Multi-band antenna

1. Field of the Invention

The invention relates to a multi-band antenna, and particularly to a multi-band antenna with simple structure adapted to be configured in a portable electrical device.

2. The Related Art

A portable communication device has an antenna structure that supports wireless communication in multiple operating frequency bands, such as global system mobile (GSM) and wideband code division multiple access (W-CDMA) nowadays. Many different types of antennas for the portable communication device are used, including helix, inverted-F, folded dipole, and retractable antenna structures. Helix antenna and retractable antenna are typically installed outside the portable communication device. Inverted-F antenna and folded dipole antenna are typically embedded inside the portable communication device case or housing.

Generally, embedded antennas are preferred over external antennas for the portable communication device owing to mechanical and ergonomic reasons. Embedded antennas are protected by the portable communication device case or housing and therefore tend to be more durable than external antennas. Nowadays, the portable communication is combined with wireless communication technology and data processing technology for multiple function purpose, such as a notebook. Therefore, the embedded antenna capable of operating at various wireless communication bands and being configured in the notebook is a development point.

An object of the present invention is to provide a multi-band antenna having a housing, a first radiating conductor, a second radiating conductor, a parasitic element, a trap circuit, a feeding conductor with a feeding point and a ground portion. The housing defines a first surface, a second surface opposite to the first surface, and a third surface connecting the first and second surfaces. The first radiating conductor and the parasitic element are arranged on the first surface of the housing and formed as an elongated shape.

The trap circuit arranged on the first surface of the housing electronically connects the first radiating conductor and the parasitic element. The ground portion is arranged on the second surface of the housing. The second radiating conductor is formed as an elongated shape, which is arranged on the third surface of the housing and spaced from the first radiating conductor and the ground portion. The feeding conductor electronically connects the first and second radiating conductors.

According to the arrangement of the first and second radiating conductors, the parasitic element and the trap circuit, the multi-band antenna has a simple structure and a small volume adapted to be configured in a portable electrical device. When the multi-band antenna operates at wireless communication, the cooperation of the first radiating conductor, the trap circuit and the parasitic element obtains the 824-960 MHz frequency band and the parasitic element and the second radiating conductor obtain the 1710-2170 MHz frequency band.

The present invention will be apparent to those skilled in the art by reading the following description of a preferred embodiment thereof, with reference to the attached drawings, in which:

FIG. 1 is an exploded view of a first preferred embodiment of a multi-band antenna according to the present invention;

FIG. 2 is perspective view of the first preferred embodiment of the multi-band antenna according to the present invention;

FIG. 3 illustrates a second preferred embodiment of the multi-band antenna according to the present invention;

FIG. 4 shows the multi-band antenna being configured on the top surface of the display of a notebook; and

FIG. 5 is a test chart recording for the multi-band antenna of FIG. 2 , showing Voltage Standing Wave Ratio (VSWR) as a function of frequency.

Please refer to FIG. 1 and FIG. 2 . A first preferred embodiment of a multi-band antenna 100 according to the present invention is shown. The multi-band antenna 100 is arranged on a housing 1 . The housing 1 has a first surface 10 , a second surface 11 opposite to the first surface 10 , a third surface 12 connecting the first surface 10 and the second surface 11 , and a fourth surface 13 connecting the first surface 10 , the second surface 11 and the third surface 12 . In this case, the housing 1 is made of insulation material and formed as a rectangle.

The area of the first surface 10 of the housing 1 is similar to the area of the second surface 11 of the housing 1 . The area of the third surface 12 of the housing 1 is larger than the area of the first surface 10 and the area of the second surface 11 of the housing 1 . The area of the fourth surface 13 of the housing 1 is smaller than the area of the first surface 10 , the area of the second surface 11 and the area of the third surface 12 of the housing 1 .

The multi-band antenna 100 has a first radiating conductor 2 , a parasitic element 3 and a trap circuit 4 . The first radiating conductor 2 is arranged on the first surface 10 of the housing 1 , which defines a first end 20 and a second end 21 opposite to the first end 20 . The parasitic element 3 is arranged on the first surface 10 of the housing 1 defining a third end 30 and a fourth end 31 . The third end 30 of the parasitic element 3 is arranged to face the second end 21 of the first radiating conductor 2 . A trap circuit 4 arranged on the first surface 10 of the housing 1 electronically connects the first radiating conductor 2 and the parasitic element 3 .

In this case, the first radiating conductor 2 and the parasitic element 3 are made of thin foil. The first radiating conductor 2 and the parasitic element 3 are formed as an elongated shape. The trap circuit 4 is arranged between the second end 21 of the first radiating conductor 2 and the third end 30 of the parasitic element 3 . The trap circuit 4 may be capacitance, inductance or combination of capacitance and inductance.

The multi-band antenna 100 further has a ground portion 5 , a second radiating conductor 6 , and a feeding conductor 7 with a feeding point 8 . The ground portion 5 is arranged on the second surface 11 of the housing 1 . The second radiating conductor 6 is arranged on the third surface 12 of the housing 1 and spaced from the first radiating conductor 2 and the ground portion 5 , which defines opposite ends. The feeding conductor 7 electronically connects the first radiating conductor 2 and the second radiating conductor 6 .

In this case, the second radiating conductor 6 and the feeding conductor 7 are made of thin foil. The second radiating conductor 6 and the feeding conductor 7 are formed as an elongated shape. The feeding conductor 7 is arranged on the fourth surface 13 of the housing 1 , which electronically connects the first end 20 of the first radiating conductor 2 and one end of the second radiating conductor 6 . The feeding point 8 is arranged where the feeding conductor 7 connects with the second radiating conductor 6 .

Please refer to FIG. 3 , which shows a second preferred embodiment of the multi-band antenna 100 . According to the purpose of balancing gain of the multi-band antenna 100 , the second radiating conductor 6 has a first radiating segment 60 , a second radiating segment 61 and a third radiating segment 62 . The first radiating segment 60 of the second radiating conductor 6 spaced from the ground portion 5 connects with the feeding conductor 7 . The second radiating segment 61 of the second radiating conductor 6 is arranged close to the first radiating conductor 2 . The third radiating segment 62 connects the first radiating segment 60 and the second radiating segment 61 .

In this case, the length of the first radiating segment 60 of the second radiating conductor 6 is shorter than the length of the second radiating segment 61 of the second radiating conductor 6 . The gap between the first radiating segment 60 of the second radiating conductor 6 and the ground portion 5 is larger than the gap between the second radiating segment 61 of the second radiating conductor 6 and the first radiating conductor 2 .

Please refer to FIG. 4 . The multi-band antenna 100 is configured in a portable electrical device 9 , and particular a notebook 9 . In this case, the multi-band antenna 100 is arranged on the top surface 90 of the display of the notebook 9 . The ground portion 5 of the multi-band antenna 100 electronically connects to ground of the notebook 9 (not shown in figures).

When the multi-band antenna 100 operates at wireless communication, the first radiating conductor 2 obtains an electrical resonance larger than a quarter wavelength corresponding to DCS1800 mega hertz (MHz). The parasitic element 3 obtains an electrical resonance of a half wavelength corresponding to DCS1800 MHz. The second radiating conductor 6 obtains an electrical resonance of a quarter wavelength corresponding to DCS1800 MHz.

Please refer to FIG. 5 , which shows a test chart recording of Voltage Standing Wave Ratio (VSWR) of the multi-band antenna 100 as a function of frequency. Note of the VSWR dropping below the desirable maximum value “2” are in the 824-960 MHz and the 1710-2170 MHz frequency bands which cover the bandwidth of wireless communications under GSM850, EGSM900, DCS1800, PCD1900 and W-CDMA2100 standard.

In this case, the cooperation of the first radiating conductor 2 , the parasitic element 3 and the trap circuit 4 of the multi-band antenna 100 obtains the 824-960 MHz frequency band. The parasitic element 3 and the second radiating conductor 6 obtain the 1710-2170 MHz frequency band. Further, adjusting of the trap circuit 4 can shift the 824-960 MHz frequency band and bandwidth of the 824-960 MHz frequency band.

According to the arrangement of the first and second radiating conductors, the parasitic element and the trap circuit, the multi-band antenna has a simple structure and a small volume capable of operating at wireless communications and covering the 824-960 MHz and the 1710-2170 MHz frequency bands for adapting to be configured in the portable electrical device.

Furthermore, the present invention is not limited to the embodiments described above; various additions, alterations and the like may be made within the scope of the present invention by a person skilled in the art. For example respective embodiments may be appropriately combined.