JPS6276917A - Two-way branching device - Google Patents

Abstract

PURPOSE:To allow the titled two-way branching device to act like a complete 2-way branching device as to a high frequency signal by short-circuiting input and output terminals in terms of high frequencies, inserting impedance to a coupling point of the input and output terminals and using an impedance matching transformer so as to branch the signal. CONSTITUTION:A signal inputted from an input terminal 1 is outputted almost as it is to an output terminal 2, a part of the input signal passes through a high pass capacitor C1 and is outputted to a branch terminal 3 through a resistor R, an impedance matching transformer T and a high pass capacitor C2. Then the signal inputted from a branch terminal 3 is transmitted in a direction opposite to the said direction and outputted uniformly to the input terminal 1 and the output terminal 2. The input terminal 1 and the output terminal 2 are coupled in such a way and branched from the coupling point through the impedance matching transformer T to make the signal flow completely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a bidirectional splitter for use in broadband bidirectional transmission lines, such as home bus systems.

2. Description of the Related Art Recently, branchers used in broadband transmission lines have come into widespread use in fields such as CATV and home bus systems. This turnout is, for example, P in "Reception System Handbook 2nd Edition" edited and published by the Television Reception Improvement Committee (published in December 1978, Japan Broadcasting Publishing Association).
The configurations of transformer type branchers and stripline type branchers described in Nos. 52 and 53 are known. Below, the second
A conventional turnout will be explained with reference to the drawings.

In Figure 2, 1 is an input terminal for inputting a signal, 2 is an output terminal for outputting a signal from input terminal 1, 3 is a branch terminal for branching and taking out a signal from input terminal 1, and 4 and 5 are input terminals. a coupler for coupling l and branch terminal 3, 6
is resistance.

The operation of the above configuration will be explained below.

First, a signal input from input terminal 1 flows to output terminal 2, and at the same time, an output of l/n2 appears at branch terminal 3 by coupler 4.5. Also, if a signal is added from branch terminal 3,
1/n" signal appears at input terminal 1, and the remaining 1-1/n
'The signal is absorbed by the resistor 6, and ideally no signal appears at the output terminal 2.

Since the incoming power is equal to the sum of the outgoing or absorbed power, there is a correlation between the power loss between input terminal 1 and output terminal 2 and the loss between input terminal 1 and branch terminal 3. Input terminal 1 and output terminal 2 depending on whether to use clB
The insertion loss between the two is determined.

The commonly used single splitter has an insertion loss of around 1 dB.
The standard branch loss is around 10 dB.

Problems to be Solved by the Invention However, with the above configuration, the signal input from the branch terminal 3 hardly appears at the output terminal 2, and conversely, the signal input from the output terminal 2 also appears at the branch terminal 3. There is a problem in that two-way signal transmission cannot be carried out because the signal becomes difficult to appear.

The present invention solves the above-mentioned problems of the prior art, and aims to provide a completely bidirectional low frequency power passing type branching switch.

Means for Solving the Problems The present invention short-circuits the input terminal and the output terminal at a high frequency, inserts an impedance from the connection point of the input terminal and the output terminal, and further branches using an impedance matching transformer. This achieves the above objective.

Effects of the present invention With the above configuration, the input loss between the input terminal and the output terminal is reduced, and the branch output is taken out from the branch terminal via an impedance from the connection point of the input terminal and the output terminal. When viewed from above, the input terminal and the output terminal are equivalent, and the connection between the branch terminal and the output terminal is the same as the connection between the branch terminal and the input terminal, making it possible to realize complete bidirectionality.

EXAMPLE A first example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a completely bidirectional low frequency pass type branching switch in one embodiment of the present invention.

In Fig. 1, input terminal 2 to which a signal is input is an output terminal to output the signal input from input terminal 1, 3 is a branch terminal to branch and take out the signal input from input terminal 1, C,... C, is a capacitor that blocks power current transmitted at low frequency and passes signal current, R is a resistor that adjusts branch loss, and T is branch terminal impedance (]IT
This is an impedance matching transformer (usually 75π or 50π).

The operation of the above configuration will be explained below.

First, the signal input from the input terminal l is outputted as is to the output terminal 2, and a part of the input signal passes through the high frequency passing capacitor C1, the resistor R, the impedance matching transformer T1, and the high frequency passing capacitor C1. It passes through C2 and is output to branch terminal 3.

On the other hand, the signal manually input from the branch terminal 3 is transmitted in the opposite direction as described above, and is equally output to the input terminal 1 and the output terminal 2.

At this time, the branch loss is the impedance of the output terminal 2 (
Usually 75π or 50π) and high frequency passing capacitor C
If the total output impedance of branch terminal 3 is 75π, the impedance of branch terminal 3 side gold from 1 is R+75K.
(-a) Here, m and n are the numbers of windings on the primary and secondary sides of the impedance matching transformer T.

The values of m, n, and resistance H are determined by the insertion loss of the target branching device, the value of branching loss, and the permissible value of the standing wave ratio at each terminal of the input, output, and branch.

As is clear from the above description, according to this embodiment, the input terminal 1 and the output terminal 2 are coupled, and the signal flow is completely controlled by branching from this coupling point using the impedance matching transformer T. It can be bidirectional.

In the above explanation, the impedance R is a resistance. However, if the branch loss has frequency characteristics, the impedance R may be a capacitor or a coil. A complex and 11 may also be used. Furthermore, if the necessary insertion loss, branching loss, etc. can be achieved only with the impedance matching transformer, the impedance R can be omitted. Furthermore, the impedance matching transformer can also be a transformer with a center tap.

Further, in the above description, one branch has been described, but another branch circuit may be inserted in parallel from the connection point of the input terminal and the output terminal to form a plurality of branchers having two or more branches.

Effects of the Invention As described above, the present invention connects an input terminal and an output terminal, passes a high frequency passing capacitor from this coupling point, passes an impedance and an impedance matching transformer, and outputs a branched output through a second high frequency passing capacitor. With the simple configuration of taking out the signal, it can be operated as a complete bidirectional splitter for high frequency signals, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a complete bidirectional branching switch according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional branching switch. ■...Input terminal, 2...Output terminal, 3...Branch terminal, C,, C2...Capacitor, R...Resistor, T...
・Transformer for impedance Matsushi ink. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2

Claims (5)

[Claims] (1) An input terminal and an output terminal that are connected to each other, a first capacitor that allows a high frequency signal to pass through the connection point and blocks direct current or low frequency current, and one end of which is connected to the first capacitor, an impedance for adjusting insertion loss and branching loss; an impedance matching transformer having one end connected to the impedance; and a second impedance matching transformer connected to the other end of the impedance matching transformer for blocking direct current or low frequency current. A bidirectional splitter comprising a capacitor and a branch terminal connected to the other end of the second capacitor. (2) The bidirectional branching switch according to claim 1, wherein the impedance is one selected from a resistor, a capacitor, and a coil, or a combination thereof. (3) The capacitor and coil are the first and second capacitors,
Alternatively, the bidirectional branching device according to claim 2 is characterized in that it is an impedance matching coil. (4) Claim 1, characterized in that it has two or more branch terminals from the connection point between the input terminal and the output terminal.
Two-way turnout as described in section. (5) The bidirectional branching device according to claim 4, wherein the plurality of branch terminals have different branch loss terminals by changing the impedance or the turns ratio of the impedance matching transformer. .