Patent Application
20230104131
The present invention generally relates to radio communications and, more particularly, to base station antennas for cellular communications systems.
Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions or “cells” that are served by respective macrocell base stations. Each macrocell base station may include one or more base station antennas that are configured to provide two-way radio frequency (“RF”) communications with subscribers that are within the cell served by the base station. In many cases, each base station is divided into “sectors.” In one common configuration, a hexagonally-shaped cell is divided into three 120° sectors in the azimuth plane, and each sector is served by one or more macrocell base station antennas that have an azimuth Half Power Beamwidth (HPBW) of approximately 65°. So-called small cell base stations may be used to provide service in high-traffic areas within portions of a cell. Typically, the base station antennas are mounted on a tower or other raised structure, with the radiation patterns that are generated by the base station antennas directed outwardly.
Most macrocell base station antennas comprise one or more linear or planar arrays of radiating elements that are mounted on a flat panel reflector assembly. The reflector assembly may serve as a ground plane for the radiating elements and may also reflect RF energy that is emitted rearwardly by the radiating elements back in the forward direction.
More recently, base station antennas have been introduced that have reflector assemblies that include integrated RF chokes.
Pursuant to embodiments of the invention, base station antennas are provided that include a reflector assembly and a radiating element. The reflector assembly includes a reflector. The radiating element extends forwardly from the reflector. The reflector includes a nonmetallic substrate, and a metal layer mounted on the substrate.
In some embodiments, the substrate is formed from a polymeric material. In some embodiments, the metal layer is bonded directly to the substrate.
According to some embodiments, the metal layer has a thickness in the range of from about 4 micrometers to 25 micrometers.
The reflector assembly may include at least one support member affixed to the substrate to support the reflector.
According to some embodiments, the metal layer is formed of a metal selected from the group consisting of copper, aluminum, silver, tin, nickel, and combinations thereof.
According to some embodiments, the metal layer has a thickness in the range of from about 0.004 mm to about 0.5 mm.
In some embodiments, the reflector assembly includes at least one support member affixed to the substrate to support the reflector.
According to some embodiments, the least one support member includes a pair of opposed support members affixed to the substrate to support the reflector.
In some embodiments, each of the support members defines a lengthwise channel or tubular passage.
In some embodiments, each of the support members includes cut outs defined therein.
According to some embodiments, the metal layer is coupled directly to the substrate.
According to some embodiments, the substrate includes integral stiffening features.
The metal layer can be at least partially patterned as patches and can be configured to define a frequency selective surface and/or substrate
The base station antenna can include a plurality of columns of first radiating elements providing the radiating element and configured for operating in a first operational frequency band, each column of first radiating elements comprising a plurality of first radiating elements arranged in a longitudinal direction of the base station antenna. The nonmetallic substrate and the metal layer can cooperate to define at least one frequency selective surface configured such that electromagnetic waves within the first operational frequency band are substantially blocked by the reflector.
The frequency selective surface can be configured to reflect the electromagnetic waves within the first operational frequency band.
The base station antenna can further include at least one second radiating element configured for operating in a second operational frequency band that is different from and does not overlap with the first operational frequency band. The at least one frequency selective surface can be further configured such that electromagnetic waves within the second operational frequency band can propagate through the reflector.
The second operational frequency band can be higher than the first operational frequency band.
The nonmetallic substrate and the metal layer are provided by a multiple layer printed circuit board.
The nonmetallic substrate can include a dielectric board having opposite first and second sides, the first and second sides facing the radiating element and front of the base station antenna. The metal layer can be formed with a periodic conductive structure on at least one of the first and second sides. The periodic conductive structure can form a frequency selective surface.
The metal layer can be provided as a first periodic conductive structure on the first side of the dielectric board and a second periodic conductive structure on the second side of the dielectric board. The periodic conductive structure on the second side of the dielectric board can be different from the periodic structure on the first side of the dielectric board.
The periodic conductive structure can have a repeating pattern of polygonal patches of metal elements.
The nonmetallic substrate and the metal layer can be implemented as a multi-layer printed circuit board, one or more layers of which can be formed with a frequency selective surface configured such that electromagnetic waves within a first frequency range propagates through the reflector. The one or more layers of the multi-layer printed circuit board can reflect electromagnetic waves in a different operational frequency band.
The metal layer can have an array of conductive patches that merges into right and left outer perimeter sides that have full metal areas.
The base station antenna can also have feed boards that may be oriented perpendicular to the reflector extending longitudinally and residing on right and left sides of the reflector.
The base station antenna can also include at least one feed board on a right side perimeter of the reflector and at least one feed board on a left side perimeter of the reflector, each at least one feed board can reside adjacent to and behind or in front of the reflector.
The base station antenna can further include feed stalks that extend forward of the reflector positioning radiating elements thereon in front of the reflector facing a radome.
The metal layer can be formed as an in-mold decoration on or into the substrate.
The substrate can include an integral stiffening features that project forward. The radiating element can extend forward of the integral stiffening features.
The stiffening features can be provided as a plurality of laterally spaced apart and longitudinally extending ribs. At least one laterally extending rib can intersect at least some of the longitudinally extending ribs.
A plurality of mounting holes can extend through at least some of the ribs (in a front to back direction).
At least one primary surface of the longitudinally extending ribs that is orthogonal to a primary surface of the reflector can include a metal layer thereby providing an isolation fence extending between neighboring radiating elements of different linear arrays of radiating antenna elements.
Some embodiments are directed to methods of forming a reflector for a base station antenna. The methods include providing an injection molded substrate and metallizing a primary surface of the injection molded substrate thereby defining the reflector.
The metallizing can be carried out by electro-spraying a metal film onto the primary surface of the substrate.
Before the metallization, the method can further include roughening the primary surface of the injection molded substrate.
The method can further include heating the injection molded substrate, then cleaning the primary surface of the injection molded substrate prior to the metallization.
The metallization can be carried out to deposit a metal layer onto the primary surface of the substrate in a thickness that is in a range of about 0.004 mm and about 0.5 mm.
The metallization can be carried out using in-mold decoration.
The injection molded substrate can have a crisscross pattern of forwardly projecting ribs. The ribs can define rectangular planar regions therebetween thereby providing spaces for mounting radiating elements in the rectangular planar regions.
The demand for cellular communications capacity has been increasing at a high rate. As a result, the number of base station antennas has proliferated in recent years. Base station antennas are both relatively large and heavy and, as noted above, are typically mounted on antenna towers. Due to the wind loading on the antennas and the weight of the antennas and associated radios, cabling and the like, antenna towers must be built to support significant loads. This increases the cost of the antenna towers.
The reflector assembly and the radome of a typical base station antenna may account for on the order of 40-50% of the total weight of a base station antenna. If the weight of the reflector assembly may be reduced, it may be possible to mount more base station antennas on a given antenna tower and/or to build new antenna towers that have lower structural loading requirements.
Pursuant to embodiments of the present invention, base station antennas are provided that include a reflector assembly having a composite or multi-layer reflector. The composite reflector includes a substrate formed of a dielectric material, and an RF electromagnetic reflector layer formed of metal mounted on the substrate. The dielectric substrate provides structural support for the metal layer, while reducing overall weight as compared to a reflector formed entirely of metal (e.g., bent sheet metal).
Embodiments of the present invention will now be discussed in greater detail with reference to the attached figures.
With reference to
In the description that follows, the base station antenna 100 and the components thereof are described using terms that assume that the base station antenna 100 is mounted for use on a tower with the longitudinal axis LA-LA of the antenna 100 extending along a vertical (or near vertical) axis and the front surface of the antenna 100 mounted opposite the tower pointing toward the coverage area for the antenna 100, even though
As shown in
Referring to
With reference to
The reflector 150 has a front side 150F. The reflector 150 includes a non-metallic substrate 160 and a metal layer 170. The reflector 150 may also include mounting holes or openings 158 defined therein and extending through each of the non-metallic substrate 160 and the metal layer 170.
The substrate 160 has a front surface 162F and an opposing rear surface 162R (
Openings 164 (
In some embodiments, the substrate 160 has a thickness T1 (
The substrate 160 is formed of a nonmetallic, dielectric material. In some embodiments, the substrate 160 is formed of a plastic or polymeric material. In some embodiments, the substrate 160 is formed of a thermoplastic. In some embodiments, the substrate 160 is formed of a fiberglass reinforced thermoplastic composite. Suitable thermoplastics may include fiberglass reinforced plastic (e.g., 40-50% content of fiberglass), fiberglass reinforced Nylon (softer), or acrylonitrile styrene acrylate (ASA) plastic. In some embodiments, the substrate 160 is formed of sheet molding compound (SMC) fiberglass.
In some embodiments, the substrate 160 is formed of a thermoplastic having a tensile strength in the range of from about 40 to 60 MPa.
In some embodiments, the substrate 160 is formed of a thermoplastic having a surface electrical resistivity in the range of from about 1.59×10−8 to 1.09×10−7 ohm-meter (Ω·m).
In some embodiments, the substrate 160 is unitary. In some embodiments, the substrate 160 is monolithic.
The substrate 160 may be formed using any suitable technique. In some embodiments, the substrate 160 is molded (e.g., injection molded). In some embodiments, the substrate 160 is extruded or otherwise formed as a sheet (which may have ribs or other non-planar structures formed therein, as discussed below), and then cut to length or shape.
The metal layer 170 has a front surface 172F and an opposing rear surface 172R, bounded by opposed lateral side edges 172S and opposed end edges 172E. In some embodiments, the front surface 172F is substantially planar.
Openings 174 (
In some embodiments, the metal layer 170 has a thickness T2 (
In some embodiments, the thickness T2 can be either in a range of about 0.004 mm to about 0.5, such as, for example about 0.1 mm.
The metal layer 170 is formed of metal. In some embodiments, the metal layer 170 is formed of aluminum or aluminum alloy. In some embodiments, the metal layer 170 is formed of one or more of copper, aluminum, silver, tin, nickel, or combinations or alloys thereof.
In some embodiments, the metal layer 170 is formed of a metal having an electrical conductivity in the range of from about 9×106 to 6.3×107 seimens per meter (S/m).
In some embodiments, the metal layer 170 is unitary. In some embodiments, the metal layer 170 is monolithic.
The metal layer 170 is secured to the substrate 160. In some embodiments, the metal layer 170 is bonded to the substrate 160. In particular, in some embodiments the rear surface 172R is bonded to the front surface 162F of the substrate 160. In some embodiments the rear surface 172R is directly bonded to the front surface 162F of the substrate 160 without an intervening adhesive (e.g., using heat bonding). In some embodiments the rear surface 172R is directly bonded to the front surface 162F of the substrate 160 by an intervening adhesive. In some embodiments, the metal layer 170 is a coating on the substrate 160.
The metal layer 170 may be formed and secured to the substrate 160 using any suitable technique. In some embodiments, the substrate 160 is preformed, and the metal layer 170 is thereafter applied and bonded to the substrate 160. Suitable methods for applying the metal layer 170 to the substrate 160 may include coating the substrate 160 with the metal 170, for example, by spraying, dipping, painting, plating, or flooding. Suitable methods for applying the metal layer 170 to the substrate 160 may also include laminating the metal 170 onto the substrate 160. In some embodiments, the metal layer 170 is co-laminated, coextruded, or co-molded (e.g., insert molded or thermoformed) with the substrate 160. In some embodiments, the layers 160, 170 are combined in a larger or extended panel or web, and the individual reflectors 150 are cut therefrom.
In some embodiments, the width W1 (
In some embodiments, the width W2 of the metal layer 170 is in the range of from about 300 mm to 650 mm. In some embodiments, the length L2 of the metal layer 170 is in the range of from about 1400 mm to 3000 mm.
In some embodiments, the surface area of the front surface 172F of the metal layer 170 is in the range of from about 0.4 m2 to 2 m2.
Each support member 180 is elongate and includes a front section or wall 184. In some embodiments, each support member 180 defines a lengthwise channel or passage 182. In some embodiments, each support member 180 is tubular.
The support members 180 may be formed of any suitable material. In some embodiments, the support members 180 are formed of a metal, such as aluminum.
The support members 180 may be formed using any suitable technique. In some embodiments, each support member 180 is extruded. For example, in some embodiments, each support member 180 is extruded as a straight, tubular member or stock, which may then be cut to length. In some embodiments, each support member 180 is unitary. In some embodiments, each support member 180 is monolithic.
Each support member 180 is affixed to the rear side 162R of the substrate 160 along or adjacent a respective one of the side edges 162S. In some embodiments, each support member 180 is affixed to the substrate 160 by fasteners 156 (e.g., screws, bolts, or nuts and bolts); however, other techniques may be used.
The cross braces 154 are connected or affixed at either end to the support members 180 (e.g., fasteners 155;
The cross braces 154 may be formed of any suitable material. In some embodiments, the cross braces 154 are formed of a metal, such as aluminum. In some embodiments, the cross braces 154 are formed of plastic.
The frame 157 is connected to the radome 110 by support brackets 122. In some embodiments, the support brackets 122 are affixed to the support members 180 (e.g., by fasteners 155;
As is further shown in
The low band radiating elements 130 are mounted along a first vertical axis (e.g., substantially parallel to the axis LR-LR) to form a linear array 131 of low band radiating elements 130. The high band radiating elements 140 may be divided into two groups that are mounted along respective second and third vertical axes to form a pair of linear arrays 141, 143 of high band radiating elements 170. The linear array 131 of low band radiating elements 130 extends between the two linear arrays 141, 143 of high band radiating elements 140. The low band radiating elements 130 may be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may be the 694-960 MHz frequency band or a portion thereof. In other embodiments, the first frequency band may be the 555-960 MHz frequency band or a portion thereof. In other embodiments, the first frequency band may be the 575-960 MHz frequency band, the 617-960 MHz frequency band, the 694-960 frequency band or portions of any thereof. The high band radiating elements 140 may be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band may be the 1.695-2.690 GHz frequency range or a portion thereof.
As is also shown in
As shown best in
In use, the base station antenna 100 may be mounted on a suitable support such as a pole or other support structure, e.g., a support structure 20 as shown in
The metal layer 170 of the reflector 150 is electromagnetically reflective. In use, the metal layer 170 serves to reflect RF energy from the radiating elements 130, 140 in the forward direction (e.g., in the same or similar manner as conventional bent metal plate reflectors). The metal layer 170 can also serve as a ground plane for the radiating elements 130, 140.
The substrate 160 provides structural rigidity and support to the reflector 150 and the metal layer 170. Moreover, the substrate 160 and the frame 157 (i.e., the support members 180 and the cross braces 154) cooperate to provide structural rigidity and support to the reflector 150 and the overall reflector assembly 151. In particular, the substrate 160 the support members 180, and the cross braces 154 can provide the reflector assembly 151 with good torsional stability. The cross braces 154 extending between support members 180 of the reflector assembly 151 provide mechanical support. This structural strength enables the reflector 150 to serve effectively as a support or carrier for other components, such as the radiating elements 130, 140.
The substrate 160 can be formed of a relatively weak plastic instead of as a heavy metal structure because the geometry of the frame 157 and the substrate 160 provides the aforementioned strength and stiffness.
The reflector 150 can be mounted on a support such as a metal pole via the support members 180. When the support members 180 are formed of metal (e.g., steel), they can reduce or prevent problems that may otherwise be caused by a difference between the thermal expansion rate of the pole and the thermal expansion rate of the substrate 160.
Because the metal layer 170 is primarily or only relied upon for electrical performance (e.g., RF reflectance and/or ground plane) rather than support, the metal layer 170 can be formed as a relatively thin layer or coating. This can reduce the overall weight of the reflector assembly 151 as compared to conventional bent metal reflectors. The use of a thin metal layer or coating can also reduce the manufacturing cost of the reflector assembly 151 as compared to conventional bent metal reflectors.
The metal layer 170 may be connected to electrical ground using a direct electrical connection. Alternatively, the metal layer 170 may be connected to electrical ground using a capacitive electrical connection through the substrate 160 to the metal layer 170.
With reference to
The reflector assembly 251 differs from the reflector assembly 151 in that the substrate 260 is further provided with integral geometric stiffening structures or features 266. The stiffening features 266 may take the form of integral, upstanding ribs or corrugations, for example. In some embodiments, the stiffening features 266 protrude from the rear side of the substrate 260 so that the front surface of the substrate 260 remains substantially planar. In some embodiments, the substrate 260, including the stiffening features 266, is monolithic.
With reference to
The reflector assembly 351 includes support members 380 corresponding to the support members 180, except as follows. Each support member 380 is U-shaped or J-shaped in cross-sectional profile. This geometric structure may provide sufficient rigidity to the reflector assembly 351 while further reducing weight and cost.
With reference to
The reflector assembly 451 includes support members 480 corresponding to the support members 180, except as follows. Each support member 480 includes side cutouts 487 in its side walls 485. This geometric structure may provide sufficient rigidity to the reflector assembly 451 while further reducing weight and cost.
With reference to
Referring to
Referring to
The at least one metal layer 570 can comprise a metamaterial. The term “metamaterial” refers to composite electromagnetic (EM) materials. Metamaterials may comprise sub-wavelength periodic microstructures.
Referring to
The dielectric substrate 560 of FSS 550F can have a dielectric constant in a range of about 2-4, such as about 3.7 and a thickness of about 5 mil with metallization patterns formed therein or thereon. The thickness can vary but thinner materials can provide lower loss.
Referring to
Referring to
The pattern 1500p can be provided by one metal layer 570 or by different metal layers 5701, 5702 (
The patches 1502 can be formed by etching a copper layer that is formed on the non-metallic substrate 560.
Referring to
In some embodiments, the FSS 550F of the reflector 550 can be configured to act like a High Pass Filter essentially allowing low band energy (i.e., RF signals in the low-band frequency range) to completely reflect (the FSS 550F can act like a sheet of metal) while allowing higher band energy (i.e., RF signals in the high-band frequency range of, for example, about 3.5 GHz or greater), to substantially pass through the FSS 550F. Thus, the FSS 550F is transparent or invisible to the higher band energy and a suitable out of band rejection response from the FSS can be achieved. The FSS 550F may allow a reduction in filters or even eliminate filter requirements for looking back into a radio of an active antenna module.
The pattern 1500p can be configured so that there is a perimeter gap space 1503 separating neighboring patches 15021, 15022, (
As shown, the large patches are metal, e.g., copper, and the adjacent region is the gap 1503 which can be defined by an exposed substrate. The grid element 1530e is spaced apart from neighboring patches 1502 by a grid element 1530e. The patches 1502 are metal and the thin grid 1530 is also metal, typically the same metal but different metals can be used. The area between the patches 1502 and the grid elements 1530e is the gap 1503 and the area of the gap 1503 between adjacent patches 1502 can have a lateral extent that is less than the area of the patch 1502 and greater than the grid element 1530e.
In some embodiments, the reflector 550 may be implemented by forming the one or more metal layer(s) 570 on a printed circuit board, optionally a flex circuit board. In some embodiments, the reflector 550, for example, may be implemented as a multi-layer printed circuit board 1500c (
Referring to
Still referring to
The FSS 550F can comprise two metal structures which are printed on the same side or on opposing sides (primary surfaces) 1510, 1512 of the nonmetallic substrate 560. One structure can be a pattern 1500p of patches 1502 of polygons, such as squares or hexagons, and the other structure can be a metal mesh or grid 1530 that looks like a honeycomb structure.
Referring to
Where used, the metal grid 1530 can optionally be positioned in front of, behind or between one or more adjacent layers providing the pattern 1500p of patches 1502. Where a metal grid 1530 is used, it can be placed or formed on a top or bottom layer of the nonmetallic substrate 560 and/or behind a rearwardmost patch 1502 (closest to the rear of the housing of the base station antenna) or in front of a forwardmost patch 1502 (closest to the front of the base station antenna).
Referring to
Referring to
In some embodiments, the FSS 550F may comprise a plurality of reflector units that are arranged periodically, where each unit may comprise a first unit structure forming the periodic conductive structure on the first primary surface of the dielectric board and a second unit structure forming the periodic conductive structure on the second primary surface of the dielectric board. A position of the first unit structure may correspond to a position of the second unit structure. In some embodiments, as viewed from a direction perpendicular to the first and second primary surfaces, the center of each first unit structure coincides with the center of corresponding second unit structure.
In some embodiments, the first unit structure may be equivalent to an inductor (L), the second unit structure may be equivalent to a capacitor (C), thereby the reflector unit comprising the first unit structure and the second unit structure that are correspondingly disposed may be equivalent to an LC resonant circuit. In some embodiments, the reflector unit may be configured to be equivalent to a parallel LC resonant circuit. A frequency range that the frequency selective surface allows to pass therethrough may be adjusted to a desired frequency range by designing the equivalent inductance of the first unit structure and the equivalent capacitance of the second unit structure.
In some embodiments, the traveling radio frequency wave that goes through FSS 550F can see a shunt LC resonator and a transmission line. The substrate has an impedance Zo depending on its thickness. The capacitance of each unit cell can be made of the coupling across the gap 1503 between the grid 1530 and the patch 1502. The inductor can be defined by/made out of metallic thin lines of the grid 1530.
The mesh/grid can define a high pass filter and the patches can define a low pass filter, together defining a band pass filter. A multiple layer printed circuit board can be used for a sharper filter response.
In some embodiments, the periodic conductive structure on the first primary surface of the dielectric board comprises a grid (array structure) 1530, the first unit structure comprises a grid element 1530e serving as a repetition unit in the grid array structure 1530, and the periodic conductive structure on the second primary surface of the dielectric board comprises a patch array pattern and/or structure 1500p, the second unit structure comprises a patch 1502 serving as a repetition unit in the patch array structure 1500p. For example, the grid element 1530e of the first unit structure may have an annular shape of a regular polygon such as a square, the patch 1502 of the second unit structure may have a shape of a regular polygon such as a square.
For example, as shown in
In the example patterns shown in
The reflector 550 can reside a distance in a range of ⅛ wavelength to ¼ wavelength of an operating wavelength behind the low band dipole antenna element(s) 130, in some embodiments. The term “operating wavelength” refers to the wavelength corresponding to the center frequency of the operating frequency band of the radiating element, e.g., low band radiating element 130. The feed stalks 130f (
Referring to
Referring to
In some embodiments, the reflector 550 can be configured with a metal pattern 1500p that merges into side segments or areas of full metal 570f which may be shaped as laterally extending metal tabs with front and/or back surfaces fully metallized. The areas of full metal 570f can couple, for example, capacitively couple, to the side segments 1570s of the passive (primary) reflector 214 residing on right and left sides of the base station antenna.
In some embodiments, as shown in
It is also noted that feed boards 1200 are not required and small or miniature power dividers with cables can be used in lieu of feed boards.
The feed boards 1200 can be positioned to be behind the reflector 550. The feed boards 1200 can be positioned to be in front of the reflector 550. The feed boards 1200 can be electrically coupled to the reflector 550 and/or primary reflector 214. The reflector 550 can be in front of or behind the primary reflector 214 and optionally can be capacitively coupled to the primary reflector 214.
As discussed above, the base station antenna 100 can include one or more arrays 131-1, 131-2 of low-band radiating elements 130, one or more arrays of mid-band radiating elements 222 (
The low-band radiating elements 130 may be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may comprise the 617-960 MHz frequency range or a portion thereof (e.g., the 617-896 MHz frequency band, the 696-960 MHz frequency band, etc.). The low-band linear arrays 131-1, 131-2 may or may not be configured to transmit and receive signals in the same portion of the first frequency band. For example, in one embodiment, the low-band radiating elements 130 in a first linear array may be configured to transmit and receive signals in the 700 MHz frequency band and the low-band radiating elements in a second linear array may be configured to transmit and receive signals in the 800 MHz frequency band. In other embodiments, the low-band radiating elements 130 in both the first and second linear arrays may be configured to transmit and receive signals in the 700 MHz (or 800 MHz) frequency band.
The other antenna elements 1140 can be high-band radiating elements that can be mounted in columns, typically in the upper medial or center portion of antenna 100, to form a massive MIMO array of high-band radiating elements. The high-band radiating elements may be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may comprise the 3300-4200 MHz frequency range or a portion thereof.
It will be appreciated that there is increasing demand for weight and cost reduction in base station antennas. Typically, around 80 percent or more of the weight of the base station antennas are from the reflector and the radome. Referring to
The thickness of the metal layer 670 on the non-metallic substrate 660 can be in a range of about 0.004 mm to about 0.5 mm, such as, for example, about 25 micrometers or such as, for example, about 0.1 mm. The metal layer 670 on the reflector 650 is provided to have a surface having metal (conductive) properties for reflecting signals from the radiating elements 1600 and for providing a ground plane for the radiating elements 1600.
The stiffening features 666 may take the form of integral (upstanding in the orientation shown) ribs 666r, for example. The stiffening features 666 can be provided as a crisscross pattern of a series of intersecting rows 666t and columns 666c as shown. In some embodiments, the stiffening features 666 protrude from the front side of the substrate 660. In some embodiments, the substrate 660, including the stiffening features 666, is monolithic.
In some embodiments, as shown in
The stiffening features 666 can be provided as forwardly projecting ribs 666r that extend in a crisscross pattern for increasing strength of the non-metallic substrate 660 and hence for the reflector 650. The rearward facing surface of the non-metallic substrate 660 can be planar and devoid of stiffening features.
Referring to
In the non-metallic substrate 660, the stiffening structures or features 666, as well as mounting holes 658 may be manufactured directly in the substrate 660. In some embodiments, the substrate 660, including the stiffening features 666 and walls defining the mounting holes 658, is monolithic. The mounting holes 658 can be provided in the stiffening features 666. Thus, undesired deformation of the reflector generated by a stamping process for a conventional metal reflector may be avoided. The mounting holes 658 can be arranged along some or all columns 666c and some or all rows 666t.
The metal layer 670 can be provided by metallization of the non-metallic substrate 660 as discussed above. The metallization can be provided as contiguous surface layer or provided in the periodic conductive patches discussed above with respect to
The reflector 650 may be produced by electroplating, spray coating, IMD (In-Mold-Decoration) and the like. The non-metallic substrate 660 may be produced by injection molding and materials for the substrate 660 may be polymers, copolymers or other engineering plastic materials having good strength, such as polycarbonate (PC), a thermoplastic polymer such as acrylonitrile butadiene styrene (ABS) and the like. Alternatively, the substrate 660 may be produced by a SMC (sheet molding compound).
Referring to
The (electrospray) coating process for the metallization can be carried out by directing gas, such as an airflow, through a nozzle of a spray coating device. A flowable lacquer can be entrained in the gas/airflow by a vacuum generated by the gas/airflow and then is sprayed out as a lacquer mist which can be deposited on the non-metallic substrate 660 as a uniform smooth lacquer (metal) film.
In some embodiments, the spray coating process may include following steps: (a) tempering the non-metallic substrate 660 whereby the substrate 660 is heated to a temperature lower than a heat deformation temperature and kept under this temperature for a defined time period, typically between 10 minutes to 10 hours, more typically at least one hour and up to several hours; (b) cleaning the surface to remove surface oil by use of a cleaning agent, then rinsing/cleaning the primary surface 660p by use of pure or sterile or substantially sterile liquid such as water, and then drying the cleaned substrate 660 by passive or active drying such as by air dry or by heated dryer; (c) removing static electricity and dust particles using high-pressure ionized air; and (d) spray coating to form a film onto the substrate 660, which can be in a range of 1-30 μm, typically about 20 μm, and then drying the coating on the substrate passively or actively by air dry or by heat. The spray coating process may be repeated several times, and air or forced heat can be used to dry each successive spray coating action. The reflector 650 can then be placed in an oven after the spray coating process when a desired thickness of metal has been applied. The thickness can be in a range or about 0.004 mm to about 0.5 mm.
In some embodiments, in-mold decorating (IMD) for transferring metal graphics to injection molding (IMD technology) can be used for providing the metallization of the metal layer 670 onto the substrate 660. For example, the non-metallic substrate 660 may be produced by a SMC process and a metal (conductive) layer 670 may be laminated or injection molded or otherwise integrated into or onto an outer primary surface 660p of the non-metal substrate 660. The metal layer 670 may be a conductive layer such as a conductive film, a conductive fabric or the like or combinations of conductive film and fabric.
It will also be appreciated that the number of linear arrays of low-band, mid-band and high-band radiating elements may be varied from what is shown in the figures. For example, the number of linear arrays of each type of radiating elements may be varied from what is shown, some types of linear arrays may be omitted and/or other types of arrays may be added, the number of radiating elements per array may be varied from what is shown, and/or the arrays may be arranged differently.
Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention 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 disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout
In the discussion above, reference is made to the linear arrays of radiating elements that are commonly included in base station antennas. It will be appreciated that herein the term “linear array” is used broadly to encompass both arrays of radiating elements that include a single column of radiating elements that are configured to transmit the sub-components of an RF signal as well as to two-dimensional arrays of radiating elements (i.e., multiple linear arrays) that are configured to transmit the sub-components of an RF signal. It will also be appreciated that in some cases the radiating elements may not be disposed along a single line. For example, in some cases a linear array of radiating elements may include one or more radiating elements that are offset from a line along which the remainder of the radiating elements are aligned. This “staggering” of the radiating elements may be done to design the array to have a desired azimuth beamwidth. Such staggered arrays of radiating elements that are configured to transmit the sub-components of an RF signal are encompassed by the term “linear array” as used herein.
As used herein, “monolithic” means an object that is a single, unitary piece formed or composed of a material without joints or seams.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (i.e., “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.).
The term “about” with respect to a number, means that the stated number can vary by +/−20%.
Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.
Aspects and elements of all of the embodiments disclosed above can be combined in any way and/or combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.
The present application claims the benefit of and priority from U.S. Provisional Patent Application No. 63/016,699 filed Apr. 28, 2020, the entire content of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/029356 | 4/27/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63016699 | Apr 2020 | US |
