Abstract:
An active antenna with a wide bandwidth coverage is disclosed. The active antenna comprises a radiator, comprising at least two feeding points corresponding to two modes, a switch control circuit, for generating a switch control signal, and an active switch circuit, for switching to be coupled to one of the at least two feeding points.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an active antenna and electronic device, and more particularly, to an active antenna and electronic device having a wide range of operation bandwidth and a compact size. 
         [0003]    2. Description of the Prior Art 
         [0004]    With the advancement of recent wireless communication technologies, demand for wireless communication has surged, and an increasing amount of information is now transmitted wirelessly, resulting in higher bandwidth requirements. Light-weight, small form factor, and compactness have also become design criteria for communication devices. 
         [0005]    Generally, a conventional mobile electronic device utilizes a passive antenna. More recent designs have also resorted to utilizing an active switch circuit with an antenna due to shortage of space, so as to improve utilization of space and communication quality. For example, a conventional mobile phone maybe equipped with an antenna switch circuit with multiple antennas for wireless reception/transmission (i.e. multiple radiators), and automatically select between an antenna with a wider receiving bandwidth coverage during stand-by, and another antenna with higher radiation efficiency during calls. 
         [0006]    However, such conventional method of switching between multiple antennas for transmission and reception incurs higher costs and larger dimensions, and often employs a single-plane architecture, which leads to limited utilizable space and reduces design flexibility. Hence, it is necessary to improve over the prior art. 
       SUMMARY OF THE INVENTION 
       [0007]    Therefore, a primary objective of the invention is to provide an active antenna and electronic device with wide bandwidth coverage and small dimensions. 
         [0008]    The invention discloses an active antenna with a wide bandwidth coverage. The active antenna comprises a radiator, comprising at least two feeding points, corresponding to at least two modes, respectively; a switch control circuit, for generating a switch control signal; and an active switch circuit, for switching to be coupled to one of the at least two feeding points according to the switch control signal . 
         [0009]    The invention further discloses an electronic device. The electronic device comprises a radio-frequency processing unit, for processing a radio-frequency signal; and an active antenna with a wide bandwidth coverage, comprising a radiator, comprising at least two feeding points corresponding to at least two modes, respectively; a switch control circuit, for generating a switch control signal; and an active switch circuit, for switching to be coupled to the one of the at least two feeding points according to the switch control signal. 
         [0010]    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 
         [0011]      FIG. 1  is a schematic diagram of an active antenna according to an embodiment of the invention. 
           [0012]      FIG. 2A  is a schematic diagram of a return loss of the active antenna shown in  FIG. 1  when an active switch circuit is coupled to different feeding points, respectively. 
           [0013]      FIG. 2B  is a schematic diagram of an antenna radiation efficiency of the active antenna shown in  FIG. 1  when the active switch circuit is coupled to the different feeding points, respectively. 
           [0014]      FIGS. 3A and 3B  are schematic diagrams of a preferred return loss and a preferred antenna radiation efficiency of the active antenna shown in  FIG. 1 , respectively. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Please refer to  FIG. 1 , which is a schematic diagram of an active antenna  10  according to an embodiment of the invention. As shown in  FIG. 1 , the active antenna  10  includes a radiator  102  (hatched area), a switch control circuit  104 , an active switch circuit  106 , and a signal feeding terminal  108 . In short, the radiator  102  includes feeding points FP 1 , FP 2  corresponding to two modes, respectively. The switch control circuit  104  generates a switch control signal Con to the active switch circuit  106 , such that the active switch circuit  106  switches between being coupled to one of the feeding points FP 1 , FP 2  according to the switch control signal Con, to operate the radiator  102  in one of the two modes. As such, the active antenna  10  can operate in different modes via switching between being coupled to different feeding points of the radiator  102 , to obtain a wider operation bandwidth. 
         [0016]    In more detail, when transmitting a signal, the switch control circuit  104  controls the active switch circuit  106  to be coupled to one of the feeding points FP 1 , FP 2  according to a communication status, such that the signal feeding terminal  108  can feed a radio-frequency signal RFin into one of the feeding points FP 1 , FP 2  via the active switch circuit  106 , and then transmit the radio-frequency signal RFin via different antenna paths of the radiator  102 . In other words, since when the radio-frequency signal RFin is fed at different feeding points, antenna paths of the radio-frequency signal RFin in the radiator  102  are also different, the radiator  102  can operate in different modes. Therefore, resonance frequency of the radiator  102  changes or shifts accordingly. Similarly, when receiving the signal, the switch control circuit  104  can also control the active switch circuit  106  to be coupled to one of the feeding points FP 1 , FP 2  according to the communication status, to operate in a suitable mode. As such, the switch control circuit  104  controls the active switch circuit  106  to be coupled to a suitable feeding point in the radiator  102  according to the communication status, to increase the operation bandwidth of the antenna and enhance communication quality. 
         [0017]    Specifically, please refer to  FIGS. 2A and 2B .  FIG. 2A  is a schematic diagram of a return loss of the active antenna  10  when the active switch circuit  106  is coupled to the feeding points FP 1 , FP 2 , respectively.  FIG. 2B  is a schematic diagram of an antenna radiation efficiency of the active antenna  10  when the active switch circuit  106  is coupled to the feeding points FP 1 , FP 2 , respectively. As shown in  FIGS. 2A and 2B , when the active switch circuit  106  is coupled to the feeding points FP 1 , FP 2 , the active antenna  10  operates in two corresponding modes, respectively. The return loss and antenna radiation efficiency of the active antenna  10  under the two different modes are represented by solid and dotted lines, respectively. As such, as shown in  FIGS. 3A and 3B , under a preferred condition when the switch control circuit  104  controls the active switch circuit  106  to be coupled to a suitable feeding point of the feeding points FP 1 , FP 2  according to the communication status, the active antenna  10  is capable of operating with a lower return loss and higher antenna radiation efficiency in the two modes, to increase antenna operation bandwidth and enhance communication quality. 
         [0018]    On the other hand, please continue to refer to  FIG. 1 . As shown in  FIG. 1 , an extension plane PL 1  of the active switch circuit  106  and an extension plane PL 2  of the radiator  102  preferably have an angle e from each other. The angle e may be 90° (i.e. the planes PL 1 , PL 2  are perpendicular to each other), or any other specific angles (i.e. the active antenna  10  is a three-dimensional structure). In such a case, an antenna ground plane of the radiator  102  and an extension plane PL 1  of the active switch circuit  106  may be disposed on a substrate Sub, as shown in  FIG. 1 . Alternatively, the antenna ground plane of the radiator  102  may be parallel to the extension plane PL 1  of the active switch circuit  106  (not shown), or be an extension of a ground plane of the active switch circuit  106  (not shown). As such, since the active antenna  10  utilizes a three-dimensional structure to implement the antenna (i.e. the radiator  102 ) and the active switch circuit  106 , it is possible to achieve higher space utilization, therefore allowing smaller dimensions. 
         [0019]    Note that, the spirit of the present invention is that the active antenna  10  may operate in different modes via switching to be coupled to different feeding points of the radiator  102 , to obtain a wider operation bandwidth. Also, the three-dimensional structure of the radiator  102  allows effective space utilization, and thus smaller dimensions. Additionally, modifications or variations may be made accordingly by those skilled in the art, and are not limited thereto. For example, the embodiment in  FIG. 1  is characterized by switching between different feeding points of the radiator  102 , and utilizing a three-dimensional structure. However, the two above features may also be implemented separately, without losing their respective advantages. Moreover,  FIG. 1  only shows two feeding points FP 1 , FP 2  corresponding to two modes, respectively. In reality, the active switch circuit  106  may switch between one of more than two feeding points, such that the radiator  102  can operate in one of more than two modes. Furthermore, the design of the radiator  102  can have different structures according to requirements, and is not limited to the structure as shown in  FIG. 1 . 
         [0020]    On the other hand, signal feeding terminal  108  is preferably a coaxial cable signal feeding terminal, i.e. the active antenna  10  is applied to mobile electronic devices such as notebook computers, tablet computers, mobile phones or electronic books, but can also be applied to other electronic devices, providing that the electronic devices include a radio-frequency processing unit for transmitting or receiving radio-frequency signals. Moreover, the switch control circuit  104  can be a voltage control circuit, utilizing the switch control signal Con with different control voltages, to switch the active switch circuit  106  to be coupled to different feeding points, but not limited thereto. Furthermore, dimensions and materials of the active antenna  10  are not limited; those skilled in the art may make suitable adjustments according to system requirements to accommodate operation frequency demands. 
         [0021]    In the prior art, performing transmission/reception via switching between multiple antennas is costly and requires more space. Also, conventional designs utilize single plane structures, which limit utilizable space, and reduce design flexibility. Comparatively, the active antenna  10  of the invention controls the active switch circuit  106  to be coupled to suitable feeding points in the radiator  102  according to the communication status, thus increasing antenna operation bandwidth and enhancing communication quality. Moreover, the three-dimensional structure helps improve space utilization, and thus allows for smaller dimensions. 
         [0022]    In summary, the active antenna of the present invention has a wider range of operation bandwidth and smaller dimensions. 
         [0023]    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. cm What is claimed is: