Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2002-03-04
2004-06-29
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S895000
Reexamination Certificate
active
06756943
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna unit for a portable radiotelephone (terminal) in a mobile communications system and, in particular, to an antenna unit having a conductive tube disposed in a main body of the portable radiotelephone.
2. Description of the Related Art
In general, portable radiotelephones, i.e., mobile communications terminals, which are alternatively referred to as “mobile stations”, serve to communicate with one or more “base stations” by radio to provide their end-users with desired radio telecommunications services. Therefore, by means of these mobile terminals, the subscribed users can be served with a diversity of radio telecommunications services such as telephone calling, e-mail transferring, or internet chatting, etc. Usually, such a mobile communications terminal is provided with at least one antenna unit for receiving and transmitting radio signals in its main body. Recently, a retractable/extendable type of antenna unit has been in wider use to ensure better sensitivity of reception for radio signals.
One of known antenna devices for the mobile communications terminals is illustrated in
FIGS. 1 and 2
, and consists of a conventional helical antenna and a whip antenna adapted to be retractable into or extendable from an antenna housing.
FIG. 1
illustrates the mobile terminal with such a whip antenna
14
(seen extended in
FIG. 2
) fully retracted into the antenna housing
12
, while
FIG. 2
illustrates the mobile terminal with the whip antenna
14
fully extended from the antenna housing
12
. Accordingly, in case the sensitivity of reception in the antenna goes down, a user may have the whip antenna
14
fully extended out of the antenna housing
12
when using of the mobile terminal. The helical antenna (not shown) is generally positioned within the antenna housing
12
in its longitudinal direction, and when the whip antenna is in a fully retracted position, a rod antenna section
14
c
is received by an insulating tube
16
disposed in the main body
10
. The rod antenna section
14
c
is provided with an insulator
14
b
for electrical isolation from the helical antenna and also provided with an antenna cap
14
a
in its uppermost end. The above figures respectively illustrate the main body
10
of a mobile terminal with its battery pack for power supply removed, wherein reference numeral
10
a
indicates a bottom surface of the main body.
Referring to
FIGS. 3 and 4
, the structure and performance of a known antenna unit consisting of a helical antenna (not shown), disposed within an antenna housing
12
, and a whip antenna
14
will be described hereinafter. When the whip antenna
14
is in a fully retracted position into the antenna housing, the helical antenna functions as a main antenna. When the whip antenna
14
is in a fully extended position out of the antenna housing, the whip antenna functions as a main antenna. The antenna housing
12
is provided in its lower end with a metal coupling
12
a
, which is preferably formed in one body with the antenna housing
12
and then screwed to the main body for attachment thereto. To the coupling
12
a
is coupled the rod antenna section
14
c
, a lower end of which is further coupled to a stopper
14
d
, forming an electrical feeder.
The rod antenna section
14
c
is received by the insulating tube
16
in a retracted position of the whip antenna
14
, while the rod antenna section is separated from the insulating tube in an extended position of the whip antenna. This insulating tube is generally disposed in a longitudinal direction adjacent to a bottom surface
10
a
of the main body, so that it could ensure smooth movement of the whip antenna
14
there through or exclude any physical intervention by any other neighboring elements.
Such a prior art antenna unit usually has a length C
1
of an insulator
14
b
much longer than a length C
3
of a helical antenna, in order to ensure that the insulator
14
b
can keep better isolation between the helical antenna and the whip antenna.
When the whip antenna
14
is in a fully retracted position in the antenna housing
12
, any insufficient or incomplete isolation between the whip antenna and the helical antenna is apt to cause the helical antenna to provide low radiation efficiency due to absorption of its radiation energy by the whip antenna. Further, it would also cause a considerable degradation of the reception efficiency for radio signals due to a reduction in a signal-to-noise ratio at a receiver, since the receiver circuit is often affected by noises induced by any harmonic components of digital clocks generated within a mobile radiotelephone itself.
Accordingly, prior art antenna units in general have been designed to have a length C
1
of the insulator of whip antenna much longer than a length C
3
of the helical antenna. Considering the length C
1
of the insulator, a length C
2
of the rod antenna section becomes shorter relatively.
However, the prior art antenna units, which are mostly designed to have a length C
1
of the insulator much longer than a length C
3
of the helical antenna and to have a shorter length C
2
of the rod antenna relatively, often give rise to a problem of degraded antenna efficiency for radio signals, since the rod antenna section
14
a
substantially functions as an operating antenna in an extended position of the whip antenna
14
. Furthermore, portable mobile communications terminals are recently being trended toward much smaller size due to striking innovations and improvements in manufacturing technology of hardware components as well as accruing from the users' ever increasing needs for compactness. Therefore, as the size of a main body of the mobile communications terminal is getting smaller and smaller, its antenna unit is also required to have a shorter length. As a result, such a shorter length of antenna unit may lead to a decrease of communication performance in the mobile communications terminal and also cause its user to be more strongly affected by radiation of probably harmful electromagnetic waves upon using of it.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an antenna unit with improved communication performance by increasing its radiation efficiency by means of an elongated rod antenna of a whip antenna in its extended position.
It is another object of the present invention to provide an antenna unit capable of providing a decreased Specific Absorption Rate (SAR), which is referred to as one of the technical criteria for measurement of electromagnetic factors harmful to a human body, proposed in “IEEE (C95.1)/FCC (P.24) safety specification to radio radiation”, by means of dispersing the radiation distribution of electromagnetic waves from the antenna unit.
Accordingly, to achieve the above objects of the present invention, an antenna unit for a mobile communications terminal includes an antenna housing extending from a predetermined position on a main body of the mobile communications terminal, the antenna housing having therein an helical antenna; a whip antenna disposed retractably or extendably with respect to the antenna housing, having in its one end an insulator with a length shorter than that of the helical antenna and in its other end a rod antenna; and a conductive tube disposed in a longitudinal direction of the main body under the antenna housing, for receiving the rod antenna in the retracted or extended position of the whip antenna, whereby the insulator is positioned within the helical antenna when the whip antenna is fully retracted into the antenna housing.
Preferably, the conductive tube is made of a metal component. The conductive tube further includes an insulating tube on its inner surface for isolation from the whip antenna. The insulating tube is disposed to extend along said conductive tube, wherein one end of the insulating tube is disposed to protrude in a longitudinal direction from a corresponding one end of the conductive tube, and a diameter of th
Hong Seong-Beom
Kim Jong-Goo
Dilworth & Barrese LLP
Ho Tan
Samsung Electronics Co,. Ltd.
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