Patent Publication Number: US-8537054-B2

Title: Antenna with multiple resonating conditions

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna with multiple resonating conditions, and more particularly, to an antenna generating multiple resonating conditions with one or more radiating-condition generating elements connected to ground, to achieve broadband operations. 
     2. Description of the Prior Art 
     An antenna is used for transmitting or receiving radio waves, to communicate or exchange wireless signals. An electronic product with a wireless communication function, such as a laptop, a personal digital assistant (PDA), usually accesses a wireless network through a built-in antenna. Therefore, for facilitating the user to access the wireless communication network more easily, an ideal antenna should have a wide bandwidth and a small size to meet the trends of compact electronic products within a permitting range, so as to integrate the antenna into a portable wireless communication equipment. 
     In the prior art, one of the common antennas for wireless communication is a planar inverted F antenna (PIFA), as implied by the name, whose shape is similar to a rotated and inverted “F”. Please refer to  FIG. 1A  and  FIG. 1B ,  FIG. 1A  is a schematic diagram of a conventional PIFA antenna  10 , and  FIG. 1B  is a schematic diagram of voltage standing wave ratio (VSWR) of the PIFA antenna  10 . As shown in  FIG. 1A , the PIFA antenna  10  includes a grounding element  100 , a radiating element  102 , a connection element  104  and a feed-in element  106 . The connection element  104  connects the grounding element  100  and the radiating element  102 , such that a resonating path of a monopole antenna is reduced from a half wavelength to a quarter wavelength, and thus the size of the antenna can be reduced effectively. 
     Besides, as can be seen from  FIG. 1B , the PIFA antenna  10  only has one resonating condition. However, as the wireless communication technology progresses, operating frequencies of different wireless communication systems may be different; therefore, an ideal antenna should cover bandwidths of different wireless communication networks within a single antenna. In such a situation, the prior art further derives a dual-band antenna with two resonating conditions from the PIFA antenna  10 . 
     Please refer to  FIG. 2A  and  FIG. 2B .  FIG. 2A  is a schematic diagram of a conventional dual-band antenna  20 , and  FIG. 2B  is a schematic diagram of VSWR of the dual-band antenna  20 . The dual-band antenna  20  includes a grounding element  200 , a radiating element  202 , a connection element  204  and a feed-in element  206 . The radiating element  202  is composed of a first radiator  2020  and a second radiator  2022  corresponding to high frequency band and low frequency band, respectively. The connection element  204  is composed of branches  2040  and  2042  connected together. The branch  2040  is connected to the radiating element  202  and the feed-in element  206 , and the branch  2042  is connected to the feed-in element  206  and the grounding element  202 . As can be seen from  FIG. 2A , the dual-band antenna  20  has advantages of low profile, i.e. a small height, small size and easy production. Meanwhile, as can be seen from  FIG. 2B , the dual-band antenna  20  has dual resonating conditions suitable for dual-band application, and achieves the optimization of the antenna characteristic. 
     Although the dual-band antenna  20  can achieve dual resonating conditions, for a wireless communication system with broad bandwidth, such as long term evolution (LTE) system, the bandwidth of the dual-band antenna  20  is still not enough, resulting in limitations of its application range. Therefore, how to increase bandwidth of an antenna has become one of the goals in the wireless technology industry. 
     SUMMARY OF THE INVENTION 
     It is therefore an object to provide an antenna with multiple resonating conditions. 
     An antenna with multiple resonating conditions includes a grounding element electrically connected to a ground, a radiating element, a connection element electrically connected between the grounding element and the radiating element, a feed-in element electrically connected between the connection element and the grounding element for receiving feed-in signals, and a radiating-condition generating element electrically connected to the grounding element and extending from the grounding element to the radiating element. 
     An antenna with multiple resonating conditions includes a grounding element electrically connected a ground, a radiating element, a connection element electrically connected between the grounding element and the radiating element, a feed-in element electrically connected between the connection element and the grounding element for receiving feed-in signals, and a plurality of radiating-condition generating elements electrically connected to the grounding element respectively and extending from the grounding element to the radiating element. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic diagram of a conventional PIFA antenna. 
         FIG. 1B  is a schematic diagram of VSWR of the PIFA antenna. 
         FIG. 2A  is a schematic diagram of a conventional dual-band antenna. 
         FIG. 2B  is a schematic diagram of VSWR diagram of the dual-band antenna. 
         FIG. 3  is a schematic diagram of an antenna according to an embodiment of the present invention. 
         FIG. 4  is a schematic diagram of an antenna according to an embodiment of the present invention. 
         FIG. 5A  is a schematic diagram of an antenna according to an embodiment of the present invention. 
         FIG. 5B  is a schematic diagram of VSWR of the antenna shown in  FIG. 5A . 
         FIG. 6A  is a schematic diagram of an antenna according to an embodiment of the present invention. 
         FIG. 6B  is a schematic diagram of VSWR of the antenna shown in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 3 , which is a schematic diagram of an antenna  30  according to an embodiment of the present invention. The antenna  30  has multiple resonating conditions, and includes a grounding element  300 , a radiating element  302 , a connection element  304 , a feed-in element  306  and a radiating-condition generating element  308 . The grounding element  300  is electrically connected to a ground for providing grounding. The radiating element  302  is composed of a first radiator  3020  and a second radiator  3022  extending along different directions and with different lengths to provide two different radiation frequency bands. The connection element  304  is composed of a first branch  3040  and a second branch  3042 . The first branch  3040  is connected to the radiating element  302  and the feed-in element  306 , and the second branch  3042  is connected to the feed-in element  306  and the grounding element  302 . Therefore, comparing  FIG. 3  with  FIG. 2 , structures of the antenna  30  and the dual-band antenna  20  are similar, while the difference is that the antenna  30  adds the radiating-condition generating element  308 . As shown in  FIG. 3 , the radiating-condition generating element  308  is extended from the grounding element  300  to the radiating element  302 , and has a shape substantially conforming to a shape of the connection element  304 . Therefore, a coupling effect between the radiating-condition generating element  308  and the radiating element  302  or the connection element  304  generates an extra current path, so as to resonate another radiating condition. 
     In short, the antenna  30  resonates dual radiating conditions through the radiating element  302 , and further resonate another radiating condition through the radiating-condition generating element  308  connected to the ground, so as to achieve effects of multiple radiating conditions or broadband. Noticeably, the present invention is to provide extra current path to the ground through the radiating-condition generating element  308 , so as to increase radiating conditions, and those skilled in this art should make modifications or alterations accordingly. For example, in  FIG. 3 , the radiating-condition generating element  308  is only connected to the grounding element  300 , and not connected to the radiating element  302 . In practice, the radiating-condition generating element  308  can connect to the radiating element  302  as well. Please refer to  FIG. 4 , which is a schematic diagram of an antenna  40  according to an embodiment of the present invention. Structures of the antenna  40  and the antenna  30  shown in  FIG. 3  are similar, and thus same elements are denoted by the same symbols. Difference between the antenna  40  and the antenna  30  is that a radiating-condition generating element  408  of the antenna  40  is connected between the grounding element  300  and the radiating element  302 , which belongs to double grounding structure of the present invention, and thus effects of multiple radiating conditions or broad band can be achieved as well. 
     Besides, in the antennas  30  and  40 , the shapes of the radiating-condition generating elements  308  and  408  both substantially conform to a meander shape of the connection element  304 . However, not limit to this, in the present invention, the radiating-condition generating element can be any kinds of shapes or be composed of multiple branches depending on the system requirements. For example, please refer to  FIG. 5A , which is a schematic diagram of an antenna  50  according to an embodiment of the present invention. Structures of the antenna  50  and the antenna  40  shown in  FIG. 4  are similar, and thus same elements are denoted by the same symbols. Difference between the antenna  50  and the antenna  40  is that a radiating-condition generating element  408  of the antenna  50  is not only connected between the grounding element  300  and the radiating element  302 , but also composed of two branches  5080  and  5082 , which belongs to the double grounding structure of the present invention, and thus effects of multiple radiating conditions or broadband can be achieved as well. 
     Please continue to refer to  FIG. 5B , which is a schematic diagram of VSWR of the antenna  50 . As can be seen from  FIG. 5 , the antenna  50  can further generate a resonating radiating condition in high frequency band, and thus achieve multiple radiating conditions. 
     According to the above embodiments, the present invention resonates extra radiating conditions mainly through the radiating-condition generating element connected to the ground to achieve multiple radiating conditions or broadband operations. However, noticeably, as shown in  FIG. 3  to  FIG. 5 , shape, position of the radiating-condition generating element, number of branches possessed by the radiating-condition generating element or whether the radiating-condition generating element is connected to the radiating element are not limited, those skilled in this art should make modifications accordingly, such that the resonating conditions generated by the radiating-condition generating element meet the system requirements, so as to achieve effects of multiple radiating condition or broadband operations. In addition, number of the radiating-condition generating element is not limited either, e.g. the present invention can further install multiple radiating-condition generating elements  308  in the antenna  30 , install multiple radiating-condition generating elements  408  in the antenna  40 , or share the radiating-condition generating element  308  and the radiating-condition generating element  408 . 
     For example, please refer to  FIG. 6A , which is a schematic diagram of an antenna  60  according to an embodiment of the present invention. Structures of the antenna  60  and the antenna  40  shown in  FIG. 4  are similar, and thus same elements are denoted by the same symbols. Difference between the antenna  60  and the antenna  40  is that the antenna  60  further adds a radiating-condition generating element  610  in addition to the radiating-condition generating element  408 , and the radiating-condition generating element  610  is connected to the grounding element  300  but not connected to the radiating element  302 , which is similar to the radiating-condition generating element  308 . In such a situation, please continue to refer to  FIG. 6B , which is a schematic diagram of VSWR of the antenna  60 . As can be seen from  FIG. 6B , the antenna  60  can generate 5 radiating conditions, and thus increase numbers of radiating conditions effectively. 
     It is known from above illustration, through increasing radiating-condition generating elements, the present invention can increase resonating conditions effectively, so as to improve antenna bandwidth. More important, as shown in  FIG. 3 ,  4 ,  5 A and  6 A, the radiating-condition generating elements  308 ,  408 ,  508 , 608  and  610  all extend from the grounding element  300  to the radiating element  302 . In other words, the present invention does not change appearance of the antenna, but lower the height of the antenna and reduce the antenna size effectively. 
     Noticeably, the abovementioned embodiments are used for illustrating concept of the present invention, those skilled in the art should make modifications accordingly, but not limit to this. For example, materials of the antennas  30 ,  40 ,  50 ,  60  can be metal materials, such as iron and copper, and the antennas  30 ,  40 ,  50 ,  60  can be disposed on another substrate, e.g. a printed circuit board (PCB). Furthermore, in  FIG. 3 ,  4 ,  5 A,  6 A, each element is combined through direct connection, but not limit to this; for example, the grounding element  300  can be disposed on a substrate, while other elements can be disposed on another substrate, and both are connected by a flexible interface, and such operation is also one of alterations of the present invention. Besides, since antenna theory is well known by those skilled in the art, principles of antenna radiation are omitted for simplicity. In practice, when those skilled in the art design an antenna with multiple resonating conditions according to the present invention, characters such as sizes, materials and positions of elements should be adjusted according to the system requirement. 
     To sum up, the present invention adds one or multiple radiating-condition generating elements connected to the ground, such that the antennas resonates multiple radiating conditions to achieve broadband operations. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.