Patent Publication Number: US-11641063-B2

Title: Beamforming antenna module comprising lens

Description:
TECHNICAL FIELD 
     The present disclosure relates to a beamforming antenna structure including a lens to ensure high gain and coverage in a 5G communication system. 
     BACKGROUND ART 
     To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
     The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications. 
     In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     In the above-mentioned multi-input multi-output (MIMO) communication environment, a single antenna may include a plurality of antenna arrays, and a lens for improving the gain and coverage of radio waves may be attached to each antenna array. 
     The lens is a device that improves the performance of the antenna array by changing the phase of radio waves radiated through the antenna array, so that the structure of the lens may be determined generally based on the antenna or antenna array combined with the lens. 
     Solution to Problem 
     An antenna module according to the disclosure may include an antenna including at least one antenna array disposed therein, and a lens. The antenna may include a first antenna array that radiates a radio wave deflected at a predetermined first angle from a vertical plane of the antenna. The lens may be spaced apart from the antenna by a predetermined first distance and may change a phase of the radio wave radiated from the antenna. 
     The first angle may be determined based on the first distance or a width of the first antenna array. 
     The antenna may further include a second antenna array spaced apart from the first antenna array by a predetermined second distance, and the second antenna array may radiate a radio wave deflected at the first angle from the vertical plane of the antenna. 
     The antenna module of claim  3 , wherein the first angle may be determined based on the first distance, a width of the first antenna array, or the second distance. 
     The lens may be a planar lens and formed integrally to cover an upper surface of the antenna. 
     A central axis of a radio wave phase of the antenna may be determined based on a central axis of the first antenna array and a central axis of the second antenna array, and a central axis of the lens may coincide with the central axis of the radio wave phase of the antenna. 
     A central axis of radio wave intensity of the first antenna array and a central axis of radio wave intensity of the second antenna array may be deflected by the first angle from the vertical plane of the antenna. 
     In a base station including an antenna module according to the disclosure, the antenna module may include an antenna including at least one antenna array disposed therein, and a lens. The antenna may include a first antenna array that radiates a radio wave deflected at a predetermined first angle from a vertical plane of the antenna. 
     The lens may be spaced apart from the antenna by a predetermined first distance and may change a phase of the radio wave radiated from the antenna. 
     The first angle may be determined based on the first distance or a width of the first antenna array. 
     The antenna may further include a second antenna array spaced apart from the first antenna array by a predetermined second distance, and the second antenna array may radiate a radio wave deflected at the first angle from the vertical plane of the antenna. 
     The first angle may be determined based on the first distance, a width of the first antenna array, or the second distance. 
     The lens may be a planar lens and formed integrally to cover an upper surface of the antenna. 
     A central axis of a radio wave phase of the antenna may be determined based on a central axis of the first antenna array and a central axis of the second antenna array, and a central axis of the lens may coincide with the central axis of the radio wave phase of the antenna. 
     A central axis of radio wave intensity of the first antenna array and a central axis of radio wave intensity of the second antenna array may be deflected by the first angle from the vertical plane of the antenna. 
     Advantageous Effects of Invention 
     According to an embodiment of the disclosure, a phase distribution center of the antenna can coincide with a phase distribution center of the lens, so that it is possible to prevent a beam radiated through the antenna from being distorted even though a plurality of antenna arrays are disposed in one antenna. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a diagram illustrating a mobile communication system that supports beamforming 
         FIG.  2    is a diagram illustrating a structure of an antenna module including a lens. 
         FIG.  3 A  is a diagram illustrating a structure of an antenna module when one antenna array is disposed in an antenna. 
         FIG.  3 B  is a diagram illustrating an intensity distribution of a beam radiated through a lens when one antenna array is disposed in an antenna. 
         FIG.  3 C  is a diagram illustrating a phase distribution of a beam radiated through a lens when one antenna array is disposed in an antenna. 
         FIG.  4    is a diagram illustrating a configuration of an antenna module when a plurality of antenna arrays are disposed in an antenna according to an embodiment of the disclosure. 
         FIG.  5 A  is a diagram illustrating a structure of an antenna module when a plurality of antenna arrays are disposed in an antenna. 
         FIG.  5 B  is a diagram illustrating a phase distribution of a beam radiated through a lens when a plurality of antenna arrays are disposed in an antenna. 
         FIG.  5 C  is a diagram illustrating an intensity distribution of a beam radiated through a lens when a plurality of antenna arrays are disposed in an antenna. 
         FIG.  6    is a graph showing a phase difference between a beam radiated from an antenna and a beam radiated through a lens when a plurality of antenna arrays are disposed in the antenna. 
         FIG.  7    is a view showing a case in which a plurality of antenna arrays are disposed in an antenna and each antenna array deflects and radiates a beam by a predetermined angle. 
     
    
    
     MODE FOR THE INVENTION 
     In the following description of embodiments, descriptions of techniques that are well known in the art and not directly related to the present invention are omitted. This is to clearly convey the subject matter of the disclosure by omitting any unnecessary explanation. 
     For the same reason, some elements in the drawings are exaggerated, omitted, or schematically illustrated. Also, the size of each element does not entirely reflect the actual size. In the drawings, the same or corresponding elements are denoted by the same reference numerals. 
     The advantages and features of the disclosure and the manner of achieving them will become apparent with reference to embodiments described in detail below and with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art. To fully disclose the scope of the disclosure to those skilled in the art, the disclosure is only defined by the scope of claims. In the disclosure, similar reference numbers are used to indicate similar constituent elements. 
     It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which are executed via the processor of the computer or other programmable data processing apparatus, generate means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer usable or computer-readable memory that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. 
     In addition, each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. 
     The term “unit”, as used herein, refers to a software or hardware component or device, such as a field programmable gate array (FPGA) or application specific integrated circuit (ASIC), which performs certain tasks. A unit may be configured to reside on an addressable storage medium and configured to execute on one or more processors. Thus, a module or unit may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functionality provided for in the components and units may be combined into fewer components and units or further separated into additional components and modules. In addition, the components and units may be implemented to operate one or more central processing units (CPUs) in a device or a secure multimedia card. Also, in embodiments, the unit may include one or more processors. 
       FIG.  1    is a diagram illustrating a mobile communication system that supports beamforming. 
     Shown is communication between each of a plurality of base stations  111  and  112  and a communication device  120  including an antenna module according to the disclosure. As described above, the 5G mobile communication may have a wide frequency bandwidth. 
     On the other hand, the gain and coverage of radio waves transmitted from the base stations  111  and  112  or the communication device  120  may become poor. Therefore, in order to solve this problem, the 5G mobile communication system basically uses a beamforming technique. 
     That is, the base stations  111  and  112  or the communication device  120  including an antenna module supporting the 5G mobile communication system may form beams at various angles, and perform communication using a beam having the best communication environment from among the formed beams. 
     Referring to  FIG.  1    as an example, the communication device  120  may form three kinds of beams radiated at different angles, and correspondingly the base station may also form three kinds of beams radiated at different angles. For example, the communication device  120  may radiate three kinds of beams having beam indexes  1 ,  2 , and  3 , the first base station  111  may radiate three kinds of beams having beam indexes  4 ,  5 , and  6 , and the second base station  112  may radiate three kinds of beams having beam indexes  7 ,  8 , and  9 . 
     In this case, through communication between the communication device  120  and the first and second base stations  111  and  112 , the communication device and the first base station may perform communication through beams having the best communication environment, e.g., a beam having a beam index  2  of the communication device  120  and a beam having a beam index  5  of the first base station  111 . In the same manner, the communication device  120  and the second base station  112  may perform communication. 
     Meanwhile,  FIG.  1    shows only one example in which the 5G communication system can be applied. That is, the number of beams that can be radiated by the communication device or the base station may be increased or decreased, so that the scope of the disclosure should not be limited to the number of beams shown in  FIG.  1   . 
     The communication device  120  shown in  FIG.  1    includes various kinds of devices capable of performing communication with the base station. For example, such devices may include customer premises equipment (CPE) or a wireless repeater. 
       FIG.  2    is a diagram illustrating a structure of an antenna module including a lens. 
     The antenna module according to the disclosure may include an antenna  200  including at least one antenna array and a lens  210 . That is, the antenna  200  according to the disclosure may include a plurality of antenna arrays. For example, one antenna  200  may include four antenna arrays, and an angle of a beam radiated through the antenna  200  may be determined finally by adjusting an angle of a beam radiated through each of the antenna arrays. 
     The beam radiated through the antenna  200  may pass through the lens  210  spaced apart from the antenna  200  by a predetermined distance. The lens  210  may change a phase of a beam (or radio wave) incident on the lens. 
     Specifically, the lens  210  may change phase values of beams incident on the lens  210  to the same phase value through a pattern formed on the lens, and then radiate them to the outside of the lens  210 . 
     Therefore, the beam radiated to the outside through the lens  210  has a sharper shape than that of the beam radiated through the antenna  200 . That is, using the lens  210  can improve the gain value of the beam radiated through the antenna  200 . A more detailed description about the gain value improvement and phase change of the beam using the lens  210  will be described below with reference to  FIGS.  3 A to  3 C . 
       FIG.  3 A  is a diagram illustrating a structure of an antenna module when one antenna array is disposed in an antenna. 
     When only one antenna array  200  is disposed in the antenna, radio waves (or a beam) radiated through the antenna array  200  may have a shape as shown in  FIG.  3 A . In addition, the intensity distribution and phase distribution of the radio waves may have a parabolic shape around a central axis of the radio waves as shown in  FIG.  3 A . 
     Meanwhile, the lens  210  spaced apart from the antenna array  200  by a predetermined distance may be disposed such that the central axis of the radio waves and the central axis of the lens coincide with each other. In this case, the phase distribution of the lens  210  may be a parabola having a shape opposite to the phase distribution of the radio waves. (The phase distribution of the lens may be determined through a pattern formed on the lens as described above. A method of forming the lens pattern for determining the phase distribution is out of the scope of the disclosure, so that a detailed description thereof is omitted.) 
     That is, in the structure of the antenna module shown in  FIG.  3 A , the central axis of the lens and the central axis of the radio waves coincide with each other, and also all of the center of the lens phase distribution, the center of the antenna radio wave phase distribution, and the center of the antenna radio wave intensity distribution coincide with each other. 
     In case of the antenna module structure disclosed in  FIG.  3 A , the intensity distribution of the beam radiated through the lens is shown in  FIG.  3 B , and the phase distribution of the beam is shown in  FIG.  3 C . 
     Through  FIGS.  3 B and  3 C , it can be seen that the gain value of the radio wave radiated through the lens is greater as it is closer to the central axis of the lens, and it can be also seen that the phase value of the radio wave is formed such that the central axis of the lens and the central axis of the radio wave coincide with each other. 
     Meanwhile, a single antenna may include a plurality of antenna arrays. Particularly, in the multi-input multi-output (MIMO) communication environment, a need for the antenna including the plurality of antenna arrays increases. 
       FIG.  4    is a diagram illustrating a configuration of an antenna module when a plurality of antenna arrays are disposed in an antenna according to an embodiment of the disclosure. 
     An antenna module  400  according to the disclosure may include an antenna  200  that includes at least one of antenna array  201 ,  202 ,  203 , and  204 . Each antenna array  201 ,  202 ,  203 , and  204  may include a plurality of antenna elements. For example, one antenna array may be composed of 16 antenna elements as shown in  FIG.  4   , and the antenna array may form beams at various angles by controlling the respective antenna elements. 
     In addition, the antenna module  400  may further include various components as necessary. For example, the antenna module  400  may further include a connector  230  for providing power to the antenna module  400 , and a DC/DC converter  210  for converting a voltage provided through the connector  230 . 
     In addition, the antenna module  400  may further include a field programmable gate array (FPGA)  220 . The FPGA  220  is a semiconductor device including a programmable logic device and programmable interconnects. The programmable logic device may be programmed by replicating logic gates such as AND, OR, XOR, and NOT and more complex decoder functions. The FPGA may also include a flip-flop or memory. 
     In addition, the antenna module  400  may include a low dropout (LDO) regulator  240 . The LDO regulator  240  is a regulator that is highly efficient when an output voltage is lower than and very close to an input voltage, and may remove noise of input power. As having low output impedance, the LDO regulator  240  may have a function of stabilizing a circuit by placing a dominant pole in the circuit. 
     Meanwhile,  FIG.  4    merely shows the structure of the antenna module according to an embodiment of the disclosure, so that the scope of the disclosure should not be limited to that. 
     That is,  FIG.  4    shows a case where four antenna arrays constitute one antenna, but the number of antenna arrays included in one antenna may be increased or decreased as necessary. In addition, the aforementioned connector  230 , DC/DC converter  210 , FPGA  220 , or LDO regulator  240  may be added or removed as needed. 
     When a plurality of antenna arrays are included in one antenna as shown in  FIG.  4   , the structure of the antenna module including the antenna and the lens is shown in  FIG.  5 A . Specifically,  FIG.  5 A  shows a case where two antenna arrays  200  and  202  are included in one antenna  500 . 
     The first antenna array  200  and the second antenna array  202  constituting the one antenna  500  are spaced apart from each other by a predetermined distance, and each of the first and second antenna arrays  200  and  202  may radiate radio waves toward the lens  210 . 
     As can be seen from  FIG.  5 A , in the configuration of the antenna module including the first and second antenna arrays  200  and  202 , the central axis of the lens  210  does not coincide with the radio wave central axis of the first antenna array  200  and the radio wave central axis of the second antenna array  202 . 
     This is because the first antenna array  200  and the second antenna array  202  cannot be located to be physically overlapped with each other. Therefore, radio waves radiated through the first and second antenna arrays  200  and  202  do not overlap and, as shown in  FIG.  5 A , are spaced apart from each other. 
     That is, an antenna radio wave angle distribution and an antenna radio wave phase distribution of radio waves radiated through the first antenna array  200  do not coincide with an antenna radio wave angle distribution and an antenna radio wave phase distribution of radio waves radiated through the second antenna array  202 . 
     In addition, the sum of the phase distribution of radio waves radiated through the first antenna array  200  and the phase distribution of radio waves radiated through the second antenna array  202  is not opposite to a phase distribution of the lens. As a result, the performance of the lens (gain value improvement and coverage improvement) may be degraded. (A condition that can maximize the performance of the lens is a case where a parabola formed by the antenna radio wave phase distribution and a parabola formed by the lens phase distribution are opposite to each other as described in  FIG.  3 A .) 
       FIG.  5 B  is a diagram illustrating a phase distribution of a beam radiated through a lens in the antenna module structure shown in  FIG.  5 A , and  FIG.  5 C  is a diagram illustrating an intensity distribution of a beam radiated through a lens in the antenna module structure shown in  FIG.  5 A . 
     As can be seen from  FIGS.  5 B and  5 C , the lens central axis does not coincide with the axis of radio waves radiated from the antenna including the first and second antenna arrays. 
     Accordingly, the intensity of radio waves radiated through the lens is evenly distributed from side to side around the central axis of the lens and the central axis of the antenna radio waves, so that the beam radiated through the lens may not have a sharp shape. (That is, the gain value improved through the lens may decrease.) 
       FIG.  6    is a graph showing a phase difference between a beam radiated from an antenna and a beam radiated through a lens when a plurality of antenna arrays are disposed in the antenna. In addition to the above-mentioned decrease of the radio wave gain value, another problem may be caused in the structure shown in  FIG.  5 A . This can be seen through the graph of  FIG.  6   . 
     Referring to the graph of  FIG.  6   , the phase distribution of the lens (labeled as ‘LENS’ in the graph) and the phase distribution of radio waves radiated from the antenna (labeled as ‘ANTENNA’ in the graph) are different from each other. Specifically, the phase distribution of the lens is formed to have a peak at an incidence angle of zero degree with respect to the central axis of the lens, whereas the phase distribution of radio waves radiated from the antenna is formed to have a peak at an incidence angle of about 12 degrees with respect to the central axis of the lens. 
     As such, in the antenna module structure as shown in  FIG.  5 A , the antenna central axis and the lens central axis may not coincide with each other, so that the antenna module may be difficult to form a beam at an accurate angle. (As mentioned above, the 5G mobile communication system uses the beamforming technology that forms a plurality of beams at predetermined angular intervals. Therefore, incapability of forming the plurality of beams at accurate angles is a serious issue in applying the 5G mobile communication system.) 
       FIG.  7    is a view showing a case in which a plurality of antenna arrays are disposed in an antenna and each antenna array deflects and radiates a beam by a predetermined angle. 
     As described above, the antenna module shown in  FIG.  5 A  has a problem that the phase distribution of radio waves radiated through the antenna does not correspond to the lens phase distribution because the antenna includes a plurality of antenna arrays. 
     Accordingly, this disclosure is intended to control radio wave radiation angles of the first and second antenna arrays  201  and  202  constituting the antenna  500  such that the phase distribution of radio waves radiated through the antenna corresponds to the lens phase distribution. 
     Specifically, as shown in  FIG.  7   , radio waves radiated through the first antenna array  201  and radio waves radiated through the second antenna array  202  are combined to form radio waves radiated through the antenna  500 . A parabola formed by the phase distribution of the radio waves radiated through the antenna  500  is opposite to a parabola formed by the lens phase distribution around the lens  210 . That is, the first and second antenna arrays  201  and  202  may be controlled such that the central axis of the antenna radio wave phase distribution and the central axis of the lens coincide with each other. 
     For example, each of the first and second antenna arrays  201  and  202  may radiate radio waves deflected at a predetermined first angle from a vertical plane of the antenna, and the first angle may be determined based on a distance between the antenna array and the lens, a width of the antenna array, or a distance between the antenna arrays. 
     Specifically, the first angle for deflection may be determined according to the following Equation.
 
θ=tan −1 (( W+p )/(2* D ))  Equation
 
     θ: first angle, W: antenna array width, D: distance between antenna array and lens, p: distance between antenna arrays 
     Meanwhile, although only a case where two antenna arrays are included in one antenna is disclosed, the scope of the disclosure should not be limited thereto. That is, if necessary, the number of antenna arrays included in the antenna may be increased or decreased. 
     In addition, although it is described above that the first and second antenna arrays may radiate radio waves deflected at the same first angle, the first and second antenna arrays may also radiate radio waves deflected at different angles as necessary. (However, even in this case, the central axis of the antenna radio wave phase distribution and the central axis of the lens should coincide with each other.) 
     While the disclosure has been described in detail with reference to specific embodiments, it is to be understood that various changes and modifications may be made without departing from the scope of the disclosure. In addition, the above-described embodiments may be selectively combined with each other if necessary. For example, some of the embodiments proposed in the disclosure may be combined with each other and used by a base station and a terminal.