JPH0136324Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a plug seat with a built-in filter circuit.

There is something commonly called a down converter for satellite broadcast reception. This mixes the broadcast signal transmitted in the 12 GHz band from the broadcasting satellite with the local oscillation signal of the local oscillation circuit, extracts the difference signal in the 1 GHz band, and sends it out from the output terminal as a transmission signal.

Since this down converter handles an extremely high frequency, local oscillation signals are likely to leak from the output terminal, and to prevent this, the local oscillation circuit must be adequately shielded. However, it is difficult to sufficiently shield the local oscillator circuit, and if an attempt is made to sufficiently shield the down converter, the structure of the box body of the down converter becomes complicated, resulting in an increase in manufacturing costs.

This invention aims to solve the above-mentioned drawbacks by providing a plug seat with a built-in filter that is connected to the output terminal of a down converter and reduces local oscillation signals leaking from the output terminal.

Therefore, the plug seat with a built-in filter of this invention has a first coaxial plug connected to the output terminal of the satellite broadcast receiving converter at one end of the cylindrical outer shell, and a coaxial cable at the other end of the outer shell. A second coaxial plug for connection is provided, and a filter consisting of a plurality of reactance elements composed of strip lines and set to a characteristic that attenuates the local oscillation frequency signal of the satellite broadcast receiving converter is installed inside the outer shell. A reactance element composed of a strip line located on the input side of the filter is connected to the center terminal of the first coaxial plug, and a reactance element composed of a strip line located on the output side of the filter is connected to the second coaxial connector. It is connected to the center terminal of a coaxial plug.

The filter built-in connector seat configured in this way is
Connect the jack to which the input side of the filter circuit is connected directly to the output terminal of the down converter, and connect the jack to which the output side of the filter circuit is connected to the coaxial cable that was originally connected to the down converter. be done.

Therefore, the local oscillation signal leaking from the output terminal of the down converter is reduced by the built-in filter, which simplifies the shielding of the local oscillation circuit in the down converter and reduces the manufacturing cost of the down converter. Can be lowered. Moreover, since the center terminals of the two coaxial connectors are directly connected to reactance elements composed of strip lines located on the input and output sides of the filter, separate strip lines for connecting the coaxial connectors are provided. This is not necessary, the circuit configuration can be simplified, and the manufacturing cost of the filter can be reduced.

Examples of this invention will be described below.

In FIGS. 1 to 3, 2 is a cylindrical outer shell having a male thread 4 at one end and a male thread 6 and a hexagonal part 8 at the other end, and this outer shell 2 is made of conductive material such as iron or aluminum. It is integrally formed with an object that has a

Inside the outer shell 2 is a rectangular single-sided printed circuit board 10.
is positioned so that its longitudinal central axis and the central axis of the outer shell 2 coincide.

As shown in FIG. 4, the upper surface of the single-sided printed circuit board 10 is made up of rectangular copper foil patterns 12a arranged at intervals, and linear copper foil patterns 12b connecting the copper foil patterns 12a. A copper foil pattern 12 is etched.

Furthermore, notches 14 and 16 are provided at both lengthwise ends of the single-sided printed circuit board 10, and these notches 14 and 16 are located within the copper foil pattern 12a located on both outer sides of the copper foil pattern 12. ing. As shown in FIG. 3, the notch 14 has a female center terminal 18, and the notch 16 has a male center terminal 20.
are respectively inserted and soldered to the copper foil pattern 12a.

Note that 22 is a waterproof rubber bushing that insulates the female center terminal 18 from the outer shell 2 and positions it on the central axis of the male screw 4. The outer shell 2 is in pressure contact with the outer shell 2 to prevent water and the like from entering the outer shell 2. 24 again
is a spacer that insulates the male center terminal 20 from the outer shell 2 and positions it on the central axis of the male screw 6.

The filter built-in connector seat configured in this way is
The copper foil pattern 12 and the conductive outer shell 2 constitute a microstrip line, which operates in the same way as a low-pass filter circuit consisting of a coil 26 and a capacitor 28 shown in FIG. As shown in FIG. 6, its frequency characteristics have an attenuation of about 40 dB at a frequency _L equal to the local oscillation frequency.

Therefore, the local oscillation signal leaking from the output plug of the down converter can be sufficiently reduced. Therefore, shielding of the local oscillation circuit of the down converter can be simplified. Generally, when connecting a filter composed of a coaxial plug and a microstrip line, using the pattern shown in FIG. Provide a lip line and connect it to the center terminal 1 of the coaxial connector.
In this embodiment, the center terminal 1 of the coaxial plug is connected to the copper foil patterns 12a, 12a.
8 and 20 are directly connected to each other. Therefore, there is no need for a microstrip line for coaxial plug connection, making it easier to manufacture the filter and reducing its manufacturing cost.

Note that the insertion loss in the 1 GHz band is 0.2 dB or less.

In this embodiment, in addition to simplifying the shielding, the copper foil pattern 12 on the single-sided printed circuit board 10 and the outer shell 2 constitute a microstrip line, so an expensive double-sided printed circuit is required to configure the microstrip line. It does not require the use of a substrate and can be manufactured at low cost.

In the above embodiment, a low-pass filter is constructed on the microstrip line, but a high-pass filter or a band-pass filter can also be easily constructed. However, the size of the built-in printed circuit board is limited due to the dimensions of the plug seat with a built-in filter, so the frequency range that can be used is the microwave range.

Although the outer shell 2 is made of a conductive metal, if the filter is mounted on a double-sided printed circuit board, the outer shell 2 does not necessarily have to be made of a conductive metal. Nor.

Further, although one male and one female connector are provided on the outer shell 2, two male connectors or two female connectors may be provided depending on the converter used.

[Brief explanation of the drawing]

Figure 1 is a side view of one embodiment based on this invention.
Fig. 2 is a longitudinal cross-sectional view of the same embodiment, Fig. 3 is a cross-sectional view of the same embodiment, Fig. 4 is a plan view of a single-sided printed circuit board used in the same embodiment, and Fig. 5 is an equivalent of the same embodiment. A circuit diagram showing the circuit, and FIG. 6 is a frequency characteristic diagram of the same embodiment. 2...Outer shell, {4...male thread, 18...female center terminal} (coaxial plug), {6...male thread, 20...
Male center terminal} (coaxial plug), 10...Printed circuit board, 12...Copper plate pattern.

Claims (1)

[Scope of utility model registration request] A first coaxial plug connected to an output terminal of a satellite broadcast receiving converter is provided at one end of the cylindrical outer shell,
A second coaxial connector for connecting a coaxial cable is provided at the other end of the outer shell, and is composed of a plurality of reactance elements made up of strip lines, and has the characteristic of attenuating the local oscillation frequency signal of the satellite broadcast receiving converter. A set filter is provided in the outer shell, and a reactance element composed of a strip line located on the input side of the filter is connected to the center terminal of the first coaxial plug, and the reactance element is located on the output side of the filter. A plug seat with a built-in filter, which is formed by connecting a reactance element composed of a strip line to the center terminal of a second coaxial plug.