Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
1999-09-29
2001-01-09
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S7000MS, C343S767000, C343S770000
Reexamination Certificate
active
06172656
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a means for supplying an electric current to a helical antenna in a non-contacting manner, and more particularly to a two-wire or four-wire wound helical antenna.
2. Description of the Related Art
The conventional antenna devices of this kind include, for example, the ¼ turn volute with split sheath balun of
FIG. 6
for a “Resonant Quadrifilar Helix Antenna” reported on the Microwave Journal, December, 1970, p49-53, and the antenna device disclosed in Japanese Patent Laid-Open No. 30006/1988.
FIG. 13
is a sketch drawing of the ¼ turn volute with split sheath balun reported on the Microwave Journal.
101
denotes a first helical antenna radiation element pair,
102
a second helical antenna radiation element pair,
103
a coaxial feeder cable,
104
a ¼ wavelength slit cut in an outer conductor of the coaxial cable
29
,
105
an impedance conversion member provided on an inner conductor of the coaxial cable
103
, and
106
a feeding point of the first and second helical antenna radiation element pairs
101
,
102
.
Both of the first and second helical antenna radiation element pairs
101
,
102
can be regarded as balanced lines just as parallel two-wire lines in view of the operating condition thereof. Therefore, when an electric current is supplied to the antenna by connecting an unbalanced line, such as the coaxial cable
103
thereto, it is necessary to provide a balance-unbalance converter between the helical antenna radiation element pairs and coaxial cable. To meet this requirement, a balun comprising the coaxial cable
103
, ¼ wavelength slit
104
and impedance conversion member
105
is provided.
The conventional antenna device shown in
FIG. 13
is formed as described above, in which the first and second helical antenna radiation element pairs
101
,
102
are connected directly to the inner conductor of the coaxial feeder cable
103
. Therefore, in order to move the helical antenna radiation element pairs
101
,
102
as movable parts, the coaxial cable has to be moved simultaneously. This makes it difficult to move the helical antenna radiation element pairs, and, when the radiation element pairs are moved repeatedly, they are broken easily.
Since the antenna of a portable telephone has to be inserted and withdrawn easily, it is difficult to use the antenna of
FIG. 13
for this purpose.
SUMMARY OF THE INVENTION
An object of the present invention is to move a helical antenna easily by supplying an electric current thereto in a non-contacting manner.
The present invention relates to an antenna device provided with the following structures (a)-(d):
(a) a dielectric tube,
(b) a conductor provided on an inner surface of the dielectric tube and having slots,
(c) strip conductors provided on an outer surface of the dielectric tube and crossing the slots, and
(d) helical antenna radiation elements inserted in the portion of an inner space of the dielectric tube which is opposed to the slots, and adapted to be driven by the slots and strip conductors.
Since the helical antenna radiation elements and slots are connected electromagnetically in a non-contacting manner with the slots connected electromagnetically to the strip conductors, an electric current can be supplied to the helical antenna in a non-contacting manner.
This enables the movements of the helical antenna to be made easily.
The antenna device according to the present invention is preferably provided with the following structures (a)-(e):
(a) a dielectric tube,
(b) a conductor provided on an inner surface of the dielectric tube and having at least two slots,
(c) at least two strip conductors provided on an outer surface of the dielectric tube and crossing the slots,
(d) a phase difference distributing circuit adapted to give a 180° phase difference between electromagnetic waves propagated through the strip conductors, and
(e) at least two helical antenna radiation elements which are provided on symmetrical portions of a column inserted in the portion of an inner space of the dielectric tube which is opposed to the slots, and which are adapted to be driven by the slots and strip conductors at a 180° phase difference.
Since an electric current can be supplied to the helical antenna in a non-contacting manner, the antenna can be moved easily.
Since the two helical antenna radiation elements can be driven at a 180° phase difference, a circularly polarized wave can be radiated.
The antenna device according to the present invention is preferably provided with the following structures (a)-(d):
(a) a dielectric tube,
(b) a conductor provided on an inner surface of the dielectric tube and having at least two slots,
(c) at least two strip conductors provided on an outer surface of the dielectric tube and crossing the slots in the opposite direction thereof, and
(d) at least two helical antenna radiation elements provided on symmetrical portions of a column inserted in the which are portion of an inner space of the dielectric tube which is opposed to the slots, and which are adapted to be driven by the slots and strip conductors at a 180° phase difference.
Since an electric current can be supplied to the helical antenna in a non-contacting manner, the antenna can be moved easily.
Since the two helical antenna radiation elements can be driven at a 180° phase difference, a circularly polarized wave can be radiated.
Since the two strip conductors are extended so as to cross the slots in the opposite direction thereof, the two helical antenna radiation elements can be driven at a 180° phase difference even when a 180° phase converter is not provided.
The antenna device according to the present invention preferably has the following structures (a)-(e):
(a) a dielectric tube,
(b) a conductor provided on an inner surface of the dielectric tube and having at least four slots,
(c) at least four strip conductors provided on an outer surface of the dielectric tube and crossing the slots,
(d) a phase difference distributing circuit adapted to give a 90° phase difference between adjacent strip conductors, and
(e) at least four helical antenna radiation elements which are provided on symmetrical portions of a column inserted in an inner space of the dielectric tube which is opposed to the slots, and which are adapted to be driven by the slots and strip conductors with 90° phase differences given thereamong.
Since an electric current can be supplied to the helical antenna, the antenna can be moved easily.
Since the four helical antenna radiation elements are driven with 90° phase differences given thereamong, a circularly polarized wave can be radiated toward an upper half surface.
The antenna according to the present invention preferably has the following structures (a)-(e):
(a) a dielectric tube,
(b) a conductor provided on an inner surface of the dielectric tube and having at least four slots,
(c) first and second strip conductors provided on an outer surface of the dielectric tube and crossing the slots in a first direction,
(d) third and fourth strip conductors provided on the outer surface of the dielectric tube and crossing the slots in a direction opposite to the first direction, and
(e) a phase difference distributing circuit adapted to give a 90° phase difference between the first and second strip conductors and between the third and fourth strip conductors.
Since an electric current can be supplied to the helical antenna in a non-contacting manner, the antenna can be moved easily.
Since the four helical antenna radiation elements are driven at a 90° phase difference with respect to one another, a circularly polarized wave can be radiated.
Since the strip conductors are extended so as to cross the a slots in the opposite direction thereof with a 90° phase difference given thereto by a distributor, the four helical antenna radiation elements can be driven at a 90° phase difference even when a 180° phase converter is not provided.
REFERENCES:
patent: 3696433 (1972-10-01), Killion et al.
patent: 5134422 (1992-07-01)
Endo Tsutomu
Miyazaki Moriyasu
Ohwada Tetsu
Mitsubishi Denki & Kabushiki Kaisha
Rothwell Figg Ernst & Manbeck
Vo Tuyet T.
Wong Don
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