Patent Publication Number: US-10312572-B2

Title: Miniaturized multi-band antenna

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Chinese Patent Application No. 201611262376.5, filed Dec. 30, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
     FIELD 
     The present disclosure relates to wireless communication, and more particularly to a miniaturized multi-band antenna. 
     BACKGROUND 
     A conventional method for transmitting and receiving radio frequency (RF) signals in different frequency bands is to use a plurality of separate antennas. However, the plurality of separate antennas is large and thus does not allow for miniaturization of antennas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic view of a multi-band antenna on a substrate. 
         FIG. 2  is an enlarged view of the multi-band antenna of  FIG. 1 , showing signal paths in three different frequency bands. 
         FIG. 3  is a schematic view of the multi-band antenna of  FIG. 1  connected to a triplexer. 
         FIG. 4  is a schematic view of the multi-band antenna of  FIG. 1  connected to two duplexers. 
         FIG. 5  is a voltage standing wave ratio diagram of the multi-band antenna of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the exemplary embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the exemplary embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     With reference to  FIGS. 1 and 2 , an exemplary embodiment of a multi-band antenna shows antenna  1  mounted on a substrate  2 . The substrate  2  may be insulating. The multi-band antenna  1  includes a ground portion  11 , a feeder  12 , a first radiator  13 , and a second radiator  14 . The ground portion  11 , the feeder  12 , the first radiator  13 , and the second radiator  14  are coplanar. 
     In the present exemplary embodiment, the ground portion  11  is elongated, and is grounded. The ground portion  11  is a metal sheet. The ground portion  11  is L-shaped, and has a ground arm  111  and a connecting arm  112 . The ground arm  111  and the connecting arm  112  are perpendicular to each other. The ground portion  11  may be copper foil. 
     The feeder  12  is elongated, and has a feed end  121 . The feed end  121  can transmit and receive RF signals. 
     In the present exemplary embodiment, the feeder  12  is single-polarized. The feeder  12  is L-shaped, and has a first feed arm  122  and a second feed arm  123 . The first feed arm  122  and the second feed arm  123  are perpendicular to each other. The feed end  121  is located at an end of the first feed arm  122  away from the second feed arm  123 . 
     The ground portion  11  and the feeder  12  are spaced from each other to generally form the shape of an open rectangular frame. The ground arm  111  of the ground portion  11  is parallel to the second feed arm  123  of the feeder  12 . The connecting arm  112  of the ground portion  11  is parallel to the first feed arm  122  of the feeder  12 . A gap (unlabeled) is formed between the second feed arm  123  and the connecting arm  112  and another gap (unlabeled) is formed between the ground arm  111  and first feed arm  122 , thus the rectangular frame being called open. 
     The first radiator  13  is elongated, and is connected to the ground portion  11 . The first radiator  13  and the feeder  12  are spaced from and not connected to each other. A gap D is formed between the first radiator  13  and the feeder  12 . The gap D can cause a coupling between the first radiator  13  and the feeder  12  to transmit the RF signal. 
     The second radiator  14  is elongated, and is connected to the ground portion  11  and the first radiator  13 . The second radiator  14  can transmit the RF signal from the first radiator  13 . 
     In the present exemplary embodiment, the first radiator  13  is L-shaped, and has a first metal arm  131  and a second metal arm  132 . The first metal arm  131  and the second metal arm  132  are perpendicular to each other. The first metal arm  131  is parallel to the first feed arm  122  of the feeder  12  to form the gap D. The gap D is less than or equal to 5 mm. The second metal arm  132  is connected between the first metal arm  131  and the connecting arm  112  of the ground portion  11 . The second metal arm  132  is parallel to the second feed arm  123  of the feeder  12 . The second radiator  14  is L-shaped, and has a third metal arm  141  and a fourth metal arm  142 . The third metal arm  141  and the fourth metal arm  142  are perpendicular to each other. The third metal arm  141  is connected between the fourth metal arm  142  and the connecting arm  112  of the ground portion  11 . An end of the third metal arm  141  connected to the connecting arm  112  and an end of the second metal arm  132  connected to the connecting arm  112  are connected to each other. The fourth metal arm  142  is parallel to the connecting arm  112  of the ground portion  11 . 
     When the multi-band antenna  1  is in use, the feeder  12  receives an RF signal through the feed end  121 , the first radiator  13  then transmits the RF signal through the coupling between the first radiator  13  and the feeder  12 . The second radiator  14  then transmits the RF signal through the first radiator  13  connected to the second radiator  14 . The RF signals in three different frequency bands can be fed to the feeder  12  along three signal paths. The first signal path sequentially passes through the connecting arm  112 , the second metal arm  132 , and the first metal section  131  (Arrow A of  FIG. 2 ). The second signal path sequentially passes through the connecting arm  112 , the third metal arm  141 , and the fourth metal arm  142  (Arrow B of  FIG. 2 ). The third signal path sequentially passes through the first feed arm  122  and the second feed arm  123  (Arrow C of  FIG. 2 ). 
     The signal paths in different frequency bands are resonantly formed depending on the length of the feeder  12 , the length of the first radiator  13 , the length of the second radiator  14 , the length of the connecting arm  112 , and the width of the gap D. The length of the first radiator  13  is less than one-quarter of the wavelength of the RF signal in a first frequency band. The length of the second radiator  14  is less than one-quarter of the wavelength of the RF signal in a second frequency band. The length of the feeder  12  is less than one-quarter of the wavelength of the RF signal in a third frequency band. Therefore, multi-band operation can be achieved together with size reduction of the multi-band antenna  1 . In the present exemplary embodiment, the first frequency band is between approximately 1575 MHz and 1900 MHz to transmit and receive GPS signals. The second frequency band is between approximately 2400 MHz and 2480 MHz to transmit and receive 2.4 GHz Wi-Fi signals. The third frequency band is between approximately 5000 MHz and 5800 MHz to transmit and receive 5 GHz Wi-Fi signals. 
     With reference to  FIG. 3 , the multi-band antenna  1  may be connected to a triplexer  20  through the feed end  121  for separating the GPS signals, the 2.4 GHz Wi-Fi signals, and the 5 GHz Wi-Fi signals. With reference to  FIG. 4 , the multi-band antenna  1  may be connected to two series-connected duplexers  30  through the feed end  121 . One duplexer  30  separates the 2.4 GHz Wi-Fi/GPS signals and the 5 GHz Wi-Fi signals, and the other duplexer  30  separates the 2.4 GHz Wi-Fi signals and the GPS signals. 
     With reference to  FIG. 5 , a voltage standing wave ratio diagram of the multi-band antenna  1  is illustrated. The multi-band antenna  1  can transmit and receive the RF signals in the first frequency band, the second frequency band, and the third frequency band. 
     The multi-band antenna  1  can transmit and receive the RF signals in other frequency bands by changing the length of the feeder  12 , the length of the first radiator  13 , the length of the second radiator  14 , and the width of the gap D. 
     The exemplary embodiments shown and described above are only examples. Many details are often found in the art such as the other features of an antenna. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the exemplary embodiments described above may be modified within the scope of the claims.