Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2002-08-05
2004-10-19
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S7000MS
Reexamination Certificate
active
06806834
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 2002-19824, filed on Apr. 11, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Filed of the Invention
The present invention relates to a multi band antenna built in a telecommunication terminal, and more particularly, to a planar inverted F antenna having a LC coupled feed line spaced-apart from a radiating patch by a predetermined distance to obtain multi frequency bands each having a wide frequency bandwidth.
2. Description of the Related Art
Recently, a mobile communication terminal is required to be compact, light, and multi-functional according to a recent demand. Electrical circuits and components built in the mobile communication terminal become smaller and multi-functional in order to satisfy the above requirement. Also, this requirement is applied to an antenna, which one of major components of the mobile communication terminal.
A conventional antenna used in the mobile communication terminal is a helical antenna and a planar inverted F antenna. The helical antenna is mounted on a top side of the mobile communication terminal together with a mono pole antenna. The helical antenna and the mono pole antenna have a quarter wavelength (&lgr;/4) and are disposed inside the mobile communication terminal to be extended to an outside of the mobile communication terminal together with the helical antenna.
Although the helical antenna has an advantage in obtaining a high gain in a frequency band, a characteristic of synthetic aperture radars (SAR), which is an industrial standard relating to an electromagnetic wave, becomes low due to a non-directional characteristic of the helical antenna. Moreover, because the helical antenna is built on an outside of the mobile communication terminal, the helical antenna is not suitable to a portable apparatus, and an outer appearance of the mobile communication terminal will not be neat. Furthermore, it is very difficult to design the mobile communication terminal to be compact since the monopole needs a space to be built inside the mobile communication terminal.
In an effort to overcome the above problems, the planar inverted F antenna has been proposed.
FIG. 1
shows a structure of a conventional planar inverted F antenna (PIFA). The PIFA includes a radiating patch
2
, a shorting pin
4
, a coaxial line
5
, a ground plane (plate)
9
. The radiating patch
2
is electrically coupled to the coaxial line
5
and has an impedance match with the ground plane
9
by forming a short circuit. A length L of the radiating patch
2
and a height H of the PIFA are designed in accordance with a first width Wp of the shorting pin
4
and a second width of the radiating patch
2
.
The PIFA reduces the amount of harmful electromagnetic waves generated toward a user because the electromagnetic waves generated by current induced in the radiating patch
2
and directed toward the ground plane
9
are re-induced to the radiating patch
2
. Moreover, the SAR characteristic is improved by a directional increase of the radiation waves induced (directed) in a direction toward the radiating patch
2
. Furthermore, the radiating patch
2
, which is used as a rectangular micro strip antenna having a predetermined length, is reduced by half in size and has a low profile structure.
The PIFA is still improved to be multi functional and developed as a dual band antenna used in two different frequency bands.
FIG. 2
shows a dual band PIFA antenna
10
using the same operational principle as the PIFA of FIG.
1
. The dual band antenna
10
includes a radiating patch
12
a shorting pin
14
coupling the radiating patch
12
to a ground, a coupling feed pin
15
feeding current to the radiating patch
12
, a dielectric block
11
having a ground plane (plate). A slot S having a U shape is formed inside the radiating patch
12
to have the dual frequency bands and divides the radiating patch
12
into two radiating patch areas to induce (direct) the current fed through the coupling feed pin
15
along the slot S to have a resonance electric length corresponding to two different frequency bands. The dual band antenna
12
may be used in a dual frequency band, for example a GSM frequency band and a DCS frequency band.
However, recently, the frequency band is variable to a CDMA frequency band (about 824-894 MHz), a GPS frequency band (about 1570-1580 MHz), a PCS frequency band (about 1750-1870 MHz or 1850-1990 MHz), or a blue tooth frequency band (2400-2480 MHz). The PIFA antenna is required to have a multi frequency band rather than the dual frequency band because the above conventional slot of the dual band antenna is not suitable to the multi band antenna. If the dual band antenna is built in the mobile communication terminal, the profile becomes too low, and a frequency bandwidth becomes too narrow.
Since a height of the dual band antenna, which is a major factor in designing the PIFA, is limited due to a limited width of the mobile communication terminal for the portability and a neat appearance, the narrow frequency bandwidth is disadvantageous in the mobile communication terminal.
A distribution circuit, such as a chip type LC component, may be additionally attached to the dual band antenna in order to remove the above problem. Although the dual band antenna obtains a much wider frequency bandwidth by controlling the impedance matching using the distribution circuit, unexpected problems, such as an efficiency of the dual band antenna, occur because the dual band antenna is interfered with the distribution circuit, which is an outside circuit coupled to the dual band antenna.
Therefore, we contemplate a PIFA to have a low profile structure, to be able to be used in a variety of frequency bands, and to improve characteristics of the narrowed frequency bands.
SUMMARY OF THE INVENTION
In order to overcome these and other problems, it is an object according to the present invention to provide a planar inverted F antenna having a LC coupled feed line spaced-apart from a radiation patch having a conductive pattern to obtain multi frequency bands each having a much wider frequency band width.
Additional objects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice.
These and other objects may be achieved by providing a planar inverted F antenna (PIFA) having predetermined structure, function, and shape of a feed line according to embodiments of the present invention.
According to an aspect of the present invention, the PIFA includes a feed pin directing a current, a feed line having one end electrically coupled to one end of the feed pin and having a predetermined resonance length, a coupling pin coupled to the other end of the feed line, and a radiating patch formed on a plane spaced-apart from the feed line by a predetermined distance to induce (feed) the current directed (fed) through the other end of the coupling pin, and a slot having one end starting at a portion of an edge and the other end disposed in an inside portion of the radiating patch, and a shorting pin having one end coupled to the radiating patch and the other end coupled to a ground.
According to another aspect of the present invention, the PIFA may include a feed pin directing a current, a feed line having one end electrically coupled to one end of the feed pin and having a predetermined resonance length, a radiating patch being spaced-apart from the feed line and being supplied through the feed pin, a shorting member having one end coupled to the radiating patch and the other end formed with a coupling pad to be coupled to a ground plate of a housing of a telecommunication terminal and to the other end of the feed line.
The PIFA may include a feed pin supplying a current, a first feed line having one end electrically coupled to one end of the feed pin and having a first resonance length,
Lowe Hauptman & Gilman & Berner LLP
Samsung Electro-Mechanics Co. Ltd.
Wimer Michael C.
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