1. Field of the Invention
The present invention relates to an antenna, more specifically, to a multi-band antenna.
2. The Related Art
According to the progress of the communication technology, telecommunication system has become more popular nowadays. A transceiver and an antenna are components of telecommunication system. Due to the antenna capable of transferring current into radio wave and transferring radio wave into current, it is a major component in telecommunication system. Thus, efficiency and gain of the antenna directly may affect the quality of voice in telecommunication system.
The mobile phone is one of essential apparatus used in telecommunication system. For the marketing purposes, the essential requirements of the mobile phone are compact size and multi-band operation. Therefore, the antenna needs to become small size and multi-band operation in accordance with the essential requirements of the mobile phone.
Please refer to
The feeding portion 906 is arranged to near the grounding portion 908, and both the feeding portion 906 and the grounding portion 908 are extended from a first side of the first end portion 910 of the first radiating portion 902. The second radiating portion 904 is extended form a second side of the first end portion 910 of the first radiating portion 902, which has a meandering portion 914 and a L-shaped portion 916.
The meandering portion 914 has a third end portion 918 connected to the first end portion 910 of the first radiating portion 902, and a fourth end portion 920 connected to the L-shaped portion 916. The first radiating portion 902 of the antenna 900 can resonate at a low frequency range and the second radiating portion 904 can resonate at a high frequency range. Thus, the antenna 900 can achieve multi-band operation. According to the arrangement of the meandering portion 914, the antenna 900 has an advantage of smaller size.
However, the arrangement of the meandering portion 914 of the antenna 900 may cause frequency shifting. Because the neighbor sections in the meandering portion 914 are close to each other, the current passing though the meandering portion 914 substantially forms a first current flow I and a second current flow I′ opposite to the first current flow I.
Thus, the vector potential caused by the first current direction may neutralize the vector potential caused by the second current direction. Especially, a self-inductance of the meandering portion 914 is therefore reduced. Because the low frequency range resonated by the second radiating portion 904 and the self-inductance of the meandering portion 914 are an inverse proportion, the frequency range may shift to close the high frequency range.
Thus, the length of the L-shaped portion 916 or the total length of the second radiating portion 904 may be increased for pull down the low frequency range into the predetermination frequency range. Therefore, the size of the antenna 900 can not be obviously reduced on account of the arrangement of the meandering portion 914.
An object of the present invention is to provide a multi-band antenna including a first radiating portion and a second radiating portion. The first radiating portion has a first end portion and a second end portion. The second radiating portion extends from the first end portion and toward the second end portion of the first radiating portion.
A gap is formed between the first radiating portion and the second radiating portion. The gap has an opening slot, a connecting slot and an end slot. The opening slot is formed between the first radiating portion and the second radiating portion. The connecting slot and the end slot are together formed in the second radiating portion. The width of the connecting slot is wider than the width of the opening slot.
The first radiating portion can resonate at a high frequency range, and the second radiating portion can resonate at a low frequency range. The connecting slot of the gap can prevent the vectors potential caused by the second radiating portion from being neutralized.
The electromagnetic coupling effect over the opening slot of the gap caused between the first radiating portion and the second radiating portion can pull down the low frequency range for reducing the size of the second radiating portion. Therefore, the multi-band antenna has a small size.
The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which:
Please refer to
The first radiating portion 6 is of rectangle shape has a first end portion 14 and a second end portion 16 opposite to the first end portion 14. The feeding point 10 is arranged to near the grounding point 12, and both of the feeding point 10 and the ground point 12 are arranged at the first end portion 14 of the first radiating portion 6.
The second radiating portion 8 is extended from the first end portion 14 of the first radiating portion 6 and extended toward the second end portion 16 of the first radiating portion 6. The second radiating portion 8 has a first radiating section 18 and a second radiating section 20. The first radiating section 18 has a first L-shaped section 22, a second L-shaped section 24 and a connecting section 26. The first L-shaped section 22 and the second L-shaped section 24 are arranged to parallel to each other.
The first L-shaped section 22 has a third end portion 28 connected to the first end portion 14 of the first radiating portion 6, and a fourth end portion 30 connected to one end of the connecting section 26. The second L-shaped section 24 has a fifth end portion 32 connected to the second radiating section 20, and a sixth end portion 34 connected to the other end of the connecting section 26. The second radiating section 20 is arranged to parallel to the first radiating portion 6.
The first radiating portion 6 and the second radiating portion 8 together form a gap 36 therebetween. The gap 36 is consisted of an opening slot 38, a connecting slot 40 and an end slot 42. The opening slot 38 is formed between the first radiating portion 6 and the second radiating section 20 of the second radiating portion 8.
The connecting slot 40 interconnects the opening slot 38 and the end slot 42. The connecting slot 40 and the end slot 42 are together formed among the first L-shaped section 22, the second L-shaped section 24 and the connecting section 26 of the first radiating section 18 of the second radiating portion 8. Especially, the connecting slot 40 and the end slot 42 are together of a L-shaped.
The width of the connecting slot 40 is wider than the width of the opening slot 38 and the width of the end slot 42. The gap 36 consisted of the opening slot 38, the connecting slot 40 and the end slot 42 is of a stair-shaped.
Please refer to
The feeding portion 44 and the grounding potion are arranged to near to each other. Both the feeding portion 44 and the grounding portion 46 are of a curved shape for elastically pressing onto corresponding pads of a printed circuit board of a mobile phone (not shown in figures). Especially, the free end of the second radiating section 20 of the second radiating portion 8 may be extended and curved for tuning a frequency range of the multi-band antenna 100.
Because the width of the connecting slot 40 arranged between the first L-shaped section 22 and the second L-shaped section 24 is wide, the first L-shaped section 22 is spaced away the second L-shaped section 24. Thus, a vector potential caused by a current flow passing through the second L-shaped 24 will prevent a vector potential caused by a current flow passing through the first L-shaped section 22 from being neutralized.
Because the width of the opening slot 38 arranged between the first radiating portion 6 and the second radiating section 20 of the second radiating portion 8 is narrow, and a current flow passing through the first radiating portion 6 and a current flow passing through the second radiating section 20 of the second radiating portion 8 are in the same direction, an electromagnetic coupling effect therebetween may pull down the low frequency range caused by the second radiating portion 8.
Thus, the length of the second radiating section 20 of the second radiating portion 8 or the total length of the second radiating portion 8 is reduced. The size of the multi-band antenna 100 is therefore reduced.
Please refer to
If the multi-band antenna 100 operates at 1710 MHz, then the VSWR value is 2.933 (Mkr3 in
As described above, the first radiating portion 6 can resonate at the high frequency range covering DCS 1800 MHz band and PCS 1900 MHz band. The second radiating portion 8 can resonate at low frequency range covering EGSM 900 MHz band. Therefore the multi-band antenna 100 can operates at three frequency band of GSM.
The connecting slot 40 of the gap 36 can prevent vectors potential caused by the first L-shaped section 22 and the second L-shaped section 24 of the second radiating portion 8 from being neutralized each other. The electromagnetic coupling effect caused between the first radiating portion 6 and the second radiating section 20 of the second radiating portion 8 can pull down the low frequency range for reducing the size of the second radiating portion 8. Therefore, the multi-band antenna 100 has a small size.
Furthermore, the present invention is not limited to the embodiments described above; diverse 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.