Patent Application
20100001922
The present invention relates to an H-type monopole isolation antenna; and, more particularly, to an H-type monopole isolation antenna for isolating a transmitting signal and a receiving signal in a co-channel, a co-polarization and a co-direction.
An isolation technology for separating transmitting/receiving signals in an antenna has been studied for a long time. The conventional isolation technology can be divided into two technologies according to propagation direction.
The first one is a unidirectional repeater, i.e., an antenna technology for receiving a receiving signal in the rear part and transmitting an amplified signal in the front part. This technology is used in a repeater system for co-channel broadcasting and it will be called a unidirectional isolation technology hereinafter. In the antenna technology, the transmitting signal is not transmitted in a direction that the transmitting signal is received, and a repeater for the co-channel broadcasting is used representatively and generally.
Since the unidirectional isolation technology gains high isolation by setting up high-directional antennas in opposition to each other and spacing them from each other, the unidirectional isolation technology has a shortcoming that it requires much space for setup.
Therefore, a broadcasting repeater using the conventional unidirectional isolation technology is used by setting up a receiving antenna in the lower part of a high iron tower and a transmitting antenna in the upper part.
The other conventional technology is a bi-directional isolation technology for re-transmitting in a co-direction. Specifically, there is a bi-directional isolation technology based on polarization.
That is, the technology raises the degree of isolation of the transmitting/receiving signals by generating polarizations of the transmitting/receiving signals.
However, the conventional bi-directional isolation technology has a problem that a distance length should be sufficiently acquired between the receiving antenna, i.e., the horizontal polarization and the transmitting antenna, i.e., the vertical polarization.
Another conventional technology, which is not applied to a practical system, generates the transmitting signal and the receiving signal, whose polarizations are perpendicular to each other, and maintains isolation between two terminals by vertically setting up their feed in a patch antenna. This is revealed in an article by Karode, in IEE National Conference on Antennas and Propagation, pp. 49-52, April 1999).
Also, Hao has realized an isolation technology by differentiating polarization generation of the patch antenna applying a photo band gap (PBG) structure in an article published in IEE, 11th International Conference on Antenna Propagation, pp. 86-89, April 2001).
However, as shown in the result, since the isolation for a co-frequency of the transmitting/receiving signals is very low, the technology is not proper as an antenna for co-channel bi-directional communications in diverse fields of mobile communications, short distance communications, a broadcasting repeater and satellite communications requiring high isolation for the co-frequency.
In the result of the conventional technologies suggested by Karodo and Hao, isolation is not more than about 60 dB although transmitting/receiving frequency bands or polarizations are different from each other.
Therefore, the isolation antenna, which is required for a co-channel wireless Local Area Network (LAN) low output repeater, a Radio Frequency (RF) reader antenna, an antenna for testing Radar Cross Section (RCS), and an isolation antenna capable of co-channel, co-polarization and bi-directional communications which is necessary in co-channel bi-directional communication devices.
It is, therefore, an object of the present invention to provide an H-type monopole isolation antenna which can gain a high bi-directional transmitting/receiving isolation between a transmitting antenna and a receiving antenna of co-channel/co-polarization by including an antenna symmetrically positioned in the right/left sides based on a a covering means between them.
Other objects and advantages of the invention will be understood by the following description and become more apparent from the embodiments in accordance with the present invention, which are set forth hereinafter. It will be also apparent that objects and advantages of the invention can be embodied easily by the means defined in claims and combinations thereof.
In accordance with one aspect of the present invention, there is provided a transmitting/receiving isolation antenna maintaining high isolation between a transmitting signal and a receiving signal, including: a cover which includes a conductor; and first and second antennas which are symmetrically positioned in right and left parts of the covering means and operated as a transmitting antenna or a receiving antenna respectively.
In accordance with another aspect of the present invention, the antenna further includes: a supporter for supporting the cover by being connected to a lower central part of the cover and a base for vertically fixing the supporter on a surface.
The present invention can acquire high isolation more than 75 dB although the transmitting/receiving antennas are set up adjacently and a small covering housing is used in a co-channel, co-polarization and co-direction.
Also, the present invention can realize high isolation by a small antenna and it can be applied to a bi-directional antenna or an antenna requiring high bi-directional transmission/reception isolation, such as a wireless Local Area Network (LAN), a Radio Frequency Identification (RFID) reader, a monitoring system, a Radar Cross Section (RCS) measuring system and a co-channel mobile communication system.
Also, since the antenna of the present invention can be fabricated in the form of a wall-hanging device or a device integrated with a power outlet, it can widen a usage range and independently realize the system in a small space.
The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:
Other objects and advantages of the present invention will become apparent from the following description of the embodiments with reference to the accompanying drawings. Therefore, those skilled in the art that the present invention is included can embody the technological concept and scope of the invention easily. In addition, if it is considered that detailed description on prior art may blur the points of the present invention, the detailed description will not be provided herein. The preferred embodiments of the present invention will be described in detail hereinafter with reference to the attached drawings.
As shown in
The antenna device 1 includes a covering housing 3, which is covered with a conductor such as gold, silver, aluminum and copper, and have a space inside, and first and second antennas 4 and 5, which are separately set up in both sides of the covering housing 3.
The first antenna 4 is an H-type monopole antenna and vertically positioned on top of the covering housing 3.
Also, the first antenna 4 includes a first antenna feeder 6 for feeding the antenna in a central part of an H-shaped form. Herein, feeding through the first antenna feeder 6 is performed horizontally to the covering housing 3.
The second antenna 5 is a general monopole antenna and is positioned in a region in contact with the covering housing 3, and includes a second antenna feeder 7 for vertically feeding the covering housing 3.
The antenna supporter 2 includes an antenna device supporter 8 and an antenna base 9 for supporting the antenna device 1.
Herein, the antenna device supporter 8 is formed in the shape of a pipe having a space inside and is set up in a central part of the antenna device 1 as shown in
The embodiment of
Therefore, since reflection by the earth surface is generated a lot in the horizontal polarization in comparison with a vertical polarization and the reflected wave deteriorates transmitting/receiving isolation, the antenna base 9 includes an electric wave absorber 10 for suppressing the reflected wave to remove the reflected wave.
Herein, reflexibility can be lowered by raising the height of the antenna device supporter 8 as well as setting up the electric wave absorber 10.
The first antenna 4 has a structure in which right and left antenna devices 11 and 12 having a pipe shape formed of a metal conductor such as gold, silver, copper and aluminum, are vertically positioned in the covering housing 3 just as a monopole, and the first antenna feeder 6 for feeding power is positioned in a region where right and left antenna supporters 13 and 14 contact each other between the right and left antenna devices 11 and 12.
As shown in the drawing, the first antenna feeder 6 includes a first connector 15 and a first connector pin 16.
Herein, the right and left antenna supporters 13 and 14 are formed in the shape of a conductive pipe.
A front head of the first connector 15 is positioned in the inside of the right antenna supporter 13, and the first connector pin 16 is welded into the left antenna supporter 14. Accordingly, the first antenna 4 has a structure that the first antenna 4 feeds horizontally a metal surface of the covering housing 3.
A coaxial cable connected to the first connector 15 is connected to the inside of the covering housing 3 having a space inside through the inside of the right antenna supporter 13 and the inside of the right antenna device 11.
Meanwhile, the covering housing 3 is directly connected to the antenna device supporter 8 through an opening 19 of the antenna device supporter.
As shown in
A front head of the second connector 17 is positioned in the inside of the covering housing 3 and formed to be able to connect the coaxial cable.
Although an antenna feeding point is entirely wrapped and fixed by using a dielectric to stand firmly against an external environment such as wind (not shown in the drawing), it does not affect a characteristic a lot.
Meanwhile, antenna devices 11 and 12 of the first antenna are formed in the shape of a pipe having a space inside and are directly connected to the inside of the covering housing 3 through an opening 20 of the first antenna device.
Also, as described above, the drawing shows that the first connector 15 connected to the first antenna feeder can be connected in an inside of the covering housing 3 through the coaxial cable.
As described above with reference to
This is for the following two objects.
One is to make the radiated electromagnetic wave and scattered wave by the antenna device supporter 8 arrive at the right and left antenna devices 11 and 12 in the same phase and same intensity, when the second antenna is excited with a transmitter.
Since it makes an electric potential difference between the right and left antenna supporters 13 and 14 identical, it prevents the radiated electromagnetic wave and scattered wave from being received after offset in the H-type monopole antenna, which is the first antenna.
The other one is also to make the radiated wave and the scattered wave arrive at the right and left antenna devices in the same phase and the same intensity, when radiated wave excited by the first antenna forms scattered wave by a surface and arrives at the second antenna. Herein, a technology for offsetting and decreasing a signal transmitted from the first antenna, which is the H-type monopole antenna, is added.
The antenna device supporter 8 can be formed in a pipe shape 19 by the conductors such as gold, silver, copper and aluminum. The coaxial cable connected to the first and second antennas in the inside of the pipe is sent under the surface and can be used by being connected to the repeater or the communications system.
The left and right antenna devices 11 and 12, the left and right antenna supporters 13 and 14, and the antenna device supporter 8 of the first antenna can be formed in the shape of a cylindrical pipe, of which a cross section is a circle.
A reference specification of an antenna used for measuring is as follows.
The second antenna has a width of 1 cm×1 cm and an entire length of 15 cm, and the first antenna also has the width of 1 cm×1 cm, which is the same as the second antenna. The left/right antenna devices 11 and 12 have a length of 13 cm, and a distance between the left/right antenna devices 11 and 12 is 6 cm. The covering housing has a size of 2 cm×16 cm×20 cm.
As shown in
Herein, all values of S11 and S22 parameters are equal to or smaller than −10 dB and it shows that impedance matching is well performed.
The measurement result shows that the H-type monopole antenna, which is the first antenna, can be used as the transmitting/receiving antenna although the H-type monopole antenna is independently operated.
Also,
That is, although a length of the covering housing is smaller than a half-wave length, high isolation is acquired. Herein, half-wave of 550 MHz is 27 cm.
The isolation is varied based on the size of the covering housing. It will be described hereinafter with reference to
As shown in
Also, when the size of the covering housing is 60 cm, the isolation rate is maintained at about −100 dB. That is, when the covering housing maintains about 1 wavelength, the isolation is maintained at about −100 dB.
As shown in
Herein, the polarization shown in the drawing is a pattern for an electric field element of an ψ direction.
As shown in
Herein, the patterns are largely generated in a direction toward the first antenna by scattered wave abandoned in the first antenna.
The polarization is the pattern for the electric field element of the direction as
Also, as shown in the drawing, a section, in which beam directions of
That is, it shows that the present invention can be used as a bi-directional repeater system, a Radio Frequency Identification (RFID) reader antenna, a wireless Local Area Network (LAN) low output bi-directional repeater antenna and a Radar Cross Section (RCS) measuring antenna.
Also, the present invention can be used as a uni-directional horizontal polarization repeater antenna which can transmit a signal transmitted from a direction of ψ=180 by the first antenna to directions of ψ=100 to 145, and ψ=215 to 260 by the second antenna.
As shown in
When the H-type monopole isolation antenna is used by setting up the antenna device supporter 8 on a wall 22 where a fixed iron is fixed, the isolation suggested above can be maintained.
Also, when the antenna device is rotated up and down as much as 90 degree the communications system for the horizontal polarization can be supported.
As shown in
In this case, it is very convenient that the present invention can be simply and independently set up wherever a power code, i.e., the outlet is.
While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2004-0109404 | Dec 2004 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR2005/004428 | 12/21/2005 | WO | 00 | 6/20/2007 |
