Wave transmission lines and networks – Long line elements and components – Waveguide elements and components
Reexamination Certificate
2000-07-20
2003-04-22
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Waveguide elements and components
C333S02100R
Reexamination Certificate
active
06552636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylindrical waveguide to be used, for example, as a satellite broadcast transmitting and receiving antenna for the transmission and reception of a polarized wave.
2. Description of the Related Art
A satellite broadcast receiving converter using a conventional cylindrical waveguide will be described below with reference to
FIGS. 8 and 9
, of which
FIG. 8
is an exploded perspective view of the conventional converter and
FIG. 9
is an explanatory diagram for explaining a bent portion of a cavity in the cylindrical waveguide of the conventional converter.
As shown in
FIGS. 8 and 9
, a body member
31
formed by aluminum or zinc die casting comprises a cylindrical waveguide
32
for introducing a polarized wave and a housing
41
for receiving a circuit portion therein, the cylindrical waveguide
32
and the housing
41
being formed integrally with each other.
The cylindrical waveguide
32
has a first cylindrical waveguide portion
34
having a horn portion
33
for introducing a polarized wave, a second cylindrical waveguide portion
35
disposed perpendicularly to the first waveguide portion
34
, and a cylindrical connection
36
which connects the first and second waveguide portions
34
,
35
with each other and which is bent 90°. As depicted in
FIG. 9
, centrally and axially of the first waveguide portion
34
is formed a first cavity
37
which is straight, and also formed centrally and axially of the second waveguide portion
35
is a second cavity
38
which is straight. The first and second cavities
37
,
38
are connected with each other through a 90°-bent cavity
39
which is formed in the connection
36
to form a cavity
40
. Inside the horn portion
33
is formed a first opening
40
a
which opens one end of the cavity
40
as shown in FIG.
8
. The opposite end side of the cavity
40
is also open.
Returning to
FIG. 8
, the housing
41
, which is formed of the same material as the cylindrical waveguide
32
, has a bottom wall portion
41
a
, a side wall portion
41
b
which is formed upright so as to enclose the bottom wall portion
41
a
, and a receptacle portion
41
c
which is open above the side wall portion
41
b
and which is enclosed with the side wall portion
41
b
. Near one end side of the bottom wall portion
41
a
is formed a second opening
41
d
which is an opposite end-side opening of the cavity
40
.
On both upper and lower sides of a single rectangular circuit board
42
constituted by an insulating board are formed annular earth electrodes
43
as soldered layers each having about the same diameter as the second opening portion
41
d
. A large number of through holes
43
a
extending vertically through the circuit board
42
are formed in both upper- and lower-side earth electrodes
43
to connect the earth electrodes with each other.
A first probe
44
for catching a vertically polarized wave is formed by a conductive pattern longitudinally of the circuit board
42
from near the center of the earth electrode
43
formed on the upper side of the circuit board. On the other hand, in the transverse direction of the circuit board
42
is formed an L-shaped, second probe
45
by a conductive pattern to catch a horizontally polarized wave. One ends of the first and second probes
44
,
45
are connected to an electric circuit (not shown) formed on the upper surface of the circuit board
42
. The circuit board
42
is placed on a stepped portion located near the bottom wall portion
41
a
out of plural stepped portions (not shown) formed inside the housing
41
and is fixed to the housing by a suitable means. At this time, the earth electrode
43
formed on the lower side of the circuit board is grounded to the bottom wall portion
41
a
while surrounding the second opening
41
d
formed in the housing
41
.
A generally square, bottomed, metallic case
46
is attached to the circuit board
42
so as to cover the earth electrode
43
formed on the upper side of the circuit board
42
, by a suitable means such as the use of screws. An inside bottom (not shown) of the metallic case
46
functions as a short-circuit surface for the first and second probes
44
,
45
.
A cover
47
constituted by a single rectangular metallic plate is placed on a stepped portion (not shown) located on a remote side from the bottom wall portion
41
a
of the housing
41
and is fixed by a suitable means. The receptacle portion
41
c
of the housing
41
is sealed hermetically and the interior thereof is held in an electrically shielded state.
A more detailed description will now be given about the cavity
40
of the cylindrical waveguide
32
. As shown in
FIG. 9
, the first and second cavities
37
,
38
are each formed at a diameter of D
1
, and on the innermost side of the cavity
40
when seen sideways of the body member
31
, the cavities
37
and
38
are constituted by an innermost wall portion
37
a
of the fist cavity
37
, an innermost wall portion
38
a
of the second cavity
38
, and an inner bent portion
39
a
as an innermost wall portion of the cavity
39
in the connection
36
which connects the first and second cavities
37
,
38
with each other. On the outermost side of the cavity
40
, the first and second cavities
37
,
38
are constituted by an outermost inner wall portion
37
b
of the first cavity
37
, an outermost inner wall portion
38
b
of the second cavity
38
, and an outer bent portion
39
b
as an outermost inner wall portion of the cavity
39
in the connection
36
.
The inner bent portion
39
a
has a quadrant circumference described with a radius of R
2
which is three times as long as the diameter D
1
from a central position C
4
, the central position C
4
lying on a 45° line Z
1
—Z
1
at an intersecting point of an extension line X
1
of the innermost wall portion
37
a
of the first cavity
37
and an extension line Y
1
of the innermost wall portion
38
a
of the second cavity
38
. The innermost wall portions
37
a
and
38
a
of the first and second cavities
37
,
38
are connected together at the radius R
2
. The outer bent portion
39
b
has a quadrant circumference described at a radius of R
3
which is four times as long as the diameter D
1
also from the central position C
4
. The outermost inner wall portions
37
b
and
38
b
are connected with each other at the radius R
3
.
In the satellite broadcast receiving converter using the conventional cylindrical waveguide, however, the central position of the radius R
2
of the inner bent portion
39
a
of the cavity portion
39
in the connection
36
and the radius R
3
of the outer bent portion
39
b
of the cavity
39
are the same and the radii R
2
and R
3
are respectively three and four times as long as the diameter D
1
, so that the cavity
39
is large in the directions of the extension lines X
1
and Y
1
, with consequent increase in size of the connection
36
, thus giving rise to the problem that the cylindrical waveguide
32
becomes larger in size.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cylindrical waveguide which has a low reflection characteristic and which is small in size.
For achieving the above-mentioned object, according to the present invention, in the first aspect thereof, there is provided a cylindrical waveguide comprising a first waveguide portion having a cylindrical cavity, a second waveguide portion disposed perpendicularly to the first waveguide portion and having a cylindrical cavity, and a connection connecting the first and second waveguide portions with each other and having a bent cylindrical cavity, wherein an inner bent portion of an inner wall portion in the cavity of the connection connects the cavities of the first and second waveguide portions with each other on a bent right-angle side and at a first radius from a first central position, while an outer bent portion of the inner wall portion in the cavity of the connection connects the cavities of the first and second waveguide portions with each other o
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
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