Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
2002-09-20
2004-08-17
Nguyen, Hoang V. (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S785000
Reexamination Certificate
active
06778146
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a satellite broadcast reception converter for receiving electric waves transmitted from a satellite, and particularly to a satellite broadcast reception converter suitable for receiving circularly polarized electric waves transmitted from a satellite.
2. Description of the Related Art
A satellite broadcast reception converter mounted in an outdoor antenna device is equipped with a waveguide having a hollow structure to which electric waves transmitted from a satellite are incident, a probe disposed at a predetermined position in the waveguide, a short cap for reflecting electric waves propagating in the waveguide to make the probe detect the electric waves, a circuit board having a processing circuit for performing appropriate processing (amplification, frequency conversion, etc.) on signals detected by the probe, etc. and the circuit board is usually covered by a shield case.
There has been hitherto known one of such satellite broadcast reception converters in which a waveguide and a shield case are integrally formed by aluminum die casting and a circuit board and a short cap are fixed in the shield case. In this case, a probe is formed on the circuit board by pattern formation, and if the short cap is fixed to the shield case by plural screws after the circuit board and the short cap are successively installed in the shield case, the circuit board could be pinched and fixed between the shield case and the short cap.
Further, in a satellite broadcast reception converter mounted on an outside antenna device for example when a right-handed circularly polarized or left-handed circularly polarized electric wave transmitted from a satellite is received, it is necessary to convert the circularly polarized wave incident into the waveguide to a linearly polarized wave in the phase converter and couple the linearly polarized wave to the probe for reception.
Still further, there has been also known a satellite broadcast reception converter in which a waveguide having a horn portion is formed of alloy of aluminum, zinc, etc. by die casting and then a phase converter called as a ridge is integrally formed on the inner wall surface of the waveguide and a circularly polarized wave incident from the horn portion into the waveguide is converted to a linearly polarized wave by the ridge. That is, the circularly polarized wave corresponds to a polarized wave having the rotating composite vector between two linearly-polarized waves that are equal in amplitude and have a phase difference of 90 degrees therebetween. Therefore, when the circularly-polarized wave passes through the ridge, the phase difference of 90 degrees is set to zero, and thus it is converted to the linearly polarized wave.
However, in the conventional satellite broadcast reception converter described above, the horn portion having desired aperture diameter and length is integrally formed at the tip of the waveguide, and the ridge having desired length and extending in the axial line direction is integrally formed on the inner wall surface of the waveguide. Therefore, not only the waveguide must be designed to be long in the axial line direction and thus miniaturization thereof is disturbed, but also the ridge serving as the phase converter is designed in an under-cut shape to make and thus a metal mold for die casting is complicated. As a result, the manufacturing cost is increased.
Therefore, there has been recently proposed a satellite broadcast reception converter in which a dielectric feeder achieved by integrally forming a radiation portion and a phase converter is used, the radiation portion is projected forwardly from the open end of a waveguide and the phase converter inserted and fixed in the waveguide is intersected to a probe at an angle of about 45 degrees. In this satellite broadcast reception converter, when a circularly polarized wave transmitted from a satellite is incident from the radiation portion of the dielectric feeder, the circularly polarized wave is converted to a linearly polarized wave in the phase converter while propagating in the dielectric feeder, and the linearly polarized wave goes into the deep portion of the waveguide and coupled to the probe.
Accordingly, according to the satellite broadcast reception converter using such a dielectric feeder, it is unnecessary to form a horn portion and a ridge (phase converter) integrally with a waveguide, so that the shape of the waveguide is simplified and the manufacturing cost can be reduced. In addition, the phase difference to the linearly polarized wave is large even when the overall length of the dielectric feeder is set to a relatively short value, the overall length of the waveguide itself can be shortened.
According to the conventional satellite broadcast reception converters thus constructed, the waveguide and the shield case are integrally formed by using aluminum die casting, and the circuit board and short cap are fixed in the shield case by using the plural screws. Therefore, the angularity between the probe pattern-formed on the circuit board and the axial line of the waveguide can be kept, and electric waves propagating in the waveguide can be surely detected. However, plural screws are required to fix the circuit board and the short cap, and also a subsequent step of coating adhesive agent to prevent loosening of the screws is needed. Therefore, the number of parts and the number of working steps are increased, which greatly causes rise-up of the manufacturing cost of the satellite broadcast reception converter.
In the satellite broadcast reception converter using the dielectric feeder, there is a merit that the manufacturing cost can be reduced and it can be miniaturized because a waveguide having a simple shape and a short length is available, however, it has some problem. That is, although the dielectric feeder is formed by injection-molding synthetic resin material, occurrence of surface sink and bubbles in synthetic resin is generally intensified when it is contracted as the volume (volumetric capacity) thereof increases. Therefore, high dimensional precision is not achievable with the dielectric feeder which is achieved by integrally forming a radiation portion and a phase converter like the prior art described above. Particularly when polyethylene (PE) which is low in price and has a low dielectric dissipation factor is used as the material of the dielectric feeder, there is a problem that the contraction after the injection molding is large and occurrence of bubbles is remarkable, so that the dimensional precision of each part of the dielectric feeder is extremely lowered, and the reception efficiency of electric waves transmitted from a satellite is lowered.
SUMMARY OF THE INVENTION
The present invention has been implemented in view of the foregoing situation of the prior arts, and has an object to provide a satellite broadcast reception converter in which a waveguide and a short cap can be simply fixed to a circuit board having a probe, and also which is suitable for reduction of the manufacturing cost and miniaturization and can enhance the dimensional precision of a dielectric feeder.
In order to attain the above object, according to a first aspect of the present invention, there is provided a satellite broadcast reception converter characterized by comprising a circuit board having a probe, at least one waveguide formed of sheet metal disposed vertically to the circuit board and at least one short cap designed to have a bottom through which the open end of the waveguide is closed, wherein snap pawls formed at the open end of the waveguide are inserted into fit holes formed in the circuit board and the short cap is fixedly fitted to the snap pawls to pinch the circuit board between the waveguide and the short cap.
According to the satellite broadcast reception converter thus constructed, the circuit board can be pinched and fixed by the waveguide and the short cap through a simple work of fixedly fitting the short cap to the snap pawls by u
Dou Yuanzhu
Nakagawa Masashi
Sasaki Kazuhiro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Nguyen Hoang V.
LandOfFree
Satellite broadcast reception converter suitable for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Satellite broadcast reception converter suitable for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Satellite broadcast reception converter suitable for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3356424