Wide band antenna

A wide band antenna includes a radiation element, a ground surface, a dielectric element, a connector; a first microstrip feeder and a second microstrip feeder. The radiation element is a rectangle shaped and includes a first side and a second side. The lengths of the first side and the second side are not equal. The dielectric element is positioned between the radiation element and the ground surface. One end of the first microstrip feeder is connected to the first side of the radiation element. One end of the second microstrip feeder is connected to the second side of the radiation element, the other ends of the first and second microstrip feeder are connected to the connector.

BACKGROUND

1. Technical Field

The present disclosure relates to a wide band antenna and, particularly, to a wide band antenna for mobile communication.

2. Description of Related Art

Referring toFIG. 1, an antenna1of related art for mobile communication is shown. The antenna1is used for receiving radio frequency (RF) signals and radiating corresponding radio waves. The antenna1includes a radiation element11, a dielectric element12, a ground surface13, a microstrip feeder14, and a connector15. The radiation element11, the ground surface13, and the microstrip feeder14are all conductive. The dielectric element12is positioned between the radiation element11and the ground surface13. The radiation element11, the dielectric element12, and the microstrip feeder14are supported by the ground surface13. The radiation element11is a rectangle shaped including a first side16and a second side17. The first side16is adjacent to the second side17. The microstrip feeder14is connected to the midpoint of the first side16and perpendicular to the first side16. If a length of the second side17of the radiation element11is L1, a frequency of the antenna1can be computed by the following formula:

f=0.49⁢VL⁢ɛr
where, ∈rrepresents a dielectric coefficient of the dielectric element12. V represents a velocity of electromagnetic wave. Because ∈rand V are both constant, the frequency f of the antenna1is determined by the length of the adjacent side of the first side16to which the microstrip feeder14is connected. Due to the two adjacent sides of the first side16both are L1, only one frequency is generated by the antenna1.

DETAILED DESCRIPTION

FIG. 2is a schematic view of a wide band antenna2in accordance with an exemplary embodiment. The wide band antenna2includes a radiation element21, a dielectric element22, a ground element23, a first microstrip feeder24, a second microstrip feeder25, and a connector26. The functions and structures of the radiation element21, the dielectric element22, the ground element23, and the connector26are substantially the same as the radiation element11, the dielectric element12, the ground surface13, and the connector15of antenna1inFIG. 1. Comparing with the antenna1, the antenna2further includes the second microstrip feeder25. The first microstrip feeder24and the second microstrip feeder25are L shaped. The radiation element21includes a first side27and a second side28. The length of the first side27is not equal to that of the second side28. One end of the first microstrip feeder24is connected to the midpoint of the first side27and substantially perpendicular to the first side27. One end of the second microstrip feeder25is connected to the midpoint of the second side28, and substantially perpendicular to the second side28. The other ends of the first microstrip feeder24and the second microstrip feeder25are connected to the connector26.

Referring toFIG. 3, the length of the first side27of the radiation element21is L1. The length of the second side28of the radiation element is L2. L1is not equal to L2. According to the formula:

f=0.49⁢VL⁢ɛr,
two frequencies of the antenna2are got. The frequency acquired by the first microstrip feeder24is:

f1=0.49⁢VL1⁢ɛr.
The frequency acquired by the second microstrip feeder25is:

f2=0.49⁢VL2⁢ɛr,
therefore, a wide band antenna is realized.

FIG. 4is an electrical characteristics diagram of the antenna2to show return losses of the antenna2at different frequencies. It can be seen from the diagram when the frequency of the antenna is 0.8 GHz, the return loss of the antenna is −20 db, and when the frequency of the antenna is 1.3 GHz, the return loss of the antenna is −14 db. The return loss corresponding to 0.8 GHz and 1.3 GHz is far below the return losses at the other frequencies. Thus, it is established that the antenna2can be an effective wide band antenna.

Although the present disclosure has been specifically described on the basis of preferred embodiments, the disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the disclosure.