Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
1999-04-28
2001-01-23
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C439S675000
Reexamination Certificate
active
06177851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency electronic device such as a television tuner.
2. Description of the Prior Art
A conventional high-frequency electronic device will now be described with reference to
FIGS. 4 and 5
.
FIG. 4
is a perspective view of a conventional high-frequency electronic device and
FIG. 5
is an explanatory diagram showing a circuit configuration of the conventional high-frequency electronic device.
In the conventional high-frequency electronic device, as shown in
FIG. 4
, a coaxial connector
22
is attached to one side face
21
a
of a shielding case
21
which houses high-frequency circuits therein, with a signal being inputted to the connector
22
from a coaxial cable (not shown). Within the shielding case
21
, as shown in
FIG. 5
, there are provided high-frequency circuits such as a band pass filter
23
consisting of a high-pass filter and a low-pass filter, a first mixer
24
, a second mixer
25
, a first local oscillator
26
and a second local oscillator
27
. Frequency conversion is performed twice by means of the first and second mixers
24
,
25
and an intermediate frequency signal is outputted from the second mixer
25
.
The high-frequency circuits provided within the shielding case
21
are each designed to be impedance-matched usually at 75 &OHgr; (ohms) or 50 &OHgr;. Therefore, the connector
22
is also designed to be 75 &OHgr; or 50 &OHgr; in characteristic impedance. A central conductor
22
a
of the connector
22
and the band pass filter are directly connected with each other, the connector and the band pass filter are impedance-matched, and a signal inputted to the connector
22
is applied to the band pass filter.
The coaxial cable connected to the connector
22
is designed to have a predetermined diameter (thickness) because it is necessary to diminish the transmission loss. Therefore, as the connector there is used one whose diameter corresponds to the diameter of the coaxial cable.
In the conventional high-frequency electronic device described above, the height of the side face
21
a
of the shielding case
21
with the connector
22
attached thereto cannot be made lower than the diameter of the connector
22
. For this reason, it has so far been impossible to thin high-frequency electronic devices such as a television tuner to be mounted in a personal computer.
The purpose of thinning the devices can be achieved by using a coaxial connector of a small diameter. However, the use of a (thin) coaxial cable of a small diameter results in an increase in transmission loss of a received signal. On the other hand, using a coaxial cable of a large diameter requires the use of another connector for the connection of the connector
22
with the coaxial cable, thus leading to an increase in price of the high-frequency electronic device concerned.
In view of the above-mentioned problems it is an object of the present invention to provide a high-frequency electronic device capable of being reduced in thickness without deterioration of performance and increase of product cost.
SUMMARY OF THE INVENTION
According to the present invention, for achieving the above-mentioned object, there is provided a high-frequency electronic device comprising a coaxial type connector and a shielding case which is in the shape of a rectangular parallelepiped, the coaxial type connector having a short diameter and a long diameter in a cross section thereof, the shielding case having a side face which has short sides and long sides, the connector being attached to the side face so that the direction of its short diameter and the direction of the short sides of the side face are parallel to each other, and wherein a filter having a predetermined nominal impedance is disposed within the shielding case, and a central conductor of the connector and the filter are connected with each other using an inductor which is for impedance matching of the connector and the filter.
In the high-frequency electronic device of the present invention, the length of each short side of the side face and the short diameter of the connector are almost equal to other.
REFERENCES:
patent: 3783321 (1974-01-01), Patterson
patent: 5407366 (1995-04-01), Briones et al.
patent: 5608415 (1997-03-01), Sugawara
patent: 5801602 (1998-09-01), Fawal et al.
patent: 5928009 (1999-07-01), Lee
patent: 62-104637 (1987-05-01), None
patent: 6-97781 (1994-04-01), None
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Nguyen Patricia T.
Pascal Robert
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