Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-08-07
2002-04-02
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S895000, C343S725000
Reexamination Certificate
active
06366247
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna device and a portable radio set, and more particularly, is suitably applied to a cellular telephone.
2. Description of the Related Art
The cellular telephone of this type has been decreased in size and weight so far in order to improve the portability. Thereby, a retract/pull-out type of whip antenna device is positively developed as an antenna device provided for a cellular telephone. There is a cellular telephone configured as shown in
FIGS. 1A and 1B
as the cellular telephone of the above type.
In case of a cellular telephone
1
having the above configuration, a whip antenna device
3
is providing for in a housing
2
made of a nonconductive material such as synthetic resin.
The antenna device
3
has an antenna section
6
provided with a rod antenna
4
made of a conductive wire rod and a helical antenna
5
formed by helically winding a conductive wire rod. The antenna section is set so as to be freely retracted and pulled out along a direction in which the antenna section
6
is pushed into the housing
2
shown by an arrow a at the upper end
2
A of the housing
2
(this direction is hereafter referred to as retracting direction) and inversely, along a direction in which the section
6
is pulled out of the housing
2
(this direction is hereafter referred to as pull-out direction).
In the antenna section
6
, a first power-supply member
7
made of a conductive material and having a protrusion
7
A is electrically and mechanically connected to the lower end of the rod antenna
4
and a joint
8
made of a nonconductive material is mechanically connected to the upper end of the rod antenna
4
.
Moreover, a second power-supply member
9
made of a conductive material is electrically and mechanically connected to the lower end of the helical antenna
5
and mechanically connected to the joint
8
. Thereby, in the antenna section
6
, the rod antenna
4
and the helical antenna
5
are mechanically connected each other by the joint
8
but they are electrically separated from each other.
Moreover, the rod antenna
4
is covered with a rod antenna cover
10
and the helical antenna
5
is stored in a cap-shaped helical antenna cover
11
so that the antennas
4
and
5
do not directly contact a user.
A circuit board (not illustrated) on which various circuit devices including a transceiving circuit
12
and a matching circuit
13
are mounted and a shielding case serving as a ground member made of a conductive material for covering the circuit board are stored in the housing
2
.
Moreover, an antenna power-supply terminal
14
made of a conductive material electrically connected to the matching circuit
13
is set inside of the upper end
2
A of the housing
2
and only either of the rod antenna
4
and helical antenna
5
is electrically connected to the antenna power-supply terminal
14
when the antenna section
6
is retracted or pulled out.
Actually, in the antenna device
3
, the antenna section
6
is pushed in and the helical antenna cover
11
is pushed in the retracting direction and made to contact the upper end
2
A of the housing
2
to push the rod antenna
4
into the housing
2
and store the rod antenna
4
in the housing
2
and electrically connect the second power-supply member
9
to the antenna power-supply terminal
14
.
Moreover in the antenna device
3
, power is supplied to the helical antenna
5
from the transceiving circuit
12
through the matching circuit
13
, antenna power-supply terminal
14
, and second power-supply member
9
in order under the above state to make the helical antenna
5
operate as an antenna.
Furthermore, in the antenna device
3
, by electrically separating the rod antenna
4
from the antenna power-supply terminal
14
by the joint
8
, the rod antenna
4
is not operated as an antenna.
In the antenna device
3
, however, when the second antenna cover
11
is pulled in the pull-out direction while the rod antenna
4
is stored in the housing
2
, the rod antenna
4
is pulled out to the outside from the upper end
2
A of the housing
2
, the protrusion
7
A of the first power-supply member
7
is made to contact the antenna power-supply terminal
14
, and thereby the first power-supply member
7
is electrically connected to the antenna power-supply terminal
14
.
Furthermore, in the antenna device
3
, power is supplied to the rod antenna
4
from the transceiving circuit
12
through the matching circuit
13
, antenna power-supply terminal
14
, and first power-supply member
7
in order under the above state to make the rod antenna
4
operate as an antenna.
Furthermore, in the antenna device
3
, by electrically separating the helical antenna
5
from the antenna power-supply terminal
14
by the joint
8
, the antenna
5
is not operated as an antenna.
In this connection, to make the rod antenna
4
and helical antenna
5
operate as antennas, the impedances of the rod antenna
4
and helical antenna
5
are matched with the impedance of the unbalanced transmission line
16
by the matching circuit
13
.
Moreover, the shielding case functions as ground for various circuit devices and moreover functions as an electrical shielding plate for preventing radio waves of external noise and radio waves emitted from the antenna section
6
from entering various circuit devices mounted on a circuit board.
Thereby, the cellular telephone
1
makes it possible to, at the time of pulling out the antenna section
6
, transmit a transmission signal configured of a high-frequency signal from the transceiving circuit
12
to the rod antenna
4
through the matching circuit
13
, transmit the transmission signal to a base station (not illustrated) through the rod antenna
4
, and transmit a reception signal configured of a high-frequency signal transmitted from the base station and received by the rod antenna
4
to the transceiving circuit
12
through the matching circuit
13
.
Moreover, the cellular telephone
1
makes it possible to prevent damage to the rod antenna
4
by storing the antenna
4
in the housing
2
at the time of retracting the antenna section
6
, transmitting a transmission signal from the transceiving circuit
12
to the helical antenna
5
through the matching circuit
13
under the above state, transmitting the transmission signal to a base station through the helical antenna
5
, and transmitting a reception signal transmitted from the base station and received by the helical antenna
5
to the transceiving circuit
12
through the matching circuit
13
.
The cellular telephone
1
having the above configuration is provided with an unbalanced transmission line
26
configured of a microstrip line formed on a circuit board, in which the rod antenna
4
or helical antenna
5
is electrically connected to the transceiving circuit
12
through the hot side of the unbalanced transmission line
26
and the matching circuit
13
sequentially, and the ground side of the unbalanced transmission line
26
is grounded to the shielding case.
Then, in the cellular telephone
1
, as shown in
FIGS. 2A and 2B
, when power is supplied to the rod antenna
4
and helical antenna
5
through the hot side of the unbalanced transmission line
26
to operate the rod antenna
4
and helical antenna
5
as antennas, a leakage current i
1
flows to the shielding case
27
having a potential almost equal to that of the ground side of the unbalanced transmission line
26
from the ground side and thereby, the shielding case
27
also operates as an antenna.
Therefore, in the cellular telephone
1
, when the shielding case
27
operates as an antenna and the housing
2
is held by a hand of a user or when the housing
2
is approached to the head of the user, antenna characteristics of the cellular telephone
1
are deteriorated because the shielding case
27
approaches a hand or the head of the user through the housing
2
.
When the antenna section
6
is pulled out, the physical length of the rod antenna
4
pulled out from the
Ito Hiroki
Sawamura Masatoshi
Le Hoang-anh
Maioli Jay H.
Sony Corporation
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