Patent Publication Number: US-2023155284-A1

Title: Wide scanning patch antenna array

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation application, claiming priority under §365(c), of an International Application No. PCT/KR2022/017722, filed on Nov. 11, 2022, which is based on and claims the benefit of a Russian Pat. Application No. 2021132942, filed on Nov. 12, 2021, in the Russian Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The disclosure relates to radio engineering. More particularly, the disclosure relates to a wide scanning patch antenna array. 
     Background 
     The constantly rising needs of users have motivated the rapid development of communication technologies. Currently, there is an active development of promising fifth generation (5G) and sixth generation (6G) communication networks, which will be characterized by higher performance indicators, such as high transmission speed and energy efficiency. 
     New applications require the introduction of a new class of radio systems capable of transmitting/receiving data/energy and having the ability to adaptively change the characteristics of the radiated electromagnetic field. An important component of such systems are controllable antenna arrays, which find their application in data transmission systems such as 5G (28 GHz), WiGig (60 GHz), Beyond 5G (60 GHz), 6G (subTHz), long-distance wireless power transmission (LWPT) (24 GHz) systems, automotive radar systems (24 GHz, 79 GHz), etc. 
     Millimeter-wave antenna arrays used in these fields shall meet several basic requirements, such as low losses and high gain, beam scanning in a wide range of angles, wide operating frequency range, and compact, cheap, repeatable hardware design applicable for mass production. 
     Nowadays, for production of millimeter-wave radiators, the technology of printed circuit boards (PCB) is widely used, since this technology makes it possible to obtain devices characterized by simplicity of design and manufacturability, ease of implementation in a single board with other electronic units, the ability to achieve a wide bandwidth of operating frequencies. 
     A patch antenna array is an array of patch antenna elements. 
     The existing millimeter-wave antenna technologies have a number of limitations that significantly affect their applicability, such as, small distance between antenna element feeding ports, surface wave propagation in antennas’ PCBs, significant gain degradation at great scan angles, the need to adapt to antenna-in-package (AiP) technology, and extremely stringent requirements for manufacturing accuracy, etc. 
     When used in communication systems, the requirements for antenna arrays as part of base stations are providing full all-round (360 deg) beam scanning at azimuth and operation with double polarization. The full beam scanning is realized by means of combining a few antenna arrays with the finite scanning sector. Obviously, the number of arrays required for a base station is defined by the scanning scope of the individual arrays used. So, if antenna array scanning bound is restricted by ±45 degrees, which is typical for antenna arrays currently used in base stations, then 4 arrays are demanded to provide full all-round (360 deg) beam scanning. When the scanning bound is extended to ±60 degrees, only 3 arrays are required for the array. Thus, an increase in the scanning bound of an antenna array can lead to a decrease in the demanded number of antenna arrays to provide a given signal coverage and, accordingly, reduce the complexity of antenna system as a whole. 
     Antenna arrays have a number of fundamental limitations for their scanning capabilities. The scanning range θ max  is determined by the space between the antenna elements d and the appearance of a diffraction lobe at the upper operating frequency ƒ of the device range:  
     
       
         
           
             f 
             = 
             
               
                 
                   c 
                   0 
                 
               
               
                 d 
                 ⋅ 
                 
                   
                     1 
                     + 
                     sin 
                     
                       θ 
                       
                         m 
                         a 
                         x 
                       
                     
                   
                 
                 , 
               
             
           
         
       
     
      where c 0  is the speed of light. However, within this scanning range, there may be angles at which a blinding effect occurs at the antenna array, consisting in sharp gain degradation while scanning. This effect is associated with the propagation of parasitic surface waves between the array elements in the PCB substrate and their addition at the points where the feeding elements are located, which leads to a mismatch of the antenna elements or, in the case of dual-polarized arrays, power flow to the 2 nd  polarization ports. The array blinding can occur at intermediate scanning angles, and can appear at angles close to θ max . 
     Dual-polarized antenna elements have an asymmetric structure, which can exacerbate these effects. At the design stage of antenna arrays, this also appears in the asymmetric radiation pattern of an individual antenna element in the entire array and the resulting asymmetry in the scanning characteristics. 
     The asymmetric structure of an element of a dual-polarized antenna array with feeding lines (ports) leads to the appearance of parasitic surface waves (PSW), and PSW propagation has a certain direction. Surface waves are summed in phase at the location of the second port. The result is a leakage of power to the second port. As a result, there is a significant gain degradation of the array element at a certain angle of radiation relative to the normal and a decrease in the operating frequency range. 
     This is illustrated as follows. 
     For an antenna array with radiation symmetry, the following equation should be true: 
     
       
         
           
             
               P 
               
                 radiation 
               
             
             
               θ 
             
             = 
             
               P 
               
                 radiation 
               
             
             
               
                 − 
                 θ 
               
             
           
         
       
     
      where P radiation (θ) is the radiation power of the antenna element at the scanning angle θ. 
     It is worth considering that 
     
       
         
           
             
               P 
               
                 radiation 
               
             
             = 
             
               P 
               
                 in 
               
             
             − 
             
               P 
               
                 reflection 
               
             
             − 
             
               P 
               
                 leakage 
               
             
             − 
             
               P 
               
                 loss 
               
             
           
         
       
     
      where P in  is the antenna element’s input power, P reflection  is reflected power at the input port, P leakage  is the leakage power (to the second port), P loss  is the power of loss in the dielectric of the PCB, conductors, etc. 
     Equation 1 is satisfied under the following conditions: 
     
       
         
           
             
               P 
               
                 reflection 
               
             
             
               θ 
             
             = 
             
               P 
               
                 reflection 
               
             
             
               
                 − 
                 θ 
               
             
             , 
           
         
       
     
     
       
         
           
             
               P 
               
                 leakage 
               
             
             → 
             0 
               
             or 
               
             
               P 
               
                 leakage 
               
             
             
               θ 
             
             = 
             
               P 
               
                 leakage 
               
             
             
               
                 − 
                 θ 
               
             
             , 
           
         
       
     
     
       
         
           
             
               P 
               
                 loss 
               
             
             → 
             0. 
           
         
       
     
     The asymmetry of the antenna array radiation (P radiation (θ)≠P radiation (-θ)), described above, is most often caused by the asymmetry of the leakage power (P leakage (θ)≠P leakage (-θ)). This occurs at high values of the coupling coefficient between ports. Thus, to ensure symmetry, measures shall be taken to reduce the leakage power (P leakage (θ)→0 and P leakage (-θ)→0). In this case, P radiation (θ)-P radiation (-θ) is possible. 
     A solution is known from the related art as described in the article “Design of a Dual-Polarized Stacked Patch Antenna for Wide-Angle Scanning Reflectarrays” by T. Chaloun, V. Ziegler and W. Menzel (IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 64, NO. 8, August 2016). This article describes a dual-polarized stacked patch antenna element for wide-angle scanning at Ka-band. The proposed highly integrated multilayer element operates from 27.8 GHz to 30.8 GHz with excellent scan performance up to ± 60 ° in both E- and H-plane. This solution demonstrates high isolation between polarizations in the entire scanning range. However, the configuration described therein requires galvanic connection of the metal grid with the patch PCB layers. 
     The article “Surface waves minimization in Microstrip Patch Antenna using EBG substrate” (published in “2015 International Conference on Signal Processing and Communication (ICSC)”) describes an antenna array with Electromagnetic Band Gap (EBG) (structure that forms an area with inhibited propagation of electromagnetic waves of a certain frequency range) surface with a resonant frequency lying in the band gap of the EBG substrate. An EBG element represents a small patch with shorting VIA (Plated Via) in the center. Two adjacent elements form a resonator, and their combination suppresses parasitic surface waves. However, additional space between elements is required for disposing of the EBG structure, while this space is restricted by maximum acceptable distance between elements. In addition, this solution operates only with one polarization. 
     The article “Meta-Surface Wall Suppression of Mutual Coupling between Microstrip Patch Antenna Arrays for THz-Band Applications” (PROGRESS IN ELECTROMAGNETICS RESEARCH LETTERS, VOL. 75, 105-111, 2018) describes an antenna array with a two dimensional (2D) meta-surface wall to increase the isolation between patch radiators. The meta-surface unit cell comprises conjoint “Y-shaped” microstrip structures which are interleaved together to create a meta-surface wall. This wall is inserted between the patches to reduce mutual coupling. Herewith the matching of antenna and radiation patterns are improved. However, additional space between the antenna array elements is required for placing the meta-surface elements. In addition, this solution operates only with one polarization. 
     The related art also describes a solution in the article “On the Merit of Asymmetric Phased Array Elements” (IEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 61, NO. 7, July 2013). This solution sets forth an antenna array with non-symmetrical patches. The patch design is obtained by numerical optimization using a genetic algorithm. The elements have with spoiled symmetry have better scan and/or bandwidth performance. However, for realization of optimal non-symmetrical structure the additional space is required. In addition, this solution operates only with one polarization. 
     Patent document US 6,211,824 B1 describes an antenna array that uses multiple patch elements to control the direction of an antenna beam over a large scan volume. The antenna contains a first combined substrate, a plurality of first patch radiators arranged on a surface of the first substrate, and a plurality of second patch radiators arranged on a surface of the second substrate. The first substrate is formed from regions with alternated dielectric constant to effectively prevent surface wave propagation, thereby increasing the scan volume of the antenna. However, this solution is characterized by a very complicate technology producing because of existence of multiplex alternated regions with different permittivity and cannot be used to transmit signals in mm and sub mm bands. In addition, this solution operates only with one polarization. 
     In the article “A technique of scan blindness elimination for planar phased array antenna using miniaturized EBG” by M.S.M. Isa et. al. (Jurnal Teknologi, vol. 69, pp. 11-15, March 2014) describes a 5x3 antenna array. In this array, to increase the scanning range, a miniaturized capacitive loaded EBG structure has been inserted between the antenna elements. However, additional space between the elements is required for disposing of the EBG structure. In addition, this solution operates only with one polarization. 
     Thus, there is a need in the art for a simple and cheap wide beam scanning antenna structure operating over a wide frequency range, having low loss, compact size, and high gain. 
     The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure. 
     SUMMARY 
     Aspects of the disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide an antenna with a simple configuration, low loss, compact size, high gain, capable of focusing/scanning a beam in a wide range of scanning angles, operating in a wide frequency range. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     In accordance with an aspect of the disclosure, an antenna array is provided. The antenna array includes a plurality of antenna array elements. Each antenna array element of the plurality of antenna array elements includes a main printed circuit board (PCB) over which a middle layer and an additional PCB are arranged. A first patch element is disposed at the main PCB, and a second patch element is disposed at the additional PCB. The antenna array element further includes a cavity in the middle layer to reduce coupling between the antenna array element and at least another antenna array element of the plurality of antenna array elements. The cavity in the middle layer includes a hole that supports coupling between the first patch element and the second patch element. The main PCB, the middle layer and the additional PCB are interconnected by means of a no galvanic connection. 
     According to another embodiment, the antenna array element further includes at least one of a cavity in the main PCB or a cavity in the additional PCB, wherein the cavity in the main PCB is defined by a plurality of first plated through holes (VIAs) surrounding the first patch element, and the cavity in the additional PCB is defined by a plurality of second plated VIAs surrounding the second patch element, and wherein the cavity in the middle layer, together with at least one of the cavity in the additional PCB or the cavity in the main PCB, form a complex cavity to reduce the coupling between the antenna array element and at least the other antenna array element of the plurality of antenna array elements. 
     According to another embodiment, the first plated VIAs defining the cavity in the main PCB, and the second plated VIAs defining the cavity in the additional PCB, are spaced apart, wherein a distance between edges of the first plated VIAs, and a distance between edges of the second plated VIAs, is less than λ diel  /2 , where λ diel  is an operating wavelength. 
     In another embodiment, the cavity in the middle layer, together with at least one of the cavity in the additional PCB or the cavity in the main PCB, which form the complex cavity are of a same shape. 
     In another embodiment, the first patch element and at least one feeding port in the main PCB are rotated relative to peripheral sides of the antenna array element by 45 degrees around normal to a plane of the antenna array element. 
     In another embodiment, the second patch element is positioned in a same position as the first patch element. 
     In another embodiment, the first patch element and the second patch element both have a shape that is symmetrical relative to polarization planes. 
     In another embodiment, the middle layer is formed of metal in which the hole is formed therethrough and walls of the hole at least partly define the cavity in the middle layer. 
     According to another embodiment, the middle layer is a PCB in which the hole is surrounded by a plurality of VIAs at least partly defining the cavity in the middle layer. 
     In another embodiment, the hole is formed through the middle layer. 
     According to another embodiment, the main PCB and the PCB of the middle layer are a single PCB, and the hole of the middle layer is formed at a certain depth in the single PCB. 
     According to another embodiment, the additional PCB and the PCB of the middle layer are a single PCB, and the hole of the middle layer is formed at a certain depth in the single PCB. 
     According to another embodiment, at least one of a gap between the main PCB and the middle layer, or a gap between the middle layer and the additional PCB, are filled with a dielectric layer or are an air gap, a height of each gap being no more than 50 µm. 
     In another embodiment, the antenna array is a dual polarized antenna array. 
     In another embodiment, the antenna array is a single polarized antenna array. 
     In another embodiment, the hole of the middle layer is an air hole. 
     In another embodiment, the first patch element is electrically connected to at least one feeding port, and the second patch element is electromagnetically coupled to the first patch element. 
     The disclosure provides an antenna with a simple configuration, low loss, compact size, high gain, capable of focusing/scanning a beam in a wide range of scanning angles, operating in a wide frequency range. 
     Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    shows a general view of a quarter-cut antenna array element according to an embodiment of the disclosure; 
         FIG.  2    is a top view of one element of an antenna array according to an embodiment of the disclosure; and 
         FIG.  3    is a top view of an antenna array and one antenna array element with indication of scanning planes according to an embodiment of the disclosure. 
     
    
    
     Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
     In accordance with an embodiment, the disclosure describes is an antenna array, wherein each element of the antenna array comprises a main printed circuit board (PCB), an additional PCB and a middle layer placed between them. The antenna array element may have a square shape. 
       FIG.  1    shows a general view of a quarter-cut antenna array element according to an embodiment of the disclosure. 
     Referring to  FIG.  1   , antenna array element  100  may include layers that are arranged from bottom to top in the following order: main PCB  102 , middle layer  104 , additional PCB  106 . The antenna array element  100  may include patch elements  110  including patch element  112  and patch element  116 . Patch element  112  may be located on the top surface of the main PCB  102 . Likewise, patch element  116  may be located on the top surface of the additional PCB  106 . The patch element  112  of the main PCB  102  and the patch element  116  of the additional PCB  106  may have a square shape. The patch element  112  of the main PCB  102  may be fed by feeding ports  120 . The antenna array element  100  may include plated-through holes (VIAs)  130  including first plated VIAs  132  and second plated VIAs  136 . The patch element  112  of the main PCB  102  may be surrounded by first plated VIAs  132  located at a distance from each other, wherein the distance between the edges of the first plated VIAs  132  shall be less than λ diel  /2 , where λ diel  is the operating wavelength in the main PCB  102 . Similarly, the patch element  116  of the additional PCB  106  may be surrounded by second plated VIAs  136  located at a distance from each other, wherein the distance between the edges of the second plated VIAs  136  shall be less than λ diel  /2 , where λ diel  is the operating wavelength in the additional PCB  106 . 
       FIG.  2    is a top view of one element of an antenna array according to an embodiment of the disclosure. 
     Referring to  FIG.  2   , VIAs  130  of an antenna array element  100  may form reflective “walls”  200  that define a cavity in the given PCB and may prevent propagation of surface waves in the antenna array element  100 . The antenna array element  100  may include a complex cavity consisting of cavities in the main PCB  102  and the additional PCB  106 , as well as cavities in the middle layer located between the main PCB  102  and the additional PCB  106 . The interior of the cavity surrounded by the first plated VIAs  132  in the main PCB  102  and the second plated VIAs  136  in the additional PCB  106  may be filled with a PCB dielectric. The main PCB  102 , the middle layer  104 , and the additional PCB  106  may be interconnected by no galvanic connection. 
     Thus, the patch element  112  of the main PCB  102  and the patch element  116  of the additional PCB patch, in an embodiment, may be located above a cavity in the corresponding PCB, wherein the cavities are defined by reflective “walls”  200  formed by a plurality of plated VIAs  130  (i.e., first plated VIAs  132  and second plated  136 ). 
     In an embodiment, the shape of the cavity in the middle layer  104  may be substantially identical to the shape of the cavities in the main PCB  102  and the additional PCB  106 . However, in alternative embodiments, the dimensions of the cavities in in or more of the main PCB  102 , the middle layer  104 , or the additional PCB  106  may be different from each other. 
     In the embodiment described above, the patch elements  110  are in the shape of a square, although such patch elements  110  can have any shape with symmetry about the polarization planes. For example, in the case of dual polarization, the patch elements  110  may be symmetrical relative to both planes. 
     Next, referring to  FIGS.  1  through  3   , an embodiment of the disclosure will be described in more detail. 
       FIG.  3    is a top view of an antenna array and one antenna array element with indication of scanning planes according to an embodiment of the disclosure, 
     The patch element  112  of the main PCB  102  may be excited by at least one feeding port  120 , which may set the polarization of a radiated signal. In the case of a single polarized antenna array  300 , the patch element  112  is excited by one feeding port  120 , and in the case of a dual polarized antenna array  300 , by two feeding ports  120 , wherein the polarizations excited by each of the feeding ports  120  are perpendicular. 
     In general, due to the wider H-plane radiation pattern, the antenna array  300  has a wider H-plane scan range (&lt;55°) than the E-plane scan range (&lt;45°). As a consequence, a double polarization antenna array  300  has different scanning characteristics in the E- and H-planes. 
     Referring to  FIG.  3   , in the disclosure, the antenna array element  100  and feeding port(s)  120  may be rotated with respect to the sides of the antenna array  300  elements by 45 degrees around the normal to the plane of the antenna array element  100 . As a result, scanning of the antenna array  300  may be performed in the D-plane of the antenna array element  100 , in which the shape of the radiation pattern of the antenna array element  100  is essentially the same for both polarizations as an intermediate section of the element pattern. 
     The antenna array element  100  may have, as a rule, different radiation patterns in the E- and H-planes, i.e., rotation-free positioning of the element will give different radiation patterns for each of the feeding ports  120 . In the D-plane, the directional patterns of different feeding ports  120 , for the mentioned case, are mirror-symmetric (D1(ϑ)=D2(-ϑ)) and are close to symmetric in the case of low power leakage between the feeding ports  120  over the entire scanning range. As a consequence, when developing an antenna array element  100  and an antenna array  300 , it may be sufficient to optimize its geometry in one plane (in the second plane, the simulation results, due to the symmetry of the radiation characteristics in the D-plane, will be the same). This also simplifies the array control as it will be possible to apply the same phase distribution to the antenna array elements  100  for scanning in both polarizations. 
     The patch element  116  of the additional PCB  106  may be positioned similarly to the patch element  112  of the main PCB  102  and is excited by an electromagnetic radiation (signal) from the patch element  112  of the of the main PCB  102 . 
     The corners of the square patch elements  110  may be rounded to make it compact. 
     In general, the cavity in the middle layer  104  includes an air hole supporting the coupling of the patch element  112  in the main PCB  102  with the patch element  116  in the additional PCB  106 . The middle layer  104  between the main PCB  102  and the additional PCB  106  in an embodiment may be a metal layer. In such a metallic middle layer  104 , the cavity is formed as a through hole, i.e. the walls of the hole form the walls of the cavity in the middle layer  104 . The hole may be filled with air. 
     One of the reasons for the asymmetry of radiation of the antenna array  300  is the leakage of the radiated power due to propagation of surface waves in the substrates of the main PCB  102  and the additional PCB  106  of the antenna array element  100 . The complex cavity, consisting of the cavities of the main PCB  102  and the additional PCB  106 , as well as the cavity in the metal middle layer  104 , prevents propagation of surface waves, which effectively reduces the coupling between the antenna array elements  100  and reduces the power loss during scanning. The cavity in the metal middle layer  104  may be a through-hole that supports coupling between the patch element  112  in the main PCB  102  and the patch element  116  in the additional PCB  106 . Reducing the coupling between the antenna array elements  100  of the antenna array  300  addresses the problem of array blindness: to reduce the power loss as a result of the mismatch of the antenna array elements  100  of the main operating polarization and the coupling with the second polarization of the antenna array element  100 . In accordance with Equation 1, this makes it possible to provide symmetric scanning characteristics of the antenna array  300  in a wide range of angles. 
     Such a structure for the antenna array  300  provides a symmetric radiation pattern of a single antenna array element  100  in the antenna array  300 , as well as achieving array gain losses of less than 3 dB even in extreme scanning positions in the range of ±60 degrees. 
     It should be noted that the shape of the cavity in the middle layer  104  in the embodiment shown in  FIGS.  1  through  3    is identical to the shape of the cavities in the main PCB  103  and the additional PCB  106 , i.e., a square shape. In alternative embodiments, the cavity in the middle layer  104  may be a rectangular hole, a rectangular hole with rounded corners, a circular hole, etc. 
     The middle layer  104  in an embodiment is in the form of a metal layer. Alternatively, the middle layer can be based on a PCB (or part of another PCB). In such a case, the hole in the middle layer  104  is surrounded by a plurality of plated VIAs  130  (not shown) forming the “walls”  200  that define the cavity in the middle layer  104 . 
     The walls  200  of the complex cavity or portions of the complex cavity in various embodiments may be parallel to the edges of the patch element  112  in the main PCB  102  and the patch element  116  in the additional PCB  106 , or may be parallel to the walls  200  of the antenna array element  100 . 
     An embodiment is possible in which the antenna array element  100  includes a cavity in the middle layer  104 , while there is no cavity in the main PCB  102  and/or additional PCB  106 . Otherwise, the structure of the antenna array element  100  in this embodiment may be the same as the embodiment described above. This embodiment has a simpler design and is effective for suppressing surface waves. That is, in such an embodiment, the cavity of the middle layer  104  significantly reduces propagation of surface waves in the antenna array  300 . At the same time, for certain parameters (e.g., thickness and dielectric constant) of the dielectric of the main PCB  102  and the additional PCB  106 , cavities in the main PCB  103  and/or the additional PCB  106  can significantly improve the characteristics of the antenna array  300 . 
     The main PCB  102 , the middle layer  104 , and the additional PCB  106  do not require a galvanic connection to transmit a signal. The mentioned parts of the antenna array element  100  can simply be fixed relative to each other with gaps between them. Said gaps can be formed naturally as a result of imperfect surfaces of the antenna array element 100 parts, or they can be specially designed to provide a fixed distance between the antenna array element  100  parts. The gaps can be filled with a dielectric (e.g., Teflon film) or can be an air gap provided by spacers. The height of the gap between said layers should not exceed 50 µm. In this case, the gap does not adversely affect the characteristics of the antenna array  300 . 
     Connection of said layers without the need to provide a galvanic connection greatly facilitates the assembly of the antenna array element  100 , and by extension, the antenna array  300 . 
     Providing the middle layer  104  and the additional PCB  106  to the main PCB  102  of the antenna array element  100  improves the scanning performance of the antenna array  300  and expands the operating bandwidth. 
     The following describes the operation of an antenna array  300  in accordance with an embodiment of the disclosure. 
     A high-frequency signal from the generator is fed to the operating polarization port of the antenna array element  100 . The input signal is characterized by amplitude and phase. In the general case, the amplitude of the signals at all antenna array elements  100  of the antenna array  300  should be the same. The phase of the signal determines the position of the antenna beam in space. 
     The signal is fed through the feeding ports  120  to the patch element  112  located on the main PCB  102 . The size and shape of the patch element  112  are resonant to the applied frequency signal. The patch element  112  on the main PCB  102  is electromagnetically coupled to the patch element  116  located on the additional PCB  106 . The patch element  112  on the main PCB  102  may not be electrically connected to the patch element  116  located on the additional PCB  106 . The additional PCB  106  is located at some distance from the main PCB  102 . This distance is fixed using a middle layer, which may be metal, located between the main PCB  102  and the additional PCB  106 , with an air hole made in it, which supports coupling of the patch element  112  of the main PCB  102  and the patch element  116  of the additional PCB  106 . The size and shape of the patch element  116  of the additional PCB  106  is resonant to the applied frequency signal. 
     The electromagnetic field, excited by each composite antenna array element  100  of the antenna array  300 , is added in the far zone of the array, as a result of which, with a certain phase distribution of the signals supplied to the antenna array elements  100 , the radiation of the antenna array  300  becomes directional and the formation of the antenna beam occurs. By controlling the phase of the supplied signal, the position of the beam in space is controlled and antenna scanning is carried out. The previously described cavities around each of the patch elements  110  help to reduce coupling between adjacent antenna array elements  100  of the antenna array  300 , which in turn improves the scanning capabilities. 
     Due to the weak coupling (&lt;-10 dB) between the polarizations of the antenna array element  100 , a signal from the generator can be applied to the feeding ports  120  of both polarizations of the antenna array element  100  both alternately and simultaneously. 
     In an alternative embodiment, the main PCB  102  and the middle layer  104  can be formed as a single PCB connected to the additional PCB  106  via (or without) an air gap. In this case, the cavity of the middle layer  104  includes a hole at a certain depth. Likewise, the additional PCB  106  and the middle layer  104  can be formed as a single PCB connected to the main PCB  102  via (or without) an air gap. Such an embodiment reduces the complexity of manufacturing the antenna array  300 . 
     Thus, the disclosure makes it possible to expand the scanning range of the antenna array  300 , increase its efficiency and reduce losses. The antenna array  300  according to the disclosure has a compact size and a simple and inexpensive configuration suitable for mass production. 
     The antenna array  300  of the disclosure is designed for use in the millimeter wavelength range. However, this configuration can be used in the design of antenna arrays  300  and other ranges, for example, centimeter, submillimeter (terahertz frequency range), etc. 
     The compact and highly efficient systems employing steerable antenna array  300  in accordance with the disclosure can find application in wireless communication systems of the promising 5G, 6G and WiGig standards. Moreover, the disclosure can be used both in base stations and in antennas of mobile terminals. The user terminal antennas are steered to point to the base station antenna position. 
     The disclosure can find application in all types of systems (e.g., long-distance wireless power transmission (LWPT) systems): outdoor/indoor, automotive, mobile, etc. This ensures high efficiency of power transmission in all scenarios. The power transmission device can be built on the basis of the described structure of the antenna array  300  and thus can implement beam focusing when charging devices in the near field or scanning the beam for transmitting power to devices located in the far zone of the transmitter antenna. 
     When used in robotics, the proposed antenna can be used to detect/avoid obstacles. 
     The disclosure can also be used in autonomous vehicle radars. 
     It should be understood that although terms such as “first”, “second”, “third” and the like may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, areas, layers and/or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, the first element, component, region, layer or section may be called a second element, component, region, layer or section without departing from the scope of the disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the respective listed positions. Elements mentioned in the singular do not exclude the plurality of elements, unless otherwise specified. 
     The functionality of an element specified in the description or claims as a single element can be implemented in practice by several components of the device, and vice versa, the functionality of elements specified in the description or in the claims as several separate elements can be implemented in practice by a single component. 
     The embodiments of the disclosure are not limited to the embodiments described herein. Basing on the information set forth in the description and knowledge of the prior art, those skilled in the art will appreciate other embodiments of the disclosure which are not apart from the essence and scope of this disclosure. 
     Elements mentioned in the singular do not exclude the plurality of elements, unless otherwise specified. 
     A person skilled in the art should understand that the essence of the disclosure is not limited to a specific software or hardware implementation, and therefore any software and hardware known in the prior art can be used to implement the disclosure. So hardware can be implemented in one or more specialized integrated circuits, digital signal processors, digital signal processing devices, programmable logic devices, user-programmable gate arrays, processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic modules capable of performing the functions described in this document, a computer, or a combination of the above. 
     The features mentioned in various dependent claims, as well as the embodiments disclosed in various parts of the description, can be combined to achieve advantageous effects, even if the possibility of such combination is not explicitly disclosed. 
     While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.