Extendable whip antenna

Details Extendable whip antenna Extendable whip antenna

1999-12-10

2001-06-12

Ho, Tan (Department: 2821)

Communications: radio wave antennas

Antennas

With radio cabinet

C343S895000

Reexamination Certificate

active

06246372

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an antenna apparatus for use in a cellular phone, a mobile radio communication apparatus, etc.
BACKGROUND ART
As an example of an antenna apparatus for use in a mobile radio communication apparatus, a whip antenna, which is used in a cellular phone, can be named.
As shown in
FIG. 1
, a cellular phone
2
, which comprises a whip antenna
1
, has an antenna configuration in which a call can be established even in a state that a whip antenna
1
is extended or contained.
In a case of a bad receiving and transmitting state, a user of cellular phone
2
extends whip antenna
1
from a main body of cellular phone
2
to improve the receiving and transmitting state, so that the user can make a call. Also, when the extended whip antenna
1
obstructs the carrying or the telephone call in a good receiving and transmitting state, the user of cellular phone
2
contains the whip antenna
1
in the main body, so that the user can make a call.
FIGS. 2A and 2B
are cross-sectional views showing the configuration of the conventional whip antenna used in the cellular phone.
FIG. 2A
shows a state that the whip antenna is extended from the main body, and
FIG. 2B
shows a state that whip antenna is contained in the main body.
As shown in
FIGS. 2A and 2B
, the conventional whip antenna
1
is attached to a housing
11
of the cellular phone
2
with an attaching member
12
. The whip antenna
1
has a configuration in which a screw antenna
13
and a mono-pole antenna
14
are combined. The screw antenna
13
and mono-pole antenna
14
are electrically insulated from each other by an insulating member
15
inserted between these antennas.
As shown in
FIG. 2A
, when the whip antenna
1
is extended, a radio circuit substrate
16
is electrically connected to a mono-pole antenna base portion
18
through a feeding spring
17
. At this time, a portion from radio circuit substrate
16
to mono-pole antenna
14
is conductive, and only mono-pole antenna
14
is electrically powered and functions as an antenna.
While, as shown in
FIG. 2B
, when the whip antenna
1
is contained in a housing
11
down to a portion where a resin mold
19
for protecting screw antenna
13
comes in contact with attaching member
12
, radio circuit substrate
16
is electrically connected to a screw antenna base portion
20
through feeding spring
17
. At this time, a portion from radio circuit substrate
16
to screw antenna
13
is conductive, and only screw antenna
13
is electrically powered and functions as an antenna.
In such an antenna apparatus for use in a mobile radio communication apparatus, there is a problem in widening the receiving and transmitting band, particularly the widening of the band of screw antenna
13
. More specifically, in the current digital system cellular system in Japan, the distance between the transmitting band and the receiving band is 112 MHz, and the band necessary for the entirety of system is 148 MHz.
The following can be considered as one of solutions to widen screw antenna
13
. Namely, a coil diameter of screw antenna
13
, the pitch, the number of turns are optimized. Moreover, as shown in
FIG. 2
, the screw antenna base portion
20
is divided into two and a spacer
21
, made of a dielectric material, is inserted therebetween, so that an LC series resonance circuit is formed. This equalizes the impedance characteristic of screw antenna
13
with that of mono-pole antenna
14
.
Since the impedance characteristic of screw antenna
13
is equivalent to that of mono-pole antenna
14
, screw antenna
13
connected to the radio circuit substrate
16
, which matches mono-pole antenna
14
, can obtain the same wide band characteristic as mono-pole antenna
14
.
However, in the conventional whip antenna
1
, both faces of spacer
21
must be bonded with an adhesive, etc., and there is a problem in which mechanical strength of the bonded portion is insufficient to bending and tension of whip antenna
1
.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide an antenna apparatus for use in a mobile radio communication apparatus, which can improve widen the band of a screw antenna as having mechanical strength sufficient to bending and tension of antenna.
The above object can be attained by the configuration in which electrostatic capacitance having an impedance characteristic equivalent to mono-pole antenna is generated between a feeder side and a screw antenna, and the electrostatic capacitance and a coil portion of the screw antenna constitute an LC series resonance circuit.


REFERENCES:
patent: 5438339 (1995-08-01), Itoh et al.
patent: 5469177 (1995-11-01), Rush et al.
patent: 5521605 (1996-05-01), Koike
patent: 5606327 (1997-02-01), Elliott et al.
patent: 5-343907 (1993-12-01), None
patent: 8-195615 (1996-07-01), None
English language abstract of JP 8-195615.
English language abstract of JP 5-343907.

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