Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1999-10-04
2001-01-09
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C455S575100, C455S090300
Reexamination Certificate
active
06172646
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna apparatus and a communication apparatus using the antenna apparatus, and more particularly relates to an antenna apparatus used in a mobile communication apparatus, and a communication apparatus using the antenna apparatus.
2. Description of the Related Art
Recently, amid advances in high-performance mobile telephones such as PHS, there are demands to provide a mobile communication apparatus wherein an antenna mounted thereon has even higher performance characteristics, such as high gain and a capability to be miniturized.
FIG. 6
shows a conventional antenna apparatus mounted on a mobile communication apparatus. In
FIG. 6
, an antenna apparatus
1
comprises a ground electrode
3
provided on one major surface
2
a
of a mount substrate
2
, the corner of the major surface
2
a
having a removed portion
3
a,
a supply wire
4
provided in the removed portion
3
a,
and a surface-mount antenna
5
mounted thereabove. Then, the supply wire
4
is connected to a supply terminal (not shown in the diagram) of the surface-mount antenna
5
, and also to a signal source
6
provided on the mount substrate
2
.
FIG. 7
shows the surface-mount antenna
5
in more detail. The surface-mount antenna
5
has the basic constitution of that disclosed in Japan Unexamined Patent Publication No. 10-13139.
In
FIG. 7
, the surface-mount antenna
5
comprises several electrodes provided on the surface of a rectangular substrate
10
, which comprises an insulating dielectric such as ceramic or resin. Firstly, a strip-shaped radiation electrode
11
is provided extending from the other major surface
10
b
of the substrate
10
, across one end face
10
d,
and returning once again to the other major surface
10
b.
One end of the radiation electrode
11
is an open end
11
a,
and the other end connects to a first ground terminal
12
, which extends from an end face
10
c
of the substrate
10
to a first major surface
10
a
thereof. Furthermore, a feeding electrode
13
is isolated from the radiation electrode
11
and is provided on a second major surface
10
b
of the substrate
10
. One end of the feeding electrode
13
connects to a feeder terminal
14
, which extends from the end face
10
c
of the substrate
10
to the first major surface
10
a
thereof. Similarly, a ground electrode
15
is provided on the other major surface
10
b
of the substrate
10
near the open end
11
a
of the radiation electrode
11
. One end of the ground electrode
15
is connected to a second ground terminal
16
, which extends from the end face
10
c
of the substrate
10
to the first major surface
10
a.
Furthermore, terminals for securing
17
and
18
are provided on the first major surface
10
a
of the substrate
10
, and connect to the radiation electrode
11
.
When the surface-mount antenna
5
is mounted on a mount substrate (not shown in the diagram), the five electrodes comprising the first and second ground terminals
12
and
16
, the feeder terminal
14
, and the terminal for securing
17
and
18
, are connected by soldering to ground electrodes, supply lines, and electrodes for securing on the mount substrate side. Therefore, the five electrodes are represented as terminals in order to distinguish them from these other electrodes.
In a surface-mount antenna
5
having such a constitution, when a high-frequency signal is input to the feeder terminal
14
, the high-frequency signal is transmitted to the radiation electrode
11
via a capacitance created between the open end
11
a
of the radiation electrode
11
and the feeding electrode
13
. The radiation electrode
11
is made to resonate by the inductance component of the radiation electrode
11
itself, and by the capacitance formed between the open end
11
a
of the radiation electrode
11
and the feeding electrode
13
. The surface-mount antenna
5
functions as an antenna by radiating a portion of the resonance energy into space as electric waves.
At this point, since one end of the radiation electrode
11
is an open end
11
a,
and the other end is a grounded end, the resonance is approximately one-quarter wavelength. A current
19
flowing to the radiation electrode
11
(i.e. the current flowing to the surface-mount antenna
5
) flows from the grounded end of the radiation electrode
11
(more specifically, the first ground terminal
12
) toward the open end
11
a.
As a result, magnetic field components of the electric waves radiated from the surface-mount antenna
5
, and the electric waves received by the surface-mount antenna
5
, vibrate mainly in the direction of the 2 axis of the coordinates shown in FIG.
7
.
The electrodes and terminals of the surface-mount antenna
5
are provided separately from each other, but it is not absolutely necessary for them to be separated by some kind of clear boundary. The electrodes and the terminals may acceptably be provided together.
In the antenna apparatus
1
shown in
FIG. 6
, when the current
19
flows to the surface-mount antenna
5
, an image current
7
which is 180 degrees out of phase with the current
19
flows mainly to the ground electrode
3
.
However, when the antenna apparatus
1
is used, the mount substrate
2
is covered by a case of plastic, metal, or the like. The case is often left in such places as on a shelf, or in a bag. When placed on a shelf or in a bag, the case often comes into close contact with conductive objects comprising metal and the like, and such objects function more or less like ground conductors. This leads to a problem that, depending on the external environment in which this type of antenna apparatus
1
is used, the ground conductors in close proximity thereto alter the direction and position of the flow of the image current
7
of the current
19
flowing to the surface-mount antenna
5
, affecting the characteristics of the antenna apparatus
1
such as its gain and directivity.
SUMMARY OF THE INVENTION
To overcome the above described problems, preferred embodiments of the present invention provide an antenna apparatus having higher gain and characteristics which are largely unaffected by the external environment in which the antenna apparatus is used, and a communication apparatus using the antenna apparatus.
One preferred embodiment of the present invention provides an antenna apparatus comprising a strip-shaped radiation electrode having one open end and one grounded end, a surface-mount antenna comprising a feeding electrode isolated from the radiation electrode, and a monopole antenna disposed in the vicinity of the surface-mount antenna. The radiation electrode, the surface-mount antenna, and the monopole antenna are provided on the surface of a base comprising an insulator. In addition, the surface-mount antenna and the monopole antenna are fed from a single feeding point, and are arranged so that an image current of current flowing to the surface-mount antenna flows to the monopole antenna, and an image current of current flowing to the monopole antenna flows to the surface-mount antenna.
Furthermore, the antenna apparatus of the present invention comprises a strip-shaped radiation electrode having one open end and one grounded end, a surface-mount antenna comprising a feeding electrode isolated from the radiation electrode, and a monopole antenna disposed in the vicinity of the surface-mount antenna. The radiation electrode, the surface-mount antenna, and the monopole antenna are provided on the surface of a base comprising an insulator. The surface-mount antenna and the monopole antenna are fed from a single feeding point. In addition, the direction of the open end of the surface-mount antenna, taking a ground end of the radiation electrode as a reference, runs opposite to the direction of the open end of the monopole antenna, taking the feeding point as a reference.
Preferably, the electrical length of the monopole antenna is between one-eighth and one-quarter of the wavelength of the frequency used by the antenna apparatus.
Furtherm
Kawahata Kazunari
Kurita Junichi
Nagumo Shoji
Okada Ken
Yuasa Atsuyuki
Clinger James
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Wong Don
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