Patent Publication Number: US-2023155301-A1

Title: Antenna module and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 110142548, filed on Nov. 16, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to an antenna module and an electronic device, and more particularly, to a planar antenna module and an electronic device. 
     Description of Related Art 
     At present, some wearable smart thermometers on the market are attached to the human body through a patch similar to a band-aid. Since it is attached to the human skin, the efficiency of the antenna will be absorbed and interfered by the human body, and the loss will be too large, which affects the radiant energy of wireless transmission thereof. In addition, a coverage of the antenna of such a device is related to a sensing distance and an overall size. 
     SUMMARY 
     The disclosure provides an antenna module and an electronic device, which have a good antenna performance. 
     An antenna module in the disclosure includes a feeding end, multiple first forked radiators, and multiple connecting parts. The first forked radiators are disposed side by side. The connecting parts respectively extend from the feeding end to the first forked radiators. The feeding end, the first forked radiators, and the connecting parts are located on a same plane. The antenna module resonates at a frequency band, and a path length from the feeding end to an end of each of the first forked radiators through the corresponding connecting part is ¼ wavelength of the frequency band. 
     An electronic device in the disclosure includes a circuit board, a Bluetooth chip, and the antenna module. The Bluetooth chip is disposed on the circuit board. The antenna module is disposed on one side of the Bluetooth chip. The feeding end is connected to the Bluetooth chip. 
     In an embodiment of the disclosure, each of the first forked radiators is U-shaped and includes two parallel sections parallel to each other. 
     In an embodiment of the disclosure, each of the first forked radiators includes three parallel sections parallel to one another. 
     In an embodiment of the disclosure, each of the first forked radiators includes two parallel sections, and a distance between two adjacent ones of the first forked radiators is greater than or equal to a distance between the two parallel sections of each of the first forked radiators. 
     In an embodiment of the disclosure, the first forked radiators include the two first forked radiators. The distance between the two first forked radiators is between 6 mm and 10 mm, and the distance between the two parallel sections of each of the first forked radiators is between 2 mm and 4 mm. 
     In an embodiment of the disclosure, the first forked radiators include the three first forked radiators. The distance between two adjacent ones of the three first forked radiators is between 2 mm and 4 mm, and the distance between the two parallel sections of each of the first forked radiators is between 2 mm and 4 mm. 
     In an embodiment of the disclosure, spaces above and below the plane where the feeding end, the first forked radiators, and the connecting parts are located are circuit clearances. 
     In an embodiment of the disclosure, the antenna module further includes multiple second forked radiator. The first forked radiators include multiple parallel sections, and the second forked radiators are disposed side by side and are respectively connected to the parallel sections of the first forked radiators. 
     In an embodiment of the disclosure, each of the second forked radiators is U-shaped and includes two parallel sections parallel to each other. 
     In an embodiment of the disclosure, the electronic device further includes a casing and a temperature sensor. The circuit board, the Bluetooth chip, and the antenna module are located in the casing, and the temperature sensor is electrically connected to the circuit board and exposed to the casing. 
     Based on the above, the first forked radiators of the antenna module in the disclosure are disposed side by side. The connecting parts respectively extend from the feeding end to these first forked radiators. The feed ending, the first forked radiators, and the connecting parts are located on the same plane, and the path length from the feeding end to the end of each of the first forked radiators through the corresponding connecting part is ¼ wavelength of the frequency band. The antenna module in the disclosure, through the structure of the forked radiators on the same plane and side by side, may have the performance of the characteristics of the broadband antenna in the limited space, and may still maintain the certain performance when the human body is close to the antenna module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic top view of an electronic device according to an embodiment of the disclosure. 
         FIG.  2    is a schematic cross-sectional view of the electronic device of  FIG.  1   . 
         FIG.  3    is a schematic top view of an antenna module in the electronic device of  FIG.  1   . 
         FIG.  4    is a schematic top view of an antenna module according to another embodiment of the disclosure. 
         FIG.  5    is an equivalent circuit diagram of the antenna module of  FIG.  4   . 
         FIG.  6    is a schematic view of a frequency and antenna efficiency of the antenna modules of  FIGS.  3  and  4   . 
         FIG.  7    is a schematic view of a frequency and VSWR of the antenna modules of  FIGS.  3  and  4   . 
         FIG.  8    is a schematic top view of an antenna module according to another embodiment of the disclosure. 
         FIG.  9    is a schematic top view of an antenna module according to another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
       FIG.  1    is a schematic top view of an electronic device according to an embodiment of the disclosure. Referring to  FIG.  1   , an electronic device  10  of this embodiment is, for example, a smart band-aid (a patch), which is a thermometer in a form of the band-aid (the patch), but a type of the electronic device  10  is not limited thereto. In this embodiment, a length L 1  of the electronic device  10  is about 75 mm, and a width L 2  is about 25 mm. Compared to smart patch products on the market, the electronic device  10  of this embodiment has a smaller size. 
     In addition, in this embodiment, the electronic device  10  includes an antenna module  100  and a near-field communication (NFC) antenna  20 . A length L 3  of the near-field communication antenna  20  and a length L 4  of the antenna module  100  are both about 22 mm, while widths are also close to 22 mm, which have relatively small sizes. 
       FIG.  2    is a schematic cross-sectional view of the electronic device of  FIG.  1   . Referring to  FIGS.  1  and  2   , the electronic device  10  further includes a casing  12 , a circuit board  14 , a battery  16 , a temperature sensor  18 , and a Bluetooth chip  19 . 
     The circuit board  14  is, for example, the flexible circuit board  14 . The battery  16  and the Bluetooth chip  19  are disposed on the circuit board  14  and are electrically connected to the circuit board  14 . The antenna module  100  is, for example, a Bluetooth antenna, but a type of the antenna module  100  is not limited thereto. The antenna module  100  is disposed on one side (a right side) of the circuit board  14  and the Bluetooth chip  19 . The antenna module  100  is connected to the Bluetooth chip  19 . 
     In addition, in this embodiment, the near-field communication antenna  20  is disposed on another side (a left side) of the circuit board  14 . That is to say, the antenna module  100  (the Bluetooth antenna) and the near-field communication antenna  20  are away from each other, and are symmetrically disposed on the two sides of the circuit board  14 . 
     The casing  12  is, for example, silicone, which is flexible and skin-friendly, but a material of the casing  12  is not limited thereto. The circuit board  14 , the Bluetooth chip  19 , the antenna module  100 , and the near-field communication antenna  20  are located in the casing  12 . The temperature sensor  18  is electrically connected to the circuit board  14  and exposed to the casing  12 . 
     In this embodiment, the electronic device  10  has a largest thickness L 5  at a center, and the thickness L 5  is about 4.6 mm. A thickness L 6  of the electronic device  10  corresponding to the antenna module  100  is about 2.6 mm. The entire electronic device  10  has a small thickness. 
     It is worth mentioning that the antenna module  100  of this embodiment has a specific design, so as to have a performance of characteristics of a broadband antenna in a limited space, and may still maintain a certain performance when a human body is close to the antenna module  100 , which will be described below. 
       FIG.  3    is a schematic top view of an antenna module in the electronic device of  FIG.  1   . It should be noted that  FIG.  3    only shows the Bluetooth chip  19 , the near-field communication antenna  20 , and the antenna module  100 , while other elements are hidden. 
     Referring to  FIG.  3   , in this embodiment, the antenna module  100  includes a feeding end  110  (a position A 1 ), multiple connecting parts  120 , and multiple first forked radiators  130 . The feeding end  110  is connected to the Bluetooth chip  19 . 
     The first forked radiators  130  are disposed side by side and extend in a direction away from the feeding end  110 . In this embodiment, the number of the first forked radiators  130  is two, and each of the first forked radiators  130  is U-shaped and includes two parallel sections  132  parallel to each other. An opening of the first forked radiator  130  faces an edge (e.g., a right edge) of the electronic device  10 . Of course, a form and configuration of the first forked radiator  130  are not limited thereto. 
     The connecting parts  120  respectively extend from the feeding end  110  to the first forked radiators  130 . The number of the connecting parts  120  corresponds to the number of the first forked radiators  130 . In this embodiment, the number of the connecting parts  120  is two. That is to say, the feeding end  110  is connected to the two first forked radiators  130  through the two connecting parts  120 . Since each of the first forked radiator  130  has the two parallel sections  132 , the feeding end  110  is connected to the four parallel sections  132  through the two connecting parts  120 , so that the antenna module  100  forms four paths (along the positions A 1 , A 2 , and A 3 ). 
     In this embodiment, structures of the feeding end  110 , the connecting parts  120 , and the side-by-side first forked radiators  130  present a dendritic distribution, which may achieve a maximum coverage and may improve frequency offsets or performance deterioration. 
     In addition, the antenna module  100  resonates at a frequency band, and a path from the feeding end  110  to an end of each of the first forked radiators  130  through the corresponding connecting part  120  is about ¼ wavelength of the frequency band. For example, if the frequency band is 2500 MHz, a length from the feeding end  110  to the parallel section  132  through the connecting part  120  may be ¼ wavelength of 2500 MHz, for example, 26 mm. Of course, the frequency band to which the antenna module  100  resonates at is not limited thereto. In an embodiment, the frequency band is, for example, between 2000 MHz and 6000 MHz. 
     In addition, a distance G 2  between two adjacent ones of the first forked radiators  130  is greater than or equal to a distance G 1  between the two parallel sections  132  of each of the first forked radiators  130 . Specifically, in this embodiment, the distance G 1  between the two parallel sections  132  of each of the first forked radiators  130  is between 2 mm and 4 mm, for example, 3 mm. The distance G 2  between the two first forked radiators  130  is between 6 mm and 10 mm, for example, 8 mm. A design of the distance G 2  greater than or equal to the distance G 1  may reduce interference between the two adjacent paths. 
     In addition, in this embodiment, the feeding end  110 , the first forked radiators  130 , and the connecting parts  120  are located on the same plane. Therefore, the antenna module  100  is a planar antenna. According to  FIG.  2   , in this embodiment, spaces above and below the plane where the feeding end  110 , the first forked radiators  130 , and the connecting parts  120  are located are circuit clearances. That is to say, there is no ground layer or other circuit structures above and below the plane where the feeding end  110 , the first forked radiators  130 , and the connecting parts  120  are located. Such a design may avoid the interference. Therefore, the antenna module  100  of this embodiment may have the better performance. 
     Hereinafter, other forms of antenna modules will be described. It should be noted that in the following embodiments, the same or like reference numerals denote the same or like elements as those of the previous embodiment, and descriptions of the same technical contents are omitted. Only main differences are described. 
       FIG.  4    is a schematic top view of an antenna module according to another embodiment of the disclosure. Referring to  FIG.  4   , the main difference between an antenna module  100   a  of  FIG.  4    and the antenna module  100  of  FIG.  3    lies in the number of first forked radiators  130  and  130   a  and connecting parts  120  and  120   a.    
     Specifically, in this embodiment, the number of the first forked radiators  130   a  is three, and the number of the connecting parts  120   a  is three. That is to say, the feeding end  110  is connected to the three first forked radiators  130   a  through the three connecting parts  120   a.  Since each of the first forked radiators  130   a  has two parallel sections  132   a  parallel to each other, the feeding end  110  is connected to the six parallel sections  132   a  through the three connecting parts  120   a,  so that the antenna module  100   a  forms six paths. In this embodiment, each of path lengths is ¼ wavelength of a frequency band of the antenna module  100   a.    
     In addition, in this embodiment, a distance G 3  between the two parallel sections  132   a  of each of the first forked radiators  130   a  is between 2 mm and 4 mm, for example, 2 mm. A distance G 4  between two adjacent ones of the three first forked radiators  130   a  is between 2 mm and 4 mm, for example, 2.5 mm. The distances G 3  and G 4  within the above range may reduce the interference between the two adjacent paths. 
     In addition, another difference between the antenna module  100   a  of  FIG.  4    and the antenna module  100  of  FIG.  3    lies in shapes of the connecting parts  120  and  120   a.  In  FIG.  3   , the connecting part  120  has a turning point, and in  FIG.  4   , the connecting part  120   a  has an arc shape. A designer may adjust the shapes of the connecting parts  120  and  120   a  according to the space configuration and process requirements. 
       FIG.  5    is an equivalent circuit diagram of the antenna module of  FIG.  4   . It should be noted that  FIG.  5    illustrates an equivalent circuit of the antenna module  100   a  of  FIG.  4    when it is close to a human body  30 . Referring to  FIG.  5   , in this embodiment, the two parallel sections  132   a  of the first forked radiator  130   a  are similar to two parallel inductances L 1 ′ and L 2 ′. The connecting part  120   a  is similar to an inductance L 3 ′, and the inductance L 3 ′ is connected in series with the two parallel inductances L 1 ′ and L 2 ′. 
     When the antenna module  100   a  is close to the human body  30 , there are multiple capacitances C 1  and C 2  between the antenna module  100   a  and the human body  30  as a distance between the antenna module  100   a  and the human body  30  is different, so that a performance of the antenna module  100   a  is not easily affected by the human body  30 . In addition, as the distance between the antenna module  100   a  and the human body  30  is different, the capacitances C 1  and C 2  between the antenna module  100   a  and the human body  30  have different response changes, which has an effect of improving the frequency offsets and performance. 
       FIG.  6    is a schematic view of a frequency and antenna efficiency of the antenna modules of  FIGS.  3  and  4   . Referring to  FIG.  6   , antenna efficiency of the antenna module  100  of  FIG.  3    and the antenna module  100   a  of  FIG.  4    is −1.1 dBi to −5.2 dBi at frequencies between 2000 MHz and 6000 MHz, which have the high performance and broadband performance. 
     In addition, after testing, compared to a conventional antenna without the forked radiator, the antenna efficiency of the antenna module  100  of  FIG.  3    and the antenna module  100   a  of  FIG.  4    may be increased by more than 15 dB. Therefore, the antenna module  100  of  FIG.  3    and the antenna module  100   a  of  FIG.  4    using the design of the side-by-side forked radiators may configure more patterns in the limited space, so as to reduce an absorption effect of the antenna attached to the human body  30  to have a better antenna performance. 
       FIG.  7    is a schematic view of a frequency and VSWR of the antenna modules of  FIGS.  3  and  4   . Referring to  FIG.  7   , VSWRs of the antenna module  100  of  FIG.  3    and the antenna module  100   a  of  FIG.  4    are less than 3 at the frequencies between 2000 MHz and 6000 MHz, which has characteristics of good impedance matching. 
       FIG.  8    is a schematic top view of an antenna module according to another embodiment of the disclosure. Referring to  FIG.  8   , the main difference between an antenna module  100   b  of  FIG.  8    and the antenna module  100  of  FIG.  3    lies in shapes of first forked radiators  130  and  130   b,  that is, the number of parallel sections  132  and  132   b  in each of the first forked radiators  130  and  130   b.    
     In this embodiment, each of the first forked radiators  130   b  of the antenna module  100   b  includes the three parallel sections  132   b  parallel to one another. Therefore, the feeding end  110  is connected to the six parallel sections  132   b  through two connecting parts  120   b,  so that the antenna module  100   b  forms six paths. Each of path lengths is ¼ wavelength of a frequency band of the antenna module  100   b.    
     Of course, in other embodiments, the number of the parallel sections  132   b  in each of the first forked radiators  130   b  may also be four or more. In addition, in other embodiments, the different first forked radiators  130   b  may have different numbers of the parallel sections  132   b,  which is not limited by the drawings. 
       FIG.  9    is a schematic top view of an antenna module according to another embodiment of the disclosure. Referring to  FIG.  9   , the main difference between an antenna module  100   c  of  FIG.  9    and the antenna module  100  of  FIG.  3    is that in this embodiment, the antenna module  100   c  further includes multiple second forked radiators  140 . The second forked radiators  140  are disposed side by side, and are respectively connected to parallel sections  132   c  of first forked radiators  130   c.    
     In this embodiment, each of the second forked radiators  140  is, for example, U-shaped, and has two parallel sections  142  parallel to each other. Therefore, the feeding end  110  is connected to the eight parallel sections  142  of the four second forked radiators  140  through two connecting parts  120   c  and the four parallel sections  132   c  of the two first forked radiators  130   c,  so that the antenna module  100   c  forms eight paths. In this embodiment, each of path lengths is ¼ wavelength of a frequency band of the antenna module  100   c.    
     It should be noted that in other embodiments, the number of the parallel sections  132   c  of the first forked radiator  130   c  and the number of the parallel sections  142  of the second forked radiator  140  may also be more than two. In addition, the number of the parallel sections  132   c  of the first forked radiator  130   c  and the number of the parallel sections  142  of the second forked radiator  140  may also be different. The number of the parallel sections  132   c  of the first forked radiator  130   c  and the number of the parallel sections  142  of the second forked radiator  140  are not limited thereto. 
     Based on the above, the first forked radiators of the antenna module in the disclosure are disposed side by side. The connecting parts respectively extend from the feeding end to these first forked radiators. The feed ending, the first forked radiators, and the connecting parts are located on the same plane, and the path length from the feeding end to the end of each of the first forked radiators through the corresponding connecting part is ¼ wavelength of the frequency band. The antenna module in the disclosure, through the structure of the forked radiators on the same plane and side by side, may have the performance of the characteristics of the broadband antenna in the limited space, and may still maintain the certain performance when the human body is close to the antenna module.