Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
1999-01-25
2001-08-21
Wang, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S702000
Reexamination Certificate
active
06278415
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multiple-wire wound helical antenna which is used mainly for a mobile radio device such as a portable telephone.
2. Related Art of the Invention
The recent years have seen a rapid development of mobile telecommunication such as portable telephones, and as a result, not only portable telephone systems using ground stations are wanted but systems using satellites as well are expected. Meanwhile, an antenna is one of important devices of a portable telephone terminal.
In the following, an example of a conventional quadrifilar helical antenna mentioned above will be described with reference to an associated drawing.
FIG. 9
is a block diagram showing a conventional quadrifilar helical antenna. In
FIG. 9
, denoted at
201
is a quadrifilar helical antenna radiant section, denoted at
202
is a 3 dB hybrid, and denoted at
203
is an input/output terminal. An operation of the quadrifilar helical antenna having such a structure will be described below.
The quadrifilar helical antenna
201
, when dimensioned to have an appropriate size and fed at the input/output terminal
203
through the 3dB hybrid
202
, exhibits radiation pattern having a conical beam characteristic as that shown in FIG.
10
.
However, since the directivity is always upward with such a structure described above, if this antenna is disposed to a portable telephone which utilizes a satellite, the directivity becomes downward with the antenna folded during stand-by, whereby a radio wave from above is failed to be received.
SUMMARY OF THE INVENTION
In view of such a problem with the conventional technique, the present invention aims at providing a multi-filar helical antenna which exhibits an upward directivity not only when stretched but even when folded as well.
The present invention is directed to a multi-filar helical antenna which comprises: an antenna radiant section which comprises n elements which are wound in spiral; and phase control means which feeds a signal to the n elements with a phase delay of 360°
each in the order of an arrangement of the n elements or a phase lead of 360°
each in the order of the arrangement of the n elements.
The present invention is also directed to a multi-filar helical antenna which comprises: an antenna radiant section which comprises four elements which are wound in spiral; two feed lines which are connected to the antenna radiant section and have substantially the same electrical length with each other; a 3 dB hybrid which comprises four terminals; and two terminating circuits, wherein two on one side out of the four terminals of the 3 dB hybrid are connected to the two feed lines, two on the other side out of the four terminals of the 3 dB hybrid are connected to a switch which switches a connection state with a signal input/output portion, two connection circuits for connecting the switch to two terminals out of the four terminals of the 3 dB hybrid are respectively connected to terminating circuits, and wherein when the signal input/output portion is conducted with either one of two terminals of the 3 dB hybrid as the switch switches over, non-conducting one of the terminals is terminated by one of the terminating circuits which is connected to the non-conducting terminal.
With such structures according to the present invention, by means of a switch, it is possible to switch the directivity of an antenna between an upward direction and a downward direction. Hence, when the antenna is attached to a portable radio terminal, it is possible to direct the directivity of the antenna always to above regardless of whether the antenna is stretched or folded.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic diagram of a quadrifilar helical antenna according to a preferred embodiment of the present invention;
FIG. 2
is a circuitry diagram of the quadrifilar helical antenna according to the preferred embodiment of the present invention;
FIG. 3
is a structure diagram of the quadrifilar helical antenna according to the preferred embodiment;
FIGS. 4 and 5
are views showing a method of feeding signal to the quadrifilar helical antenna according to the preferred embodiment;
FIG. 6
is a view showing a radiation pattern of the quadrifilar helical antenna according to the preferred embodiment;
FIG. 7
is a circuitry diagram of a phase control circuit of an octafiler helical antenna according to the preferred embodiment of the present invention;
FIG. 8
is a view showing the quadrifilar helical antenna according to the preferred embodiment attached to a satellite portable telephone, as it is stretched and folded;
FIG. 9
is a block diagram of a conventional quadrifilar helical antenna; and
FIG. 10
is a view showing a radiant pattern of the conventional quadrifilar helical antenna.
REFERENCES:
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patent: 6075501 (2000-06-01), Kuramoto et al.
patent: 6133891 (2000-10-01), Josypenko
patent: 0 169 823 (1988-01-01), None
A. Sharaiha et al. “Printed Quadrifilar Resonant Helix Antenna Integrated Feeding Network”Electronics Letters, GB, IEE Stevenage vol. 33, No. 4, Feb. 13, 1997 pp. 256-257.
Paul Shumaker et al. “A New GCPW Resonant Quadrifilar Helix Antenna For GPS Land Mobile Applications”IEEE Antennas and Propagation Society International SymposiumUS, New York, NY:IEEE, Jul. 14, 1997 pp. 1344-1347.
Matsuyoshi Toshimitsu
Nakamura Hiroyuki
Ogawa Koichi
Takahashi Ken'ichi
Dinh Trinh Vo
Matsushita Electric - Industrial Co., Ltd.
Smith , Gambrell & Russell, LLP
Wang Don
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