1. Field of the Invention
The present invention relates to an antenna, and more particularly to a dipole antenna being an antenna of one wavelength of electricity having a radiation portion with an electric length of a half of a wavelength and two matching portions respectively with an electric length of a quarter of a wavelength for receiving or transmitting radio signals.
2. Description of the Related Art
With advances of technology nowadays, people can transmit information through a wireless transmission system without restriction. The antenna is an important element in the wireless transmission system. It generally is located in a wireless transmission device (such as a base station, wireless network card, bridge, router, or handset) to transform the voltage and current of a transmitter to radio signals, and broadcast the radio signals in the air by radiation. It also can receive and transform the radio signals to voltage and current to be processed in a receiver. In the prevailing trend that demands ‘slim’ and ‘light’ for wireless transmission devices, the conventional antenna is out of date. How to shrink the antenna and maintain the antenna function has become an important issue in research and development.
The commonly used dipole antenna mostly is formed in a cylindrical manner with a stripped coaxial cable housed and soldered in a metallic barrel. The copper conductive wire of the coaxial cable is connected to a transmission circuit of a circuit board in a wireless transmission device. The metallic mesh of the coaxial cable is connected to the barrel and the ground terminal of the circuit board. Its structure is generally like the one shown in
While the construction set forth above has substantially shrunk the length and size of the conventional antenna, its cylindrical shape is difficult to be installed on the wireless transmission device. Hence it usually needs a ground terminal on a distal terminal of the antenna body, to be installed securely on the wireless transmission device. Moreover, such an antenna often is extended outside the installed wireless transmission device. It is prone to be hit and damaged during transportation or use.
Refer to
The first element 210 is located on one side of a dielectric substrate 200 and is an elongate and dipolar conductive strip. The first element 210 has a radiation portion 212 on one terminal and a feed portion 214 on other end. The second elements 220 and 230 are located on two sides of the axis of the first element 210 and have one terminal connecting to the ground portion 240 on a location about one quarter of a wavelength from the radiation terminal of the first element 210. The two second elements 220 and 230 are conductive strips at a length of one quarter of a wavelength. The ground portion 240 is located on another side of the dielectric substrate 200 opposite to the first element 210, and is also a conductive strip, which has one terminal connecting to the feed portion 214.
The printed antenna mentioned above is directly formed on a circuit board of a desired wireless transmission device in the fabrication process of the printed circuit board. While the finished wireless transmission device does not need to add an extra antenna, the fabrication cost is higher. There is still a need for a low cost antenna that is easy to install and provides required functions.
Accordingly, the invention is directed to a dipole antenna thereof that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
The dipole antenna according to the invention is made of a metal sheet that has a conductive effect and may be installed securely on a wireless transmission device.
In one aspect, the dipole antenna according to the invention has two matching portions to brace a radiation portion, which is spaced from a ground portion at a distance, to form a stereoscopic structure to shrink the total size of the antenna.
In another aspect, the radiation portion of the dipole antenna according to the invention has an electric length of a half of a wavelength, and the two matching portions have an electric length of a quarter of a wavelength.
In yet another aspect, the dipole antenna of the invention may be made of metal in an integrated manner.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the dipole antenna including: a radiation portion, a first matching portion, a second matching portion and a ground portion. The radiation portion receives radio signals. The first matching portion includes a body section and a feed section. One terminal of the body section connects to the radiation portion and another terminal connects to the feed section. One terminal of the second matching portion connects to the radiation portion and another terminal connects to the ground portion. The first and second matching portions brace the radiation portion.
The radiation portion has an electric length of a half of a wavelength and the two matching portions have respectively an electric length of a quarter of a wavelength.
The radiation portion, first and second matching portions and ground portion are made of a thin sheet of conductive metal in an integrated manner.
The orientation of the feed section is substantially in parallel with the orientation of the ground portion. The feed section is spaced from the ground portion at a determined distance to generate a capacity effect. The determined distance is depended on the capacity to be demanded. If a region of the ground portion opposite to the feed section is a gap that is slightly larger than the feed section, the feed section and the ground portion may be located on the same plane.
In yet another aspect, one terminal of a conductive wire is soldered through the juncture of the body section and the feed section and another terminal connects to a transmission circuit of the wireless transmission device. In addition, the conductive wire may be a coaxial cable to transmit signals between the antenna and the wireless transmission device. When a coaxial cable is used, a small section of one terminal of the coaxial cable is stripped its outer layer and two terminals of the small section are respectively soldered through the juncture and on the ground portion to generate an inductance effect so as to improve the performance of the antenna.
In this case, the dipole antenna of the invention further includes an anchor section connecting to the ground portion for installing the antenna. An included angle between the anchor section and the ground portion is about 90 degrees. Moreover, the anchor section, the radiation portion, first matching portion, second matching portion and ground portion may also be made of metal in an integrated manner.
The invention will become more fully understood from the detailed description given herein below illustration only, and thus are not limitative of the present invention, and wherein:
With reference to
The ground portion 440 may be securely mounted onto a wireless transmission device through a bonding means, such as a double-sided adhesive tape, Velcro strips or the like.
The radiation portion 410 has an electric length of a half of a wavelength and the first and second matching portions 420 and 430 have respectively an electric length of a quarter of a wavelength to generate a matching impedance with the radiation portion 410.
The radiation portion 410, first and second matching portions 420 and 430, and ground portion 440 are made of a thin sheet of conductive metal, such as nickel,copper or the like. The dipole antenna may also be formed in an integrated manner. Namely, the aforesaid four portions 410, 420, 430 and 440 may be fabricated from one thin metal sheet to form the dipole antenna.
The radiation portion 410 and the ground portion 440 are substantially rectangular. The two matching portions 420 and 430 are formed in the wandering shape to shorten the distance between the radiation portion 410 and the ground portion 440. Moreover, besides the substantial rectangle, the radiation portion 410 and ground portion 440 may also be formed in other geometric shapes. The two matching portions 420 and 430, besides the zigzag shape, may also be formed in other geometric shapes.
The two matching portions 420 and 430 are formed in a direction substantially normal to the direction of the radiation portion 410, and also substantially normal to the direction of the ground portion 440. Thus, the radiation portion 410 and the ground portion 440 are substantially parallel with each other. The feed section 424 of the first matching portion 420 is substantially normal to the first matching portion 420. When the radiation portion 410 and the ground portion 440 are substantially parallel with each other, the feed section 424 also is substantially parallel with the ground portion 440. Hence, the ground portion 440 and the feed section 424 are spaced from each other at a determined distance; thereby a capacity effect is generated. Moreover, a notch is formed in a region of the ground portion 440 opposite to the feed section 424, that is slightly larger than the feed section 424, so as to define a gap between the feed section and the ground portion. Then the feed section 424 and the ground portion 440 may be located on the same plane.
The body section 422 and the feed section 424 are connected on a juncture, which may be run through by one terminal of a conductive wire that is anchored by soldering. The conductive wire has another terminal connecting to a transmission circuit of a wireless transmission device. In addition, a coaxial cable 450 may be used to transmit signals between the antenna and the wireless transmission device. When the coaxial cable 450 is used, the outer layer of a small section of one terminal thereof can be stripped to expose the metal mesh. One terminal of the small section without the outer layer is soldered through the juncture of the body section 422 and the feed section 424, and another terminal thereof is soldered on the ground portion 440, so as to form an induction effect to enhance antenna performance as shown in
Refer to
However, in this embodiment the ground portion 540 has an anchor section 542 substantially normal to the ground portion 540. When the ground portion 540 is mounted onto a wireless transmission device by a bonding means, the anchor section 542 may be wedged in a slit of a wireless transmission device to anchor the dipole antenna more securely on a selected location of the wireless transmission device. The anchor section 542 may be formed in a rectangle or other geometric shape.
The test results of the invention based on the embodiment shown in
While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments, which do not depart from the spirit and scope of the invention.
Number | Name | Date | Kind |
---|---|---|---|
5754145 | Evans | May 1998 | A |
6344823 | Deng | Feb 2002 | B1 |
6456246 | Saito | Sep 2002 | B1 |
6650301 | Zimmerman | Nov 2003 | B1 |
6864854 | Dai et al. | Mar 2005 | B1 |
Number | Date | Country | |
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20060152428 A1 | Jul 2006 | US |