JPH0715245Y2 - Antenna shield box with mixer - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION The present invention mixes a VHF signal transmitted by a 75Ω coaxial cable and a UHF signal transmitted by a 300Ω parallel two-wire feeder line, and eliminates a ghost caused by mixing a VHF signal into the feeder line. The present invention relates to an antenna shield box with a mixer to prevent.

[0002]

Problems to be Solved by the Prior Art and Invention: 75Ω
As is well known, a mixer (mixer) that mixes the VHF signal from the coaxial cable and the UHF signal from the 300Ω feeder line and outputs the mixed signal to the 75Ω coaxial cable, after passing the UHF signal through a 300Ω / 75Ω impedance conversion transformer. , Which is given to the signal mixing circuit and mixed with the VHF signal, at this time, the VHF band signal mixed with the UHF signal transmitted by the 300Ω parallel two-wire feeder line is also mixed at the same time, and a ghost is generated when the VHF is received. There was something to do.

Further, conventionally, the antenna shield box for connecting the antenna side and the tuner side is formed separately from the mixer, and no particular countermeasure has been taken for the ghost radio wave entering the mixer portion.

Therefore, an object of the present invention is to provide an antenna shield box with a mixer capable of removing a VHF band signal mixed in the UHF signal and preventing a ghost due to this.

[0005]

In order to achieve the above-mentioned object, the antenna shield box with a mixer of the present invention is
A terminal board provided with a 75Ω VHF input terminal for a coaxial cable to which a VHF signal is applied and a 300Ω UHF input terminal for a parallel two-wire feeder line to which a UHF signal is applied, and 300
An impedance conversion transformer for outputting the UHF signal from the ΩUHF input terminal to the 75Ω circuit and the impedance conversion transformer integrally provided on the back surface of the terminal plate, and connected to the external side of the 75ΩVHF input terminal and one terminal of the impedance conversion transformer. Shield box, a signal mixing circuit housed in the shield box for mixing the UHF signal and the VHF signal, and UHF / VH mixed by the circuit
An output terminal for outputting an F mixed signal is provided, and a UHF band pass filter for cutting a VHF band signal included in the UHF signal is provided in a UHF signal input section of the signal mixing circuit.

[0006]

[Operation] According to the above configuration, V mixed in the UHF signal
The HF band signal is removed by the UHF band pass filter. Therefore, the signal mixing circuit should be
3 from the VHF signal to the ΩVHF input terminal and the feeder line
The UHF signal is applied to the 00Ω UHF input terminal. Further, since the signal mixing circuit is housed in the shield box, it is possible to prevent ghost radio waves and the like from entering the circuit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a front view of the same from the terminal board side, FIG. 3 is a side view, FIG. 4 is a sectional view of a shield box, and FIG. 5 is a shield box. FIG.

The antenna shield box 1 with a mixer is
Impedance conversion for impedance conversion to output a 75 Ω VHF input terminal 2 for a coaxial cable and a 300 Ω UHF input terminal 3 for a parallel two-wire feeder line and a UHF signal from the 300 Ω UHF input terminal 3 to a 75 Ω circuit. The transformer 5, the shield box 6 integrally provided on the back surface of the terminal board 2, the VHF signal from the 75Ω VHF input terminal 2 and the UHF signal from the impedance conversion transformer 5, which are housed in the shield box 6. Signal mixing circuit 7 for mixing
And an output terminal 8 for outputting a UHF / VHF mixed signal mixed by.

The shield box 6 has 75 ΩVH.
The external conductor 2a of the F input terminal 2 and one terminal 3a of the impedance transformer 5 are connected to each other, and a predetermined resistor R and capacitor C are used on the printed circuit board 9 housed in the shield box 6. The configured signal mixing circuit 7 is configured. This signal mixing circuit 7 has 75ΩV
The internal conductor 2b of the HF input terminal 2 and the other terminal 3b of the impedance conversion transformer 5 are connected.

UH in the signal mixing circuit 7
The F signal input unit is provided with a UHF band pass filter F that cuts signals other than the UHF band, including VHF band signals. The VHF signal and the UHF signal are provided at the next stage of the UHF band pass filter F. A mixer M for mixing is provided. Therefore, in the mixer M, the UHF signal obtained by cutting the VHF band signal and the VH signal transmitted by the 75Ω coaxial cable are used.
Since the F signal is mixed, it is possible to prevent the occurrence of ghost due to the VHF band signal transmitted from the UHF signal side at the time of receiving the VHF.

The output terminal 8 has an outer conductor 8a.
Is directly connected to the external circuit 9a on the printed circuit board 9,
The inner conductor 8b is connected to the inner circuit 9b, and the coaxial cable used in the conventional antenna shield box is omitted.

This antenna shield box 1 with a mixer
As shown in FIG. 5, the 75Ω VHF input terminal 2 is provided on one side surface of the box body 6a formed by press-molding a conductive thin metal plate, and the outer conductor thereof electrically connects to the box body 6a. The printed circuit board 9 is mounted in the box body 6a via the insulating holding member 6b so that the inner conductor of the 75Ω VHF input terminal 2 and the output terminal 8 are connected. After that, an insulating inner lid 6c and a conductive outer lid 6d are attached, the terminal board 2 is further attached, and the projecting portion 9 of the printed board 9 is attached.
c to 300Ω through impedance conversion transformer 5
It can be manufactured by connecting the UHF input terminal 3.

The UHF band pass filter F and the mixer M can have an appropriate circuit configuration according to the required performance.

[0015]

As described above, in the antenna shield box with a mixer of the present invention, the mixer for mixing the VHF signal and the UHF signal is integrally housed in the antenna shield box, and the UHF signal input section of the signal mixing circuit is also included. Since the UHF band pass filter is installed in the unit, it is possible to prevent the intrusion of ghost radio waves in the VHF band, which has conventionally entered from the mixer unit, and the mixer and antenna shield box are integrated, so both are manufactured separately. It is possible to achieve a significant cost reduction compared to

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a front view of the shield box as viewed from the terminal plate side.

FIG. 3 is a side view of the same.

FIG. 4 is a sectional view of the same.

FIG. 5 is an exploded perspective view of the same.

[Explanation of symbols]

1 ... Antenna shield box with mixer 2 ... 75Ω
VHF input terminal 3 ... 300Ω UHF input terminal 4 ... Terminal plate 5 ... Impedance conversion transformer 6 ... Shield box
7 ... Signal mixing circuit 8 ... Output terminal 9 ... Printed circuit board F ... UHF band pass filter M ... Mixer

Claims (1)

[Scope of utility model registration request] 1. A terminal plate provided with a 75Ω VHF input terminal for a coaxial cable to which a VHF signal is applied and a 300Ω UHF input terminal for a parallel two-wire feeder line to which a UHF signal is applied, and a UHF signal from the 300Ω UHF input terminal.
An impedance conversion transformer for outputting to a 5Ω circuit and a 75ΩVH provided integrally on the back surface of the terminal board.
A shield box to which the external side of the F input terminal and one terminal of the impedance conversion transformer are connected, and the UHF signal and VH housed in the shield box.
A signal mixing circuit for mixing the F signals, and an output terminal for outputting the UHF / VHF mixed signal mixed by the circuit, and the UHF signal input section of the signal mixing circuit,
UH that cuts the VHF band signal included in the UHF signal
An antenna shield box with a mixer provided with an F band pass filter.