Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2002-10-24
2004-10-19
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
Reexamination Certificate
active
06806835
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an antenna structure used in a communication device, such as a folding cellular phone terminal, a method of using the antenna structure and the communication device.
Related Art of the Invention
Downsizing and slimming of cellular phone terminals are being rapidly advanced. In addition, incorporation of an antenna of a cellular phone terminal into a housing thereof is a world trend.
FIG. 19
shows a configuration of an internal antenna of a conventional cellular phone terminal.
FIG.
19
(
a
) is a schematic perspective view of the internal antenna of the conventional cellular phone terminal, and FIG.
19
(
b
) is a side view thereof. In FIGS.
19
(
a
) and
19
(
b
), an antenna element
1201
is to send or receive radio wave from the cellular phone terminal or from another cellular phone terminal, and a shielding case
1206
and a radio circuit for communication
1207
housed in the shielding case
1206
are disposed on a substrate
1202
. An LCD
1203
is to display information processed in the cellular phone terminal.
The antenna element
1201
is supplied with power from a feeding point
1204
on the substrate
1202
and has an end electrically connected to a part of the substrate
1202
via a conductive connection
1205
. Here, the part of the substrate
1202
and the shielding case
1206
are electrically connected to each other and form a bottom board of the antenna element
1201
. Thus, the antenna element
1201
, the part of the substrate
1202
and the shielding case
1206
constitutes the internal antenna.
Such a cellular phone terminal has gone beyond serving as a telephone and has been transformed to data terminal equipment that enables transmission of e-mails, browsing of WWW web pages or the like. Thus, upsizing of the display thereof is being promoted.
Under such circumstances, the folding cellular phone terminal has become popular because it is considered to be suitable for downsizing and display upsizing.
Conventionally, the folding cellular phone terminal includes a whip antenna, in addition to the internal antenna. The internal antenna and the whip antenna are used when the cellular phone terminal is folded and when it is not folded, respectively. In general, the impedances of the antennas differ according to whether the cellular phone is folded or not. Thus, the internal antenna and the whip antenna are adjusted to accommodate the difference in impedance, so that the folding cellular phone terminal has a good antenna characteristic both when it is folded and when it is not folded.
FIGS.
20
(
a
)-
20
(
b
) show configurations of parts of the folding cellular phone terminal associated with the internal antenna. FIG.
20
(
a
) is a front view of the folding cellular phone terminal and FIG.
20
(
b
) is a side view thereof.
The folding cellular phone terminal has an upper housing
102
and a lower housing
103
coupled with each other by a hinge part
104
, and is configured so that the upper housing
102
can be folded on the lower housing
103
via the hinge part
104
.
A display
109
is incorporated in the upper housing
102
, an upper bottom board
207
is incorporated in the housing at the back side of the display
109
, and an upper internal antenna element
205
is incorporated in the housing on a side of the upper bottom board
207
opposite to the display
109
.
However, the whip antenna is inconvenient because it needs to be drawn from the housing when the folding cellular phone is used and needs to be retracted into the housing after use. And, the whip antenna has a problem in that such drawing and retraction may cause damage thereto.
Thus, the folding cellular phone terminal has problems in that the whip antenna is burdensome because it needs to be drawn and retracted and that the whip antenna is susceptible to damage due to such operations.
In addition, in the folding cellular phone terminal shown in
FIG. 20
, the upper internal antenna element
205
, the upper bottom board
207
and the lower bottom board
208
constitute the upper internal antenna. In this case, the upper bottom board
207
and the lower bottom board
208
are electrically connected to each other and serve as a bottom board of the upper internal antenna.
When the cellular phone terminal is folded, the antenna bottom board constituted by the upper bottom board
207
and the lower bottom board
208
is also folded. Therefore, the length of the bottom board is about half of that at the time when the cellular phone terminal
201
is not folded. In this case, if the upper bottom board
207
is shorter than a quarter of a wavelength, there is no current standing wave on the bottom board for a desired frequency band, and thus, the bottom board less contributes to radiation of the radio wave from the antenna.
Therefore, in order to use the upper internal antenna both in the states where the cellular phone terminal
201
is folded and is not folded, the antenna needs to have such a wide-band characteristic as to accommodate the difference in the impedance between the cases where it is folded and where it is not folded and the difference in the contribution of the bottom board to the radiation.
That is, since the antenna of the folding cellular phone terminal needs to have a good characteristic both when the cellular phone terminal is folded and when it is not folded, the upper internal antenna becomes large, and in particular, is increased in thickness.
Even if components in the upper housing
102
except for the upper internal antenna, such as display
109
, are reduced in thickness, the thick upper internal antenna prevents the upper housing
102
from being slimmed. Similarly, even if components in the lower housing
103
except for the lower internal antenna are reduced in thickness, the thick lower internal antenna prevents the lower housing
103
from being slimmed. Thus, folding portable radio terminals including the folding cellular phone terminal have a problem in that they becomes thick if the internal antenna is used.
SUMMARY OF THE INVENTION
In consideration of the problems described above, an object of the present invention is to provide an antenna structure, a method of using the antenna structure and a communication device that eliminate the need to draw and retract an antenna when a folding portable radio terminal is to be used.
Furthermore, in consideration of the problems described above, an object of the present invention is to provide an antenna structure, a method of using the antenna structure and a communication device that enable the folding cellular phone terminal to be further slimmed.
One aspect of the present invention is an antenna structure used in a folding portable ratio terminal, comprising:
a first antenna; and
a second antenna,
wherein said first antenna is used at least when said portable radio terminal is not folded, and
said second antenna is used at least when said portable radio terminal is folded.
Another aspect of the present invention is the antenna structure, wherein when said portable radio terminal is not folded, a diversity reception is carried out with said first antenna serving as a main antenna and said second antenna serving as a sub-antenna, and
when said portable radio terminal is folded, a diversity reception is carried out with said first antenna serving as a sub-antenna and said second antenna serving as a main antenna.
Still another aspect of the present invention is the antenna structure, wherein when said portable radio terminal is not folded, a diversity transmission is carried out with said first antenna serving as a main antenna and said second antenna serving as a sub-antenna, and
when said portable radio terminal is folded, a diversity transmission is carried out with said first antenna serving as a sub-antenna and said second antenna serving as a main antenna.
Yet still another aspect of the present invention is the antenna structure, wherein said first antenna has a better characteristic when said portable radio terminal is not folded, a
Asahina Toshihiro
Iwai Hiroshi
Kamaeguchi Shinji
Ogawa Koichi
Yamada Ken'ichi
Ho Tan
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
LandOfFree
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