RF directional coupler circuit assembly for matching high frequency cable TV apparatus

An RF directional coupler circuit assembly for matching high frequency cable TV apparatus includes a cover body, and a printed circuit board. The cover body includes a space. The space includes a bottom surface. An RF directional coupler circuit is arranged on the printed circuit board. A 0.01 mm˜2 mm gap is formed between the RF directional coupler circuit and the bottom surface when the printed circuit board is deposited in the space. The distance between the printed circuit board and the cover body is shorten because of the gap, so that the reflections of the high frequency signals and the signal fading are decreasing to achieve matching high frequency impedance characteristics.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high frequency cable TV apparatus, and in particular to an RF directional coupler circuit having improved high frequency (1.0 GHz or above 1.0 GHz) impedance matching with signal taps of high frequency cable TV apparatus.

2. Description of Prior Art

Currently the signals of cable TV are tapped and transmitted by the cable TV apparatus, so that the signals of cable TV are transmitted to different buildings or communities. Accordingly, users in the buildings or communities can watch cable TV programs.

Currently the frequencies of the signals of cable TV are higher and higher (1.0 GHz), so that when the signals of cable TV are transmitted, the signals of cable TV are fading, and the image quality of TV in client sites is worse. The main reason is that the high frequency impedance is not matching.

A conventional cable TV apparatus10(as shown in theFIG. 1) includes a cover body101having a space102. A printed circuit board20is arranged on a plurality of protruding pillars103in the space102. A long distance30is formed between the printed circuit board20and the bottom of the space102. When the high frequency signals are transmitted through an RF directional coupler circuit201on the printed circuit board20, there are a lot of signal reflections because of the distance30, so that the impedance is not matching, the signals of cable TV have serious fading, and the image quality of TV in clients is worse.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to solve the disadvantages of the conventional cable TV apparatus. The present invention is to provide a design shortening the distance between the printed circuit board and the bottom surface of the cover body, for improving high frequency impedance matching for RF directional coupler circuits inside RF directional couplers and signal taps of high frequency cable TV apparatus.

Another object of the present invention is to match a metal plate with the layouts or components on the printed circuit board, to decrease the fading of the transmitted high frequency signals.

In order to achieve the object mentioned above, the present invention is to provide a RF directional coupler circuit assembly for matching high frequency cable TV apparatus. The RF directional coupler circuit assembly for matching high frequency cable TV apparatus includes a cover body, and a printed circuit board.

The cover body includes an edge part. An enclosure wall is provided within the edge part. A joint trough is between the edge part and the enclosure wall. The joint trough is used to assemble the cover body with a base body of the high frequency cable TV apparatus. Besides, a space is defined in the enclosure wall. A plurality of protruding pillars is provided on a bottom surface of the space. Each of the protruding pillars includes a threaded hole. The protruding pillars are used to support the printed circuit board. The printed circuit board is screwed to the threaded holes to be fixed on the protruding pillars. Besides, the edge part includes a plurality of protruding parts. Each of the protruding parts includes a screw bolt for assembling and screwing with the base body of the high frequency cable TV apparatus.

The printed circuit board is disposed in the space. The printed circuit board includes a plurality of through holes. The printed circuit board is disposed on the protruding pillars with a plurality of screws screwing to the threaded holes through the through holes. Besides, an RF directional coupler circuit is on the printed circuit board. After the printed circuit board is disposed on the protruding pillars, a gap is formed between the RF directional coupler circuit on the printed circuit board and the bottom surface of the space.

Moreover, the gap between the bottom surface and the RF directional coupler circuit is 0.01 mm˜2 mm. The reflections of the high frequency signals and the signal fading are decreasing to match the high frequency impedance characteristics when the high frequency signals are transmitted.

In order to achieve another object mentioned above, the present invention is to mount a metal plate on the printed circuit board. The metal plate is nearby the RF directional coupler circuit on the printed circuit board, so that the metal plate matches the layouts or components on the printed circuit board, to decrease the fading of the transmitted high frequency signals.

DETAILED DESCRIPTION OF THE INVENTION

Regarding the technology and the detailed description of the present invention, now describe with diagrams as below:

FIG. 2shows an exploded view of a high frequency cable TV apparatus of the present invention.FIG. 3shows a perspective view of a high frequency cable TV apparatus of the present invention. As shown in theFIG. 2and theFIG. 3, the high frequency cable TV apparatus of the present invention includes a cover body1, and a printed circuit board2.

The cover body1includes an edge part11. An enclosure wall12is provided within the edge part11. A joint trough13is between the edge part11and the enclosure wall12. The joint trough13is used to assemble the cover body1with a base body of the high frequency cable TV apparatus (not shown in the Fig.). Besides, a space14is defined in the enclosure wall12. A plurality of protruding pillars15is provided on a bottom surface141of the space14. Each of the protruding pillars15includes a threaded hole151. The protruding pillars15are used to support the printed circuit board2. The printed circuit board2is screwed to the threaded holes151such that the printed circuit board2is fixed on the protruding pillars15.

A metal bump16is provided on the bottom surface141of the space14. One side of the printed circuit board2is closer to the cover body1because of the metal bump16. Besides, the edge part11includes a plurality of protruding parts17. Each of the protruding parts17includes a screw bolt18for assembling and screwing with the base body of the high frequency cable TV apparatus (not shown in the Fig.).

In theFIG. 2and theFIG. 3, the metal bump16and the cover body1are integrally-formed. Or the metal bump16and the cover body1are separately-formed, but the metal bump16could be added into the space14of the cover body1when the metal bump16is required. Moreover, the high frequency cable TV apparatus includes an RF directional coupler and a signal tap.

The input signals of cable TV are processed by the printed circuit board2, and then transmitted to the next high frequency cable TV apparatus or clients. The printed circuit board2includes a plurality of through holes21. The printed circuit board2is disposed on the protruding pillars15with a plurality of screws23, where the screws are screwed to the threaded holes151through the through holes21.

Besides, an RF directional coupler circuit22is provided on the printed circuit board2. After the printed circuit board2is disposed on the protruding pillars15, the RF directional coupler circuit22is disposed corresponding to the metal bump16in the space14to form a gap3between the printed circuit board2and the metal bump16. Shortening the distance between the printed circuit board2and the cover body1(cabinet) will achieve the high frequency impedance matching. In the Fig., the gap3is 0.01 mm˜2 mm.

FIG. 4shows a circuit diagram of the RF directional coupler circuit of the high frequency cable TV apparatus of the present invention.FIG. 5shows a sectional view of the combination of the cover body and the printed circuit board of the high frequency cable TV apparatus of the present invention. As shown in theFIG. 4and theFIG. 5, the RF directional coupler circuit22is electrically connected to a first port24, a second port25, and a third port26. After the signals of cable TV are inputted into the first port24, the signals of cable TV are processed by the RF directional coupler circuit22, and then outputted from the third port26to clients.

Because the printed circuit board2is disposed corresponding to the metal bump16of the cover body1, the distance between the printed circuit board2and the cover body1(cabinet) is shorten, and the reflections of the transmitted signals and the signal fading are decreasing to achieve matching high frequency impedance characteristics when the frequency of the input signal is 1.0 GHz or above 1.0 GHz.

The printed circuit board2is fixed on the cover body1, so that the RF directional coupler circuit22of the printed circuit board2is corresponding to the metal bump16in the space14to form the gap3between the printed circuit board2and the metal bump16. The high frequency impedance matching could be adjusted by the width of the gap3. Moreover, the gap3could be used for waveguide.

FIG. 6shows a diagram of another embodiment of the present invention. As shown in theFIG. 6, a metal plate4is mounted on the printed circuit board2and nearby the RF directional coupler circuit22, so that the metal plate4matches the layouts or components on the printed circuit board2, to decrease the fading of the transmitted high frequency signals.

FIG. 7shows a diagram of another embodiment of the present invention. As shown in theFIG. 7, the disclosed technology is similar withFIG. 2toFIG. 5. The difference is that the bottom surface141of the space14is higher, so that when the printed circuit board2is deposited in the space14, the distance between the bottom surface141of the space14and the printed circuit board2is shorten. Accordingly, a 0.01 mm˜2 mm gap3is formed between the RF directional coupler circuit22on the printed circuit board2and the bottom surface141of the space14. The gap3is used to decrease the reflections of the high frequency signals and the signal fading to achieve matching high frequency impedance characteristics when transmitting high frequency signals.