Patent Grant
11600915
The present disclosure pertains to antenna apparatuses for satellite communication systems.
Satellite communication systems generally involve Earth-based antennas in communication with a constellation of satellites in orbit. Earth-based antennas are, of consequence, exposed to weather and other environmental conditions. Therefore, described herein are antenna apparatuses and their housing assemblies designed with sufficient durability to protect internal antenna components while enabling radio frequency communications with a satellite communication system, such as a constellation of satellites.
In accordance with one embodiment of the present disclosure, an antenna apparatus is provided. The antenna apparatus includes: a housing assembly including a radome portion and a lower enclosure portion, wherein the radome portion and lower enclosure portion are couplable to form an inner compartment for housing antenna components of the antenna assembly; an antenna stack assembly disposed within the inner compartment, wherein the antenna stack assembly generates heat when in operation; and a heat transfer system within the inner compartment configured to facilitate the flow of heat toward the radome portion.
In accordance with another embodiment of the present disclosure, a housing for an antenna system having a plurality of antenna elements defining an antenna aperture is provided. The housing includes: a chassis portion having an internal support portion for internal components for the plurality of antenna elements including a bonding portion for bonding an internal carrier to the chassis portion; a heat sink extending from an external surface of the chassis portion; and a radome portion configured for coupling to the chassis portion to define an inner chassis chamber.
In accordance with another embodiment of the present disclosure, an antenna apparatus is provided. The antenna apparatus includes: a substantially planar radome; and a lower enclosure, the upper radome and lower enclosure together enclosing an inner compartment having an antenna stack assembly disposed within the inner compartment, wherein the radome or the lower enclosure are configured to dissipate heat.
In any of the embodiments described herein, the heat transfer system may include a thermally conductive feature disposed in the inner compartment for in-plane heat transfer.
In any of the embodiments described herein, the radome portion may have an interior portion and an outer perimeter portion, and wherein the thermally conductive feature is disposed at or near the outer perimeter portion of the radome portion.
In any of the embodiments described herein, the antenna assembly may include a patch antenna including an upper patch antenna layer, a lower patch antenna layer, and a spacing therebetween, and wherein the thermally conductive feature is disposed on the outer perimeter of the upper patch antenna layer.
In any of the embodiments described herein, the thermally conductive feature may be a conductive metal disposed on the upper patch antenna layer.
In any of the embodiments described herein, the thermally conductive feature may be formed on a PCB layer.
In any of the embodiments described herein, the PCB layer may have an upper surface facing toward the radome portion and a lower surface facing away from the radome portion, and the thermally conductive layer may be disposed on the upper surface of the PCB layer.
In any of the embodiments described herein, the heat transfer system may include a conductive portion of the radome portion for through-plane heat transfer.
In any of the embodiments described herein, the radome portion may include a radome and a radome spacer, and wherein the radome spacer has heat conductive properties.
In any of the embodiments described herein, the radome spacer may include a structure including a plurality of cells defining a plurality of apertures surrounded by cell walls, wherein the plurality of cells are configured to align with a plurality of antenna elements in the antenna assembly, and wherein the cell walls are configured to conduct heat generated by the plurality of antenna elements.
In any of the embodiments described herein, the radome spacer may be formed from a plastic having thermal conductive properties.
In any of the embodiments described herein, the radome spacer may be formed from a plastic having a thermal conductivity value of greater than 0.35 W/m-K or greater than 0.45 W/m-K.
In any of the embodiments described herein, the housing may further include a chassis disposed between the radome portion and the lower enclosure portion, wherein the chassis divides the inner compartment into a first compartment portion and a second compartment portion for housing antenna components of the antenna assembly, the chassis having heat conductive properties.
In any of the embodiments described herein, the antenna stack assembly may be thermally coupled to the chassis.
In any of the embodiments described herein, the chassis may be thermally coupled to a thermally conductive feature disposed at or near the outer perimeter portion of the radome portion.
In any of the embodiments described herein, the heat sink may include a plurality of fins.
In any of the embodiments described herein, the plurality of fins may be oriented in an orientation perpendicular to the orientation of the bonding portion including a plurality of bonding bars.
In any of the embodiments described herein, the plurality of fins may be arranged in a parallel configuration.
In any of the embodiments described herein, the antenna apparatus or housing further may include a heat sink extending from an external surface of the lower enclosure whereby the lower enclosure dissipates heat.
In any of the embodiments described herein, the heat sink may include a plurality of fins.
In any of the embodiments described herein, the antenna apparatus or housing further may include a heat transfer layer within the inner compartment configured to facilitate the flow of received by the heat transfer layer toward the radome, wherein the radome dissipates heat.
In any of the embodiments described herein, the heat transfer layer may be a radome spacer layer.
Various embodiments of the disclosure are discussed in detail below. While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described herein in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and the appended claims.
In the drawings, some structural or method features may be shown in specific arrangements and/or orderings. However, it should be appreciated that such specific arrangements and/or orderings may not be required. Rather, in some embodiments, such features may be arranged in a different manner and/or order than shown in the illustrative figures. Additionally, the inclusion of a structural or method feature in a particular figure is not meant to imply that such feature is required in all embodiments and, in some embodiments, it may not be included or may be combined with other features.
References in the specification to “one embodiment,” “an embodiment,” “an illustrative embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may or may not necessarily include that particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. Language such as “top”, “bottom”, “upper”, “lower”, “vertical”, “horizontal”, “lateral”, in the present disclosure is meant to provide orientation for the reader with reference to the drawings and is not intended to be the required orientation of the components or to impart orientation limitations into the claims.
Embodiments of the present disclosure are directed to antenna apparatuses including antenna systems designed for sending and/or receiving radio frequency signals to and/or from a satellite or a constellation of satellites.
The antenna systems of the present disclosure may be employed in communication systems providing high-bandwidth, low-latency network communication via a constellation of satellites. Such constellation of satellites may be in a non-geosynchronous Earth orbit (GEO), such as a low Earth orbit (LEO).
A communication path may be established between the endpoint terminal 102 and a satellite 104. In the illustrated embodiment, the first satellite 104, in turn, establishes a communication path with a gateway terminal 106. In another embodiment, the satellite 104 may establish a communication path with another satellite prior to communication with a gateway terminal 106. The gateway terminal 106 may be physically connected via fiber optic, Ethernet, or another physical connection to a ground network 108. The ground network 108 may be any type of network, including the Internet. While one satellite 104 is illustrated, communication may be with and between a constellation of satellites.
The endpoint or user terminal 102 may include an antenna apparatus 200, for example, as illustrated in
A tilting mechanism 240 (details not shown) disposed within the lower enclosure 204 permits a degree of tilting to point the face of the radome portion 206 at a variety of angles for optimized communication and for rain and snow run-off (see
As discussed in greater detail below, an alternate embodiment of an antenna apparatus is provided in
Returning to
In various embodiments, the antenna apparatus 200 includes an antenna system designed for sending and/or receiving radio frequency signals to and/or from a satellite or a constellation of satellites. The antenna system, as described below, is disposed in the housing assembly 202 and may include an antenna aperture 208 (see
As seen in the exploded view of
Referring to
Radome Portion of the Housing
Referring to
In radio frequency communication, the presence of water can attenuate electromagnetic signal transmission and/or reception by the antenna aperture 208. Therefore, radome portions in accordance with embodiments of the present disclosure are designed to mitigate the accumulation of snow, rain, and other moisture. In addition to design features for durability in various environmental conditions, radome portions described herein may be constructed from material that minimally attenuates the radio frequency signals transmitted or received by the antenna system of the antenna apparatus 200.
Referring to
In the illustrated embodiment of
Referring to
On advantageous effect of a planar top surface 220 for the radome portion 206 is that the flat surface allows for minimal tuning of specific antenna elements 212 in an antenna array to account for differences in radome thickness and/or differences in spacing between the radome portion 206 and each of the individual antenna elements 304 in the antenna array 308. With a constant thickness of the radome portion 206, all of the individual antenna elements 304 in the antenna array 308 can be tuned the same to account for attenuation of the electromagnetic signal by the radome portion 206 and also for impedance matching between the antenna elements 304 and the radome portion 206.
Referring to
In one embodiment of the present disclosure, the radome 305 is designed to be an outer layer, which is exposed to the outdoor environment and has mechanical properties of good strength to weight ratios, a high modulus of elasticity for stiffness and resistance to deformation, and a low coefficient of thermal expansion (CTE). So as not to impede RF signals, the radome 305 has electrical properties of a low dielectric constant, a low loss tangent, and a low coefficient of thermal expansion (CTE). In addition, in some embodiments, the radome 305 has chemical properties of bondability for bonding with adhesive and low or near zero water absorption. Without such bondability, the radome lay-up can buckle in extreme weather conditions.
The radome 305 is designed to maintain high mechanical values and electrical insulating qualities in both dry and humid conditions over thermal cycles between −40° C. and 85° C. In some embodiments, the radome 305 has high yield strength and a high enough modulus to spread load on the radome 305 to the radome spacer 310. In some embodiments of the present disclosure, the radome 305 has a dielectric constant of less than 4. In some embodiments of the present disclosure, the radome 305 has a loss tangent of less than 0.001.
In one embodiment of the present disclosure, the radome 305 may be constructed of a fiberglass base for mechanical strength. The fiberglass may be laminated with a polymer or copolymer of polyethylene, which may be functionalized with fluorine and/or chlorine. The laminate may be a fluorinated polymer (fluoro polymer), such as polytetrafluoroethylene (PTFE) or a copolymer of ethylene and chlorotrifluoroethylene, such as ethylene chlorotrifluoroethylene (ECTFE). The radome 232 may be fiberglass-reinforced epoxy laminate material, such as FR-4 or NEMA grade FR-4. In other embodiments, the radome 305 may be another type of high-pressure thermoset plastic laminate grade, or a composite, such as fiberglass composite, quartz glass composite, Kevlar composite, or a panel material, such as polycarbonate. In addition, the radome 305 may include a top hydrophobic layer may include a layer having hydrophobic paint or a polytetrafluoroethylene (PTFE) coating.
In accordance with embodiments of the present disclosure, the radome 305 may be a lay-up made from a first layer made from fibrous material, such as fiberglass or Kevlar fibers, preimpregnated with a resin, such as an epoxy or polyethylene terephthalate (PET) resin. The radome 305 may include one or more additional layers that include UV protection and/or water mitigation. For example, a second layer may be made from a fluorinated polymer (fluoropolymer), such as polytetrafluoroethylene (PTFE) to aid in hydrophobic properties resulting in beading of water droplets on the surface of the radome 305. The second layer may include titanium dioxide doping at up to 10% for UV protection.
In one non-limiting example, the radome 305 layers may be combined by a lamination process, which may require activation of the fluoropolymer layer for bonding. Suitable activation may include sodium etching, plasma treatment, flame treatment, or other suitable activation treatments to create bonding sites. In another non-limiting example, the fluoropolymer layer may be coated on the first layer of the radome 305 using an emulsion coating.
The thickness of the radome 305 may be in the range of less than or equal to 60 mil (1.5 mm), less than or equal to 30 mil (0.76 mm), less than or equal to 20 mil (0.51 mm), or less than or equal to 10 mil (0.25 mm). The thickness may depend on the conditions of the environment in which the antenna apparatus 100 resides, for example, with greater radome 305 thickness being used in geographic locations having harsh weather conditions, such as heavy rain and hail. However, a thinner radome 305 may reduce RF signal attenuation from the antenna array. In one embodiment, the radome 305 has a thickness of 0.5 mm.
A radome spacer 310 supports the radome 305 in providing mechanical and environmental protection to the antenna aperture 208 and other electrical components inside the housing assembly 202 of the antenna apparatus 200. The radome spacer 310 also provides suitable spacing between the antenna elements of the antenna aperture 208 and the outer top surface 220 of the radome 305.
In one non-limiting example, the radome spacer 310 is a plastic or foam layer having properties of low dielectric constant, low loss tangent, good compression strength, and a suitable coefficient of thermal expansion (CTE). In addition, the radome spacer 310 may have bondability for bonding with adhesive for coupling with other layers in the antenna stack assembly 300.
Like the radome 305, the radome spacer 310 is also designed to maintain high mechanical values and electrical insulating qualities in both dry and humid conditions over thermal cycling between −40° C. and 85° C. In some embodiments of the present disclosure, the radome spacer 310 has a dielectric constant of less than 1.0. In some embodiments of the present disclosure, the radome spacer 310 has a loss tangent of less than 0.001.
The radome 305 may be adjacent or coupled to a radome spacer 310 to space the outer top surface of the radome 305 from components of the antenna stack assembly 300. As described in greater detail below, such spacing can provide advantages in reduced signal attenuation due to environmental effects on the outer top surface of the radome 305, such as dirt, dust, moisture, rain, and/or snow.
In one embodiment, the radome 305 may be coupled to the radome spacer 310, for example, by adhesive bonding. As mentioned above, the radome 305 and radome spacer 310 may together be referred to as a radome portion or radome assembly 206. The radome spacer 310 may also have a planar and circular shape corresponding to that of the radome 305.
As seen in the cross-sectional view of
The radome spacer 310 may include a spacing configuration to space the radome 305 from the antenna aperture 208 with air. As one non-limiting example, the radome spacer 310 may be made from foam material having air disposed within the structure of the foam. Foam spacers may be advantageous materials in some environments because of their lower dielectric constant and lower thermal conductivity. For example, in cold environments (such as cold climates or for antenna apparatuses 200 disposed on airplanes) foam spacers may provide an insulative effect for electrical components). One suitable foam may be a polymethacrylimide (PMI) or a urethane foam. However, other foams are within the scope of the present disclosure. Foams, unlike other materials described herein having thermal conductivity, may require separate heating systems for snow melt.
In other embodiments, the radome spacer 310 may be a frame structure. In one suitable embodiment, the frame structure may be designed to have air spaces within the structure of the plastic. One suitable frame structure may be a honeycomb structure. A suitable honeycomb structure may be made from a low-loss plastic material (such as thermoplastic or another suitable plastic material), which may be configured in a honeycomb frame construction.
In other embodiments, the radome spacer 234 may be air.
In the illustrated embodiment of
Each of the plurality of cell walls 316 may include an opening at the top, an opening at the bottom, and a vertical pathway therebetween defining an aperture 315 (see
In accordance with embodiments of the present disclosure, the radome spacer 310 may be made of a suitable material for strength and integrity in the antenna stack assembly 300 and also to mitigate any RF interference with antenna signals from the antenna array 308. As described in greater detail below, the apertures 315 in the radome spacer 310 may also be designed and configured such that the thermal path of heat transmits through the cell walls 316 surrounding the apertures 315.
In one embodiment, the radome spacer 310 may be made from a plastic such as polyethylene (PE), such as linear low density polyethylene (LLDPE), high density polyethylene (HDPE), as well as other plastics such as polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chlorine (PVC), or other suitable polymers. A suitable plastic may be thermally conductive and capable of dissipating heat through its structure, while also have a low dielectric constant. In one embodiment of the present disclosure, the radome spacer 310 may have a dielectric constant of less than 3.0, and a thermal conductivity value of greater than 0.35 W/m-K or greater than 0.45 W/m-K.
In particular, LLDPE may be employed, and may have a melt index of from about 10 to about 30 g/min, or alternatively from about 15 to about 25 g/min, or alternatively about 20 g/min at 190° C./2.16 kg. A commercially available suitable LLDPE includes the Bapolene® family of LLDPEs. Radome spacers 310 made from plastic may be formed by injection molding or any other suitable method of manufacture. In addition, radome spacers 310 may include UV additives to protect the radome spacer 310 from any UV light that passes through the radome 305.
Although illustrated and described as a single spacing layer, the radome spacer 310 may be a plurality of spacer elements defining the space between the radome portion 305 and the top layer of the patch antenna assembly 334.
As mentioned above and as shown in
As mentioned above, and as seen in
The cell walls 316 of the interior portion 327 radome spacer 310 may provide a greater proportion of air to mitigate any RF interference with antenna signals from the antenna array 308. In some embodiments, the volumetric ratio of air to solid surface area or the body of the radome spacer 310 is greater than about 50:50, or alternatively greater than about 65:45, or alternatively greater than about 75:25, or alternatively greater than about 80:20, or alternatively greater than about 85:15, or alternatively greater than about 90:10.
The radome 305 and the radome spacer 310 may be joined to each other using suitable joining methods, as described in detail below. Likewise, the radome portion 206 may be joined with a lower enclosure 204 to form the housing 202 of the antenna apparatus 200, as described in greater detail below. In some embodiments of the present disclosure, the radome spacer 310 may include a plurality of projecting fasteners (see
RF signal attenuation due to gain degradation can be significant as a result of rain or moisture accumulation on the planar top surface 220 of the radome portion 206. Regarding rain and moisture accumulation, water has a significant relative permittivity which can introduce a non-trivial interface for an antenna aperture causing RF reflection. Such RF reflection results in gain degradation in the RF signal.
Snow accumulation on the planar top surface 220 of the radome portion 206 was generally not found to be as degrading to the RF signal power as water accumulation. However, snow with any moisture content was found to be degrading, such as snow at or near 0° C., or melting snow or ice resulting in water accumulation on the on the planar top surface 220 of the radome portion 206 was found to significantly degrade the RF signal power.
For moisture mitigation and to aid in the run-off of water or moisture accumulating on the radome 232, the planar top surface 220 of the radome 232 may include a top hydrophobic layer (not shown) having low surface energy to cause water to bead up and not spread out. Non-limiting examples of a top hydrophobic layer may include a layer having hydrophobic paint or a polytetrafluoroethylene (PTFE) coating. In other non-limiting examples, the radome 232 may include additives, such as plasticizers, within the radome 232 to cause the radome 232 have hydrophobic properties.
In addition to surface treatments for the planar top surface 220 of the radome portion 206, tilting of the radome portion 206, as described in greater detail below (see
To mitigate signal attenuation due to the lingering presence of droplets of rain, the top surface 220 of the radome portion 206 is spaced a predetermined distance from the antenna aperture 208. In accordance with embodiments of the present disclosure, the radome spacer 310 provides a suitable thickness to the radome portion 206 (described above) to space the top surface 220 of the radome portion 206 a predetermined distance from the upper patch layer 330 of the antenna elements 306 of the antenna array 304. In one embodiment of the present disclosure, the top surface of the radome portion 206 is equidistantly spaced from the upper patch antenna element of each individual antenna element in the antenna array at a distance of at least 3.0 mm.
The radome reduces the effect of gain degradation due to snow accumulation. With no radome and 1 inch of snow on the antenna aperture, degradation in received power was found to be 4 dB (receiving) and 9 dB (transmitting). Minimum degradation in received power observed over all trials was 0.7 dB and 2.2 dB (with and without radome, respectively). Corresponding maximum degradation was 7.8 dB and 19.4 dB (with and without radome, respectively). With a radome composed of about 3.0 mm foam in accordance with embodiments of the present disclosure, gain degradation was reduced to 0.8 dB (receiving) and 2.6 dB (transmitting).
The radome reduces gain degradation due to water accumulation. With no radome and water accumulation on the antenna aperture, gain degradation was found to be up to 3 dB. With a radome composed of about 3.0 mm foam in accordance with embodiments of the present disclosure, gain degradation was reduced to about 1 dB.
Four radome spacings were measured (with the spacing distance spanning from the top surface of the radome to the top surface of the antenna aperture) to evaluate the effect on gain degradation as a result of rain accumulation: 1.5 mm, 3.0 mm, 4.5 mm, and 6.0 mm. The data showed significant reductions in gain degradation for a radome thickness of 3.0 mm. For a radome thickness greater than 3.0 mm, additional reductions in gain degradation were nominal.
Chassis and/or Lower Enclosure Support of Antenna Stack Assembly
Referring to
In the illustrated embodiment of
In the illustrated embodiment of
The bonding bars 348 of the chassis 345 provide multiple points of bonding between the antenna stack assembly 300 and the chassis portion 204 to mitigate buckling of the PCB assembly 380 (as a result of thermal cycling). In previously designed systems, printed circuit board (PCB) assemblies were generally screwed down to a chassis. Such screw configuration is difficult to design to withstand buckling.
The antenna stack assembly 300 may be bonded to the bonding bars 348 using a low stiffness adhesive to further mitigate buckling. In some embodiments of the present disclosure, the adhesive is an acrylic foam adhesive. In some embodiments, the shear modulus of a 0.5 mm bondline of adhesive is less than 0.34 MPa. In some embodiments, the shear strain capability of the bondline is greater than 150%. The adhesive allows for stress distribution, shock absorption, and has the flexibility to expand and contract to adjust to extreme temperatures without disconnecting from the components to which it is connected. As a non-limiting example, the adhesive may be a VHB brand tape manufactured by 3M Corporation. Such adhesive may have poor heat conductivity.
Although shown as bonding bars 348, other configurations of chassis bonding systems designed to mitigate buckling of a PCB assembly are within the scope of the present disclosure. As a non-limiting example, the bonding system may include a grid of bonding posts instead of bonding bars.
Referring to
The chassis may be made from any suitable material. In one embodiment, the chassis 345 may be made from metal, such as aluminum, or another conductive material to provide a thermal path for heat dissipation from the radiating components in the antenna apparatus 200. The chassis portion 204 may be manufactured as a discrete part, for example, by a process for integrally forming a part, such as a casting process. The bonding bars 348 and the moat sections 350 both add to stiffness of the chassis portion 204. Such stiffness provides advantages in durability. In addition, the bonding bars 348 and the moat sections 350 assist with mold flow during manufacturing.
Extending outwardly around the inner wall 347, the chassis 345 includes a perimeter section 351 configured for interfacing with the radome portion 206. A plurality of detents 346 around the outer perimeter of the chassis 345 accommodate a fastening system 510 (described below) between the radome portion 206 and the lower enclosure 204.
As seen in the illustrated embodiment of
Referring to
Antenna Array
In accordance with embodiments of the present disclosure, phased array antennas described herein include a plurality of antenna elements to simulate a large directional antenna. An advantage of the phased array antenna is its ability to transmit and/or receive signals in a preferred direction (i.e., the antenna's beamforming ability) without physically repositioning or reorienting the system.
In accordance with one embodiment of the present disclosure, a phased array antenna system is configured for communication with a satellite that emits or receives radio frequency (RF) signals. The antenna system includes a phased array antenna including a plurality of antenna elements distributed in one or more rows and/or columns and a plurality of phase shifters configured for generating phase offsets between the antenna elements.
A two-dimensional phased array antenna is capable of electronically steering in two directions. An exemplary phased array antenna may include a lattice of a plurality of antenna elements distributed in M columns oriented in a first direction and N rows extending in a second direction at an angle relative to the first direction (such as a 90 degree angle in a rectangular lattice or a 60 degree angle in a triangular lattice) configured to transmit and/or receive signals in a preferred direction.
In accordance with embodiments of the present disclosure, the antenna stack assembly 300 is designed to meet various goals of antenna performance, heat transfer, and manufacturability. In that regard, antenna performance is most optimal if the upper and lower antenna patches 330a and 370a are spaced from each other by spacers that approximate air with a space above the upper patch 330a that approximates air, while also being thermally conductive. Through-plane heat transfer vertically through the radome spacer 310 and the antenna spacer 335 requires the presence of thermally conductive material (for example, defining the cell walls) in the near vicinity of the upper and lower antenna patches 330a and 370a. Likewise, the manufacturability of the radome spacer 310 and antenna spacer 335 is improved by a minimum wall thickness in the cell structure.
In accordance with embodiments of the present disclosure, the upper and lower patch antenna elements may have a longest dimension in the range of 6 mm to 8 mm. The center of each of the upper and lower patch antenna elements may spaced from the center of adjacent upper and lower patch antenna elements by a distance in the range of 11 mm to 13.5 mm. The cell height of the antenna spacer 335 may be in the range of 1 mm to 2 mm. Likewise, the cell walls of the antenna spacer 335 are in the range of 1 mm to 2 mm wide. The adhesive patterns at either end of the cell walls may have a height in the range of 0.005 mm to 0.01 mm.
A suitable plastic for the antenna spacer 335 may be thermally conductive and capable of dissipating heat through its structure, while also have a low dielectric constant. In one embodiment of the present disclosure, the antenna spacer 335 may be made from the same or similar materials as the radome spacer 310 and may have a dielectric constant of less than 3.0, and a thermal conductivity value of greater than 0.35 W/m-K or greater than 0.45 W/m-K.
The radome spacer 310 may have similar dimensions, properties, and adhesive properties. However, the radome spacer 310 may have a different height than the antenna spacer 335, for example, in the range of 2 mm to 3 mm.
As one non-limiting example, the lower patch antenna element is 6.8 mm in diameter, and the upper patch antenna is 7.5 mm in diameter. In the illustrated embodiment, adjacent antenna elements may be spaced 12.3 mm from each other in a triangular lattice (see
Antenna Layers
Referring to
In the illustrated embodiment of
As illustrated in
In the illustrated embodiment of
In the illustrated embodiment, the array 308 of individual patch antenna elements 304 is formed from a plurality of patch antenna layers, including the upper patch antenna layer 330 (see also
The antenna spacer 335 may be made up of the same or similar materials and by similar manufacturing processes as the radome spacer 310. As seen in
In the illustrated embodiment, the patch antenna assembly 334 is mechanically and electrically supported by a printed circuit board (PCB) assembly 380. The PCB assembly 380 is generally configured to connect electronic components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. The PCB assembly 380 may be a single or multilayer assembly with various layers copper, laminate, substrates and may have various circuits formed therein.
A dielectric layer 375 provides an electrical insulator between the patch antenna assembly 334 and the PCB assembly 380. The dielectric spacer 375 may have a low dielectric constant (which may be referred to as relative permittivity), for instance in the range of about 1 to about 3 at room temperature.
In accordance with embodiments of the present disclosure, in addition to being an electrical insulator, the dielectric spacer 375 may be configured to be a fire enclosure for the antenna apparatus 200. In that regard, the dielectric spacer 375 may be manufactured to have flame retardant properties, for example, by inclusion of 5% decabromodiphenyl ethane (DBDPE) together with the dielectric materials of the dielectric spacer 375. Therefore, the fire enclosure is a part of the antenna stack assembly 300.
In an alternate embodiment, a single layer dielectric spacer may be replaced with an array of discrete spacers, such as puck spacers 575. See, for example,
In typical PCB construction, individual PCB layers are typically made up of fiberglass material surrounding a pattern of copper traces defining electrical connections. The copper and fiberglass having similar CTE values and generally have no purposeful air gaps within the structure. Therefore, the various layers defining a multi-layer PCB can be laminated together under high heat and pressure conditions. In typical patch antenna assemblies, the upper patch layer, the lower patch layer, and the spacing therebetween may be formed using a conventional PCB lamination process.
In contrast to typical PCB lamination, in the design of the antenna stack assembly 300 of the present disclosure, high heat may damage some of the spacing components (e.g., the radome spacer 310 and the antenna spacer 335) of the antenna stack assembly 300. In the embodiments described herein, the spacing components are made from injection molded plastics having purposeful air gaps, which would be damaged under typical PCB lamination process.
In accordance with embodiments of the present disclosure, for improved bonding between dissimilar materials and to avoid lamination heat damage, adhesives may be applied to the various layers of the antenna stack assembly 300 to join the various layers of the antenna stack assembly 300 together. The adhesives described herein for bonding the various layers of the antenna assembly may be any adhesives capable of adhesively coupling adjacent layers to each other.
As described above, plastic materials used in the spacing components (e.g., the radome spacer 310 and the antenna spacer 335) of the antenna stack assembly 300 may include polyethylene (PE) materials including linear low density polyethylene (LLDPE), high density polyethylene (HDPE), as well as other plastics such as polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chlorine (PVC), or other suitable polymers. Suitable adhesives in accordance with embodiments of the present disclosure are capable of bonding to such plastics. Moreover, to allow for assembly alignment, suitable adhesives may be curable adhesives, which may cure in the presence of or as a result of being exposed to heat above room temperature, for instance in a range of 70° C. to 110° C., above 100° C., or in range from about 100° C. to about 325° C. In lieu of heat curing, the adhesive may be curable over time, using UV curing techniques, and/or additives may be added for crosslinking the adhesive. The adhesive may have a dielectric constant of less than 3.0 and a thermal conductivity in the range of 0.1 to 0.5 W/m-K.
As a non-limiting example, a suitable adhesive may be an epoxy adhesive. Epoxy may be any adhesive composition formed from epoxy resins, epoxides, or compounds including epoxide functional groups. The epoxy adhesive may be a one-part self-curing epoxy or a two-part epoxy, either of which may include cross linkers or reactants such as amines, acids, acid derivatives such as anhydrides, thiols, or other functional groups which assist in hardening and cross-linking.
In embodiments of the present disclosure, the epoxy adhesive may be a low durometer adhesive in the range of 25 to 100 (Shore A) to allow for some movement between components as a result of the differences in coefficients of thermal expansion (CTEs) between components in the adhesive layer stack 390. As the antenna apparatus 200 is exposed to heating and cooling cycles during normal outdoor environmental conditions, the different components of the adhesive layer stack 390 may expand and contract in different amounts and at different rates due to CTE mismatch. Therefore, an elastic (low durometer) adhesive allows for some movement of components relative to each other without breaking the adhesive bond between components. Therefore, the adhesive designed for use in accordance with embodiments of the present disclosure holds the layers of the antenna stack assembly 300 in alignment with the PCB assembly 380 over temperature swings and also provided a thermal path for through-plane heat dissipation to the radome 305.
The application of adhesive to the various surfaces of the antenna assembly 300 will be described in detail below. Although illustrated and described as being applied to upper surface of various components in the electronic assembly 300, adhesive may be suitably applied to upper surfaces or undersurfaces of the layering components.
Referring to
In addition to the adhesive layer stack 390, in some embodiments, the PCB assembly may also be adhered by adhesive bonding and heat pressed with the adhesive layer stack 390 as shown by arrow 398 in
As seen in
Moving from top to bottom in the adhesive layer stack 390 in
Arrow 398 indicates the coupling between the PCB assembly 380 and adhesive layer stack 390. The adhesive layer stack 390 may be coupled together first, and then separately coupled with the PCB assembly 380, or the adhesive layer stack 390 and PCB assembly 380 may be coupled simultaneously. In each instance, a heat press may be used, as further described below.
Prior to discussing the coupling of the adhesive layer stack 390 and the PCB assembly 380, each of the individual components of the antenna stack assembly 300 will be described in greater detail.
The radome portion 206 (including the radome 305 and radome spacer 310) has been described above.
As seen in
The upper patch antenna layer 330 further includes an exterior portion 328 extending to its perimeter portion 329, which may include thieving features and/or thermally conductive features, which may be formed from the same conductive metal as the upper antenna patch elements 330a. Accordingly, the exterior portion 329 flows heat radially from the overall electronic assembly 300 outward to the perimeter portion 329 of the upper patch layer 330 and to the perimeter portion 329 of the radome portion 206 (as described in greater detail with reference to
Between the exterior portion 328 and the interior portion 327 of the upper patch layer 330 is a gap section which may contain no conductive features. The gap section and the thieving section isolate the thermally constructive rim from the antenna elements.
In addition to the array of individual upper antenna patch elements 330a, a GPS antenna portion 306 may be provided on the upper patch antenna layer 330 to facilitate GPS use in the electronic assembly 300. As the GPS produces heat, the heat can also be dissipated by the heat dissipation features of the exterior portion 328 of the upper patch antenna layer 330.
In one embodiment, the upper patch antenna layer 330 is a PCB substrate having a plurality of upper antenna patch elements 330a. The features of the upper patch antenna layer 330 may be formed by suitable semiconductor processing to obtain the desired feature patterns and shapes.
As shown in
The lower antenna stack 340 may be made up of one or a plurality of components. For instance, it may be made up of a stack of antenna spacer 335, lower patch antenna layer 370, dielectric spacer, and PCB assembly 380. In contrast to the upper stack 342, the lower antenna stack 340 has a difference shape around it outer perimeter. For example, as shown the layers of the lower antenna stack 340 be generally rectangular with straight edges yet have curved edges. Other shapes maybe suitably employed. The lower antenna stack 340 may be designed to fit within the inner wall 347 of the chassis 345 which may be provided to surround and hold the lower antenna stack 340 in a static position (see
Referring to
In the illustrated embodiment, the lower patch antenna layer 370 includes a grid of conductive material between lower patch antenna elements 370a to create an anisotropic dielectric layer, as described in greater detail below.
As seen in
As seen in
Below the upper and lower antenna patch elements 330a and 370a is the PCB assembly 380, which includes circuitry that may be aligned with the upper and lower antenna patch elements 330a and 370a, which together may form a resonant antenna structure.
The PCB assembly 380 is separated from the lower patch antenna 370 by a dielectric spacer 375.
Antenna Lay-Up and Methods of Manufacture
The adhesive patterning for coupling each of the layers in the antenna stack assembly 300 of
The patterns may have a predetermined design, and may be applied to the top or bottom of one or more of such a layers for example by stencil printing or other methods. The patterns applied to each layer may depend on if the layer is a spacer layer, such as radome spacer 310 and antenna spacer 335, which may include honeycomb structure or apertures. For these layers, the adhesive pattern may be applied along the cell walls forming each of the cell apertures in the honeycomb structure.
The patterns may be applied differently for layers having antenna elements or electronic circuitry, such as the upper patch antenna layer 330, the lower patch antenna layer 370, and the PCB assembly 380.
Each exemplary layer having a specific adhesive pattern will now be described. The radome spacer adhesive pattern 402 may be applied to the upper surface of the radome spacer 310, such that the adhesive is applied along the top of the walls forming the apertures of the cells 315.
The upper patch adhesive pattern 404 may be applied to the upper surface of the upper patch antenna layer 330.
The antenna spacer adhesive pattern 406 may be applied to the upper surface of the antenna spacer surface 335.
The lower patch adhesive pattern 408 maybe applied to the upper surface of the lower patch antenna layer 370.
The dielectric adhesive pattern 410 may be applied to the upper surface of the dielectric spacer 375.
The PCB assembly adhesive pattern 412 may be applied to the upper surface of the PCB assembly 380.
The illustrated adhesive patterns are provided as exemplary patterns in
The close-up adhesive pattern 412/410 for the PCB assembly 380 and the dielectric spacer 375 includes a plurality of adhesive pattern elements 418 shown as discrete hexagonal shapes. The shapes of the adhesive pattern elements 418 may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. While a hexagonal shape is illustrated for the adhesive pattern elements 418, any other polygonal or circular shape including those corresponding to the shape of antenna elements may be suitably employed.
As can be seen in
Referring to
The close-up adhesive pattern 408/406 for the antenna spacer 335 and the lower patch layer 370 will now be described. Like the other adhesive patterns, the shape of the adhesive pattern elements may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. While a 9-sided polygonal shape is illustrated for the adhesive pattern elements 428, any other polygonal or circular shape including those corresponding to the shape of antenna elements may be suitably employed. The adhesive making up the adhesive pattern elements 428 are generally in triangular shapes which may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. Other polygonal or circular shapes including those corresponding to the shape of antenna elements may be suitably employed. In addition, simple dots of adhesive may also be suitably employed.
As seen in
As shown, the adhesive pattern 408/406 for the antenna spacer 335 and the lower patch layer 370 may be distributed evenly across the entire layers (as compared to the other patterns 404 and 402 in which adhesive is provided in different patterns along the outer perimeter portions compared to the interior portions of the associate layers).
The close-up adhesive pattern 404 for the upper patch layer 330 will now be described. Like the other adhesive patterns, the shape of the adhesive pattern elements may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. While a 9-sided polygonal shape is illustrated for the adhesive pattern elements 438, any other polygonal or circular shape including those corresponding to the shape of antenna elements may be suitably employed. The adhesive making up the adhesive pattern elements 438 are generally polygonal shapes which may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. Other polygonal or circular shapes including those corresponding to the shape of antenna elements may be suitably employed.
As seen in
As shown, the adhesive pattern 404 for the upper patch layer 330 is provided in a different pattern along the outer perimeter portions compared to the interior portion of the upper patch layer pattern. A perimeter adhesive pattern for the upper patch layer 330 is designed for secure coupling only the other perimeter.
The close-up adhesive pattern 402 for the radome spacer will now be described. Like the other adhesive patterns, the shape of the adhesive pattern elements may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. While a 12-sided polygonal shape is illustrated for the adhesive pattern elements 448, any other polygonal or circular shape including those corresponding to the shape of antenna elements may be suitably employed. The adhesive making up the adhesive pattern elements 448 are generally triangular shapes which may correspond to the shape of the apertures of the honeycomb structures of the radome and antenna spacers, and/or the individual patch layers of the antenna elements. Other polygonal or circular shapes including those corresponding to the shape of antenna elements may be suitably employed. Likewise, the adhesive may simple be patterned as a plurality of dots to minimize adhesive use.
As seen in
As shown, the adhesive pattern 402 for the radome spacer pattern is provided in a different pattern along the outer perimeter portions compared to the interior portion of the upper patch layer pattern. A perimeter adhesive pattern for the radome spacer 310 is designed for secure coupling only the other perimeter.
The adhesive may have dielectric properties that enhance the antenna performance when applied in a step function with more adhesive closest to the dielectric layer 385 and the PCB assembly 380 and less adhesive in the layers closer to the radome portion 206. As seen in the illustrated exemplary adhesive patterning of
As a non-limiting example, adhesive thickness is generally constant, for example, in a range of about 0.050 mm to about 0.100 mm, or at about 0.075 mm. However, adhesive coverage at each layer may range from, for example, 5%-20% at the uppermost layers to 50%-80% at the lowermost layers, and a middle range at the middle layers. Adhesive in accordance with embodiments of the present disclosure may have a dielectric constant of less than 3.0.
The adhesive may include a stopping mechanism, such as glass beads or plastic bumps, to control spreading when the adhesive layer stack 390 is pressed together. Such stopping mechanisms control spreading providing a small amount of spacing between adjacent layers within which the adhesive resides.
The patterns provided in
In processes designed in accordance with embodiments of the present disclosure, a stencil may be placed on a first layer, which may be, for example, the top surface of a PCB assembly 380, or alternatively, the dielectric spacer 375, or any other of the layers of the antenna stack assembly 300. A stencil is used to apply adhesive in a desired pattern, for instance, one of the patterns of
To press an antenna stack assembly 300, such as the adhesive layer stack 390 of
The curing temperatures may range for example from about 80° C. to about 120° C., or alternatively from 90° C. to 110° C., or alternatively from 95° C. to 105° C., however the temperature should remain below the melt temperature of any plastics with the assembly, such as PE, LLDPE, or HDPE. After curing, the antenna assembly may be placed on a chassis 345, and the antenna apparatus 200 may be joined by a coupling between the radome portion 206 and the lower enclosure 204.
Joining of Radome and Lower Enclosure to Form Housing
As discussed above, the housing assembly 202 includes a radome portion 206 coupled with a lower enclosure 204 to form an interior compartment 250 for components of the antenna stack assembly 300 as well as to prevent the ingress of unwanted dirt, moisture, or other materials. In accordance with embodiments of the present disclosure, the housing assembly 202 may have a fastener system 318 for coupling the radome portion 206 to the lower enclosure 204 with a seal therebetween (see
Referring to
The housing assembly 202 may be exposed to changes and swings in temperature as a result of environmental conditions and/or heating cycles of electronic components. Such temperature changes may impact the thermal expansion of different components of the housing assembly 202. In particular, the components making up the housing assembly 202, such as the radome spacer 310, and the lower enclosure 204 may be made from different materials have different coefficients of thermal expansion (CTE). As a result, the radome spacer 310 and the lower enclosure 204 may expand and contract at different rates of expansion and by different amounts. Likewise, the radome spacer 310 and the lower enclosure 204 maybe exposed to different heating cycles as a result of different components in the antenna apparatus 200.
As result of a mismatch in CTE, undesirable stress may be imposed on conventional fastener systems, which can weaken the housing assembly 202 and may even lead the breakage of certain components of the housing assembly 202. Accordingly, in embodiments described herein, a suitable fastener system is designed and configured to permit the relative movement between the radome portion 206 (including the radome 305 and the radome spacer 310) and the lower enclosure 204 resulting from differences in expansion and contraction amounts of the components. In particular, the fastener system 318 may include radial apertures as fastener receiving portions. Such radial apertures are aligned with a radial axis extending from a central axis of the radome spacer 310 or lower enclosure 204. Such radial apertures permit sliding engagement of fastener portions relative one another radially inward and outward to permit varying amounts of thermal expansion among of the components of the housing assembly 202.
In the illustrated embodiment of
Although shown in the illustrated embodiment of
In alternative embodiments, fastener portions may be radially arranged around the circumferential perimeter of the radome 305 (instead of the radome spacer 310) thereby extending around or through the radome spacer, or in embodiments where no radome spacer is employed. Likewise, the mating fastener portions may be alternatively disposed in the chassis instead of the lower enclosure in some embodiments having a chassis and a lower enclosure, or in embodiments having only a chassis and no lower enclosure.
In the illustrated embodiment of
Referring to
Accordingly, the upper radome spacer 310 couples to and engages the lower enclosure 204 via the engagement of the plurality of projecting fastener portions 520 with the plurality of receiving fastener portions 560. This coupling encloses and forms the inner chambers 355 and 356 above and below the chassis 345 in the housing assembly 202. Within inner chamber 355, the other components of the antenna stack assembly 300 may reside, including the upper patch antenna layer 330 and the lower antenna stack 340 and the chassis 345. Within inner chamber 356, other components relating to the power supply and the tilting mechanism for the antenna apparatus 200 may reside.
The antenna stack assembly 300 rests on the support platform 349 of the chassis 345 and may rest within the inner wall 347 of the chassis 345 which may be provided to surround and maintain the antenna stack assembly 300 in a supported position. The chassis 345 may have a plurality of bonding bars 348 to provide multiple points of bonding between antenna stack assembly 300 and the chassis portion 345 to mitigate buckling (as a result of thermal cycling).
Therefore, the housing assembly 202 is formed with the radome portion 206 (radome 305 and radome spacer 310) at the top and the lower enclosure 204 at the bottom to support with the components of the antenna apparatus therein. Further, all of the components, including the radome 305, radome spacer 310, the chassis 345, and the lower enclosure 204 may all share a common central axis 562 represented by the dashed line 352 in
As seen in
Referring to
The antenna stack assembly 300 including the upper patch antenna layer 330 and the lower antenna stack 340 may generate heat in operation. Further, other electrical components (not shown) associated with the antenna system within the inner chamber 355 may generate heat, such as a modem, Wi-Fi card and Wi-Fi antennas, GPS antenna, or other circuitry or PCB's. The heat generated by the antenna components or other electrical components may cause many of the components making up the housing assembly 202 and the antenna stack assembly 300 to expand and contract (grow and shrink). Further, weather conditions external the housing assembly 202 may involve changes in temperature, which also may impact the expansion and contraction of components making up housing assembly 202.
As discussed above, the radome spacer 310 may be made from plastic such as polyethylene (PE), such as linear low density polyethylene (LLDPE), high density polyethylene (HDPE), as well as other plastics such as polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chlorine (PVC), or other suitable polymers. A suitable plastic may be conductive and capable of dissipating heat through its structure
In contrast, the lower enclosure 204 may be made up of a material, which may be different than the material of the radome spacer. For example, the lower enclosure 204 may be made from metal or from a plastic have good stiffness and that does not creep at temperature. A drawback of a metal lower enclosure 204 is that it is more difficult to form the shape of such a metal component. Because heat conductivity is not required for the lower enclosure, a suitable plastic material for the lower enclosure may be a thermoplastic material, such as a polycarbonate or a polycarbonate and acrylic-styrene-acrylate terpolymer (ASA) blend that offers good resistance to both UV and moisture. Other suitable materials may include thermoplastics, such as polypropylene (PP) or polyphenylene ether (PPE).
The various components making up the housing assembly 202 may have different CTEs. As a result, the various components expand and contract by different degrees and therefore move relative to one another. Consequently, the different degrees of expansion and contraction can cause instability or threaten the structural integrity of the housing. Accordingly, the fasteners as disclosed herein permit the relative movement and sliding of the components relative to one another to accommodate the changes in size as expansion and contraction occurs.
In particular, the coefficient of thermal expansion (CTE) of the lower enclosure 204 may be different than the CTE of the radome spacer 310. Accordingly, the lower enclosure 204 may expand and contract a different degree and/or rate than the radome spacer 310. Furthermore, the components bonded to the radome spacer 310 (such as the radome 305, the upper patch antenna layer 330, and the lower antenna stack 340) may also have different CTEs, and therefore, may expand and contract differently than the lower enclosure 204.
Even if the radome spacer 310 and the lower enclosure 204 were made from the same plastic materials, the radome spacer 310 is disposed within the adhesive layer stack 390. Accordingly, the other components within the adhesive layer stack 390 may mechanically impose contraction and expansion to the radome spacer 310, thereby altering the CTE of the radome spacer 310.
As shown by the dual arrows 388 in
In some embodiments, the lower enclosure 204 may be made from material having a relatively high CTE, for example, equal to or greater than about 50 ppm/° C., alternatively equal to or greater than about 60 ppm/° C., alternatively equal to or greater than about 70 ppm/° C., alternatively equal to or greater than about 100 ppm/° C. In one non-limiting example, a plastic material including a polycarbonate-ASA blend has a CTE in the range of about 60-65 ppm/° C. With a fiberglass additive, the CTE may be in the range of about 40-50 ppm/° C.
In some embodiments, the radome spacer 310 and the antenna spacer 335 may be made from a conductive plastic material having a very high CTE, for example, more than 100 ppm/° C. In one non-limiting example, for LLDPE, the CTE of the radome spacer 310 is 150 ppm/° C. However, because the radome spacer 310 is disposed within and adhesively coupled to the adhesive layer stack 390, the combined CTE changes to a much lower value. For example, radome 305, upper patch antenna layer 330, lower patch antenna layer 370, dielectric spacer 375, and PCB assembly 380, may be PCBs or other non-plastic materials made from fiberglass, copper and other substrate materials, and may have a CTE of less than about 45 ppm/° C., alternatively equal to or less than about 30 ppm/° C., alternatively equal to or less than about 20 ppm/° C. In one non-limiting example, the PCB components in the adhesive stack assembly 390 may have a CTE of about 14 ppm/° C.
Due to the low CTE and general stiffness of most components of the adhesive stack assembly 390, the combined CTE of the radome spacer 310 and the adhesive stack assembly 390 also becomes much lower, such as equal to or less than about 45 ppm/° C., alternatively equal to or less than about 30 ppm/° C., alternatively equal to or less than about 20 ppm/° C. In one non-limiting example, the combined CTE of the radome spacer 310 and the adhesive stack assembly 390 is 17 ppm/° C.
Because of the differences in the CTE values of the plastic components in the assembly, such as the radome spacer 310, the antenna spacer 335, and the lower enclosure 350, and because of the relatively high CTE values of the plastic components compared to the other non-plastic components in the antenna apparatus 200, the plastic components are typically manufactured in temperature controlled environments. With temperature-controlled manufacturing, parts are manufactured to be within tolerances during assembly (which also may be in a temperature-controlled environment).
In addition to manufacturing tolerances, the differences in CTE of the radome spacer 310 and the lower enclosure 350, as well as in the other components of the antenna stack assembly 300 may cause the radome spacer 310 and the lower enclosure 350 to shift relative to one another as the components expand and contract. Accordingly, the plurality of projecting fasteners 520 and the plurality of receiving fasteners 560 are design to accommodate such shifting.
Likewise, the detents 346 around its perimeter of the chassis 345, and the ports 332 in the upper patch antenna layer 330 through which the engaged projecting fasteners 520 and receiving fasteners 560 may pass are also designed and configured to allow a mismatch in expansion and contraction of the radome space 310 and the lower enclosure 204.
As shown in the cross-sectional views of
The projecting fastener portions 320 of the radome spacer 310 engage the receiving fastener portions 360 of the lower enclosure 204 are oriented relative to the housing assembly 202 such that, when engage, the projecting fastener 320 may slide relative to the receiving fastener 360 in both radially inward and radially outward directions from the center of the housing assembly 202. Further, annular seal 325 (see
The receiving fastener 360 includes dual walls 510A and 510B separated by an aperture 515 which is a longitudinal passageway aligned with a radial axis extending from the radome spacer 310 and/or lower enclosure 204. Further, in the embodiment shown, the aperture 515 is open to a radial axis, however in other embodiments it can be enclosed. However, in each case, the aperture 515 provides a passageway aligned with a radial axis extending from the central axis 352 (see
To shift from the disengaged configuration of
Regarding the lower enclosure 204, the plurality of receiving fasteners 360 are provided in the perimeter area of the lower enclosure 204. The lower enclosure 204 also has a center point 560 from which radial axes extend represented by the arrows 565.
As shown, radial axis 570 is aligned with the aperture 515 of receiving fastener 360. The radial axis 570 is shown for representative purposes only; each of the plurality of apertures 515 of each receiving fastener 360 are aligned with a corresponding radial axis extending from the center point 560 of the lower enclosure 204. In particular, the aperture 515 forms a longitudinal passageway aligned with a radial axis 570 extending from the center point 560, which permits sliding engagement of the projecting fasteners 320 extending downwardly from the radome spacer 310 and the aperture 515 of the receiving fasteners 360 on the lower enclosure 204 relative to each other in the radial direction. Such radial movement may be inward and outward relative to the respective center points 550 and 560 of the radome spacer 310 and lower enclosure 204, as the parts expand and contract and shift and move with respect to one another during normal operation of the antenna apparatus 200.
Dissipation of Heat
The dissipation and/or flow of heat generated by the antenna stack assembly 300 and/or other electrical components will now be described with reference to
During operation, heat may be generated by the PCB and other various components in the antenna stack assembly 300. Heat transmitted to the radome portion 206 may be transmitted in a pattern to the radome 305 via the cell walls 316 of the radome spacer 310 or via the chassis 345 to the outer rim of the upper patch layer 330 then to the outer rim of the radome portion 206. In accordance with some embodiments of the present disclosure, the heat dissipated through the radome 305 and the outer rim of the upper patch layer 330 may be sufficient to melt snow and/or ice that may be present on the radome 305. Likewise, the heat dissipated may be sufficient to prevent or inhibit the buildup of such snow and/or ice.
In alternative embodiments, heat may be dissipated via a heat sink or heat spreader, which may extend from a bottom region of the housing assembly on the chassis or lower enclosure. In one non-limiting example, a suitable heat sink may include fins along the length of the external surface of the lower enclosure (see
The radome spacer 310 may act as a heat transfer layer that is configured to facilitate the flow of heat generated by the antenna, electronic components or other components to the outer surfaces of the antenna apparatus 200, for example, through the top surface of the radome portion 206, through the outer perimeter of the antenna apparatus 200, or through the lower enclosure 204. Heat dissipated through the through the top surface of the radome portion 206 or through the outer perimeter of the antenna apparatus 200 can be used for snow and moisture mitigation.
As described above, the radome spacer 310 may include a structure including an interior portion 337 defining a plurality of cell walls 315 and extending toward an exterior portion 338, which is adjacent the outer perimeter 339 of radome spacer 310 (see
While the radome spacer 310 provides a heat dissipation function, the radome spacer 310 includes a large amount of air in the apertures 315 defined by the cell walls 316. This air spacing is designed to align with the antenna elements 304 so as not to impede communication of the antenna array 308. Therefore, the apertures 315 within the cell walls 316 of the honeycomb structure provide a proportion of air, such that the ratio of air to solid surface area or the body of the radome spacer 310. A consistent pattern, such as a honeycomb pattern, in the cell walls 315 radome spacer 310 reduces a potential temperature gradient across the body of the radome spacer 310.
As discussed above, the radome spacer 310 may be adjacent and/or coupled to an upper patch antenna layer 330. The conductive features of the upper patch layer 330 serves as a heat transfer layer. As shown in
At certain locations along the perimeter portion 329 of the upper patch layer 330, the exterior portion 328 may include an intermediate portion 331, which may include gridline features extending in toward the interior portion 327, so as to provide thieving effects to increase the in-plane stiffness of the upper patch layer and better balance the laminate outside of the PCB. The grid features makes the structure less visible to the antenna, while still greatly increasing the stiffness. While the grid features do not have high in-plane thermal conductivity, the solid copper features near the outer perimeter have high in-plane thermal conductivity for heat transfer effects.
In some embodiments, the antenna array 308 may be offset from a center point of the antenna apparatus 200 (see central axis 352 in
The perimeter portion 328 of the upper patch layer 330 may be interrupted by ports 332 through which projecting fasteners 320 of the fastener system 318 may be configured to pass to couple the radome portion 206 (for example, the radome spacer 310) to the lower enclosure 204. However, in some embodiments, the perimeter portion 328 may be a continuous portion without ports 332 or other apertures.
The thermally conductive features on the exterior portion 329 of the upper patch layer 330 may include metal patterning or features on the upper surface of the upper patch antenna layer 330. The metal of the metal features may be a single type of metal, or a mixture of metals, an alloy or a composite having a metal. The metal may be one or more of copper, aluminum, brass, steel, bronze, carbon, graphene, or other thermally conductive metals.
In one embodiment, the upper patch layer 330 may be a PCB layer and the thermally conductive exterior portion 329 of the upper patch layer 330 may be metal features formed on a PCB, such as copper layers on the upper and/or lower surface of the upper patch layer 330. The copper, or other conductive metal, may be patterned to form the discrete antenna elements, thieving elements, and the thermally conductive features.
The thermally conductive features of the upper patch antenna layer 330 may have any thickness suitable for flowing or otherwise conducting heat. The thickness may be in the range about 0.5 mil to about 5.0 mil (about 0.0005 inches to about 0.0050 inches), or about 0.1 mil to about 3.0 mil (about 0.0010 inches to about 0.0030 inches), or about 1.2 mil to about 2.5 mil (about 0.0012 inches to about 0.0025 inches). In one embodiment, the thickness may be about 1.4 mil (about 0.0014 inches). While not being held to any particular thickness in view of differences in materials and conditions, there may be improved benefits in heat dissipation in other thicknesses.
Accordingly, the upper patch layer 330 may accordingly be considered a patch antenna layer and a heat transfer layer or a thermally conductive layer that transfers heat to the radome spacer 310 for heat dissipation through the radome 305.
Referring to
Referring to
As seen in
With the stack assembly 300 thermally coupled to the chassis 345, the chassis 345 may act as a heat spreader to facilitate in-plane thermal flow across its body, including in a direction radially outward from the center axis 352 (see
Extending outwardly around the inner wall 347, the chassis 347 includes a perimeter section 351 configured for interfacing with the radome portion 206. Accordingly, heat may spread along the body of the chassis 345 radially outward to the perimeter section 351, then flow into the conductive features on the upper patch layer 330. Such heat may then further spread radially outward by the conductive features on the exterior portion 338 of the upper patch layer 330 to the radome spacer 310. This conductive path defined by the chassis 345, upper patch layer 330, and radome spacer 310 has the effect of spreading heat in plane, which is shown in
The chassis 345 may extend radially to the same radius as the placement of the plurality of fasteners 320 extending from the radome spacer 330 in the fastener system 318 and may have a plurality of detents 346 around its outer perimeter through which the engaged projecting fasteners 320 and receiving fasteners 360 may pass. The detents 346 that connect with such fasteners 320 and 360 may further aid in heat dissipation from the chassis 345 to the other housing assembly 202 components, such as the radome spacer 330 and/or to the lower enclosure 204 (which also may be made from a conductive material, such as conductive plastic).
Arrows are provided showing the flow of heat. In particular, the arrows 710, 711, and 712 illustrate the flow of heat from the PCB assembly 380 upwards and outward to the perimeter of the radome spacer 305. For instance, as shown by flow arrows 711, the heat may flow through-plane, such as through the cell walls 316 in both the antenna spacer 335 and the radome spacer 310, to the radome 305, from which is dissipates to the surrounding environment.
Furthermore, arrows 714 and 715 show the flow of heat from the PCB assembly 308 downward via the thermal interface material 385 to the chassis 345. The chassis 345 may act as an in-plane heat spreader, and as indicated, heat flows radially along its body, toward the perimeter of the housing assembly 300 and radome 305.
As heat is dissipated to the radome 305, the radome itself spreads heat along its body and/or surfaces, radially in both directions as indicated by flow arrows 712. This heat spreading assists in reducing the temperature gradient across radome 305 so that there is a consistent temperature across its area. As described above, the heat transferred to the radome 305 may be sufficient to melt or inhibit the buildup of snow or ice.
On the left side of
In one non-limiting example, the radome spacer 310 is made from a conductive plastic having a thermal conductivity of about 0.5 W/mK. Because the radome spacer 310 has a short height (for example, about 2.35 mm) compared to a very long in-plane length, the radome spacer 310 generally moves heat along its shorter dimension (i.e., vertically) through the radome spacer 310, but generally has poor in-plane conductivity. To complement the vertical heat dissipation effects of the radome spacer 310, the chassis (or heat spreader) 345 may be made from aluminum, having a thermal conductivity of about 138 W/mK (for 5052 aluminum). Therefore, the chassis 345 is largely responsible for the in-plane heat transfer through the antenna assembly 200. The heat travels downward through the PCB assembly 380 and the TIM material 385 to the chassis 345, then in-plane along the chassis 345 to the outer rim in upper patch layer 330 that is in contact with the chassis 345, and then to the environment at the outer perimeter of the antenna assembly 200. The outer rim of the upper patch layer 330 may include a copper feature, which has a thermal conductivity of about 385 W/mK.
Various features and aspects of the present invention are illustrated further in the examples that follow. EXAMPLE 4 shows the benefit of a perimeter conductive feature on the upper patch layer 330. EXAMPLE 5
Referring to
Referring to
In one embodiment of the present disclosure, the first radome layer 832 is designed to be an outer layer, which is exposed to the outdoor environment and has the properties of good strength to weight ratios and near zero water absorption. So as not to impede RF signals, the first radome layer 832 also has a low dielectric constant, a low loss tangent, and a low coefficient of thermal expansion (CTE). In addition, in some embodiments, the first radome layer 832 has bondability for bonding with adhesive. Without such bondability, the radome lay-up can buckle in extreme weather conditions.
The first radome layer 832 is designed to maintain high mechanical values and electrical insulating qualities in both dry and humid conditions over thermal cycles between −40° C. and 85° C. In some embodiments, the first radome layer 832 has high yield strength and a high enough modulus to spread load on the first radome layer 832 to the second radome layer 834. In some embodiments of the present disclosure, the first radome layer 832 has a dielectric constant of less than 4. In some embodiments of the present disclosure, first radome layer 832 has a loss tangent of less than 0.001.
As one non-limiting example, the first radome layer 832 is fiberglass-reinforced epoxy laminate material, such as FR-4 or NEMA grade FR-4. In other embodiments, the first radome layer may be another type of high-pressure thermoset plastic laminate grade, or a composite, such as fiberglass composite, quartz glass composite, Kevlar composite, or a panel material, such as polycarbonate.
In accordance with embodiments of the present disclosure, the first radome layer 832 has a thickness in the range of less than or equal to 60 mil (1.5 mm), less than or equal to 30 mil (0.76 mm), less than or equal to 20 mil (0.51 mm), less than or equal to 10 mil (0.25 mm). Thicker first radome layers 832 may be used in extreme weather conditions, such as hail conditions.
A second radome layer 834 supports the first radome layer 832 in providing mechanical and environmental protection to the antenna aperture 808 and other electrical components inside the housing 802 of the antenna apparatus 800. The second radome layer 834 also provides suitable spacing between the antenna elements of the antenna aperture 808 and the top surface 820 of the first radome layer 832.
As seen in the cross-section view of the illustrated embodiment in
Like the first radome layer 832, the second radome layer 834 is also designed to maintain high mechanical values and electrical insulating qualities in both dry and humid conditions over thermal cycling between −40° C. and 85° C. In some embodiments of the present disclosure, the second radome layer 834 has a dielectric constant of less than 1. In some embodiments of the present disclosure, the second radome layer 834 has a loss tangent of less than 0.001.
As one non-limiting example, the second radome layer 834 is polymethacrylimide (PMI) foam. In other embodiments, the second radome layer 834 may be a honeycombed low-loss material (as described above) or another suitable foam material (such as urethane foam). In other embodiments, the second radome layer 834 may be air. For example, the second radome layer 834 may include a spacing configuration to space the first radome layer 832 from the antenna aperture 808 with air.
In accordance with embodiments of the present disclosure, the second radome layer 834 has a thickness in the range of greater than 3.0 mm, less than 4.5 mm, or in the range of 3.0 mm to 4.5 mm. The thickness of the second radome layer 834 is described in greater detail above with reference to EXAMPLE 3.
As seen in
As seen in the illustrated embodiment of
When mated with the chassis portion 804, a seal 848 may be formed around the outer radome lip 840 to prevent moisture and dirt ingress at the interface. In one embodiment of the present disclosure, the seal may be a silicone seal. The seal may be formed during manufacture of the antenna apparatus 800 from dispensed material. In the illustrated embodiment of
Referring to
As described above with reference to
In the illustrated embodiment of
The bonding bars 856 of the present disclosure provide multiple points of bonding between the antenna system and the chassis portion 804 to mitigate buckling (as a result of thermal cycling) of the carrier 814 (for example, a printed circuit board (PCB)). In previously designed systems, a printed circuit board (PCB) is generally screwed down to a chassis. Such screw configuration may not be designed to withstand such buckling.
The antenna apparatus 800 may be bonded to the bonding bars 856 using a low stiffness adhesive to further mitigate buckling. In some embodiments of the present disclosure, the adhesive is an acrylic foam adhesive. As a non-limiting example, the adhesive may be a VHB brand tape manufactured by 3M Corporation. In some embodiments, the shear modulus of a 0.5 mm bondline of adhesive is less than 0.34 MPa. In some embodiments, the shear strain capability of the bondline is greater than 150%.
Although shown as bonding bars 856, other configurations of chassis bonding systems designed to mitigate buckling of a PCB are within the scope of the present disclosure. As a non-limiting example, the bonding system may include a grid of bonding posts instead of bonding bars.
Extending around at least a portion of the outer perimeter of the support platform 854 is a moat section 858 of the inner chassis chamber 854. The moat section 858 provides spacing for components of the electronic features of the antenna apparatus 800, such as power inductors. Various city-scaping protrusions 878 extend from the moat section to provide additional support and thermal mitigation to the electronic components of the antenna system outside the regions of the bonding bars 856. In one embodiment of the present disclosure, the city-scaping protrusions 878 are made from a metal material, such as aluminum, and provide a thermal path to the heat sink 920.
The chassis portion 804 may be manufactured as a discrete part, for example, by process for integrally forming a part, such as a casting process. The bonding bars 856 and the moat section 858 both add to stiffness of the chassis portion 804. Such stiffness provides advantages in durability. In addition, the bonding bars 856 and the moat section 858 assist with mold flow during manufacturing.
Referring to the illustrated embodiment of
In one non-limiting example, the one or more antenna pockets 862 and 864 may be Wi-Fi antenna 868 pockets and the card pocket 866 may be a Wi-Fi card 886 pocket.
Referring to
In accordance with embodiments of the present disclosure, the Wi-Fi antennas may be plastic pieces printed with antenna electronics. As a non-limiting example, the antennas may be manufactured using a laser direct structuring (LDS) process. Therefore, the antennas may form a cover, the antenna itself, and a seal for the holes 870 and 872 into the inner chassis chamber 852.
The first pocket section 860 may include shielding such that the Wi-Fi signal emanating from the WI-Fi antennas 868 does not interfere with the beams emanating to and from the antenna aperture 808. In the illustrated embodiment, the shielding includes a flange 898 extending around the rim of the upper surface of the first pocket section 860. The flange 898 is designed to interface with the Wi-Fi card 886 to enclose the Wi-Fi antennas 868 within the shielded pocket. The Wi-Fi card 886 is secured to the flange 898 by a series of screws, with the location of the screws shown by the receiving holes 900 in
When the antennas 868 are inserted in the antenna pockets 862 and 864 extending through the holes 870 and 872, the antennas 868 are configured to form seals with a flange 902 in each of the antenna pockets 862 and 864. The seals prevent dirt or moisture ingress into the inner chassis chamber 850.
Referring to
In the illustrated embodiment, the power supply 882 has a first end 890 connected to an external power source and a second end 892 coupled to the internal electronic circuitry of the antenna apparatus 800. In accordance with some embodiments of the present disclosure, the second pocket 880 is configured such that the first end 890 of the power supply 882 is positioned adjacent the mounting system 810. In the illustrated embodiment, the mounting system 810 is a center-mounted system (see
The second pocket section 880 includes a cover 884 (see
Referring to
In the illustrated embodiment of
In the illustrated embodiment, the fins 922 are equally spaced and parallel to one another and run in a single direction. Comparing
Referring to
The fins 922 of the heat sink are made from a metal material suitable to optimizing heat dissipation, such as aluminum. Likewise, if integrally formed, the chassis portion 804 may be made from the same material, such that the chassis portion 804 also enable thermal migration from the chassis portion to the heat sink 920 for further heat dissipation.
Referring to
Moreover, such spacing from the surface on which the antenna assembly 800 is mounted allows the antenna assembly 800 to be located outside the heat boundary layer of the surface S on which it is mounted. For example, if the antenna assembly 800 is mounted on a roof of a building. The external roof surface may be heated by radiating heat from the sun or by conducting heat from inside the building through the surface of the roof. By spacing the antenna assembly 800 a predetermined distance from the surface S on which it is mounted, the heat sink 922 can avoid being heated by the radiation or conduction heat H emanating from the surface S on which it is mounted (see
Still referring to
Referring to
As described above with reference to
Referring to
Referring to
Referring to
Still referring to
As seen in the illustrated embodiment, the pin 944 may be a roll pin (or a spring pin) to add resistance to the hinge assembly 940, allowing for achieving precision in the mounting angle.
Referring to
As mentioned above, the first portion 966 of the channel 952 of the first knuckle portion 946 is designed to provide an interface for a tilt locking mechanism 970 for the tilt-able mounting system 810. The tilt locking mechanism 970 includes a set screw 934 which is received within a hole 988 defining the tilt locking mechanism 970 in the head 886 of the leg 930. The set screw 934, when tightened, is configured to press against a wedge 936, such that the wedge 936 interfaces with the channel 952 of the first knuckle portion 946 (see
At the base of the leg 930, a mounting device 980 similar to a bicycle seat mounting device provides for a secure mount to a roof receiver (not shown).
Now referring to
After the antenna apparatus 800 is mounted on an external surface of a building, the cabling can be connected to an outlet external to the building.
While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 62/856,730, filed Jun. 3, 2019, the disclosure of which is expressly incorporated by reference herein in its entirety.
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