Patent Publication Number: US-2023133099-A1

Title: Base station antenna

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Chinese Patent Application Serial Number 202111280615.0, filed on Nov. 1, 2021, the full disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to the technical field of communication technology, and in particular to a base station antenna. 
     Related Art 
     The base station antenna is an important connection bridge in mobile communication devices, and the quality of the base station antenna affects the communication quality of the mobile device. At present, the multi-input/multi-output (MIMO) technology that uses multiple radiation units for signal transmission and reception has attracted the attention of related industries because it can improve the utilization efficiency of spectrum and energy through different dimensions (e.g., the spatial domain, the time domain, the frequency domain, and the polarization domain), and achieve greater wireless data traffic and connection reliability. 
     In existing base station antennas, the oscillator of the radiation unit is generally a die-cast oscillator or a sheet metal oscillator. However, the radiation unit using the die-cast oscillator has the problem of poor performance of the base station antenna due to insufficient beam width convergence, and the radiation unit using the sheet metal oscillator has the problem that the base station antenna have insufficient performance due to insufficient horizontal beam width convergence and poor cross polarization ratio. 
     Therefore, how to improve the convergence of the horizontal beam width and the cross polarization ratio of the base station antenna is a technical problem to be solved. 
     SUMMARY 
     The present disclosure provides a base station antenna, which can effectively solve the problems of insufficient convergence of the horizontal beam width and poor cross polarization ratio of the base station antenna in the prior art. 
     In order to solve the above technical problem, the present disclosure is implemented as follows. 
     The present disclosure provides a base station antenna, which includes a substrate and an antenna sub-array. The antenna sub-array includes a feeding plate, a plurality of radiation units and two metal baffles. The feeding plate is disposed on the substrate. The plurality of radiation units are disposed on the feeding plate along a first direction and electrically connected to the feeding plate. The two metal baffles are respectively disposed on two sides of the feeding plate along a second direction perpendicular to the first direction, and each metal baffle extends along the first direction. Each metal baffle is provided with an opening slot, and a length of the opening slot of each metal baffle along the first direction corresponds to a wavelength of a center frequency of the base station antenna. 
     In the embodiment of the present disclosure, by disposing two metal baffles each having the opening slot on two sides of the feeding plate provided with multiple radiation units along the first direction, respectively, and the length of each opening slot along the first direction corresponds to the wavelength of the center frequency of the base station antenna, the base station antenna can achieve the technical effects of converging the horizontal beam width and optimizing the cross polarization ratio. 
     It should be understood, however, that this summary may not contain all aspects and embodiments of the present disclosure, that this summary is not meant to be limiting or restrictive in any manner, and that the disclosure as disclosed herein will be understood by one of ordinary skill in the art to encompass obvious improvements and modifications thereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the exemplary embodiments believed to be novel and the elements and/or the steps characteristic of the exemplary embodiments are set forth with particularity in the appended claims. The Figures are for illustration purposes only and are not drawn to scale. The exemplary embodiments, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which: 
         FIG.  1    is a three-dimensional schematic diagram of a base station antenna according to an embodiment of the present disclosure. 
         FIG.  2    is a top view of the base station antenna of  FIG.  1   . 
         FIG.  3    is a side view of the base station antenna of  FIG.  1   . 
         FIG.  4    is an enlarged schematic diagram of the area A of the base station antenna of  FIG.  1   . 
         FIG.  5    is a cross-sectional view of the base station antenna of  FIG.  4    along line BB. 
         FIG.  6    is a three-dimensional schematic diagram of the radiation unit of  FIG.  1   . 
         FIG.  7    is a simulation diagram of the voltage standing wave ratio of the base station antenna of  FIG.  1   . 
         FIG.  8    is a simulation diagram of the isolation of the base station antenna of  FIG.  1   . 
         FIG.  9    is a simulation diagram of the horizontal beam width of the base station antenna of  FIG.  1   . 
         FIG.  10    is a simulation diagram of the polarization ratio of the base station antenna of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. This present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. 
     Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but function. In the following description and in the claims, the terms “include/including” and “comprise/comprising” are used in an open-ended fashion, and thus should be interpreted as “including but not limited to”. 
     The following description is of the best-contemplated mode of carrying out the disclosure. This description is made for the purpose of illustration of the general principles of the disclosure and should not be taken in a limiting sense. The scope of the disclosure is best determined by reference to the appended claims. 
     Moreover, the terms “include”, “contain”, and any variation thereof are intended to cover a non-exclusive inclusion. Therefore, a process, method, object, or device that includes a series of elements not only includes these elements, but also includes other elements not specified expressly, or may include inherent elements of the process, method, object, or device. If no more limitations are made, an element limited by “include a/an . . . ” does not exclude other same elements existing in the process, the method, the article, or the device which includes the element. 
     It must be understood that when a component is described as being “connected” or “coupled” to (or with) another component, it may be directly connected or coupled to other components or through an intermediate component. In contrast, when a component is described as being “directly connected” or “directly coupled” to (or with) another component, there are no intermediate components. In addition, unless specifically stated in the specification, any term in the singular case also comprises the meaning of the plural case. 
     In the following embodiment, the same reference numerals are used to refer to the same or similar elements throughout the disclosure. 
     Please refer to  FIGS.  1  to  3   , wherein  FIG.  1    is a three-dimensional schematic diagram of a base station antenna according to an embodiment of the present disclosure,  FIG.  2    is a top view of the base station antenna of  FIG.  1   , and  FIG.  3    is a side view of the base station antenna of  FIG.  1   . As shown in  FIGS.  1  to  3   , the base station antenna  100  comprises a substrate  110  and an antenna sub-array  120 . The antenna sub-array  120  comprises a feeding plate  122 , a plurality of radiation units  124  and two metal baffles  126 . The feeding plate  122  is disposed on the substrate  110 . The plurality of radiation units  124  are disposed on the feeding plate  122  along the first direction R and are electrically connected to the feeding plate  122 . The two metal baffles  126  are respectively disposed on two sides of the feeding plate  122  along a second direction S perpendicular to the first direction R, and each metal baffle  126  extends along the first direction R. Each metal baffle  126  is provided with an opening slot  50 , and the length L of the opening slot  50  of each metal baffle  126  along the first direction R corresponds to a wavelength of a center frequency of the base station antenna  100 . The first direction R is the extension direction of the substrate  110  and the feeding plate  122 . The feeding plate  122  provides radio frequency signals to the radiating units  124 , which are electrically connected to the feeding plate  122 , for transmission. and receives radio frequency signals from the radiating units  124 , which are electrically connected to the feeding plate  122 . In this embodiment, the number of radiation units  124  included in the antenna sub-array  120  may be but not limited to five, and the actual number of radiation units  124  included in the antenna sub-array  120  can be adjusted according to actual requirements. 
     In an example, the substrate  110  is a reflective plate for reflecting radiation. In an example, the substrate  110  is a part of the housing of the base station antenna  100 . 
     In an embodiment, the propagation velocity (v) of the electromagnetic wave is the product of the frequency (f) of the electromagnetic wave and the wavelength ( 2 ) of the electromagnetic wave, and the wave velocity of the electromagnetic wave in the air is approximately 3×10 8  m/s, so the length L of the opening slot  50  of each metal baffle  126  along the first direction R may be approximately 55 millimeters (mm) when the center frequency of the base station antenna  100  may be 4.15 GHz. Therefore, the length L of the opening slot  50  of each metal baffle  126  along the first direction R may be 0.8 times the wavelength of the center frequency of the base station antenna  100 , wherein one times the wavelength is 72 mm. 
     In an embodiment, the height H of the metal baffle  126  may be greater than the height of each radiation unit  124 , so as to improve the isolation of the base station antenna  100 , as shown in  FIG.  2   , wherein the metal baffle  126  completely shades the radiation units  124  in the side view along the second direction S. 
     In an embodiment, when the metal baffle  126  is provided with only a single opening slot  50 , the opening slot  50  of the metal baffle  126  is located at the center position of the metal baffle  126  along the first direction R. 
     In an embodiment, the metal baffle  126  may be provided with a plurality of opening slots  50 , and the greater the number of the opening slots  50  provided within the limited length of the metal baffle  126 , the better the convergence of the horizontal beam width of the base station antenna  100 . In an example, the number of opening slots  50  provided by the metal baffle  126  may be but not limited to two, as shown in  FIG.  3   , and the actual number of opening slots  50  provided by the metal baffle  126  can be adjusted according to actual requirements. In addition, the number of opening slots  50  provided by each of the two metal baffles  126  can be the same or different, and can be adjusted according to actual requirements. 
     In an embodiment, when the metal baffle  126  is provided with a plurality of opening slots  50 , the plurality of opening slots  50  of the metal baffle  126  are located symmetrically with respect to the center position of the metal baffle  126  along the first direction R. 
     In an example, when the number of opening slots  50  provided by the metal baffle  126  is 2N+1, the middle position of the (N+1)th opening slot  50  along the first direction R is located at the center position of the metal baffle  126  along the first direction R, wherein N is a positive integer. 
     In another example, when the number of opening slots  50  provided by the metal baffle  126  is 2N, the 2N opening slots  50  are located symmetrically along the first direction R with the center position of the metal baffle  126  as the symmetric point, wherein N is a positive integer. 
     In an embodiment, when the metal baffle  126  is provided with a plurality of opening slots  50  along the first direction R, the distance D between two adjacent opening slots  50  may be equal to 0.25 times the wavelength of the center frequency of the base station antenna  100 . 
     In an embodiment, the feeding plate  122  has a central axis C extending along the first direction R and located in the middle position between the two sides of the feeding plate  122  along the second direction S, the plurality of radiation units  124  are arranged along the central axis C, and the distance E between the central axis C and any one of the two metal baffles  126  along the second direction S may be 0.5 times the wavelength of the center frequency of the base station antenna  100 . When the distance E in the second direction S between the central axis C and any metal baffle  126  is greater than or less than 0.5 times the wavelength of the center frequency of the base station antenna  100 , the convergence of the horizontal beam width of the base station antenna  100  becomes poor. 
     In an embodiment, please refer to  FIG.  1    and  FIG.  4   , wherein  FIG.  4    is an enlarged schematic diagram of the area A of the base station antenna of  FIG.  1   . As shown in  FIGS.  1  and  4   , the base station antenna  100  may further comprise an isolation component  128 , which is correspondingly disposed on the antenna sub-array  120 , and the isolation component  128  is disposed between two adjacent radiation units  124  and between the two metal baffles  126  to achieve the effect of debugging and optimizing the isolation of the base station antenna  100 . There is no special restrictions on the shape of the isolation component  128 . It should be noted that the isolation component  128  does not contact the feeding plate  122  and the radiation units  124 . 
     In an embodiment, referring to  FIGS.  1  and  4   , the base station antenna  100  may further comprise two isolation columns  129 , which are disposed between two adjacent radiation units  124  and between the two metal baffles  126 , and the isolation component  128  is connected with the two isolation columns  129 . The height of the isolation column  129  may be less than, equal to or greater than the height of the radiation unit  124 . When the height of the isolation column  129  is greater than the height of the radiation unit  124 , the isolation effect of the base station antenna  100  can be improved. 
     In an embodiment, please refer to  FIG.  4    and  FIG.  5   , wherein  FIG.  5    is a cross-sectional view of the base station antenna of  FIG.  4    along the line BB. As shown in  FIGS.  4  and  5   , each metal baffle  126  comprises a folded edge  80 , each metal baffle  126  is connected to the substrate  110  through the corresponding folded edge  80 , the bottom ends of the two isolation column  129  are connected to the folded edges  80  of the two metal baffles  126 , the top ends of the two isolation columns  129  are connected to the isolation component  128 , and the isolation component  128  does not contact the feeding plate  122  (that is, the two isolation columns  129  can raise the isolation component  128  so that the isolation component  128  does not contact the feeding plate  122 ). In more detail, the substrate  110  may further comprise two protruding columns  90  formed integrally extending upward. The two protruding columns  90  can pass through the folded edges  80  of the two metal baffles  126  and be inserted into the two isolation columns  129 , and the two fixing members  92  can pass through the isolation component  128  and be inserted into the two isolation columns  129 , so that the top end of each isolation column  129  is fixedly connected to isolation component  128 . The number of the protruding columns  90  and the number of the fixing members  92  may correspond to the number of the isolation columns  129 . 
     In an example, each isolation column  129  may be provided with a through hole  85  having an internal thread, each fixing member  92  may be, but not limited to, a screw having an external thread that matches the internal thread, and the surface of the protruding column  90  is provided with the external thread matching with the internal thread. That is, through the matching of the internal thread and the external thread, the isolation columns  129  and the metal baffles  126  can be fixed on the substrate  110 , and the fixing members  92  and the isolation component  128  can be fixed on the isolation columns  129 . 
     In an embodiment, please refer to  FIG.  1    and  FIG.  6   , wherein  FIG.  6    is a three-dimensional schematic diagram of the radiation unit of  FIG.  1   . As shown in  FIGS.  1  and  6   , each radiation unit  124  comprises a balun support part  70  and an antenna oscillator part  72 , wherein the antenna oscillator part  72  is disposed on and electrically connected to the balun support part  70 , the balun support part  70  is disposed on the feeding plate  122 , and the antenna oscillator part  72  and the balun support part  70  are both composed of printed circuit boards. Therefore, the antenna oscillator part  72  and the balun support part  70  of each radiation unit  124  are both made of printed circuit boards, so that each radiation unit  124  can be widely used in various antennas (e.g., MIMO antennas, notebook computer antennas, base station antennas), and the cost and product weight can be greatly reduced, while the intermodulation performance is effectively improved. 
     In an embodiment, referring to  FIG.  6   , the balun support part  70  may be provided with a curved balun wiring  71  to reduce the height of the radiation unit  124 . Specifically, the balun wiring  71  with multiple bends is disposed on the balun support part  70 , so that the routing arrangement of the balun wiring  71  is concentrated. In this way, the height of the balun support part  70  can be reduced to meet the low profile requirement of the radiation unit  124 , so that the base station antenna  100  can be smaller and lighter in weight. 
     In an embodiment, referring to  FIG.  6   , the antenna oscillator part  72  may comprise at least a pair of oscillator arms  73 , and a length of each oscillator arm  73  is 0.25 times the wavelength of the center frequency of the base station antenna  100 . The shape of each oscillator arm  73  may be, but not limited to, a diamond shape, and the oscillator arms  73  included in the antenna oscillator part  72  may be arranged in a ring around a point. 
     In an example, the radiation unit  124  is a single-polarized antenna unit, the antenna oscillator part  72  may comprise a pair of oscillator arms  73  (that is, two oscillator arms  73 ), and the two oscillator arms  73  may constitute the horizontally polarized oscillator arms or the vertically polarized oscillator arms. 
     In another example, the radiation unit  124  is a dual-polarized antenna unit, and the antenna oscillator part  72  may comprise two pairs of oscillator arms  73 , wherein one pair of oscillator arms  73  are a first oscillator arm  731  and a second oscillator arm  732 , and the other pair of oscillator arms  73  are a third oscillator arm  733  and a fourth oscillator arm  734 . The first oscillator arm  731  and the third oscillator arm  733  belong to the same polarized oscillator arm, and the second oscillator arm  732  and the fourth oscillator arm  734  belong to the same polarized oscillator arm. The first oscillator arm  731 , the second oscillator arm  732 , the third oscillator arm  733 , and the fourth oscillator arm  734  are set around one point in sequence, the first oscillator arm  731  and the second oscillator arm  732  are disposed opposite to each other, and the third oscillator arm  733  and the fourth oscillator arm  734  are disposed opposite to each other. The first oscillator arm  731  and the third oscillator arm  733  are +45-degree polarized oscillator arms, and the second oscillator arm  732  and the fourth oscillator arm  734  are −45-degree polarized oscillator arms; or the first oscillator arm  731  and the third oscillator arm  733  are −45-degree polarized oscillator arms, the second oscillator arm  732  and the fourth oscillator arm  734  are +45-degree polarized oscillator arms; or the first oscillator arm  731  and the third oscillator arm  733  are horizontal polarized oscillator arms, and the second oscillator arm  732  and the fourth oscillator arm  734  are vertically polarized oscillator arms; or the first oscillator arm  731  and the third oscillator arm  733  are vertically polarized oscillator arms, and the second oscillator arm  732  and the fourth oscillator arm  734  are horizontally polarized oscillator arms. 
     In an embodiment, the distance between the antenna oscillator parts  72  of two adjacent radiation units  124  (that is, the distance between the points surrounded by the antenna oscillator parts  72  of the two adjacent radiation units  124 ) is 0.8 times the wavelength of the center frequency of the base station antenna  100 . Therefore, the mutual coupling between the antenna oscillator parts  72  of the two adjacent radiation units  124  can be effectively reduced, and the isolation and upper sidelobe suppression can be improved. 
     In an embodiment, the number of the antenna sub-array  120  is plural, and the distance between two adjacent antenna sub-arrays  120  (that is, the distance between the central axis of the two adjacent antenna sub-arrays  120 ) is 1.5 times the wavelength of the center frequency of the base station antenna  100 . Therefore, the mutual coupling between the antenna sub-arrays  120  can be effectively reduced. In an embodiment, the plurality of antenna sub-arrays  120  are arranged at intervals along the second direction S, and the distance between two adjacent antenna sub-arrays  120  in the second direction S is 1.5 times the wavelength of the center frequency of the base station antenna  100 . 
     In an embodiment, referring to  FIG.  1   , when the base station antenna  100  comprises a plurality of antenna sub-arrays  120 , the plurality of antenna sub-arrays  120  are arranged in parallel. 
     In an embodiment, referring to  FIG.  1   , the base station antenna  100  may further comprise a coaxial connector  130  and a coaxial cable  140 , and the coaxial connector  130  is connected to the feeding board  122  through the coaxial cable  140 . Therefore, the base station antenna  100  can feed power to the multiple radiating units  124  of the antenna sub-array  120  through the coaxial connector  130  and the coaxial cable  140 , and the base station antenna  100  has a stable structure and has the certain advantage in intermodulation. 
     In an embodiment, referring to  FIGS.  1  and  6   , when the radiation unit  124  is a dual-polarized antenna unit, the coaxial connector  130  may comprise a first coaxial connector  130   a  and a second coaxial connector  130   b , the first coaxial connector  130   a  is connected to the feeding plate  122 , the first oscillator arm  731  and the second oscillator arm  732  through the first coaxial cable  140   a , and the second coaxial connector  130   b  is connected to the feeding plate  122 , the third oscillator arm  733  and the fourth oscillator arm  734  through the second coaxial cable  140   b.    
     In an embodiment, each metal baffle  126  further comprises two inner folding pieces  62 , the two inner folding pieces  62  are connected to opposite ends of each metal baffle  126  in the first direction R, and the two inner folding pieces  62  are respectively deflected from the opposite ends of each metal baffle  126  toward the corresponding radiation units  124 , which is beneficial to further improve the convergence of the horizontal beam width of the base station antenna  100 . 
     In a practical example, the base station antenna  100  may further comprise a radome not drawn, and the radome is configured to be assembled with the substrate  110  to protect the antenna sub-array  120 . The material of the radome may comprise, but is not limited to, polycarbonate and acrylonitrile butadiene styrene (ABS). In one example, the radome and the substrate  110  can be assembled by buckling to facilitate subsequent maintenance of the base station antenna  100 . In another example, the radome and the substrate  110  can be assembled by bonding to prevent moisture from entering the inner space of the base station antenna  100 . The actual method of assembling the radome and the substrate  110  can be adjusted according to actual needs. 
     Please refer to  FIG.  1    and  FIGS.  7  to  10   .  FIG.  7    is a simulation diagram of the voltage standing wave ratio of the base station antenna of  FIG.  1   ,  FIG.  8    is a simulation diagram of the isolation of the base station antenna of  FIG.  1   ,  FIG.  9    is a simulation diagram of the horizontal beam width of the base station antenna of  FIG.  1   , and  FIG.  10    is a simulation diagram of the polarization ratio of the base station antenna of  FIG.  1   , wherein the operating frequency range of the base station antenna  100  is from 3.3 GHz to 5 GHz. 
     In  FIG.  7   , the horizontal axis represents the frequency in GHz, and the vertical axis represents the voltage standing wave ratio, the solid line and the dashed line are the voltage standing wave ratio curves of different input ports, respectively. It can be seen from  FIG.  7    that in the frequency range of 3.3 GHz to 5 GHz, the voltage standing wave ratio of the base station antenna  100  is less than 1.4. Therefore, the base station antenna  100  has good voltage standing wave ratio performance and a good radiation characteristic. 
     In  FIG.  8   , the horizontal axis represents the frequency in GHz, and the vertical axis represents the isolation in dB. It can be seen from  FIG.  8    that in the frequency range of 3.3 GHz to 5 GHz, the isolation of the base station antenna  100  is below −25.00 dB, so the base station antenna  100  has good isolation. 
     In  FIG.  9    and  FIG.  10   , the horizontal axis represents the horizontal angle in degree, the vertical axis represents the level value in dB, the curves in  FIG.  9    and  FIG.  10    are the simulation curves of the horizontal beam widths and polarization ratios of the base station antenna  100  at the nine frequency of 3.3 GHz, 3.5125 GHz, 3.725 GHz, 3.9375 GHz, 4.15 GHz, 4.3625 GHz, 4.575 GHz, 4.7875 GHz and 5 GHz. It should be noted that since the results presented by the nine simulation curves in  FIG.  9    and  FIG.  10    are similar, they are not labeled and described. It can be seen from  FIG.  9    and  FIG.  10    that in the frequency range of 3.3 GHz to 5 GHz, the horizontal beam width can converge within the range from 62 degrees to 64 degrees, the axial cross polarization ratio is less than −18 dB, and the cross polarization ratio in the ±60-degree directions is less than −10 dB. Therefore, the base station antenna  100  can achieve the technical effects of converging the horizontal beam width, improving the cross polarization ratio, and improving the overall radiation performance. 
     In summary, in the embodiment of the present disclosure, by disposing two metal baffles each having the opening slot on two sides of the feeding plate provided with multiple radiation units along the first direction, respectively, and the length of each opening slot along the first direction corresponds to the wavelength of the center frequency of the base station antenna, the base station antenna can achieve the technical effects of converging the horizontal beam width and optimizing the cross polarization ratio. In addition, the radiation unit is composed of a printed circuit board, which can be widely used in various antennas to reduce costs and effectively improve intermodulation. Furthermore, through the design of the curved balun wiring, the profile height of the base station antenna is effectively reduced. Moreover, the isolation of the base station antenna is optimized through the arrangement of the isolation component and/or the isolation columns. Therefore, the base station antenna can meet the demand for 5G low-profile base station antennas in the current market. 
     Although the present disclosure has been explained in relation to its preferred embodiment, it does not intend to limit the present disclosure. It will be apparent to those skilled in the art having regard to this present disclosure that other modifications of the exemplary embodiments beyond those embodiments specifically described here may be made without departing from the spirit of the disclosure. Accordingly, such modifications are considered within the scope of the disclosure as limited solely by the appended claims.