This Application claims priority of Taiwan Patent Application No. 097148494, filed on Dec. 12, 2008, the entirety of which is incorporated by reference herein.
1. Field of the Invention
The present invention relates to an antenna module, and in particular relates to an antenna module providing single directional radiation.
2. Description of the Related Art
Circular polarization antennas have two-way radiation properties. In conventional antenna modules, a reflector is disposed under a circular polarization antenna (slot antenna) with a distance of a quarter wave length, and an inphase mapping current is generated below the circular polarization antenna to provide single directional radiation. However, dimension of the conventional antenna module is limited by the position of the reflector (the quarter wave length), so the size thereof is large, and the antenna module cannot be utilized in common portable electronic devices.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
An antenna module is provided. The antenna module includes an antenna and an electromagnetic band gap (EBG) element. The EBG element includes an EBG ground layer, a plurality of reflective units and a plurality of connection posts. The reflective units are arranged in a matrix, a gap is formed between the nearby reflective units, and the reflective units are corresponding to the antenna. Each connection post connects the reflective unit to the EBG ground layer.
Utilizing the antenna module of the embodiment of the invention, the EBG element provides single directional radiation property. The EBG element is directly connected to the slot antenna with adhesive material, rather than kept at a quarter wavelength from the slot antenna distance. The volume of the antenna module is reduced. Thus, the antenna module of the embodiment can be utilized in various portable electronic devices.
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
a is an assembly view of an antenna module 1 of an embodiment of the invention;
b is an exploded view of the antenna module 1 of the embodiment of the invention;
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
a is an assembly view of an antenna module 1 of an embodiment of the invention.
With reference to
The EBG element 200 corresponding to the slot antenna 100, comprise an EBG ground layer 210, a plurality of reflective units 221, and EBG substrate 230 and a plurality of connection posts 240. The reflective units 221 are arranged in a matrix on the antenna ground layer 130, and define a slot area 131 on the antenna ground layer 130. The feed conductor 120 extends corresponding to the slot area 131. A gap 222 is formed between the nearby reflective units 221, and each reflective unit 221 is connected to the ground layer 210 via the connection post 240.
The third surface 231 faces the second surface 112.
In the embodiment of the invention, the slot antenna 100 is a circular polarization antenna.
In the embodiment of the invention, the EBG element 200 provides single directional radiation property for the slot antenna with an operation principle similar to the Perfect Magnetic Conductor (PMC) principle. Thus, the EBG element is directly connected to the slot antenna with adhesive material, rather than kept at a quarter wavelength from the slot antenna distance. In the embodiment of the invention, the EBG element 220 has a reflection phase, and the reflection phase is −90° to provide improved matching effect.
In the embodiment of the invention, the reflective units define the slot area on the antenna ground layer. However, the invention is not limited thereto. A common slot antenna can also be combined with the EBG element of the invention. For example, in one embodiment, an antenna ground layer has a slot, reflective units of an EBG element are corresponding to the slot, and the reflective units and the antenna ground layer are located on a same plane.
In the embodiment of the invention, the cycle length Lp is 2.4 mm, the unit length Lu is 2 mm, the gap width g is 0.2 mm and the diameter φ is 0.5 mm. The thickness h of the EBG substrate 230 is 2.4 mm, and a dielectric coefficient of the EBG substrate 230 is 4.4.
Utilizing the antenna module of the embodiment of the invention, the EBG element provides single directional radiation property. The EBG element is directly connected to the slot antenna with adhesive material, rather than kept at a quarter wavelength from the slot antenna distance. The volume of the antenna module is reduced. Thus, the antenna module of the embodiment can be utilized in various portable electronic devices.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
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TW097148494 | Dec 2008 | TW | national |