Patent Publication Number: US-11050149-B2

Title: Dual-band antenna

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 62/767,518, filed on Nov. 15, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     TECHNICAL FIELD 
     The invention relates to an antenna, and more particularly, to a dual band antenna. 
     BACKGROUND 
     In order to support multiple communication protocols, at present, mobile devices need to be disposed with multiple antennas or broadband antennas. In the case that multi-input multi-output (MIMO) technology has become the mainstream communication technology, mobile devices need to be disposed with at least two antennas of the same frequency band to implement MIMO technology. However, a mutual coupling between the antennas of the same frequency band has a negative impact to antenna performance, thereby reducing the transmission of MIMO. In order to reduce the mutual coupling between the antennas of the same frequency band, antenna engineers often reduce the influence of the mutual coupling by increasing a distance between the antennas of the same frequency band, but such approach will increase a size of the mobile device. Accordingly, how to reduce the coupling phenomenon for the antennas of the same frequency band without increasing the distance between the antennas of the same frequency band is one of the goals of those in the field. 
     SUMMARY 
     The invention provides a dual-band antenna capable of significantly reducing the mutual coupling between antennas of the same frequency band. 
     The dual-band antenna of the invention includes a first antenna, a second antenna, and a grounding component. The first antenna has a first feed point for transceiving a first signal. The second antenna has a second feed point. The grounding component is electrically coupled to the first feed point and the second feed point, wherein the grounding component forms a first path and a second path between the first feed point and the second feed point, wherein a first path length of the first path and a second path length of the second path are integer multiples of a first wavelength of the first signal. 
     In an embodiment of the invention, the second feed point is configured to transceive a second signal, and the first path length and the second path length are integer multiples of a second wavelength of the second signal. 
     In an embodiment of the invention, the grounding component is an annulus structure. 
     In an embodiment of the invention, the grounding component includes a meander structure, wherein the meander structure forms a part of the first path and a part of the second path. 
     In an embodiment of the invention, the grounding component includes an inductor, wherein the inductor forms a part of the first path and a part of the second path. 
     In an embodiment of the invention, the grounding component includes a hinge of a notebook computer. 
     In an embodiment of the invention, the first antenna is disposed in a second body of the notebook computer, and the second antenna is disposed in a first body of the notebook computer. 
     In an embodiment of the invention, the grounding component includes a first grounding part, a second grounding part and a third grounding part, wherein the second grounding part is a polyhedron and one of sections of the second grounding part is a C shape, wherein the second grounding part connects the first grounding part to the third grounding part. 
     In an embodiment of the invention, the first grounding part is a second polyhedron and one of sections of the first grounding part is an inverted-L shape, wherein the first feed point of the first antenna is disposed on a first side on the second polyhedron, wherein the first side is located at a lower edge of the inverted-L shape. 
     In an embodiment of the invention, the third grounding part is a cuboid, and the second feed point of the second antenna is disposed on a first side of the cuboid, wherein the first side is partially in contact with the second grounding part. 
     Based on the above, the dual-band antenna of the invention uses the grounding component to form the two paths between the two antennas, and the path length of each path is designed to be integer multiple of the wavelength of the input/output signal so as to reduce the mutual coupling between antennas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a dual-band antenna according an embodiment of the invention. 
         FIG. 2  is a schematic diagram illustrating the dual-band antenna disposed on a notebook computer according an embodiment of the invention. 
         FIG. 3  is a schematic diagram illustrating S parameter of the dual-band antenna in  FIG. 2  according an embodiment of the invention. 
         FIG. 4A  is a schematic diagram illustrating the modularized dual-band antenna according an embodiment of the invention. 
         FIG. 4B  is an exploded view illustrating the dual-band antenna in  FIG. 4A  according an embodiment of the invention. 
         FIG. 5  is a schematic diagram illustrating another aspect of the dual-band antenna according an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. In addition, whenever possible, identical or similar reference numbers stand for identical or similar elements in the figures and the embodiments. The language used to describe the directions such as “up”, “down”, “left”, “right”, “front”, “back” or the like in the reference drawings is regarded in an illustrative rather than in a restrictive sense. Thus, the language used to describe the directions is not intended to limit the scope of the invention. 
     It should be understood that although the terms “first” and “second” or “a”, “another” and “yet another” may be used herein to describe different elements, these elements should not be limited by these terms. These terms are only used to distinguish elements from one another. For example, a first element may be referred to as a second element, and, similarly, the second element may be referred to as the first element without departing from the scope of the inventive concept. As another example, an element may be referred to as another element, and, similarly, said another element may be referred to as yet another element without departing from the scope of the inventive concept. 
       FIG. 1  is a schematic diagram illustrating a dual-band antenna  10  according an embodiment of the invention. The dual-band antenna  10  includes a first antenna  100 , a second antenna  200 , and a grounding component  300 . The dual-band antenna  10  can be mounted to an electronic device having a wireless communication function to enable the electronic device to transmit or receive wireless signals through the dual-band antenna  10  according to MIMO technology. 
     The first antenna  100  has a first feed point  110  for transmitting or receiving a first signal. Here, the first signal is, for example, a signal of 2.4 GHz or 2.45 GHz frequency band, but the invention is not limited thereto. The first antenna  100  is, for example, a monopole antenna, a dipole antenna, an inverted-L antenna, an inverted-F antenna (IFA), a planar IFA (PIFA), a loop antenna or a slot antenna, but the invention is not limited thereto. In an embodiment, the first antenna  100  is made of, for example, a flexible printed circuit (FPC) that can be bent according to the design requirements of antenna engineers. 
     The second antenna  200  has a second feed point  210  for transmitting or receiving a second signal. Here, the second signal is, for example, a signal of 2.4 GHz or 2.45 GHz frequency band, but the invention is not limited thereto. In a preferred embodiment of the invention, the first signal and the second signal are signals of the same frequency band. Nonetheless, the first signal and the second signal may also be signals of different frequency bands. The invention is not limited in this regard. The second antenna  200  is, for example, a monopole antenna, a dipole antenna, an inverted-L antenna, an inverted-F antenna (IFA), a planar IFA (PIFA), a loop antenna or a slot antenna, but the invention is not limited thereto. In an embodiment, the second antenna  200  is made of, for example, a flexible printed circuit that can be bent according to the design requirements of antenna engineers. 
     The grounding component  300  is electrically coupled to the first feed point  110  and the second feed point  210 , and forms two paths between the first feed point  110  and the second feed point  210 . Here, the two paths include a first path  310  and a second path  320 . A path length of the first path  310  is, for example, integer multiple of a wavelength of the first signal (and the second signal), and a path length of the second path  320  is, for example, integer multiple of the wavelength of the first signal (and the second signal). When the path lengths of the first path  310  and the second path  320  are designed to be integer multiples of the wavelength of the first signal (and the second signal), a mutual coupling between the first antenna  100  and the second antenna  200  may be minimized. 
     In order to form the first path  310  and the second path  320  between the first antenna  100  and the second antenna  200 , the grounding component  300  may be, for example, an annulus structure, as shown by  FIG. 1 . 
       FIG. 2  is a schematic diagram illustrating the dual-band antenna  10  disposed on a notebook computer  40  according an embodiment of the invention. In this embodiment, the grounding component  300  may be replaced by a part of the notebook computer  40 . 
     The notebook computer  40  includes a first body  41 , a second body  42 , a hinge  43  and a hinge  44 . The first body  41  includes a keyboard and the second body  42  includes a display, but not limited thereto. Two ends of the hinge  43  and two ends of the hinge  44  are connected to the first body  41  and the second body  42 , respectively. The hinge  43  and the hinge  44  can allow the first body  41  and the second body  42  to rotate along a fixed axis of rotation relatively. The first body  41  may include an edge  411 . Here, the edge  411  is an edge closest to the second body  42  among four edges of the first body  41 . The second body  42  may include an edge  421 . Here, the edge  421  is an edge closest to the first body  41  among four edges of the second body  42 . In this embodiment, the first antenna  100  may be disposed in the second body  42  of the notebook computer  40 , and the second antenna  200  may be disposed in the first body  41  of the notebook computer  40 . A metallic material capable of grounding the first antenna  100  and the second antenna  200  is disposed inside (or on surfaces of) the edge  411 , the edge  421 , the hinge  43  and the hinge  44  of the notebook computer  40 . Accordingly, the edge  411 , the edge  421 , the hinge  43  and the hinge  44  can constitute the grounding component  300 . 
     The edge  411 , the edge  421 , the hinge  43  and the hinge  44  can form a slot  330 , as shown by  FIG. 2 . Antenna engineers can simply adjust the path lengths of the first path  310  and the second path  320  by changing a size of the slot  330  so that the path lengths are integer multiples of the wavelength of the first signal (or the second signal). In other words, antenna engineers can adjust the path lengths of the first path  310  and the second path  320  by changing sizes of the edge  411 , the edge  421 , the hinge  43  or the hinge  44 . 
       FIG. 3  is a schematic diagram illustrating S parameter of the dual-band antenna  10  in  FIG. 2  according an embodiment of the invention. Here, a curve  11  represents S 11  parameter of the first antenna  100 , a curve  21  represents S 11  parameter of the second antenna  200 , and a curve  31  represents S 21  parameter between the first antenna  100  and the second antenna  200 . As shown by  FIG. 3 , when the path lengths of the first path  310  and the second path  320  are integer multiples of the wavelength of the first signal (or the second signal), the mutual coupling between the first antenna  100  and the second antenna  200  (i.e., S 21  parameter) from 2.4 to 2.5 GHz may be less than −20 dB. 
       FIG. 4A  is a schematic diagram illustrating the modularized dual-band antenna  10  according an embodiment of the invention.  FIG. 4B  is an exploded view illustrating the dual-band antenna  10  in  FIG. 4A  according an embodiment of the invention. Referring to  FIG. 4A  and  FIG. 4B  together, in this embodiment, the grounding component  300  may include a first grounding part  510 , a second grounding part  521 , a third grounding part  530  and a fourth grounding part  522 . Here, one end of the first grounding part  510  is connected to one end of the third grounding part  530  by the second grounding part  521 , and another end of the first grounding part  510  is connected to another end of the third grounding part  530  by the fourth grounding part  522 . 
     The first grounding part  510  is a polyhedron and one of sections of the first grounding part  510  may be an inverted-L shape, but not limited thereto. The first feed point  110  of the first antenna  100  may be disposed on one side of the first grounding part  510  (e.g., a side  511 ). The side  511  is located at a lower edge of the section of the inverted-L shape of the first grounding part  510  and the side  511  is not in contact with the second grounding part  521  and the fourth grounding part  522 . 
     The third grounding part  530  is a cuboid. The second feed point  210  of the second antenna  200  may be disposed on one side of the third grounding part  530  (e.g., a side  531 ). The side  531  is in contact with the second grounding part  521  and the fourth grounding part  522 , and the side  531  is the only side in contact with the second grounding part  521  and the fourth grounding part  522  among six sides of the third grounding part  530 . In another embodiment, the second feed point  210  of the second antenna  200  may be disposed on another side of the third grounding part  530  (e.g., a side  532 ). The side  532  is adjacent to the side  531  but not in contact with the second grounding part  521  and the fourth grounding part  522 , and the side  532  is a side closest to the first grounding part  510  among multiple sides of the third grounding part  530  adjacent to the side  531 . 
     The second grounding part  521  is a polyhedron and one of sections of the second grounding part  521  may be a C shape, but not limited thereto. Two ends of the second grounding part  521  may be respectively connected to the first grounding part  510  and the third grounding part  530  to form the second path  320  between the first feed point  110  and the second feed point  210 . 
     The fourth grounding part  522  is a polyhedron and one of sections of the fourth grounding part  522  may be a C shape, but not limited thereto. Two ends of the fourth grounding part  522  may be respectively connected to the first grounding part  510  and the third grounding part  530  to form the first path  310  between the first feed point  110  and the second feed point  210 . 
       FIG. 5  is a schematic diagram illustrating another aspect of the dual-band antenna  10  according an embodiment of the invention. In this embodiment, the grounding component  300  include a meander structure  311  forming a part of the first path  310  and a meander structure  321  forming a part of the second path  320 . When there is not enough space to extend the first path  310  such that the first path  310  is integer multiple of the wavelength of the first signal (or the second signal), antenna engineers can add the meander structure  311  in the grounding component  300 . The meander structure  311  can extend the first path  310  with a small space. Similarly, when there is not enough space to extend the second path  320  such that the second path  320  is integer multiple of the wavelength of the first signal (or the second signal), antenna engineers can add the meander structure  321  in the grounding component  300 . The meander structure  321  can extend the second path  320  with a small space. 
     In an embodiment, the meander structure  311  or the meander structure  321  may be realized by an inductor. In this way, antenna engineers can easily adjust the path length of the first path  310  or the second path  320  by changing a specification of the inductor included in the grounding component  300 . 
     In summary, the dual-band antenna of the invention uses the grounding component to form the two paths between the two antennas, and the path length of each path is designed to be integer multiple of the wavelength of the input/output signal. As such, S 21  parameter between the antennas will be significantly reduced. In order to form the two paths between the antennas, the grounding component may be, for example, the annulus structure. For allowing the path lengths between the antennas to be integral multiples of the wavelength of the signal in different scenarios, the grounding component can have many different aspects. The grounding component may include, for example, the meander structure or the inductor, so antenna engineers can adjust the path lengths simply by changing the length of the meander structure or the specification of the inductor.