JPS6040026Y2 - turnout - Google Patents

Description

[Detailed description of the invention] This invention relates to a branching device used in communal reception facilities such as televisions.

In a conventional branching switch, a primary coil of a first coupling transformer is connected between the input terminal and the output terminal, and a second coupling transformer in the form of an autotransformer is connected between the input terminal and the ground. A configuration in which the second coupling transformer of the transformer is connected, and the intermediate terminal of the second coupling transformer is connected to the branch terminal along with one end of the secondary coil of the first coupling transformer is reverse coupling. It had the disadvantage of small losses.

In order to solve this problem, it was considered to insert a resistor between the input terminal and the ground through the second coupling transformer, but in such a circuit, the reverse coupling loss If the resistance value is set to be large, the VSWR will be bad, and if the VSWR is set to be good, the reverse coupling loss will be small. There is a drawback that the characteristic values are limited to values that take each other into consideration.

Therefore, in communal reception facilities using this branch, the image quality of the connected television receiver may sometimes deteriorate, or
Alternatively, a problem may arise in that an interference signal emitted from one location appears on many other television receivers.

Therefore, the present invention is designed to eliminate the above-mentioned drawbacks, and the V
It is an object of the present invention to provide a splitter in which both SWR and reverse coupling loss can take the best values without being affected by each other.

The drawings showing the embodiments of the present application will be described below.

Figure 1 shows the circuit of a branch. In the figure, 1 is an input terminal, 2 is an output terminal, and 3 is a branch terminal. When a branch is incorporated into various circuits, it may be constructed as a mere conductor for connection to other circuits.

T1 is a first coupling transformer, which has a core T1C made of a ferromagnetic material (for example, a ferrite material), a primary coil T1a, a secondary coil T1a, and a Tl
b.

It is constructed by winding a primary coil T1a and secondary coils T and b.

The turns ratio between the primary coil T1a and the secondary coil T1b is determined depending on the amount of signal (coupling loss value) transmitted from the primary coil T1a side to the secondary coil T1b side. For example, When the coupling loss is 118 dB, the turns ratio is 1
: Will be reduced to 3.

T2 is a second coupling transformer that matches the impedance of the branch terminal 3 with the characteristic impedance of a circuit connected thereto (for example, a transmission line of a community reception facility), and its configuration is the same as that of the first coupling transformer described above. The coupling transformer T1
The primary coil T2a and the secondary coil T are attached to the same core T2C.
The primary coil T2a is configured by winding the primary coil T2b.
and the secondary coil T2b are configured like an autotransformer.

In addition, the turns ratio of these coils T2a and T2b is determined in order to obtain the above-mentioned impedance matching effect and according to the above-mentioned coupling loss value. For example, the characteristic impedance of each terminal 1.3 is set to 75Ω and the coupling loss value is 11 odB, the turns ratio is 3:
Becomes 1.

R1 is a first resistor designed to match the impedance of the branch terminal 3 with the characteristic impedance of the circuit connected thereto.

Although its value varies depending on the impedance described above, it is mainly selected within the range of 50 to 150Ω.

R2 is a second resistor, which is used to increase the reverse coupling loss from the branch terminal 3 to the output terminal 2, and its value can be determined by, for example, the reverse coupling loss as described later. The value is chosen such that it is the largest.

Next, FIGS. 2 and 3 show the characteristics of a branch circuit constructed as described above and measured for it, as well as the same person who used the conventional circuit to obtain the best characteristics. This is a graph comparing the characteristics measured for a designed and manufactured product.

(The solid line shows the characteristics of the circuit of this embodiment, and the broken line shows the characteristics of the conventional circuit.

In addition, the design value of the circuit and the value of each element are such that the impedance is 7.
50, coupling loss is -□.

dB, the value of resistance R□ is 57Ω, and the value of resistance R2 is 2350
, the value of the resistance in the conventional circuit is 143.

) As is clear from these figures, in the brancher of this example, the coupling loss is as designed, and the VSWR and reverse coupling loss of the branch terminal are both much better values than those of the conventional circuit. was gotten.

Next, FIGS. 4 and 5 show a method for determining utt R2 when designing and manufacturing the above-mentioned turnout.

First, the resistance R1 is determined by a circuit as shown in FIG.

That is, a well-known sweep signal generator 11, a VSWR bridge 12, a wave detector 13, an oscilloscope 14, and the above-mentioned branching device A are connected as shown.

Further, the resistor R1 in the branching device A is replaced with a variable resistor VR1, and the input/output terminals 1 and 2 are terminated with a terminator ro having a target characteristic impedance (for example, 75Ω).

In this state, each measuring device is operated and the variable resistor VR
The resistance value of 1 is changed sequentially, and the oscilloscope 14
The size of the reflected wave displayed on the screen should be minimized.

The resistance value of the variable resistor VR1 in this state is the resistance R1
The value should be .

Next, the resistance w2 is determined by a circuit as shown in FIG.

That is, the above-mentioned measuring devices are connected as shown, and the resistor R2 in the branch A is replaced with a variable resistor R2.

In this state, the same operation as above is performed, and the resistance value of the variable resistor VR2 when the value of the signal displayed on the oscilloscope 14 becomes the smallest is set as the value of the resistor R2.

Next, FIG. 6 shows a different embodiment of the present application, in which a commercial frequency low-voltage alternating current (
For example, it shows a circuit that allows the passage of AC (24 to 30 V), and C□ and C2 are capacitors that block the passage of the above-mentioned low-voltage AC but allow high-frequency signals (for example, TV signals) to pass. .

It should be noted that parts that are functionally the same or equivalent to those of the previous embodiment are given the same reference numerals as those of the previous embodiment with the letter "e", and redundant explanations are omitted.

(Also, in the following example, the same idea is used, and the alphabet f is added to omit the redundant explanation.

) Next, in Figure 7, the impedance of the branch terminal 3f is 300.
This is a terminal to which a (200)Ω feeder can be connected.

Note that 15 is a well-known matching device, and 16 is a capacitor for passing high frequency signals.

As described above, in this invention, when a television receiver is connected to the output terminal 2 and the branch terminal 3 respectively to receive television images, the signal input to the input terminal 1 is This has the effect of providing the signal from the output terminal 2 to the receiver and the signal from the branch terminal 3 to other receivers so that each receiver can receive a television image.

Moreover, in the above case, even if the performance of the receiver connected to the branch terminal 3 is poor and a large interference signal flows back from the receiver to the branch terminal 3, in the present brancher, the first coupling transformer , one end of the primary coil is connected to the input terminal and the other end to the output terminal, and one end of the secondary coil is connected to the connection point between the primary coil and the secondary coil in the second coupling transformer, and the other end is connected to the connection point of the primary coil and the secondary coil in the second coupling transformer. In the second coupling transformer, the connection point between the primary coil and the secondary coil is connected to a branch terminal, and the other end of the secondary coil is grounded through the first resistor, and the primary coil Since a second resistor is interposed between the other end and the input terminal, an unprecedentedly large reverse coupling loss is obtained, and the interference signal flowing back to the branch terminal 3 is transferred to the output terminal 2. It is possible to extremely reduce the amount of leakage and output from the output terminal 2, which prevents interference with the image in the receiver that receives the TV signal from the output terminal 2 and produces a high-quality image. It has practical effects that can be continued.

Furthermore, when receiving images with the receivers connected to the output terminal 2 and the branch terminal 3, the splitter of the present invention should be provided with the first and second resistors R1 and R2 separately as described above. Therefore, not only can a large reverse coupling loss as described above be obtained, but also the VSWR values of output terminal 2 and branch terminal 3 are extremely good, and both of the above-mentioned receiver types can produce high-quality images without double images. There are effects that can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a circuit diagram of a branch switch, FIG. 2 is a graph showing characteristics of each loss, FIG. 3 is a graph showing VSWR characteristics of a branch terminal, and FIGS. FIG. 5 is a schematic diagram showing the state in which the value of each resistor is determined at the time of design, and FIGS. 6 and 7 are diagrams showing different embodiments. 1...Input terminal, 2...Output terminal, 3
...Branch terminal, T□...First coupling transformer, T2...Second coupling transformer, R□,
R2...Resistance.

Claims (1)

[Scope of utility model registration request] A first coupling transformer having a primary coil and a secondary coil, and a second coupling transformer having a primary coil and a secondary coil, both of which are in the form of an autotransformer, are separated from each other. In the first coupling transformer, one end of the primary coil is connected to the input terminal and the other end to the output terminal, and one end of the secondary coil is connected to the connection point between the primary coil and the secondary coil in the second coupling transformer. In the second coupling transformer, the connection point between the primary coil and the secondary coil is connected to the branch terminal, the other end of the primary coil is connected to the input terminal, and the other end of the primary coil is connected to the input terminal. In a brancher whose other end is grounded, the other end of the secondary coil in the second coupling transformer is grounded via the first resistor, and the other end of the primary coil in the second coupling transformer is grounded through the first resistor. A branching switch characterized in that a second resistor is interposed between the input terminal and the input terminal.