25, 34...
Transformer output terminal.

Claims (1)

[Claims for Utility Model Registration] First to fifth coaxial lines 6 to 10 are provided, and the first coaxial line 6 has its input side internal conductor connected to one end 13 of the input terminal, and its output side The inner conductor of the second coaxial line 7 is connected to one end 25 of the output terminal, the input inner conductor of the second coaxial line 7 is connected to the input outer conductor of the first coaxial line, and the output inner conductor of the second coaxial line 7 is connected to the input outer conductor of the first coaxial line. The third coaxial line 8 is connected to one end 25 of the terminal, and its output side outer conductor is connected to the output side outer conductor of the first coaxial line, and the input side inner conductor of the third coaxial line 8 is connected to one end of the input terminal. The fourth coaxial line 9 has its output internal conductor connected to the output external conductor of the second coaxial line, and the input internal conductor of the fourth coaxial line 9 has its output side internal conductor connected to the input side of the third coaxial line. The fifth coaxial line 10 is connected to an internal conductor on its output side, and its output side internal conductor is connected to the output side internal conductor of the third coaxial line, and the input side internal conductor of the fifth coaxial line 10 is connected to the output side internal conductor of the fourth coaxial line. and its output internal conductor is connected to the output internal conductor of the fourth coaxial type line, and the input external conductor of the second coaxial type line and the fifth coaxial type line. The input external conductor of the line is connected to the other end 22 of the input terminal, and the output external conductor of the third coaxial line, the output external conductor of the fourth coaxial line, and the fifth coaxial line An impedance conversion transformer characterized in that an output side external conductor is connected to the other end 34 of the output terminal, and at least the first to fourth coaxial lines are surrounded by a magnetic material.