Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1998-03-18
2001-09-11
Nguyen, Lee (Department: 2683)
Communications: radio wave antennas
Antennas
With radio cabinet
C455S575100, C455S090300, C343S752000, C343S7000MS
Reexamination Certificate
active
06288680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna apparatus and a portable radio gear using the same, and more particularly, to an antenna apparatus provided with a radiative conductor and a portable radio gear using the same.
2. Description of the Related Art
Monopole antennas and loop antennas have been conventionally used for portable radio gears such as a portable telephone and a pager. As a portable radio gear has been made compact, an antenna is required to be made compact. Since a monopole antenna and a loop antenna need to have a radiative conductor with a length of one-fourth the wavelength of the used signal, however, the antennas become large and a demand for compact antennas cannot be satisfied.
To solve this drawback, the applicant has proposed a chip antenna, such as that shown in
FIG. 12
, in the Japanese Unexamined Patent Publication No. 8-316725. A chip antenna
50
is provided with a rectangular-parallelepiped base member
51
having a mounting surface
511
and made from dielectric ceramic including barium oxide, aluminum oxide, and silica as its main components. Inside the base member
51
, a spirally wound conductor
52
is formed. A power-supply electrode
53
for applying a voltage to the conductor
52
is formed on surfaces of the base member
51
. One end of the conductor
52
is drawn to a surface of the base member
51
and connected to the power-supply electrode
53
. The other end of the conductor
52
forms a free end
54
inside the base member
51
.
When a compact chip antenna having a low resonant frequency is produced with the use of the above conventional chip antenna, however, since a conductor for transmitting and receiving a radio wave is short, the gain and bandwidth are reduced.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above drawback. Accordingly, it is an object of the present invention to provide an antenna apparatus having a high gain and a wide bandwidth at a low resonant frequency and a portable radio gear using it.
To solve the foregoing drawback, the present invention provides an antenna apparatus including a chip antenna and a mounting substrate on which the chip antenna is mounted, the chip antenna including a base member made from ceramic, a conductor formed on the base member, and a power-supply electrode to which one end of the conductor is connected and a terminal electrode to which the other end of the conductor is connected, both formed on a surface of the base member, and the mounting substrate including a radiative conductor and a ground electrode, wherein the terminal electrode of the chip antenna is connected to one end of the radiative conductor of the mounting substrate.
According to the above antenna apparatus, since the mounting substrate is provided with the radiative conductor to be connected to the conductor of the chip antenna, the effective length of the conductor of the antenna apparatus becomes long. Therefore, since the current distribution of the conductor in the antenna apparatus becomes large and the radiative electric field of the antenna apparatus becomes strong, a high gain and a wide bandwidth are obtained in a low resonant frequency.
The above antenna apparatus may be configured such that a circuit board on which a ground electrode is formed at the side corresponding to that of the mounting substrate at which the chip antenna is mounted is disposed such that the mounting substrate is substantially parallel to the circuit board, and the ground electrode of the mounting substrate is connected to the ground electrode of the circuit board.
With this structure, the current flowing through the antenna apparatus flows into the ground electrode of the circuit board. Therefore, the characteristics of the antenna apparatus are unlikely to be subject to an effect of a ground disposed at the side of the mounting substrate where the chip antenna is not mounted.
The above antenna apparatus may be configured such that the base member is formed of a laminated member including a plurality of layers; each of the layers has a main surface; the base member has a lamination direction substantially perpendicular to the main surface; and the conductor is formed in a spiral shape and has a spiral axis substantially perpendicular to the lamination direction of the base member.
In the above antenna apparatus, the conductor may have a meander shape.
The present invention also provides a portable radio gear including the above antenna apparatus, a transmitting circuit connected to the antenna apparatus, a receiving circuit connected to the antenna apparatus, and a casing for covering the antenna apparatus, the transmitting circuit, and the receiving circuit.
Since the above portable radio gear has an antenna apparatus which can have a high gain and a wide bandwidth in a low resonant frequency, it can be used for transmission and receiving in a low frequency region. In addition, since it has an antenna apparatus which is unlikely to be subject to an effect of the ground, deterioration caused by the ground, in transmission and receiving of the portable radio gear is prevented.
REFERENCES:
patent: 5696517 (1997-12-01), Kawahata et al.
patent: 5760746 (1998-06-01), Kawahata
patent: 5973651 (1999-10-01), Suesada et al.
patent: 0621653 (1994-04-01), None
patent: 0743699 (1996-11-01), None
patent: 0749214 (1996-12-01), None
patent: 0831546 (1998-03-01), None
Kanba Seiji
Mandai Harufumi
Oida Toshifumi
Tsuru Teruhisa
Arguyen Simm
Murata Manufacturing Co. Ltd.
Nguyen Lee
Ostrolenk Faber Gerb & Soffen, LLP
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