Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-02-10
2001-04-03
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S725000, C343S749000, C343S895000
Reexamination Certificate
active
06211830
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a radio antenna apparatus, and in particular, to a radio antenna apparatus for use in a portable telephone or a mobile telephone for use in mobile communications.
BACKGROUND ART
A radio set comprising a conventionally publicly known radio antenna apparatus is shown in
FIG. 17
so as to schematically show an antenna and related parts. The radio set of the prior art is constituted by an external antenna
602
such as a whip antenna or a helical antenna, a built-in antenna
603
such as a plane antenna, feeder lines
604
and
605
, a transceiver unit
606
including a transceiver, and a microphone
609
connected to the transceiver unit
606
, which are provided in a radio set housing
601
. The external antenna
602
and the built-in antenna
603
are arranged in proximity to each other so as to be electromagnetically coupled with each other, constitute a receiving space selective diversity antenna. The external antenna
602
is arranged so as to be electrically insulated from the radio set housing
601
, while a predetermined point of the built-in antenna
603
is grounded to the radio set housing
601
through a short-circuiting line
603
a
, and the built-in antenna
603
constitutes an inverted-F antenna.
When a power is supplied to the external antenna
602
, a switch
607
is turned on so that the external antenna
602
is connected to the transceiver unit
606
provided in the radio set housing
601
through the feeder line
604
. At the same time, the switch
608
is turned off, and the feeder line
605
connected to the built-in antenna
603
is disconnected from the transceiver unit
606
.
On the other hand, When the built-in antenna
603
is supplied with power, the switch
608
is turned on so that the built-in antenna
603
is connected to the transceiver unit
606
through the feeder line
605
. At the same time, the switch
607
is turned off so that the feeder line
604
connected to the external antenna
602
is disconnected from the transceiver unit
606
.
In the radio set comprising the conventional radio antenna apparatus described above, the external antenna
602
and the built-in antenna
603
are designed to have a high gain primarily in a free space, and have a uniform horizontal plane directivity or radiation pattern along the x-y plane with a center of the external antenna
602
and the built-in antenna
603
. In other words, as shown in
FIG. 17
, in the case where the orthogonal coordinates are set so that the z-axis direction is coincident with the axial direction of the external antenna
602
and the x-axis direction is coincident with the direction of the normal to the built-in antenna
603
, the horizontal plane directivity pattern of the antenna of the conventional radio set in a free space is shown in
FIG. 18
, and it has a shape of a circle (as indicated by a thick solid line of
FIG. 18
) with the center of the z-axis on the x-y plane, as shown in FIG.
18
. It is to be noted that the microphone
108
is arranged under the radio set housing
101
on the side nearer to the whip antenna
102
in the x-axis direction.
The conventional radio antenna apparatus described above has the same horizontal plane directivity pattern in the x-y plane and hence a horizontal plane non-directivity pattern. Therefore, in a case where a human head or the like obstacle approaching the microphone
609
exists in proximity to the radio set comprising the conventional radio antenna apparatus described above, the radio wave is interrupted by the obstacle, and this leads to a problem of gain deterioration.
An object of the present invention is to solve the above-mentioned problems and to provide a radio antenna apparatus, in which the horizontal plane directivity pattern of the antenna is changed in a direction not affected by an obstacle, and radio wave interference by the obstacle is reduced so as to improve a radiation efficiency thereof.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a radio antenna apparatus connected to a transceiver unit of a radio set, comprising an antenna element, a passive element arranged in proximity to the antenna element so as to be electromagnetically coupled with the antenna element, a load impedance element, connected to the passive element, and capable of changing an impedance value thereof, and control means for changing a directivity pattern of the antenna element by changing the impedance value of the load impedance element.
Also, the above-mentioned radio antenna apparatus preferably further comprises an impedance matching circuit, connected between the antenna element and the transceiver unit of the radio set, for matching the impedance of the antenna element with the impedance of the transceiver unit of the radio set.
Also, according to a radio antenna apparatus of the present invention, there is provided a radio antenna apparatus connected to the transceiver unit of a radio set, comprising at least two antenna elements including first and second antenna elements arranged close enough to each other so as to be electromagnetically coupled with each other and constituting a space selective diversity antenna, a load impedance element capable of changing an impedance value thereof, first switching means for selectively switching over so as to connect one of the first and second antenna elements to the transceiver unit of the radio set, and to connect another one thereof to the load impedance element, and control means for changing a directivity pattern of the antenna element by changing the impedance value of the load impedance element.
Further, the above-mentioned radio antenna preferably further comprises an impedance matching circuit, connected between the first or second antenna element connected to the transceiver unit of the radio set, and the transceiver unit of the radio set, for matching the impedance of the antenna element with the impedance of the transceiver unit of the radio set.
Still further, in the above-mentioned radio antenna apparatus, the control means preferably changes a correlation coefficient between the first antenna and the second antenna by changing the value of the load impedance element.
Also, in the above-mentioned radio antenna apparatus, preferably, one of the first and second antennas is at least one of a whip antenna and a helical antenna, and another one of the first and second antennas is a plane antenna.
Further, in the above-mentioned radio antenna apparatus, the control means preferably changes the directivity pattern of the antenna elements by selectively changing the value of the load impedance element between a standby mode and a speech mode of the transceiver unit of the radio set.
Still further, the above-mentioned radio antenna apparatus preferably further comprises first detecting means for detecting a strength of a received signal received by the transceiver unit of the radio set, wherein the control means changes the directivity pattern of the antenna elements by changing the value of the load impedance element in accordance with the strength of the received signal detected by the first detecting means at a standby mode of the transceiver unit of the radio set.
Also, in the above-mentioned radio antenna apparatus, the load impedance element preferably includes an impedance variable element.
Further, in the above-mentioned radio antenna apparatus, the load impedance element preferably includes a reactance element.
Still further, in the above-mentioned radio antenna apparatus, the load impedance element preferably includes a plurality of impedance elements, and second switching means for selectively switching the plurality of the impedance elements, wherein the control means changes the value of the load impedance element by controlling the switching of the second switching means.
Also, in the above-mentioned radio antenna apparatus, the impedance matching circuit preferably includes a plurality of impedance matching circuit units, and third switching means for selectively switching the plurality of th
Koyanagi Yoshio
Matsuyoshi Toshimitsu
Monma Kenji
Ogawa Koichi
Matsushita Electric - Industrial Co., Ltd.
Phan Tho
Wenderoth Lind & Ponack, LLP.
LandOfFree
Radio antenna device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radio antenna device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radio antenna device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2468256