Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
2001-05-22
2002-04-09
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S702000, C343S872000, C343S893000
Reexamination Certificate
active
06369777
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an antenna device mainly used in wireless unit for mobile communication or the like, and a method of manufacturing the same.
BACKGROUND ART
Recently there is a rapidly increasing demand for wireless unit for mobile communication such as cellular phone. The wireless unit is diversified in function so as to transmit and receive more information by one unit. To meet such demand for multiple functions, a wireless unit capable of transmitting and receiving radio waves in plural frequency bands is developed. To cope with plural frequencies, the wireless unit has an antenna setting two or more impedance characteristics.
As the antenna applicable to plural frequency bands, the helical antenna with coil winding is widely used.
A conventional antenna is explained by referring to FIG.
28
.
FIG. 28
is a sectional view of a conventional antenna device applicable to two frequency bands. As shown in
FIG. 28
, a conventional antenna device
6
comprises:
a) a first helical antenna element (HAE)
1
made of copper wire or copper alloy wire,
b) a second HAE
4
made of copper wire or copper alloy wire,
c) a core
3
made of insulating resin for winding the HAE
1
and HAE
4
while insulating the HAE
1
and HAE
4
,
d) a mounting bracket
2
made of metal for mounting the core
3
on which the HAE
1
and HAE
4
are wound, and further mounting on the wireless unit, and
e) an insulating cover
5
for covering the outer circumference of the HAE
1
, HAE
4
, and core
3
.
The HAE
1
includes an upward coil winding
1
A, and a junction
1
B for electrically connecting to the mounting bracket
2
. The mounting bracket
2
has a circular recess
2
A for fitting the lower end of the core
3
. The winding
1
A of the HAE
1
is wound around the core
3
which is fixed to the recess
2
A. The junction
1
B at the lower end of the HAE
1
is electrically connected to the recess
2
A of the mounting bracket
2
. The winding diameter and winding pitch of the HAE
1
are same as the winding diameter and winding pitch of the HAE
4
. In the winding pitch of the winding
1
A of the HAE
1
, the HAE
4
is wound. As a result, the HAE
1
and HAE
4
are mutually insulated. The HAE
4
is parasitic, and is insulated from the mounting bracket
2
. An insulating cover
5
is formed by insert molding of insulating resin on the outer circumference of the core
3
on which the HAE
1
and HAE
4
are wound.
In the antenna device
6
thus composed, when sending and receiving radio waves, an electric current is induced between the windings of the HAE
1
and HAE
4
by electromagnetic inductive action. Making use of the induced current, the wireless unit having the antenna
6
can send and receive radio waves in at least two frequency bands.
The configuration of the HAE
1
and parasitic HA
4
requires high precision so as not to contact with each other and to maintain the desired antenna characteristic. In the conventional antenna
6
, however, the winding may be uneven in pitch or may be deformed when winding the copper wire or copper alloy wire on the core
3
and covering with the insulating resin
5
. Therefore, in the conventional antenna device having such structure, it is hard to obtain an impedance characteristic corresponding to a desired frequency band. That is, in the gain of the conventional antenna device, fluctuations were large. Accordingly, in order to obtain an antenna having a desired characteristic, it was necessary to sort out. There was also a limit for enhancing the yield of the conventional antenna device. In the conventional antenna device, therefore, reduction of cost was limited by the sorting process and the yield.
SUMMARY OF THE INVENTION
The invention relates to an antenna device having two or more impedance characteristics capable of solving the problems of the conventional antenna device. It is hence an object of the invention to present an antenna device hardly causing uneven pitch or deformation of antenna elements, stable in gain, and high in reliability. It is also an object of the invention to present a method of manufacturing antenna devices excellent in productivity.
To achieve the object, the antenna device of the invention comprises:
a) a first antenna element (FAE) of spiral form having nearly parallel plural bands formed so that both ends may be connected alternately and consecutively, and formed so that at least one or more bands may be projected,
b) a second antenna element (SAE) of meandering form having nearly parallel plural bands formed so that both ends may be connected alternately and consecutively, and formed so that at least one or more bands may be projected,
c) a core made of an insulating resin for disposing the FAE and SAE nearly at concentrical positions,
d) a mounting bracket connected to one end of the FAE, and
e) a cover made of an insulating resin for covering the outer circumference of each member, by exposing a part of the mounting bracket.
The FAE and SAE are formed by pressing a conductive thin metal plate punched in a specified shape into a desired shape. In order that the FAE and SAE may be mutually insulated, each inner side is fixed to the core. One end of the FAE is electrically connected to the mounting bracket. The mounting bracket has a threaded portion for mounting on a wireless unit for mobile communication such as cellular phone. The threaded portion is exposed.
Thus is presented an antenna device hardly causing uneven pitch or deformation of the antenna elements during manufacture, and having two or more impedance characteristics. It is high in reliability because uneven pitch or deformation hardly occurs.
Moreover, the antenna device having such structure can be produced easily, and the product yield is high.
The invention also provides a method of manufacturing antenna device which comprises:
a) a step of forming a first element plate by a step of punching a conductive thin metal plate of a specified dimension, and a step of pressing a part of the punched thin metal plate,
b) a step of forming a second element plate by a step of punching a conductive thin metal plate of a nearly same dimension as the first element plate, and a step of pressing a part of the punched thin metal plate,
c) a step of stacking up the outer circumferential parts of the first element plate and second element plate in the thickness direction,
d) a step of primary insert molding of a resin dielectric element for forming a core having a plurality of resin support parts by fixing the pressed portion of the stacked first element plate and the pressed portion of the second element plate,
e) a step of separating the core from the outer circumference by cutting off the flat outer circumferential parts of the pressed portion of the first element plate and the pressed portion of the second element plate near the core, and
f) a step of secondary insert molding of a resin dielectric element for forming a cover for covering the outer circumference by holding the resin support parts.
In the step of forming the first element plate of the invention,
a conductive thin metal plate of a specified dimension is blanked, and nearly parallel plural rectangular holes of same length are provided so that both ends may be convex and concave alternately, thereby forming plural linear portions,
one side of convex and concave portion of the plural rectangular holes is separated from the outer circumferential part in a linked state,
a band is formed by pressing at least a part of the linear portion of the plural linear portions,
the band is formed so as to be coupled to the outer circumference at the other side, and
a mounting bracket is connected and fixed to one end of the band, thereby forming a first element plate.
In the step of forming the second element plate of the invention,
a conductive thin metal plate is blanked, and nearly parallel plural hook holes of same length are provided alternately in reverse directions, so that plural linear portions are linked in a thin linkage alternately right and left,
one side of the plural hook
Ishito Yusuke
Kishimoto Yasunori
Koumoto Shinzo
Nishida Norihisa
Ohara Masahiro
Chen Shih-Chao
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
Wong Don
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