Patent Publication Number: US-2023155304-A1

Title: Three-dimensional antenna module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 110143062, filed on Nov. 18, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technology Field 
     The disclosure relates to an antenna module, and in particular, to a three-dimensional antenna module. 
     Description of Related Art 
     There are three metrics in the industrial regulations for the built-in antenna for an IP network camera (or IP camera). The first metric is that the coverage area of the antenna radiation pattern should be wide, without blind spots for reception. The second metric is low peak gain. When the antenna radiates the maximum gain, the industry specification expects it to not exceed 6 dBi. Otherwise, in order to comply with CE&#39;s effective isotropically radiated power (EIRP) regulations, it is necessary to reduce the power of the amplifier circuit, and the relative communication distance is reduced accordingly. The third metric is that the isolation between each antenna is at the standard −20 dB or less. However, in the prior art, when the distance between two antennas is less than 20 mm, the isolation and the coverage area of radiation pattern may not meet the regulations. 
     SUMMARY 
     The disclosure provides a three-dimensional antenna module that may meet the wide coverage area of the antenna radiation pattern, low antenna gain, and good isolation. 
     A three-dimensional antenna module of the disclosure includes a first antenna, a second antenna, and a conductor. The first antenna includes a first main radiator and a first feeding section connected to the first main radiator, the first main radiator includes a first open end and a second open end, and the first main radiator is bent to form a first opening. The second antenna includes a second main radiator and a second feeding section connected to the second main radiator. The second main radiator includes a third open end and a fourth open end. The second main radiator is bent to form a second opening. A direction the first opening faces is different from a direction the second opening faces. The conductor is disposed between the first antenna and the second antenna. 
     In an embodiment of the disclosure, an outline shape of the conductor corresponds to a portion of an outline shape of the first main radiator or the second main radiator. 
     In an embodiment of the disclosure, each of the first main radiator and second main radiator is U-shaped. 
     In an embodiment of the disclosure, the conductor is L-shaped. 
     In an embodiment of the disclosure, a direction the first opening faces is opposite to a direction the second opening faces. 
     In an embodiment of the disclosure, the three-dimensional antenna module couples out a frequency band, and a length of the first main radiator is between ½ wavelength of the frequency band. 
     In an embodiment of the disclosure, the three-dimensional antenna module couples out a frequency band, and a length of the second main radiator is between ½ wavelength of the frequency band. 
     In an embodiment of the disclosure, the three-dimensional antenna module couples out a frequency band, and a length of the conductor is between ¼ wavelength of the frequency band. 
     In an embodiment of the disclosure, the frequency band is 2.4 GHz. 
     In an embodiment of the disclosure, a distance between the first antenna and the second antenna is between 2 cm and 10 cm. 
     Based on the above, the three-dimensional antenna module of the disclosure includes a first antenna and a second antenna, and the direction the first opening of the first main radiator faces is different from the direction the second opening of the second main radiator faces. Such a design may make the radiation pattern of the first antenna different from the radiation pattern of the second antenna, and may have the effect of complementing the pattern, and may reduce peak gain. In addition, the conductor is disposed between the first antenna and the second antenna, so as to effectively improve the isolation between the first antenna and the second antenna. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a three-dimensional antenna module according to an embodiment of the disclosure. 
         FIG.  2    is a schematic diagram of the three-dimensional antenna module of  FIG.  1    disposed in an electronic device. 
         FIG.  3    is a frequency-S11 diagram of the three-dimensional antenna module of  FIG.  1   . 
         FIG.  4    is a frequency-isolation diagram of the three-dimensional antenna module of  FIG.  1   . 
         FIG.  5 A  to  FIG.  5 C  are radiation patterns of the first antenna and the second antenna of the three-dimensional antenna module of  FIG.  1    on the XY plane, the XZ plane, and the YZ plane. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG.  1    is a schematic diagram of a three-dimensional antenna module according to an embodiment of the disclosure. Please refer to  FIG.  1   , a three-dimensional antenna module  100  of the present embodiment includes a first antenna  110 , a second antenna  120 , and a conductor  130 . The first antenna  110 , the second antenna  120 , and the conductor  130  are all made of a conductive material, such as a metal. 
     The first antenna  110  includes a first main radiator  111  and a first feeding section  112  connected to the first main radiator  111 . The first main radiator  111  includes a first open end  114  and a second open end  116 . 
     In the present embodiment, the first feeding section  112  is closer to the first open end  114 , the position of the first feeding section  112  may be a position where the impedance between the first open end  114  and the second open end  116  is 50Ω and the reactance should be close to zero, in order to achieve good impedance matching to excite the electromagnetic wave radiation for signal transmission. 
     Moreover, the second antenna  120  includes a second main radiator  121  and a second feeding section  122  connected to the second main radiator  121 . The second main radiator  121  includes a third open end  124  and a fourth open end  126 . 
     In the present embodiment, the second feeding section  122  is closer to the third open end  124 , the position of the second feeding section  122  may be a position where the impedance between the third open end  124  and the fourth open end  126  is 50Ω and the reactance should be close to zero, in order to achieve good impedance matching to excite the electromagnetic wave radiation for signal transmission. 
     In the present embodiment, the shape and length of the first main radiator  111  and the second main radiator  121  are the same. The three-dimensional antenna module  100  resonates at a frequency band, and the frequency band is, for example, 2.4 GHz, but not limited thereto. The length of the first main radiator  111  is between ½ wavelength of the frequency band, and the length of the second main radiator  121  is between ½ wavelength of the frequency band. 
     That is, the first antenna  110  may resonate at this frequency band, and the second antenna  120  may resonate at the same frequency band as well. The design that both the first antenna  110  and the second antenna  120  may resonate at the same frequency band may be used to increase the bandwidth of this frequency band. 
     It is worth mentioning that the first main radiator  111  is bent into a U shape and has a first opening  118  located between the first open end  114  and the second open end  116 . The second main radiator  121  is bent into a U shape and has a second opening  128  located between the third open end  124  and the fourth open end  126 . 
     In the present embodiment, the direction the first opening  118  faces is different from the direction the second opening  128  faces. Such a design may make the radiation pattern of the first antenna  110  different from the radiation pattern of the second antenna  120 , and may have the effect of complementing the pattern, and therefore may reduce peak gain. 
     Specifically, as shown in  FIG.  1   , the direction the first opening  118  faces (to the right) is opposite to the direction the second opening  128  faces (to the left). Of course, in other embodiments, the direction the first opening  118  faces may also only be different from the direction the second opening  128  faces. For example, the angle between the direction the first opening  118  faces and the direction the second opening  128  faces may be greater than 0 degrees and less than 180 degrees, such as 45 degrees or 90 degrees. 
     In addition, a distance D between the first antenna  110  and the second antenna  120  is, for example, between 2 cm and 10 cm. Since the distance D between the first antenna  110  and the second antenna  120  is very small, in order to avoid mutual interference between the first antenna  110  and the second antenna  120 , in the present embodiment, the conductor  130  is disposed between the first antenna  110  and the second antenna  120  to increase the isolation between the first antenna  110  and the second antenna  120 . 
     In the present embodiment, the length of the conductor  130  is between ¼ times the wavelength of this frequency band, so as to provide a good isolation. Further, the outline of the conductor  130  corresponds to a portion of the outline of the first main radiator  111  or the second main radiator  121 . 
     For example, in the present embodiment, the conductor  130  may be L-shaped, matching to the portion of the second main radiator  121  extending from the fourth open end  126  to the right and upper side of  FIG.  1   . Of course, in other embodiments, the conductor  130  only needs to match a portion of the outline of the first main radiator  111  or the second main radiator  121 , and it is not necessary to match from the open end. 
       FIG.  2    is a schematic diagram of the three-dimensional antenna module of  FIG.  1    disposed in an electronic device. Referring to  FIG.  2   , an electronic device  10  of the present embodiment is, for example, an IP camera. The electronic device  10  includes a casing  20 , a circuit board  12 , a lens  14 , a battery  16 , and the three-dimensional antenna module  100  of  FIG.  1   . An RF circuit, a CPU, a memory, a baseband circuit, etc., may be disposed on the circuit board  12 . The three-dimensional antenna module  100  is electrically connected to the circuit board  12 . 
     The casing  20  is, for example, a plastic casing  20 , and the casing  20  is divided into a first space  22  and a second space  24  by, for example, a partition  25 . The circuit board  12  and the battery  16  are disposed in the first space  22 , and the three-dimensional antenna module  100  is disposed in the second space  24 . Of course, in other embodiments, the casing  20  may only have the first space  22 , and the three-dimensional antenna module  100  may also be disposed in the first space  22 . 
       FIG.  3    is a frequency-S11 diagram of the three-dimensional antenna module of  FIG.  1   . Referring to  FIG.  3   , the first antenna  110  of the three-dimensional antenna module  100  may excite at a first resonance frequency (position L1) and a second resonance frequency (position L2) in a frequency band near WiFi 2.4G. The second antenna  120  may also excite at the Wi-Fi 2.4G frequency band. It may be seen from  FIG.  3    that the S11 of the first antenna  110  and the second antenna  120  at WiFi 2.4G may both be lower than −10 dB to achieve good performance. 
       FIG.  4    is a frequency-isolation diagram of the three-dimensional antenna module of  FIG.  1   . Please refer to  FIG.  4   , the isolation of the three-dimensional antenna module  100  at 2.4 GHz is −20.35 dB. If the structure omits the conductor  130  (that is, there are only the first antenna  110  and the second antenna  120 ), the isolation is −9.31 dB. That is to say, the design of the conductor  130  disposed between the first antenna  110  and the second antenna  120  of the three-dimensional antenna module  100  may effectively reduce the isolation from −9.31 dB to −20.35 dB. 
       FIG.  5 A  to  FIG.  5 C  are radiation patterns of the first antenna and the second antenna of the three-dimensional antenna module of  FIG.  1    on the XY plane, the XZ plane, and the YZ plane. Referring first to  FIG.  5 A , on the XY plane, the radiation pattern of the first antenna  110  is slightly suppressed at 135 degrees to 285 degrees, and the radiation pattern of the second antenna  120  at 135 degrees to 285 degrees may complement the suppression of the radiation pattern of the first antenna  110  at 135 degrees to 285 degrees, thereby reducing the blind spot of receiving and transmitting signals in space. 
     Referring to  FIG.  5 B , on the XZ plane, the radiation patterns of the first antenna  110  and the second antenna  120  at 135 degrees to 225 degrees and 240 degrees to 30 degrees complement each other, thereby reducing the blind spot of receiving and transmitting signals in space. Specifically, the radiation pattern of the first antenna  110  is slightly suppressed at 240 degrees to 30 degrees, and the radiation pattern of the second antenna  120  at 240 degrees to 30 degrees may complement the suppression of the radiation pattern of the first antenna  110  at 240 degrees to 30 degrees. In addition, the radiation pattern of the second antenna  120  is slightly suppressed at 135 degrees to 225 degrees, and the radiation pattern of the first antenna  110  at 135 degrees to 225 degrees may complement the suppression of the radiation pattern of the second antenna  120  at 135 degrees to 225 degrees. 
     Referring to  FIG.  5 C , on the YZ plane, the radiation patterns of the first antenna  110  and the second antenna  120  at 45 degrees to 150 degrees and 225 degrees to 15 degrees complement each other, thereby reducing the blind spot of receiving and transmitting signals in space. Specifically, the radiation pattern of the first antenna  110  is slightly suppressed at 225 degrees to 15 degrees, and the radiation pattern of the second antenna  120  at 225 degrees to 15 degrees may complement the suppression of the radiation pattern of the first antenna  110  at 225 degrees to 15 degrees. In addition, the radiation pattern of the second antenna  120  is slightly depressed at 45 degrees to 150 degrees, and the radiation pattern of the first antenna  110  at 45 degrees to 150 degrees may complement the depression of the radiation pattern of the second antenna  120  at 45 degrees to 150 degrees. 
     In addition, according to the practical measured 3D pattern, the peak gain of the first antenna  110  at a frequency of 2440 MHz is 4.1 dBi, and the antenna efficiency thereof is 70.8%. The peak gain of the second antenna  120  at the frequency of 2440 MHz is 3.3 dBi, the antenna efficiency thereof is 72.6%, and therefore good performance is achieved. 
     From the above, it may be seen that the three-dimensional antenna module  100  of the present embodiment may meet the requirements of the built-in antenna used in an IP camera. Specifically, first, in the three-dimensional antenna module  100  of the present embodiment, via the design in which the first opening  118  of the main radiator  111  and the second opening  128  of the second main radiator  121  face different directions, the coverage area of the antenna radiation pattern may be wide. 
     Second, the peak gain of the antenna radiation of the three-dimensional antenna module  100  of the present embodiment is about 3 dBi to 4 dBi, which does not exceed the 6 dBi expected by industry specifications. Therefore, there is no need to reduce the power of the amplifier circuit, and the communication distance is not shortened as a result. 
     Third, when the distance D between the first antenna  110  and the second antenna  120  is less than 20 mm, the first antenna  110  and the second antenna  120  may meet the requirement that the isolation is at the standard of −20 dB or less. Therefore, the three-dimensional antenna module  100  of the present embodiment is quite suitable for use in an IP camera. Of course, the application field of the three-dimensional antenna module  100  of the present embodiment is not limited thereto. 
     Based on the above, the three-dimensional antenna module of the disclosure includes the first antenna and the second antenna, and the first opening of the first main radiator and the second opening of the second main radiator face different directions. Such a design may make the radiation pattern of the first antenna different from the radiation pattern of the second antenna, and may have the effect of complementary the pattern, and may reduce peak gain. In addition, the conductor is disposed between the first antenna and the second antenna, so as to effectively improve the isolation between the first antenna and the second antenna.