Electronic device and antenna structure thereof

The invention relates to an antenna structure, and more particularly to an antenna structure providing improved radiation pattern.

FIGS. 1 a and 1 b show an antenna structure 12 disclosed in U.S. Pat. No. 6,339,404, which comprises a substrate 14 , radiation elements 22 , a conductive element 24 , a conductive element 26 , a reflective element 28 , impedance matching elements 46 and cables 44 . The substrate 14 comprises a first surface 16 and a second surface 18 . The reflective element 28 is disposed on the first surface 16 . The radiation elements 22 are disposed on two sides of the reflective element 28 . The cables 44 comprise conductive lines 42 and 48 . The conductive lines 42 are coupled to the reflective element 28 . The conductive element 24 , the conductive element 26 and the impedance matching elements 46 are disposed on the second surface 18 . The conductive element 24 and the conductive element 26 are connected to the impedance matching elements 46 . The conductive lines 48 are coupled to the conductive element 24 and the conductive element 26 .

Conventional antenna structure 12 , however, comprises two conductive lines 48 , two independent impedance matching elements 46 and two conductive elements 24 and 26 , the structure thereof is complicated, and the radiation pattern cannot be improved by modifying the conductive line 48 , or the conductive elements 24 and 26 . Additionally, when a plurality of antenna structures 12 are connected in parallel to achieve an improved signal transmission, the size thereof is large.

An embodiment of an antenna structure for transmitting a wireless signal comprises a substrate, a reflective element, a first radiation unit, a second radiation unit, a first impedance matching unit, a second impedance matching unit, a feed point, a first conductive line and a second conductive line. The substrate comprises a first surface and a second surface. The reflective element is disposed on the second surface. The first radiation unit is disposed on both sides of the reflective element. The second radiation unit is disposed on both sides of the reflective element. The first impedance matching unit is disposed on the first surface corresponding to the first radiation unit. The second impedance matching unit is disposed on the first surface corresponding to the second radiation unit. The feed point is coupled between the first impedance matching unit and the second impedance matching unit. The first conductive line is coupled to the feed point. The second conductive line is coupled to the reflective element.

The antenna structure of the invention can be disposed in a housing of an electronic device.

The antenna structure of the invention provides a more symmetrical radiation pattern and improved signal transmission with smaller size.

The invention will be more fully understood from the following detailed description and the accompanying drawings, given by the way of illustration only and thus not intended to limit the invention.

FIG. 1 a is a bottom view of a conventional antenna structure;

FIG. 1 b is a top view of the conventional antenna structure;

FIG. 2 a shows an antenna structure of the invention;

FIG. 2 b is a bottom view of the antenna structure of the invention;

FIG. 3 is a top view of the antenna structure of the invention;

FIG. 4 shows signal transmission of the antenna structure of the invention;

FIG. 5 shows a modified example of the antenna structure of the invention; and

FIG. 6 shows the antenna structure of the invention disposed in an electronic device.

FIGS. 2 a and 2 b show an antenna structure 100 of the invention, which comprises a substrate 170 , a reflective element 101 , a first radiation unit 110 , a second radiation unit 120 , a feed point 130 , a first impedance matching unit 150 , a second impedance matching unit 160 , a first conductive element 141 and a second conductive element 142 . The substrate 170 comprises a first surface 171 and a second surface 172 (with reference to FIG. 2 b ). The reflective element 101 , the first radiation unit 110 and the second radiation unit 120 are disposed on the second surface 172 . The reflective element 101 is longitudinal. The first radiation unit 110 and the second radiation unit 120 are disposed on two sides of the reflective element 101 . The first impedance matching unit 150 , the second impedance matching unit 160 , the first conductive element 141 , the second conductive element 142 and the feed point 130 are disposed on the first surface 171 . The first impedance matching unit 150 is connected to the first conductive element 141 , and the first conductive element 141 is connected to the feed point 130 . The second impedance matching unit 160 is connected to the second conductive element 142 , and the second conductive element 142 is connected to the feed point 130 . The first impedance matching unit 150 is a sleeve-shaped structure corresponding to the first radiation unit 110 , and the second impedance matching unit 160 is a sleeve-shaped structure corresponding to the second radiation unit 120 .

With reference to FIG. 2 b , the antenna structure 100 further comprises a cable 180 . The cable 180 comprises a first conductive line 181 and a second conductive line 182 . The first conductive line 181 is coupled to the feed point 130 and passes through the reflective element 101 and the substrate 170 . The second conductive line 182 is coupled to the reflective element 101 . The first radiation unit 110 comprises two radiation elements 111 and two radiation elements 112 disposed on both sides of the reflective element 101 , wherein each side of the reflective element 101 comprises one radiation element 111 and one radiation element 112 disposed thereon. The radiation elements 111 and the radiation elements 112 are L-shaped, and the ends thereof extend in opposite directions. The second radiation unit 120 comprises two radiation elements 121 and two radiation elements 122 disposed on both sides of the reflective element 101 , wherein each side of the reflective element 101 comprises one radiation element 121 and one radiation element 122 disposed thereon. The radiation elements 121 and the radiation elements 122 are L-shaped, and the ends thereof are extending in opposite directions.

With reference to FIG. 3 , the first conductive element 141 and the second conductive element 142 are aligned on a straight line. The first impedance matching unit 150 comprises a first portion 151 and a second portion 152 . The first portion 151 is corresponding to the first radiation unit 110 , the second portion 152 is connected to the first conductive element 141 , and the first portion 151 is connected to the second portion 152 .

The second impedance matching unit 160 comprises a third portion 161 and a fourth portion 162 . The third portion 161 is corresponding to the second radiation unit 120 , the fourth portion 162 is connected to the second conductive element 142 , and the third portion 161 is connected to the fourth portion 162 .

The width d 1 of the first conductive element 141 is thinner than the width d 2 of the second portion 152 . The impedance matching of the antenna structure 100 is modified by changing the width d 1 of the first conductive element 141 and the width d 2 of the second portion 152 . The radiation pattern of the antenna structure 100 is modified by changing the length L 1 of the first conductive element 141 and the length L 2 of the second portion 152 . The width d 3 of the second conductive element 142 is thinner than the width d 4 of the fourth portion 162 . The impedance matching of the antenna structure 100 is modified by changing the width d 3 of the second conductive element 142 and the width d 4 of the fourth portion 162 . The radiation pattern of the antenna structure 100 is modified by changing the length L 3 of the second conductive element 142 and the length L 4 of fourth portion 162 .

A total length of the first conductive element 141 , the second conductive element 142 , the second portion 152 and the fourth portion 162 is about 0.8λ˜1λ, and λ is a wave length of the wireless signal. The length L 1 of the first conductive element 141 , the length L 2 of the second portion 152 , the length L 3 of the second conductive element 142 and the length L 4 of the fourth portion 162 can be modified to achieve improved signal transmission.

FIG. 4 shows the signal transmission of the antenna structure 100 of the invention, wherein the bands thereof (bands are defined as signals having voltage standing wave ratios lower than 2) is between 4.85 GHz˜6 GHz.

FIG. 5 shows a modified antenna structure 100 ′ of the invention, which further comprises a third conductive element 191 , an impedance matching element 192 , an impedance matching element 194 , an impedance matching element 195 and a third radiation unit 193 . The impedance matching element 194 is connected to the first impedance matching unit 150 . The third conductive element 191 is connected to the impedance matching element 194 . The impedance matching element 195 is connected to the third conductive element 191 . The impedance matching element 192 is connected to the impedance matching element 195 . The impedance matching element 192 and the impedance matching element 195 compose a third impedance matching unit. The third radiation unit 193 is disposed on two sides of the reflective element 101 . The third conductive element 191 , the impedance matching element 192 , the impedance matching element 194 , the impedance matching element 195 and the third radiation unit 193 symmetrize the radiation pattern of the antenna structure 100 ′.

The antenna structure of the invention is utilized in transmitting various wireless signals, particularly signals conformed to IEEE 802.11(a).

The antenna structure of the invention provides a more symmetrical radiation pattern and improved signal transmission with smaller size.

With reference to FIG. 6 , the antenna structure 100 of the invention can be disposed in a housing 210 of an electronic device 200 .

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. 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 to encompass all such modifications and similar arrangements.