Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
1999-05-19
2001-04-24
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S821000, C343S702000
Reexamination Certificate
active
06222505
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composite antenna apparatus for transmitting and receiving different frequencies and which is capable of providing a plurality of mobile communication services on differing frequency bands with a single portable terminal.
DESCRIPTION OF THE PRIOR ART
In recent years, mobile communication services using various frequency bands have come into use. In order to provide a plurality of mobile communication services on a single terminal apparatus, the number of composite type antennas has increased.
Diagram
1
is a perspective diagram showing the components, in simplified form, of a kind of composite antenna apparatus known as a mobile-use 2-cycle shared double whip antenna as an example of a conventional mobile terminal antenna similar to that disclosed at the 1994 Electronic Communications Conference Autumn Session Exhibit B-73. In the diagram, reference numeral
1
represents the body of the portable terminal,
2
is a first antenna joined to the body
1
and
3
is a second antenna joined in a similar fashion.
In composite antennas for use with mobile terminals such as the mobile-use 2-cycle shared double whip type composite antenna shown in diagram
1
, the first antenna
2
has a length h
1
, about half the wavelength of the low frequency f
1
and the second antenna
3
has a length h
2
about half the wavelength of the high frequency f
2
. In this kind of composite antenna apparatus, signals at a low frequency f
1
and signals at a high frequency f
2
are fed to the first antenna
2
and the second antenna
3
respectively.
Diagrams
2
and
3
are explanatory views showing, respectively, the vertical plane of the emission pattern, calculated according to the law of moments, of the effect of the first antenna
2
short circuiting when the second antenna is fed and of the effect of the second antenna
3
short circuiting when the first antenna
2
is fed. Although diagram
2
shows that there is little effect due to the first antenna
2
short circuiting when the second antenna
3
is fed, as can be seen from diagram
3
, when the second antenna
3
short circuits after the first antenna
2
is fed, the emission pattern changes greatly from the normal dipole antenna emission pattern due to the influence of the second antenna
3
.
Thus in a conventional composite antenna apparatus, since one antenna (the second antenna
3
) may influence the other antenna (the first antenna
2
) while the first antenna
2
is being fed with the result the that the emission pattern is changed greatly from a normal dipole antenna emission pattern, the problem arises that gain in the horizontal plane is reduced and so the antenna is unsuitable for a portable terminal used by a person communicating in a random environment in all horizontal directions.
The further problem arises that the arrangement of the two antennas
2
,
3
, in parallel increases the occupied volume and therefore decreases the portability of the portable terminal.
The purpose of the present invention is to solve the above mentioned problems by the provision of a composite antenna apparatus having antennas corresponding respectively to two different mobile communication services on the same axis. The respective antennas have equivalent gain in the horizontal plane as well as a reduced occupied volume.
Furthermore, it is a purpose of the present invention to provide a composite antenna apparatus which improves the portability of the portable terminal by using the movability of respective antennas constructed on the same axis so that they may be stored in the wireless body when not in use.
DISCLOSURE OF THE INVENTION
The composite antenna apparatus of the invention according to the scope of claim
1
provides for, at one end of a coaxial line, a balun, connected to an inner conductor and connected to the balun, one end of a helical element formed by a pair of line conductors. The other end of the helical element is aligned symmetrically, facing the balun, by turning it around the coaxial line using the coaxial line as a center and connected to the outer conductor at the other end of the coaxial line where the inner conductor connecting terminal joined to the inner conductor and the outer conductor connecting terminal joined to the outer conductor are located. In such a way, the composite antenna apparatus formed by the helical antenna fed by the coaxial line and the monopole antenna created by the outer conductor of the coaxial line running through its center are constructed on the same axis, thus allowing equivalent gain in the horizontal plane and a reduction in the occupied volume.
The composite antenna apparatus of the invention according to the scope of claim
2
includes, on the same axis, a monopole antenna created by the outer conductor of said coaxial line and a two-wire wound helical antenna fed by said coaxial line and constructed by a pair of helical elements and a single coaxial line. In this way, a composite antenna apparatus having equivalent gain in the horizontal plane and a reduction in the occupied volume can easily be constructed.
The composite antenna apparatus of the invention according the scope of claim
3
includes, on the same axis, a monopole antenna created by the outer conductor of the coaxial line and a four-wire wound helical antenna fed by the coaxial line. The helical antenna is formed by providing a balun and a phase delay element on one end of a single coaxial line, one end of a first helical element is connected directly to the balun and an end of a second helical element is connected to the balun through the phase delay element. In this way, it is possible to improve the symmetry of the emission pattern and provide more equivalent gain in the horizontal plane.
The composite antenna apparatus of the invention according to the scope of claim
4
includes, on the same axis, a monopole antenna created by the outer conductor of the coaxial line and a plurality of helical antennas formed by grouping a plurality of coaxial lines so that the outer conductors are in mutual contact, placing a balun at the end of each coaxial line, connecting one end of the helical element to each balun and connecting the other end of the helical element to the outer conductor at the other end of the coaxial line. In such a way, it is possible to construct, on a single axis, antennas corresponding respectively to a plurality of different kinds of services as well as providing equivalent gain in the horizontal plane and reduced occupied volume.
The composite antenna apparatus of the invention according to the scope of claim
5
includes, on a single axis, a monopole antenna created by the outer conductor of the coaxial line and two four-wire wound helical antennas formed by providing a first phase delay element and a first balun at one end of a first coaxial line and a second phase delay element and a second balun at one end of a second coaxial line, one end of the two pairs of helical elements forming the first helical antenna is connected to the first balun either directly or through the first phase delay element and one end of the two pairs of helical elements forming the second helical antenna is connected to the second balun either directly or through the second phase delay element. In such a way, it is possible to construct on a single axis antennas respectively corresponding to three different kinds of services and, due to the improvement in the symmetry of the emission pattern, to provide equivalent gain in the horizontal plane.
The composite antenna apparatus of the invention according to the scope of claim
6
provides an outer conductor connecting terminal connected to the outer conductor and an inner conductor connecting terminal connected to the inner conductor of the coaxial line placing at one end of the coaxial line mutually insulated slide-action contactors rotatable around the center of the axis of rotation orthogonal to the axis of the coaxial line. In such a way, the composite antenna apparatus, when not in use, may be piled and compacted within
Chiba Isamu
Endo Tsutomu
Konishi Yoshihiko
Ohtsuka Masataka
Urasaki Shuji
Ho Tan
Mitsubishi Denki & Kabushiki Kaisha
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