Patent Publication Number: US-10312584-B2

Title: Dual antenna device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 106216214 filed in Taiwan on Nov. 11, 2017, the entire contents of which are hereby incorporated by reference. 
     TECHNICAL FIELD 
     This disclosure relates to an antenna device, and more particularly to a dual antenna device applied in wireless communication equipment. 
     RELATED ART 
     The antenna is an important component is wireless communication products. The size and the performance of the antenna almost determine the quality of the wireless communication products. For example, the proposed specification of the fifth generation mobile network (5G) discloses that the available bandwidth is around 1 GHz at the band of 28 GHz. Single antenna already cannot completely cover such wide bandwidth. The common solution is to provide two antennas, one antenna for high band and another antenna for low band, and to use two channels to transmit the data. However, the development of wireless communication product is getting smaller and thinner. The limited size of device leads to the interference from one antenna to another antenna thus leading to the loss of transmission efficiency. Therefore, the isolation of antennas becomes an important indicator when designing the dual antenna or multi-antennas. 
     SUMMARY 
     According to one or more embodiments of this disclosure, a dual antenna device comprising a substrate comprising an installation surface; a first antenna comprising a first grounding edge, a first shorting edge and a first opening edge, wherein the first antenna protrudes from the installation surface and couples to the installation surface by the first grounding edge, wherein the first shorting edge couples to the first grounding edge and extends along a direction facing away from the installation surface, wherein the first opening edge is substantially in parallel to the first grounding edge and couples to the first shorting edge; a second antenna, comprising a second grounding edge, a second shorting edge and a second opening edge, wherein the second antenna protrudes from the installation surface and couples to the installation surface by the second grounding edge, wherein an extension direction of the second grounding edge and an extension direction of the first grounding edge form an angle, wherein the second shorting edge couples to the second grounding edge and extends along the direction facing away from the installation surface, wherein both the second shorting edge and the first shorting edge are located in a first reference plane, wherein the second opening edge is substantially in parallel to the second grounding edge and couples to the second shorting edge; and an isolation element, comprising a first isolation portion and a second isolation portion, wherein the isolation element protrudes from the installation surface and disposes in a second reference plane vertical to the substrate so that the first antenna and the second antenna respectively locate at both sides of the second reference plane, wherein the isolation element couples to the installation surface by a bottom side of the first isolation portion, wherein the isolation element and the first antenna form a first interval in the extension direction of the first grounding edge, wherein the isolation element and the second antenna form a second interval in the extension direction of the second grounding edge, wherein the second isolation portion couples to one side of the first isolation portion and passing through the first reference plane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present disclosure and wherein: 
         FIG. 1  is a perspective view of the dual antenna device according to an embodiment of the present disclosure; 
         FIG. 2A  is a is a front view of the dual antenna device directly facing the first reference plane according to an embodiment of the present disclosure; 
         FIG. 2B  is a side view of the dual antenna device directly facing the second reference plane according to an embodiment of the present disclosure; 
         FIG. 2C  is a top view of the dual antenna device directly facing the substrate according to an embodiment of the present disclosure; 
         FIG. 3  is a graphical representation of the radiation pattern of the dual antenna device according to an embodiment of the present disclosure; 
         FIG. 4  is a diagram of the isolation of the dual antenna device according to an embodiment of the present disclosure; 
         FIG. 5  is a perspective view of the dual antenna without the isolation element; 
         FIG. 6  is a graphical representation of the radiation pattern of the dual antenna device without the isolation element; 
         FIG. 7  is a diagram of the isolation of the dual antenna device without the isolation element. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings. 
     A dual antenna device of the present disclosure is, for example, adapted to a wireless communication equipment.  FIG. 1  is a perspective view showing an embodiment of the present disclosure. The dual antenna device  1  comprises a substrate  10 , a first antenna  20 , a second antenna  30  and an isolation element  40 . As shown in  FIG. 1 , the substrate  10  is a rectangular structure with an installation surface  12  comprising two long edges and two short edges. Practically, depending on the real product, the substrate  10  may combine with a baffle or a fixing component. The substrate  10  can also have through holes based on the need for assembly. The substrate  10  of the present disclosure is not limited to the rectangular shape shown in  FIG. 1 . 
     Please refer to  FIG. 2A . The first antenna  20  comprises a first radiation portion  22 , a first feeding portion  24  and a first grounding portion  26 . The first radiation portion  22  comprises a first opening branch  222  and a first shorting branch  224 . The first opening branch  222  comprises a first opening edge  222   a . The first shorting branch  224  comprises a first shorting edge  224   a . The first grounding portion  26  comprises a first grounding edge  26   a . One end of the first opening branch  222  and one end of the first shorting branch  224  form an L-shaped connection. The first radiation portion  22  comprises a first defined length L 1  that is the sum of the length of the first opening edge  222   a  and the length of the first shorting edge  224   a . Practically, the first defined length L 1  is substantially 0.25 wavelength of the radio signal sent by the first antenna  20 . One end of the first feeding portion  24  and one end of the first opening branch  222  form a T-shaped connection so that the first radiation portion  22  and the first feeding portion  24  form an F-shaped connection. One end of the first grounding portion  26  couples to another end of the first shorting branch  224  while said another end of the first shorting branch  224  does not couple to the first opening branch  222 , and the first grounding portion  26  is substantially parallel to the first opening branch  222 . 
     Please refer to  FIG. 2A . The second antenna  30  comprises a second radiation portion  32 , a second feeding portion  34  and a second grounding portion  36 . The second radiation portion  32  comprises a second opening branch  322  and a second shorting branch  324 . 
     The second opening branch  322  comprises a second opening edge  322   a . The second shorting branch  324  comprises a second shorting edge  324   a . The second grounding portion  36  comprises a second a grounding edge  36   a . One end of the second opening branch  322  and one end of the second shorting branch  324  form an L-shaped connection. 
     The second radiation portion  32  comprises a second defined length L 2  that is the sum of the length of the second opening edge  322   a  and the length of the second shorting edge  324   a . Practically, the second defined length L 2  is substantially 0.25 wavelength of the radio signal sent by the second antenna  30 . One end of the second feeding portion  34  and one end of the second opening branch  322  form a T-shaped connection so that the second radiation portion  32  and the second feeding portion  34  form an F-shaped connection. One end of the second grounding portion  36  couples to another end of the second shorting branch  324  while said another end of the second branch  324  does not couple to the second opening branch  322 , and the second grounding portion  36  is substantially parallel to the second opening branch  322 . As set forth above, the second antenna  30  and the first antenna  20  have similar structures. It should be noticed that the realistic size of each component of the first antenna  20  and the second antenna  30  depends on the requirement of antenna design. 
     Please refer to  FIG. 1  and  FIG. 2A . The first antenna  20  protrudes from the installation surface  12  of the substrate  10  while the protruding direction is the extension direction of the first shorting edge  224   a . In an embodiment of the present disclosure, the first shorting branch  224  is vertical to the installation surface  12  but the present disclosure is not thus limited. The first antenna  20  couples to the installation surface  12  by the first grounding edge  26   a  that is the bottom edge of the first grounding portion  26 . One end of the first shorting edge  224   a  couples to the first grounding edge  26   a , another end of the first shorting edge  224   a  couples to the first opening edge  222   a  of the first opening branch  222 . The first opening edge  222   a  is the farthest edge of the first antenna  20  facing away from the installation surface  12 . 
     Please refer to  FIG. 1  and  FIG. 2A . The second antenna  30  protrudes from the installation surface  12  of the substrate  10  while the protruding direction is the extension direction of the second shorting edge  324   a . In an embodiment of the present disclosure, the second shorting branch  324  is vertical to the installation surface  12  but the present disclosure is not thus limited. The second antenna  30  couples to the installation surface  12  by the second grounding edge  36   a  that is the bottom edge of second grounding portion  36 . One end of the second shorting edge  324   a  couples to the second grounding edge  36   a , another end of the second shorting edge  324   a  couples to the second opening edge  322   a  of the second opening branch  322 . The second opening edge  322   a  is the farthest edge of the second antenna  30  facing away from the installation surface  12 . As set forth above, the connection manner between the second antenna  30  and the installation surface  12  is similar to the connection manner between the first antenna  20  and the installation surface  12 , and the connection components of the second antenna  30  are named correspondingly to those of the first antenna  20 . It should be noticed that the first antenna  20  and/or the second antenna  30  can have an angle with the installation surface  12  of the substrate  10  depending on the requirement of antenna design. The present of the invention does not limit that the first shorting branch  224  and/or the second shorting branch  324  must be vertical to the installation surface  12 . In addition, in other embodiments, the design of the first grounding portion  26  can be not protruding from the first shorting branch  224  in the extension direction of the first grounding edge  26   a  while the design of the second grounding portion  36  can be not protruding from the second shorting branch  324  in the extension direction of the second grounding edge  36   a.    
     Please refer to  FIG. 1 ,  FIG. 2A  and  FIG. 2C . The first shorting edge  224   a  and the second shorting edge  324   a  locate at the first reference plane P 1 . In the installation surface  12 , the extension direction of the first grounding edge  26   a  and the extension direction of the second grounding edge  36   a  form an angle A. In an embodiment of the present disclosure, this angle is 180 degrees so that the first antenna  20  with the first grounding edge  26   a  and the second antenna  30  with the second grounding edge  36   a  are all in the first reference plane P 1 . The planar structures of first antenna  20  and the second antenna  30  are shown in  FIG. 2A , with a view directly facing the first reference plane P 1 . Please refer to  FIG. 2C . In an embodiment of the present disclosure, the extension direction of the first opening edge  222   a  and the extension of the second opening edge  322   a  form 180 degrees so that the first antenna  20  and the second antenna  30  do not interfere each other as much as possible when they send the radio signals in their own radiation direction. 
     In an embodiment of the present disclosure, the first antenna  20  is configured for high band transmission and the working frequency is 5.45-5.85 GHz, while the second antenna  30  is configured for low band transmission and the working frequency is 5.15-5.35 GHz. 
     The working frequencies of the first antenna  20  and the second antenna  30  are not limited to the above numbers. Practically, the length of the first feeding portion  24   a  can be adjusted shorter than the length of the second feeding portion  34  according to the different working frequencies of the first antenna  20  and the second antenna  30 , but the present disclosure is not limited to the above adjustment. In other embodiments, the first antenna  20  and the second antenna  30  are configured to operate at the same working frequency, thus the length of the first feeding portion  24  is the same as the length of the second feeding portion  34 . 
     Please refer to  FIG. 1 ,  FIG. 2B  and  FIG. 2C . For improving the isolation and adjusting the radiation direction of the dual antenna device  1 , the dual antenna device  1  comprises an isolation element  40 . The isolation element  40  protrudes from the installation surface  12  and disposes in the second reference plane P 2  that is substantially vertical to the substrate  10 . The first antenna  20  and the second antenna  30  respectively locate on both sides of the second reference plane P 2 , as shown in  FIG. 2C . In a view directly facing the installation surface  12 , the  FIG. 2C  shows that the isolation element  40  with a thickness is in the middle of the substrate  10 , the first antenna  20  is on the right side of the isolation element  40 , and the second antenna  30  is on the left side of the isolation element  40 . 
     Please refer to  FIG. 1  and  FIG. 2B . The isolation element  40  comprises a first isolation portion  401 , a second isolation portion  402  and a third isolation portion  403 . In a view directly facing the second reference plane P 2 , the  FIG. 2B  shows that the planar shape of the isolation element  40 , in an embodiment of the present disclosure, is substantially T-shape. The second isolation portion  402  couples to one side of the first isolation portion  401  and said one side is near to the first reference plane P 1 . The third isolation portion  403  couples to one side of the first isolation portion  401  and said one side is away from the first reference plane P 1 . The isolation element  40  couples to the installation surface  12  by a bottom side of the first isolation portion  401 . The extension direction of the bottom side of the first isolation portion  401  is vertical to the connection direction of the first grounding edge  26   a  and the second grounding edge  36   a , so that the isolation magnitude of the first antenna  20  and the second antenna  30  can be balanced. However, the present disclosure is not limited to the aforementioned vertical condition. 
     Please refer to  FIG. 1  and  FIG. 2A . In the extension direction of the first grounding edge  26   a , there is a first interval D 1  between and defined by the isolation element  40  and the first antenna  20 . In the extension direction of the second grounding edge  36   a , there is a second interval D 2  between and defined by the isolation element  40  and the second antenna  30 . In an embodiment of the present disclosure, the first interval D 1  is 0.07-0.1 wavelength of a radio signal sent by the dual antenna device  1 , and the second interval D 2  is 0.07-0.1 wavelength of the radio signal sent by the dual antenna device  1 . In this embodiment, the first antenna  20  and the second antenna  30  both are in the first reference plane P 1 , so the distance from the first shorting edge  224   a  to the second shorting edge  324   a  is 0.16-0.2 wavelength of the radio signal sent by the dual antenna device  1 , while said distance is substantially the sum of the first interval D 1 , the second interval D 2  and the thickness of the isolation element  40 . 
     Please refer to  FIG. 1  and  FIG. 2B . In the extension direction of the bottom side of the first isolation portion, there is a third interval D 3  between and defined by the bottom side of the first isolation portion  401  and the first grounding edge  26   a  or between and defined by the bottom side of the first isolation portion  401  and the second grounding edge  36   a . In an embodiment of the present disclosure, the third interval D 3  is 0.03-0.06 wavelength of the radio signal sent by the dual antenna device  1 . The second isolation portion  402  passes through the first reference plane P 1 . Furthermore, there is a fourth interval D 4  between and defined by a bottom side of the second isolation portion  402  and the first opening edge  222   a  or between and defined by the bottom side of the second isolation portion  402  and the second opening edge  322   a . Said bottom side of the second isolation portion  402  faces the installation surface  12 , and the fourth interval D 4  lies in the extension direction of the first shorting edge  224   a  or in the extension direction of the second shorting edge  324   a . From another perspective, the fourth interval D 4  can be viewed as the difference of the perpendicular distance from the bottom side of the second isolation portion  402  to the installation surface  12  and the perpendicular distance from the first opening edge  222   a  or the second opening edge  322   a  to the installation surface  12 . In an embodiment of the present disclosure, because the first shorting edge  224   a  and the second shorting edge  324   a  both are vertical to the installation surface  12  and have the same length, the distance from the bottom side of the second isolation portion  402  to the first opening edge  222   a  in the extension direction of the first shorting edge  224   a  and the distance from the bottom side of the second isolation portion  402  to the second opening edge  322   a  in the extension direction of the second shorting edge  324   a  are the same, which are 0.004-0.007 wavelength of the radio signal sent by the dual antenna device  1 . 
     In other embodiments, if the height of the first antenna  20  and the height of the second antenna  30  are different, then the fourth interval D 4  is set as a smaller one of the distances between the bottom side of the second isolation portion  402  and the first opening edge  222   a  and between said bottom side and the second opening edge  322   a.    
     Please refer to  FIG. 2B . The first isolation portion  401  and the second isolation portion  402  form a third defined length L 3 . The third defined length L 3  is the sum of the perpendicular distance from the first isolation portion  40  to the installation surface  12  and the length of the second isolation portion  402  that is substantially parallel to the installation surface  12 . The first isolation portion  401  and the third isolation portion  403  form a fourth defined length L 4 . The fourth defined length L 4  is the sum of the perpendicular distance from the first isolation portion  401  to the installation surface  12  and the length of the third isolation portion  403  that is substantially parallel to the installation surface  12 . In an embodiment of the present disclosure, the third defined length L 3  and the fourth defined length L 4  both are 0.25 wavelength of the radio signal sent by the dual antenna device  1 . 
     Please refer to  FIG. 3 .  FIG. 3  shows two radiation patterns of the dual antenna device  1  in the perspective of the x-y plane. Specifically, the right graph is the pattern of the first antenna  20  and the left graph is the pattern of the second antenna  30 . Practically, by adjusting the feeding current of the first feeding portion  24  and the second feeding portion  34 , the first antenna  20  and the second antenna  30  have opposite phases with the same magnitude of the amplitude of radio wave. Meanwhile, according to an embodiment of the present disclosure, due to the size of isolation element  40  (the third defined length L 3  and the fourth defined length L 4 ), the distance relationship among the isolation element  40 , the first antenna  20  and the second antenna  30  (the first interval D 1 , the second interval D 2 , the third interval D 3  and the fourth interval D 4 ), the lengths/interval settings stated above, part of the radiation range of the first antenna  20  can cancel out part of the radiation range of the second antenna  30 . The canceled parts are located at one side of the first isolation portion  401 , which is the side connected to the second isolation portion  402 . As shown in  FIG. 3 , the radiation range of the first antenna  20  at its 9-10 o&#39;clock and the radiation range of the second antenna  30  at its 2-3 o&#39;clock direction have obviously hollow parts. According to the above descriptions and  FIG. 3 , it shows the effect of isolation element  40  in the present disclosure. Moreover, since the effect levels of isolation resulted from the first isolation portion  401  and the second isolation portion  402  are different, the isolation element  40  has the effect of enabling the independent adjustment of the radiation directions of the two antennas. In  FIG. 2C  which has the same perspective as  FIG. 3  to the dual antenna device  1 , the radiation direction of the first antenna  20  is about 2 o&#39;clock direction thereof as the arrow shown in  FIG. 3 , and the radiation direction of the second antenna  30  is about 10 o&#39;clock direction thereof as the arrow shown in  FIG. 3 . The radiation directions stated above are affected by the isolation element  40  disposed along the y-axis in  FIG. 3 . 
     Please refer to the  FIG. 5 , it shows an embodiment of the present disclosure but the isolation element  40  is removed. Please refer to  FIG. 6  and  FIG. 3 .  FIG. 6  is a simulation result according to the dual antenna device  5  in  FIG. 5 . Compared to the dual antenna device  1  with the isolation element  40 , the radiation pattern in  FIG. 6  does not have hollow parts as the radiation pattern shown in  FIG. 3 . The radiation direction of first antenna  20  extends in 3 o&#39;clock direction thereof and the radiation of second antenna  30  extends in 9 o&#39;clock direction thereof. 
       FIG. 4  shows the S-parameter of an embodiment of the present disclosure.  FIG. 7  shows the S-parameter of an embodiment of the present disclosure without the isolation element  40 . According to the number variation of S 2 , 1  and S 1 , 2  under the different frequencies, it is obvious that the isolation element  40  of the present disclosure improves the isolation magnitude from −14.5 dB (marked as M 71 ) to −33.5 dB (marked as M 41 ). 
     In an embodiment of the present disclosure, the substrate  10 , the first antenna  20 , the second antenna  30  and the isolation element  40  are integrally formed by the conductive material such as metal. For example, the planar structures of the first antenna  20  and the second antenna  30  can be processed additionally when manufacturing the substrate  10 . 
     The first antenna  20  and the second antenna  30  protrude from the installation surface  12  of substrate  10  after bending said planar structures, as three-dimensional structure shown in  FIG. 1 . The isolation element  40  can also be formed by bending the substrate  19  after cutting the first isolation portion  401 , the second isolation portion  402  and the third isolation portion  403  from the substrate  10 , so that the isolation element  40  protrudes from the installation surface  12 , as the three-dimensional structure shown in  FIG. 1 . 
     However, the method of manufacturing the dual antenna device  1  does not limit by the above descriptions. Practically, after the manufacture work of the first antenna  20 , the second antenna  30  and the isolation element  40  are done, the dual antenna device  1  can be formed by the combination of these components. 
     In sum, the dual antenna device of the present disclosure comprises the isolation element with a specific structure between the first antenna and the second antenna and the isolation element has the first/second interval related to the first/second antenna so that the isolation magnitude can be improved and the radiation direction can be adjusted when the dual antenna device is applied in small size antenna.