Telecommunications – Wireless distribution system – Receiver for satellite broadcast
Reexamination Certificate
1999-07-06
2001-10-09
Vo, Nguyen T. (Department: 2682)
Telecommunications
Wireless distribution system
Receiver for satellite broadcast
C455S328000
Reexamination Certificate
active
06301464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a satellite broadcasting converter with high productivity and high performance.
2. Description of the Related Art
A conventional satellite broadcasting converter will be described below with reference to
FIGS. 7
to
10
.
Referring to
FIG. 7
, a box-shaped metal housing
21
, a cylindrical metal waveguide section
22
, and a funnel-shaped metal horn section
23
are integrally formed by die casting using aluminum.
A circuit section (not shown) for receiving satellite broadcast waves, such as an RF circuit, is contained inside the housing
21
, and cables are connected to a plurality of connectors
24
attached to the housing
21
so as to lead received waves indoors.
As shown in
FIGS. 8 and 9
, a converting portion
22
b
, formed of a nearly trapezoidal projection, projects from an inner surface
22
a
of the waveguide section
22
toward the center.
Circularly polarized waves are converted into linearly polarized waves by the converting portion
22
b
, and are input the satellite broadcast wave receiving circuit section.
Next, a description will be given of a method of producing the waveguide section
22
and the horn section
23
for the conventional satellite broadcasting converter.
As shown in
FIG. 10
, first, a columnar mold
31
for forming the inner surface of the hollow waveguide section
22
is placed to abut on a truncated conical mold
32
for forming the inner surface of the horn section
23
and a part of the inner surface of the waveguide section
22
.
In this case, recesses
31
a
and
32
a
for defining the projecting converting portion
22
b
are formed in the abutting portions between the molds
31
and
32
, which allows the mold
31
and the mold
32
to be pulled out in the directions of the arrows X and Y, respectively, after molding.
Moreover, a plurality of split molds
33
for forming the outline of the waveguide section
22
and the horn section
23
are placed to define a space portion
34
between the molds
31
,
32
, and
33
, where the waveguide section
22
, the converting portion
22
b
, and the horn section
23
are to be formed.
Subsequently, molten aluminum is injected in the space portion
34
. When the aluminum has solidified, the mold
31
is pulled out in the direction of the arrow X, the mold
32
is pulled out in the direction of the arrow Y, and the molds
33
are removed, whereby the production of the waveguide section
22
and the horn section
23
is completed.
Since the converting portion
22
b
projects from the inner surface of the waveguide section
22
in the conventional satellite broadcasting converter, the production of the converter requires the mold
31
for forming the inner surface of the waveguide section
22
, and the mold
32
for forming the inner surface of the waveguide section
22
and the inner surface of the horn section
23
. This increases the number of molds, and therefore, increases the cost. Moreover, since the molds
31
and
32
must abut on each other, they suffer serious abrasion damage, and the service life thereof is shortened.
Furthermore, since the molds
31
and
32
must abut at the projecting converting portion
22
b
, burrs are formed in the abutting portions therebetween, which deteriorates performance, and necessitates deburring.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a satellite broadcasting converter that can be produced by a mold having a simple structure and without forming burrs.
In order to solve the above problems, according to an aspect of the present invention, there is provided a satellite broadcasting converter including a metal housing, a metal waveguide section connected to the housing at one and a metal horn section connected to the waveguide section at one end, wherein the horn section has a funnel-shaped inner face portion that gradually slopes to broaden away from the portion connected to the waveguide section, and a converting portion for converting circularly polarized waves into linearly polarized waves projects from a part of the inner face portion.
Preferably, the converting portion is formed of a triangular projection formed in a section surrounded by a linear portion having the same diameter as the inner diameter of the waveguide section to extend outward, a slope portion extending outward from one end of the linear portion toward the inner face portion, and the inner face portion.
The converting portion may be formed of a triangular projection formed in a section surrounded by a first slope portion that extends outward to gradually become greater than the inner diameter of the waveguide section, away from the portion connected to the waveguide section, a second slope portion extending outward from one end of the first slope portion toward the inner face portion, and the inner face portion.
Further objects, features, and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.
REFERENCES:
patent: 4991228 (1991-02-01), Ohta et al.
patent: 5471664 (1995-11-01), Kim
patent: 5584064 (1996-12-01), Nakamura
patent: 8-84002 (1996-05-01), None
Alps Electric Co. ,Ltd.
Vo Nguyen T.
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