JPH0588076U - Satellite Broadcast Converter - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a shield structure for reducing invasion of unnecessary radiation from an oscillator into an RF signal processing circuit section in a BS converter. [Structure] Satellite broadcasting radio waves are received by the antenna, and BS
The RF signal input section of the converter is guided to a circuit for high-frequency amplified signal processing. Substrate 1 equipped with this signal processing circuit
0 is attached to the chassis 2 and its circuit mounting surface is R
It is covered with the F cover 7. At least the periphery of the RF cover 7 and the chassis 2 of the RF cover 7 having the substrate 10 built therein.
A metal mesh sheet 11 is sandwiched between and to fix the metal mesh sheet 11 to form a BS converter structure in which unwanted radiation from the oscillator 3 is blocked.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement in a satellite broadcast receiving converter, and more particularly to a converter seal structure that reduces the radiation generated from a BS converter.

[0002]

[Prior Art]

 Radio waves from a broadcasting satellite are received by a parabolic antenna or a plane antenna, input to a BS converter to convert a 12 GHz band signal into a 1.2 GHz band BS-IF signal, and are amplified and given to a BS tuner.

FIG. 3 is a side view showing the internal structure of a BS converter which has been conventionally used, and FIG. 4 is a perspective view showing an RF signal input section 1 for receiving radio waves from an antenna integrated in a chassis 2. There is. An oscillator 3, a power supply board 4, and an IF board 5 are attached to the back side of the chassis 1, and an F connector 6 serving as an output portion is attached to the end of the chassis 2. On the other hand, an RF substrate made of Teflon having a microstrip formed on the surface thereof is attached to the front surface side of the chassis 2 while electrically connecting to the circuit elements on the rear surface side. A signal processing circuit such as a high-frequency amplifier is mounted on the microstrip of the RF board and is connected to the F connector 6 which is an IF signal output section. The RF board is attached to the chassis 2 and the surface thereof is covered with the RF cover 7. In this way, the high-frequency radio wave reception input section attached to the chassis 2 is further covered with the rectangular cover 8 to be shielded from the outside. 13 indicates a screw.

In the BS converter having the above structure, conventionally, it is possible to prevent the signal leaked from the oscillator 3 from affecting the signal processing circuit mounted on the RF board and to radiate the signal from the RF input section to the outside. In order to prevent it, a copper tape 9 is attached to seal the gap 12 formed at the joint between the RF cover 7 and the chassis 2.

[0005]

[Problems to be solved by the device]

 In the above conventional sealing structure, the intended purpose cannot be fully achieved because the signal leaks from the gap between the adhesives to which the copper foil is attached, and the copper tape is attached to a surface other than a flat surface. However, there was a problem that it could not be adopted in a limited range. Furthermore, the copper tape must have sufficient strength, which requires time and effort for mounting work, and there is also a problem in economic efficiency.

The present invention has been made in view of the problems of the conventional seal structure of the BS converter, and therefore provides a structure for sandwiching and sealing a metal mesh in an RF cover.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a BS converter in which a circuit board having a circuit for high-frequency amplification signal processing of radio waves received by an antenna is mounted on a chassis, and the circuit board is covered with an RF cover. A metal mesh is sandwiched between at least the circumference of the RF cover and the chassis to fix the metal mesh to form a satellite broadcast receiving converter.

[0008]

[Action]

 Since a metal mesh is inserted between the RF cover and the chassis, a complete electrical seal can be achieved. Even if a gap may be created between the RF cover and the seal, the signal from the oscillator will not interfere with the RF cover. It cannot reach the internal RF board, and can prevent the intrusion of signals from the oscillator regardless of the irregularities of the cover and chassis.

[0009]

【Example】

 FIG. 1 is a perspective view showing an embodiment of the present invention, in which a part having the same structure as the conventional BS converter shown in FIGS. 3 and 4 is omitted and a particularly improved main part is shown.

In FIG. 1, a signal processing circuit including an amplification element for amplifying a radio wave received by an antenna is mounted on an insulating resin substrate 10 such as Teflon having a microstrip 14 formed on the surface thereof, and is attached to a chassis 2. Has been. The surface of the insulating resin substrate 10 attached to the chassis 2 is covered with an RF cover 7 and sealed from the outside. At this time, a copper mesh sheet 11 is interposed at the peripheral joint between the RF cover 7 and the chassis 2. It is inserted and screwed. That is, when the RF cover 7 is attached to the chassis 2, the copper mesh sheet 11 electrically shields the gap around the RF cover 2 which is formed at the joint with the chassis 2.

In order to achieve the sealing effect of the copper mesh sheet 11, it is desirable that the mesh sheet itself has flexibility and has a certain thickness (0.5 to 0.7 mm). However, this thickness does not necessarily fall within the above range due to unevenness and the surface of the joint surface, but the effect is hardly impaired. Further, since the frequency of shielding is determined by the size of the mesh sheet 11, the size of the mesh sheet mesh that can shield 10 GHz to 11.5 GHz and the second harmonic of 20 GHz to 23 GHz in the case of a BS converter. is necessary. Therefore, it is desirable to use a mesh sheet having a mesh size of 0.5 mm or less.

FIG. 2 shows a result of comparing unnecessary radiation from an oscillator signal to the RF signal processing unit in the BS converter having the above seal structure and the converter having the conventional structure. When the unnecessary radiation of the oscillator signal is measured without covering the chassis 2 with the rectangular cover 8, both the present embodiment and the conventional structure have the same degree and almost no difference is observed. This is because the leak signal from the oscillator 3 is radiated into the air and is not radiated to the input section.

On the other hand, when covered with the rectangular cover 8, the signal cannot be radiated into the air and enters the signal processing unit through the gap between the RF cover 7 and the chassis 2. Comparing the present embodiment with the conventional structure in this state, it can be seen that the difference between both of the unwanted radiation reaches about 35 dB, and that the structure of the present embodiment has a remarkable shielding effect and is greatly improved.

Further, in the structure of the present embodiment, not only the unnecessary radiation of the oscillator signal but also the contact property between the RF cover 7 and the ground surface of the chassis 2 is improved, and the improvement in NF (noise figure), gain, etc. is recognized. In addition, the effect of blocking unnecessary radiation to the input section of the second harmonic of the oscillator can be obtained.

[0015]

[Effect of the device]

 As described above, according to the present invention, the unnecessary radiation of the oscillator and the radiation of the second harmonic are processed by the RF signal processing by inserting the metal mesh sheet in the gap formed between the chassis and the RF cover in the BS converter. It is possible to shield the circuit from entering and improve the reliability of the converter. In addition, due to the flexibility of the metal mesh, an excellent sealing effect can be obtained with a simple structure regardless of the uneven shape of the chassis or RF cover.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing an embodiment according to the present invention.

FIG. 2 is a diagram comparing a shielding effect between a structure according to an embodiment of the present invention and a conventional structure.

FIG. 3 is a side view showing the structure of a conventional BS converter.

FIG. 4 is a perspective view showing the structure of a conventional BS converter.

[Explanation of symbols]

 1 RF signal input section 2 Chassis 3 Oscillator 7 RF cover 8 Square cover 10 Insulating resin substrate 11 Copper mesh sheet

Claims (1)

[Scope of utility model registration request] 1. A BS converter comprising a circuit board on which a circuit for high-frequency amplified signal processing of received radio waves is mounted, a chassis to which the circuit board is attached, and an RF cover for covering the surface of the circuit board attached to the chassis. 2. A converter for satellite broadcasting reception, wherein a metal mesh is sandwiched and fixed between at least the periphery of the RF cover and the chassis.