Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2002-08-29
2004-01-27
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000
Reexamination Certificate
active
06683573
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi band chip antenna with dual feeding ports and a mobile communication apparatus using the multi band chip antenna, and more particularly to a multi band chip antenna, in which dual feeding ports are formed on a radiation electrode structure, thereby being usable at multi frequency bands, and a mobile communication apparatus using the multi band chip antenna.
2. Description of the Related Art
Recently, development trends of mobile communication terminals have been directed toward miniaturization, light-weight, and multi-functionality. In order to satisfy this trend, circuits and parts of the mobile communication terminals have been miniaturized and made multi-functional. Therefore, antennas of the mobile communication terminals have also been miniaturized and-made multi-functional.
Generally, antennas which are used in the mobile communication terminals are divided into two types, i.e., a helical antenna and a planar inverted F-type antenna (referred to as a “PIFA”). The helical antenna is an external antenna, which is fixed to the upper surface of the terminal. The helical antenna is mostly used in combination with a monopole antenna. This combined structure of the helical antenna and the monopole antenna has a length of &lgr;/4. Herein, the monopole antenna is an internal antenna, which is stored within the terminal. The monopole antenna is pulled out, thereby being used as the antenna of the terminal in combination with the external, helical antenna.
The combined structure of the helical antenna and the monopole has high gain. However, this combined structure of the helical antenna and the monopole antenna has a low SAR(Specific Absorption Rate) characteristic due to the non-directivity. Herein, the SAR characteristic is an index of harmfulness of an electromagnetic wave to the human body. It is difficult to aesthetically and portably design the appearance of the helical antenna. Further, the monopole antenna requires a storage space within the terminal. Therefore, the combined structure of the helical antenna and the monopole antenna limits the miniaturization of the mobile communication product using this structure. In order to solve these problems, a chip antenna having a low profile structure has been introduced.
FIG. 1
is a schematic view illustrating a principle of operation of a conventional chip antenna. The chip antenna of
FIG. 1
is referred to as the planar inverted F-type antenna (PIFA). The name of the chip antenna is due to its shape. As shown in
FIG. 1
, the chip antenna comprises a radiation patch (RE), a short-circuit pin (GT), a coaxial line (CL), and a ground plate (GND). Herein, power is supplied to the radiation patch (RE) through the coaxial line (CL). The radiation patch (RE) is connected to the ground plate (GND) through the short-circuit pin (GT), thereby performing the impedance matching. It is to be noted that the chip antenna is designed so that the length (L) of the radiation patch (RE) and the height (H) of the antenna are determined by the width (Wp) of the short-circuit pin (GT) and the width (W) of the radiation patch (RE).
In this chip antenna, among beams generated by the induced current to the radiation patch (RE), beams directed toward the ground plane are re-induced, thereby reducing the beams directed toward the human body and improving the SAR characteristic. Further, the beams induced toward the radiation patch (RE) are improved. And, the chip antenna has a lower profile structure, thereby being currently spotlighted. Further, in order to satisfy the trend of multi-functionality, the chip antenna has been variously modified, thereby being particularly developed as a dual band chip antenna, which is usable at multiple frequency bands.
FIG. 2
a
is a perspective view of a conventional dual band chip antenna, and
FIG. 2
b
is a schematic view of a configuration of a mobile communication apparatus using the conventional dual band chip antenna.
With reference to
FIG. 2
a
, the conventional dual band chip antenna
10
comprises a radiation patch
12
formed in a planar square shape, a short-circuit pin
14
for grounding the radiation patch
12
, a power-feeding pin
15
for feeding power to the radiation patch
12
, and a dielectric block
11
provided with a ground plate
19
. In order to achieve dual band function, an U-type slot may be formed on the radiation patch
12
. Herein, the radiation patch
12
is substantially divided into two areas by the slot, thereby inducing the current flowing along the slot to have different lengths so as to resonate in two different frequency bands. Therefore, the dual band chip antenna
10
is operated in two different frequency bands, for example, GSM band and DCS band.
However, recently, the usable frequency band has been variously diversified, i.e., CDMA (Code Division Multiple Access) band (approximately 824~894 MHz), GPS (Global Positioning System) band (approximately 1,570~1,580 MHz), PCS (Personal Communication System) band (approximately 1,750~1,870 MHZ or 1,850~1,990 MHZ), and BT (Blue Tooth) band (approximately 2,400~2,480 MHz), thereby requiring a multiple band characteristic more than the dual band characteristic. Therefore, the system using the aforementioned slot is limited in designing the antenna with the multiple band characteristic. Further, since the conventional antenna has a low profile so as to be mounted on the mobile communication terminal, the usable frequency band is narrow. Particularly, the height of the antenna is restricted by the limited width of the terminal of the mobile communication apparatus, thereby further increasing the problem of the narrow frequency band.
The dual band chip antenna of
FIG. 2
a
comprises one feeding port connected to the power-feeding pin
15
. In case that this dual band chip antenna is installed on a mobile communication apparatus, such as a dual band phone, as shown in
FIG. 2
b
, the mobile communication apparatus requires a band splitting unit
21
for splitting the frequency band from the chip antenna
10
into GPS band and CDMA band. For example, the band splitting unit
21
is a diplexer or a switch. Therefore, it is difficult to miniaturize the mobile communication apparatus using the dual band chip antenna. Further, the band splitting unit incurs a loss to the gain.
In order to solve the problem of the narrow frequency bandwidth, a distribution circuit such as a chip-type LC device is additionally connected to the antenna, thereby controlling the impedance matching and achieving a somewhat wide frequency band. However, this method, in which the external circuit is involved in the frequency modulation, causes another problem, i.e., the deterioration of the antenna efficiency.
FIG. 3
is a perspective view of another conventional chip antenna. With reference to
FIG. 3
, the chip antenna
10
comprises a body
2
having a hexahedral shape, which is made of dielectric material or magnetic material, a ground electrode
3
formed on one whole surface of the body
2
, a radiation electrode
4
formed on at least another whole surface of the body
2
, and a power-feeding electrode
5
formed on yet another surface of the body
2
. One end
4
a
of the radiation electrode
4
is opened and is formed adjacent to the power-feeding electrode
5
. The one end
4
a
of the radiation electrode
4
is spaced from the power-feeding electrode
5
by a gap
6
. The other end of the radiation electrode
4
is branched into multiple sections, thereby forming ground terminals
4
b
and
4
c
. The ground terminals
4
b
and
4
c
are connected to the ground electrode
3
via different surfaces of the body
2
. Japanese Laid-open Publication No. Heisei 11-239018 discloses the configuration of this chip antenna in detail.
In accordance with this chip antenna, the radiation electrode is divided into two sections. The divided two sections are grounded by two ground terminals
4
b
and
4
c
. Therefore, the current flows along each one of the ground terminals
4
Ho Tan
Lowe Hauptman & Gilman & Berner LLP
Samsung Electro-Mechanics Co. Ltd.
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