Patent Publication Number: US-2023140166-A1

Title: Periodic metal array structure

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This non-provisional application claims priority to and the benefit of, under 35 U.S.C. § 119(a), Taiwan Patent Application No. 110140473, filed Oct. 29, 2021 in Taiwan. The entire content of the above identified application is incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a periodic metal array structure, and more particularly to a periodic metal array structure located between two antenna modules to form a planar antenna array system and including a plurality of rows of metal unit assemblies each including a plurality of metal units. 
     BACKGROUND 
     With the rapid advancement of the wireless communication industry, wireless communication devices have been improved and upgraded continually. In the meantime, market requirements for such devices have evolved beyond a thin and compact design to also include communication quality, such as the stability of signal transmission. “Antennas” are a key element of wireless communication devices and are indispensable to the reception and transmission of wireless signals and to data transfer. The development of antenna-related technologies has been a focus of attention in the related technical fields as the wireless communication industry continues to flourish. 
     As a result of the design trend of wireless communication equipment toward miniaturization, the volume of the antennas adopted therein needs to be reduced accordingly. The current small antennas are mostly chip antennas and planar antennas. Among them, planar antennas are mostly micro-strip antennas and printed antennas. However, due to the light and thin design of wireless communication equipment, the circuit boards therein are also relatively short and small. If a manufacture needs to preserve an area on a circuit board for antenna installation, not only would the installation areas of other electronic components be reduced, which increases the circuit board design difficulty for a manufacturer, but also will the antenna and other electronic components be very close to each other. Particularly, when there are multiple antennas on a circuit board, the isolation of the antennas can easily deteriorate due to mutual coupling, resulting in a decrease in radiation quality, and serious affection on the signal quality of the antennas. 
     In order to solve the aforementioned issues, many manufacturers have developed a variety of isolation methods for multiple antennas. For example, increasing the distance between the antennas, or adding decoupling mechanism between the antennas in the hope of reducing the amount of coupling between the antennas. Nevertheless, as antenna configurations and operating frequencies differ, corresponding adjustments must be made respectively to the various isolation methods, with no simple generalization available. In other words, antenna isolation remains to be a major difficulty in antenna design. Therefore, one of the important issues addressed in the present disclosure is to improve antenna isolation in a limited area for antenna arrays. 
     SUMMARY 
     Where the antennas of wireless communication equipment are applied in various frequency bands, the shape of antenna radiation fields and antenna system performance are decided by factors including the relative strengths of the feed signals of antenna modules, input impedance difference, demand for high gain characteristics, etc. Therefore, the strength and isolation of antenna signals are extremely important for an antenna system. Therefore, in order to stand out in a highly competitive market, based on years of in-depth practical experience in the design, processing and manufacturing of various antenna systems, the excellence-striving research spirit, and longtime research and experimentation, the present disclosure presents a periodic metal array structure whose advent is expected to provide users with better use experience. 
     Certain aspects of the present disclosure are directed to a periodic metal array structure located between two antenna modules to form a planar antenna array system and including a plurality of rows of metal unit assemblies arranged in a transverse direction. Each adjacent two metal unit assemblies are spaced apart from each other by a first interval. Each metal unit assembly includes a plurality of metal units connected to each other in a longitudinal direction. Each of the metal units has a first longitudinal strip extending in the longitudinal direction, two first transverse strips extending in the transverse direction and respectively connected with the top and bottom ends of the first longitudinal strip, two second longitudinal strips extending in the longitudinal direction and respectively disposed on left and right sides of the first longitudinal strip, and two second transverse strips extending in the transverse direction and disposed on the left and right sides of the first longitudinal strip respectively. At least one of the first transverse strips can be connected with a first transverse strip of another one of the metal units. Each second longitudinal strip has a shorter longitudinal length than a longitudinal length of the first longitudinal strip, and is spaced apart from the first longitudinal strip by a second interval. Each of the second transverse strips has one end connected to the first longitudinal strip and the other end connected to a corresponding one of the second longitudinal strips. 
     In certain embodiments, a working frequency of the planar antenna array system is 28 GHz. 
     In certain embodiments, the first interval is 0.3 mm. 
     In certain embodiments, at least one of the metal unit assemblies includes three metal units, and a total longitudinal length of the metal unit assembly is 4.98 mm. 
     In certain embodiments, the periodic metal array structure includes three rows of metal unit assemblies. 
     In certain embodiments, the two second longitudinal strips do not extend beyond two ends of each of the first transverse strips in the transverse direction. 
     In certain embodiments, each of the first transverse strips has a transverse length of 0.5 mm. 
     In certain embodiments, the first transverse strip has a longitudinal length of 0.08 mm. 
     In certain embodiments, each of the second longitudinal strip has a longitudinal length of 1 mm and a transverse length of 0.08 mm. 
     In certain embodiments, the other end of the second transverse strip is connected to a central region of the corresponding second longitudinal strip. 
     In certain embodiments, the second transverse strip has a transverse length of 0.11 mm. 
     In certain embodiments, the second transverse strip has a longitudinal length of 0.08 mm. 
     These and other aspects of the present disclosure will become apparent from the following description of the embodiment taken in conjunction with the following drawings and their captions, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the following detailed description and accompanying drawings. 
         FIG.  1    is a schematic diagram of a planar antenna array system according to certain embodiments in the present disclosure. 
         FIG.  2    is a schematic diagram of a periodic metal array structure according to certain embodiments in the present disclosure. 
         FIG.  3    is a schematic diagram of a metal unit according to certain embodiments in the present disclosure. 
         FIG.  4    is a schematic diagram showing the results of isolation characteristics of the planar antenna array system having and not having the periodic metal array structure according to certain embodiments in the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Like numbers in the drawings indicate like components throughout the views. As used in the description herein and throughout the claims that follow, unless the context clearly dictates otherwise, the meaning of “a”, “an”, and “the” includes plural reference, and the meaning of “in” includes “in” and “on”. Titles or subtitles can be used herein for the convenience of a reader, which shall have no influence on the scope of the present disclosure. 
     The accompanying drawings are schematic and may not have been drawn to scale. The terms used herein generally have their ordinary meanings in the art. In the case of conflict, the present document, including any definitions given herein, will prevail. The same thing can be expressed in more than one way. Alternative language and synonyms can be used for any term(s) discussed herein, and no special significance is to be placed upon whether a term is elaborated or discussed herein. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms is illustrative only, and in no way limits the scope and meaning of the present disclosure or of any exemplified term. Likewise, the present disclosure is not limited to various embodiments given herein. Numbering terms such as “first”, “second” or “third” can be used to describe various components, materials, objects, or the like, which are for distinguishing one component/material/object from another one only, and are not intended to, nor should be construed to impose any substantive limitations on the components, materials, objects, or the like. D 1 rectional terms (e.g., “front”, “rear”, “left”, “right”, “upper/top” and/or “lower/bottom”) are explanatory only and are not intended to be restrictive of the scope of the present disclosure. As used herein, a numeral value referred in the present disclosure can include a value, or an average of values, in an acceptable deviation range of a particular value recognized or decided by a person of ordinary skill in the art, taking into account any specific quantity of errors related to the measurement of the value that may resulted from limitations of a measurement system or device. For example, a particular numeral value referred in the embodiments of the present disclosure can include ±5%, ±3%, ±1%, ±0.5% or ±0.1%, or one or more standard deviations, of the particular numeral value. 
     Referring to  FIG.  1   , a periodic metal array structure  1  can be located between two antenna modules  21 ,  22  to form a planar antenna array system S. In certain embodiments, the working frequency of the planar antenna array system S is 28 GHz, and the two antenna modules  21 ,  22  can be planar antennas. In certain embodiments, each of the two antenna modules  21 ,  22  has a rectangular shape with a length, from the left, side to the right side, of 3.2 mm, a width, from the top side to the bottom side, of 2.4 mm. The two antenna modules  21 ,  22  can be spaced apart by a distance D 1 , and be disposed on a circuit board  3 . In certain embodiments, the distance D 1  can be 3.2 mm. However, the present disclosure is not limited thereto. In certain embodiments, a manufacturer can adjust the working frequency of the planar antenna array system S or adjust the distance D 1  of the antenna modules  21 ,  22  according to product requirements. The planar antenna-circuit board electrical connection relationship and feed point therebetween are omitted herein for the brevity of description. 
     Referring to  FIG.  1    and  FIG.  2   , the periodic metal array structure  1  includes a plurality of metal unit assemblies  11  arranged in rows. In certain embodiments, the periodic metal array structure  1  includes three rows of metal unit assemblies  11  sequentially arranged from left to right in a transverse direction (with reference to the directions shown in  FIG.  1   ), and each adjacent two metal unit assemblies  11  are spaced apart from each other by an interval D 2 . In certain embodiments, the interval D 2  can be 0.3 mm. Neither of the two outer metal unit assemblies  11  is in contact with the adjacent antenna module  21  or  22 . Each metal unit assembly  11  includes a plurality of metal units  12  that are sequentially connected to each other in a longitudinal direction. In certain embodiments, each metal unit assembly  11  includes three metal units  12  and has a total longitudinal length T 1  of 4.98 mm. However, the present disclosure is not limited thereto, and in certain embodiments, the number of the metal units  12  in each metal unit assembly  11  may be adjusted according to practical needs. 
     Referring to  FIG.  3    in conjunction with  FIG.  2   , a metal unit  12  has a first longitudinal strip  121 , two second longitudinal strips  122 , two first transverse strips  123 , and two second transverse strips  124 . The first longitudinal strip  121  extends in the longitudinal direction (i.e., the direction extending through the top and bottom edges of  FIG.  2   ). The top and bottom ends of the first longitudinal strip  121  are respectively connected with the first transverse strips  123 . Each of the first transverse strips  123  extends in the transverse direction (i.e., the direction extending through the left and right edges of  FIG.  2   ). In certain embodiments, each first transverse strip  123  has a transverse length W 1  of 0.5 mm and a longitudinal length L 1  of 0.08 mm, and each of the two ends of the first longitudinal strip  121  is connected to a central region of a corresponding first transverse strip  123  such that, as shown in  FIG.  3   , each first transverse strip  123  has a left section and a right section that do not correspond to the first longitudinal strip  121 . Each of the left and right sections can have a transverse length W 11  of 0.21 mm. However, the present disclosure is not limited thereto. Each two adjacent metal units  12  in the same row can be connected through corresponding first transverse strips  123 . For example, as shown in  FIG.  2   , the middle metal unit  12  in each row has its two first transverse strips  123  respectively connected to the corresponding first transverse strips  123  of the adjacent metal units  12 . In other words, in  FIG.  2   , each metal unit  12  has at least one first transverse strip  123  connected to a corresponding first transverse strip  123  of another metal unit  12 . 
     Referring again to  FIG.  3    in conjunction with  FIG.  2   , the two second longitudinal strips  122  extend in the longitudinal direction, have shorter longitudinal lengths than the longitudinal length of the first longitudinal strip  121 , and are respectively disposed on the left and right sides of the first longitudinal strip  121  in such a way that the two second longitudinal strips  122  lie between the two first transverse strips  123 . In certain embodiments, the two second longitudinal strips  122  do not extend beyond the two ends of each first transverse strip  123  in the transverse direction. In certain embodiments, the outer peripheral of at least one of the two second longitudinal strips  122  may extend beyond the corresponding outer end edges of the first transverse strips  123  in the transverse direction, either in response to product requirements or as allowed within manufacturing tolerances. In certain embodiments, each second longitudinal strip  122  has a longitudinal length L 2  of 1 mm and a transverse length W 2  of 0.08 mm and is spaced apart from the first longitudinal strip  121  by an interval. In certain embodiments, the interval may be 0.11 mm. 
     With continued reference to  FIG.  3    in conjunction with  FIG.  2   , the two second transverse strips  124  extend in the transverse direction, are disposed on the left and right sides of the first longitudinal strip  121  respectively, and are located respectively within the two intervals between the first longitudinal strip  121  and the second longitudinal strips  122 . Each second transverse strip  124  has one end connected to the first longitudinal strip  121  and the other end connected to a corresponding second longitudinal strip  122  such that the two second longitudinal strips  122  and the two second transverse strips  124  roughly form an H shape. In certain embodiments, each second transverse strip  124  has a longitudinal length L 3  of 0.08 mm and a transverse length W 3  of 0.11 mm (which is equivalent to the interval between the first longitudinal strip  121  and a second longitudinal strips  122  being 0.11 mm), and the other end of each second transverse strip  124  is connected to a central region of a corresponding second longitudinal strip  122  such that, as viewed in  FIG.  3   , each second longitudinal strip  122  has an upper section and a lower section that do not correspond to the second transverse strip  124  and each of which has a longitudinal length L 21  of 0.46 mm. 
     According to the simulation test results shown in  FIG.  4   , the isolation between the antenna modules  21  and  22  at an working frequency of 28 GHz is −24.156 dB when the planar antenna array system S is not provided with the periodic metal array structure  1  (see the thick dashed line in  FIG.  4   ), and the isolation between the antenna modules  21  and  22  at the same working frequency of 28 GHz becomes −47.081 dB when the planar antenna array system S is provided with the periodic metal array structure  1  (see the thin dashed line in  FIG.  4   ). It can be inferred from the above that by the periodic metal array structure  1 , better isolation can be provided by disturbing the surface current of the antenna modules  21  and  22  and reducing the field quantities of back radiation. Therefore, the radiation intensity of main-beam signals of antenna arrays is enhanced while the intensity of side-lobe signals is suppressed. Moreover, the periodic metal array structure  1  and the antenna modules  21  and  22  can be designed on the same plane to maintain the integrity of the grounding surfaces of the antenna modules  21  and  22 . 
     The foregoing description of the exemplary embodiments of the disclosure has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. 
     The embodiments were chosen and described in order to explain the principles of the disclosure and their practical application so as to enable others skilled in the art to utilize the disclosure and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present disclosure pertains without departing from its spirit and scope.