JPS6025129Y2 - Multi-channel mixer/demultiplexer - Google Patents

Description

[Detailed description of the invention] This invention is a multi-channel device that can be used as a splitter that distributes UHF band television signal waves to each channel or a mixer that mixes television signal waves of each channel. Regarding mixing and demultiplexing filters.

Conventionally, there is a multi-channel mixing/branching circuit for mixing and distributing television signal waves of each channel in the U)(F band) as shown in FIG.

In Figure 1, 2 is a connector, and connector 2 is used as an input connector when this multi-channel mixer/brancher is used as a duplexer, and as an output connector when used as a mixer. Ru.

The outer peripheral terminal 4 of the plug 2 is grounded, and the center terminal 6 is connected to the central portion of the strip line 10 in a shielded space (not shown).

Filter circuits 12a to 12n that pass only the television signal waves of the corresponding channels are connected to the strip line 10 at equal intervals, and terminals 14a to 14n are connected to the filter circuits 12a to 12n, respectively.
is provided.

In the multi-channel mixer/brancher configured in this way, if the shape of the filter circuits 12a to 12n is large or if a large number of filter circuits 12a to 12n are connected, the strip line 10 becomes long. There were cases in which the distance from the circuits 12a to 12n coincided with 174, 172, or an integral multiple of the wavelength of the television signal wave, resulting in resonance.

If the multi-channel mixer/brancher is used as a splitter in such a state, a specific television signal wave will be increased or decreased and supplied to the filter circuits 12a to 12n, and the input to the plug 2 will be increased or decreased. There is a drawback in that the filter circuits 12a to 12n cannot obtain predetermined frequency characteristics for the television signal waves.

Therefore, correction capacitors 16a to 16n are connected between the strip line 10 and the ground.
A predetermined frequency characteristic was obtained by adjusting the capacitances of a to 16n.

However, as the number of filter circuits 12a to 12n increases, the number of correction capacitors 16a to 16n also increases.
The respective correction capacitors 16a to 16n influence each other, making adjustment difficult.

Further, there is a drawback that the loss caused by the correction capacitors 16a to 16n is large.

This invention aims to prevent the strip line 10 from resonating with the television signal wave using a simple method and provide a multi-channel mixing/branching filter with low loss.

This invention will be explained below based on illustrated embodiments.

Note that the same parts as in the conventional example are given the same reference numerals, and the description thereof will be omitted.

FIG. 2 shows a multi-channel mixer/demultiplexer which is a first embodiment of this invention, and 18a to 18 in FIG.
n is a capacitor.

These capacitors 18a to 18n are connected to the filter circuit 12.
A to 12n are connected in parallel with the strip line 10 between the connection points with the strip line 10, and the strip line 10
inductance component and parallel resonant circuits 19a to 19n
is formed.

Normally, adjacent channels are not used for television signal waves, so each filter circuit 12a to 12n has one
For example, as shown in FIG. 3, there is an empty channel between each passing frequency band 20a to 2On, and the capacitors 18a to 18n are connected so that the parallel resonant circuits 19a to 19n resonate in the frequency band corresponding to this empty channel. The capacitance is adjusted, and the frequency characteristics of the strip line 10 are as represented by the curve 21 in FIG. 3.

When the multi-channel mixer/brancher configured in this way is used as a splitter, the television signal waves of each channel input from the plug 2 are supplied to the filter circuits 12a to 12n via the strip line 10. However, the television signal wave of the unnecessary channel is connected to the parallel resonant circuit 19.
The filter circuit 12a is attenuated by a to 19n.
It is not supplied to 12n to 12n.

Similarly, when used as a mixer, the filter circuit 12
The television signal waves of unnecessary channels that could not be completely attenuated by the parallel resonant circuit 19
It can be removed from a to 19n.

Furthermore, the strip line 10 has parallel resonant circuits 19a to 1
9n, and the strip line 1
0 corresponds to 174.1/2, an integral multiple, etc. of the wavelength of the television signal wave, and there is no resonance.

FIG. 4 shows a second embodiment in which this invention is applied to a mains amplifier in a public listening system. It is configured.

The amplifiers 24a to 24n can adjust the gain,
They are connected between the filter circuits 12a to 12n of the multichannel mixer/brancher 22 and the filter circuits 12a' to 12n' of the multichannel mixer/brancher 22, respectively.

The mains amplifier thus constructed operates as follows.

Among the television signal waves of each channel input from the input terminal 2, television signal waves of unnecessary channels are transmitted to the parallel resonant circuits 19a to 19n and the filter circuit 12a.
After being attenuated by the amplifiers 24a to 12n, only the television signal waves of the necessary channels are transmitted to the amplifiers 24a to 24, respectively.
n is amplified to a certain level.

Next, the television signal waves of the unnecessary channels are attenuated again by the parallel resonant circuits 19a' to 19n' and the filter circuits 12a' to 12n', and then mixed and sent out from the plug 2.

At this time, the television signal waves of each channel can be amplified without resonance of the television signal waves on the strip lines 10, 10'.

As explained above, according to this invention, by matching the resonant frequencies of the parallel resonant circuits 19a to 19n, 19a' to 19n' to the television signal waves of unnecessary channels, the loss of the strip line 10. 10
'A multi-channel mixer/brancher that does not resonate television signal waves can be realized.

In the first and second embodiments, the plug 2 is connected to the center of the strip line 10, but it may be connected to other parts, for example, one end of the strip line 10. The spacing between 12a' and 12n' also corresponds to the parallel resonant circuits 19a to 19n and 19a' to 19n.
They do not need to be evenly spaced as long as the space is such that ' is formed.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional multi-channel mixer/demultiplexer;
The figure shows a circuit diagram of the first embodiment based on this invention, FIG. 3 shows the attenuation characteristics of the strip line and filter circuit of the same embodiment, and FIG. 4 shows a circuit diagram of the second embodiment based on this invention. be. 2.2'...Connection, 10,10'...
Strip line, 12a to 12n, 12'' to 12n'...Filter circuit, 14...
Terminals, 18a to 18n, 18a' to 18n'...
...Capacitors, 19a to 19n, 19a' to 1
9n'...Parallel resonant circuit.

Claims (1)

[Scope of utility model registration request] a first terminal, a strip line connected to the first terminal, a plurality of filter circuits each having one end attached to the strip line at a predetermined interval, and a plurality of filter circuits each attached to the other end of the filter circuit. and a capacitor connected in parallel with the strip line between the connection point of the strip line and the filter circuit.