WO2016183160A1

WO2016183160A1 - Air knife system for antenna radome

Info

Publication number: WO2016183160A1
Application number: PCT/US2016/031792
Authority: WO
Inventors: Brian Cross
Original assignee: Commscope Technologies Llc
Priority date: 2015-05-12
Filing date: 2016-05-11
Publication date: 2016-11-17

Abstract

An antenna system includes an antenna, a radome mounted on the antenna; and an air knife having at least one nozzle that is positioned adjacent the radome. The air knife may blow air cross the radome to reduce or prevent accumulation of moisture on the radome.

Description

AIR KNIFE SYSTEM FOR ANTENNA RADOME

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority under 35 U.S.C. § 119 to U.S.

Provisional Application Serial No. 62/160,137, filed May 12, 2015, the entire content of which is incorporated by reference herein as if set forth in its entirety.

FIELD OF THE INVENTION

[0002] The current disclosure relates to antenna systems and particularly, although not exclusively, to microwave dish antenna systems with radomes.

BACKGROUND

[0003] Microwave dish antennas, used for transmission of electromagnetic-radiation signals, are typically outfitted with an antenna shield and a radome for outdoor operation. The antenna shield functions to attenuate radiation that is emitted from the antenna in undesired directions. The radome provides protection from environmental hazards such as rain, snow, ice, moisture, dirt, and animals.

[0004] Fig. 1 is a top view of conventional antenna system AA including mount AB, dish antenna AC, cylindrical shield AD, and radome AE. The forward transmission direction for antenna AC is indicated by arrow AF. Antenna AC may also be referred to as a reflector antenna. Cylindrical shield AD may comprise a metallic material on the outside, exposed surface and a microwave-absorbent material on the inside surface. Conventional radomes for dish antennas, such as radome AE, may be made of a polymer fabric or other suitable material.

[0005] Fig. 2 is a perspective view of an antenna assembly 9 for another

conventional antenna system comprising dish antenna 7 outfitted with a radome 1 , but no cylindrical shield analogous to shield AD of Fig. 1. Consequently, radome 1 is mounted on the rim of dish antenna 7, thereby covering the antenna aperture.

[0006] Outdoor antenna systems may be exposed to environmental conditions - such as, for example, sub- freezing temperatures and humidity - that cause the formation of ice or frost on components of the antenna system. Although the radome protects the antenna dish from ice accumulation on the reflector and other antenna components, ice can accumulate on the radome itself. Ice accumulation on the radome can degrade the transmission and/or reception performance of the antenna. In addition, ice accumulation on the radome can physically damage the radome, antenna mount, or other components of the antenna system. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a top view of conventional antenna system that includes a dish antenna, an antenna mount, a cylindrical shield and a radome.

[0008] Fig. 2 is a perspective view of another conventional antenna system that includes a dish antenna and a radome but no cylindrical shield.

[0009] Fig. 3 is a perspective view of a conventional air knife system.

[0010] Fig. 4 is a perspective view of an antenna system in accordance with one embodiment of the present invention.

[0011] Fig. 5 is a perspective view of the air knife included in the antenna system of

Fig. 4.

[0012] Fig. 6 is an exploded, inverted, perspective view of the air knife, plug and inlet fitting of the antenna system of Fig. 4.

[0013] Fig. 7 is a perspective view of an air knife in accordance with an alternative embodiment of the invention.

[0014] Fig. 8 is a perspective view of an air knife in accordance with another alternative embodiment of the invention.

[0015] Fig. 9 is a perspective view of a system in accordance with an embodiment of the invention.

[0016] Fig. 10 is a perspective view of an antenna system in accordance with yet another embodiment of the present invention.

DETAILED DESCRIPTION

[0017] Fig. 3 is a perspective view of a conventional air knife system CA comprising blower CB, connector tube CC, air knife CD, and conveyor belt CE. Blower CB is an air pump that compresses ambient air and sends the compressed air via tube CC to air knife CD. Air knife CD receives the compressed air in its air carrier (not shown), which is an elongated plenum chamber, and blows a sheet of air CH out onto conveyor belt CE through a nozzle CJ. Nozzle CJ may be a single narrow elongated nozzle or a compound nozzle comprising a plurality of linearly arranged nozzles connected at regular intervals to the air carrier.

Conveyor belt CE moves in the direction of arrow CF. Air knife CD is metallic and linear, which is well suited for industrial applications such as those described above. Air knife systems such as system CA have multiple industrial uses, such as, for example, drying, cooling, and blowing off dirt or other particles. [0018] Air knives may be modified and adapted for use in antenna systems to prevent the accumulation of moisture - either solid or liquid - on radome surfaces. This is accomplished by creating an air knife that covers the radome surface with a sheet of high velocity air. This sheet of high velocity air, which may be steadily applied, does not allow moisture enough time to adhere to the radome surface and begin the process of forming an ice layer.

[0019] Fig. 4 is a perspective view of an antenna system DA in accordance with one embodiment of the present invention. Fig. 5 is a perspective view of the air knife DE of Fig. 4. Fig. 6 is an exploded, inverted, perspective view of the air knife DE, the plug DL, and the inlet fitting DM of Fig. 4. Antenna system DA comprises dish antenna DB, antenna mount DC, and radome DD. Antenna mount DC is connected to the back of antenna DB and is configured to mount antenna system DA onto a tower or pole (not shown) so that radome DD is substantially vertical. Antenna system DA further comprises air knife DE mounted onto a portion of perimeter DJ of antenna DB. Air knife DE is mounted onto antenna DB using a plurality of mounting holes DH located in mounting lip DN of the air knife DE. Mounting holes DH may be used in conjunction with attachment elements (not shown) such as, for example, screws or rivets, to mount the air knife DE onto antenna DB.

[0020] Air knife DE also comprises tubular air carrier DP, which has a plurality of nozzles DK directed generally towards the outer surface of radome DD. Nozzles DK may be holes drilled or punched into air knife DE. Air knife DE has two ends DF. A first end DF is plugged with plug DL. An inlet fitting DM is inserted in the second end DF. The inlet fitting DM is adapted to interface with a connector tube (not shown) that connects air knife DE to a source of compressed air (not shown), such as, for example, an air pump. The connector tube may be made of rubber or other flexible material. With air knife DE, which is mounted at the top of radome DD, blowing down and gravity pulling down, any droplet that may end up on the outer surface of radome DD should be blown down and fall away from that surface.

[0021] Fig. 9 is a perspective view of system JA, in accordance with an embodiment of the invention. System JA includes antenna system DA of Fig. 4, as well as air pump JB and connector tube JC. Connector tube JC attaches to air knife DE using inlet fitting DM. Air pump JB generates compressed air, which is provided to air knife DE via connector tube JC.

[0022] Fig. 7 is a perspective view of an air knife GE in accordance with an alternative embodiment of the invention. Air knife GE, like air knife DE of Figs. 4-6, has tubular air carrier GP with a plurality of nozzles GK and a mounting lip GN with a plurality of mounting holes GH. In addition, air knife GE has a shielding lip GQ, located along air carrier GP opposite from mounting lip GN. Shielding lip GQ functions like an awning or canopy when air knife GE is mounted on a corresponding antenna (not shown) and helps prevent ice accumulation on the nozzles GK themselves. Note that, in alternative

implementations, shielding lip GQ may be connected to air carrier GP at a different angle and not be directly opposite mounting lip GN.

[0023] Fig. 8 is a perspective view of an air knife HE in accordance with another alternative embodiment of the invention. Air knife HE, like air knife DE of Figs. 4-6, has an air carrier HP with a plurality of nozzles HK and a mounting lip HN. Mounting lip HN does not have mounting holes. Air knife HE may be attached to a corresponding antenna (not shown) using an adhesive or a clamping mechanism.

[0024] A super hydrophobic coating may be added to the radome surface to improve the overall performance of the air knife. The super hydrophobic coating causes moisture to bead and greatly reduces its ability to stick to the radome surface. The super hydrophobic coating may be generated using a commercially available aerosol. Alternatively, it is possible to add microscopic features to the molding tools used to manufacture the radome to change the surface finish of the radome and, thereby, give it hydrophobic properties without the need for additional coatings. Other suitable techniques may also be used to generate a hydrophobic radome surface.

[0025] The air knife may be an extruded part made from UV stabilized UHMWPE (ultra-high-molecular-weight polyethylene) or other suitable flexible material, where the mounting holes and the nozzles may be punched/drilled as a secondary operation after extrusion and prior to rolling the nozzle onto a bulk spool. Bulk packaging allows the air knife to be custom cut to fit different radomes, as needed. In other words, a section of a spooled bulk air knife may be unwound from the bulk spool, measured to fit a particular antenna, and then cut accordingly and subsequently mounted on the particular antenna, the cut section flexing to fit the contours of its mounting location on the antenna.

[0026] The air blown out of the nozzles may be modified from the ambient air in one or more of the ways described below. These modifications may be performed by the air pump, by the air knife, or by additional intermediary components. The air may be dehumidified (i.e., dried) for improved moisture removal. The air may be heated for improved moisture removal. The chemical composition of the air may be modified by adding or removing particular compounds and/or elements. The rate of air flow through the nozzles may be varied - e.g. , pulsed - to improve moisture removal. [0027] The operation of the air knife and/or any of the above modifications may be thermostatically controlled, where the air knife operates and/or the modification is performed only when the ambient temperature is within one or more preset temperature ranges, which may help save energy by avoiding operating the air knife or modifying the air if, for example, the ambient temperature is such that ice formation is unlikely. The operation of the air knife and/or any of the above modifications may be alternatively or additionally hydrostatically controlled, where operation and/or modification is performed only when the ambient humidity is within one or more preset humidity ranges.

[0028] In some embodiments, the antenna system includes a cylindrical antenna shield, like antenna shield AD of Fig. 1, located between, and connecting, the radome and the antenna. In these embodiments, the air knife is mounted onto the end of the antenna shield.

[0029] In some embodiments, the air knife may be a compound air knife comprising a plurality of air knife segments mounted on the antenna or antenna shield adjacent to the radome. The individual air knife segments may be connected to each other with additional connector tubes, with only one air-knife segment connected to the air pump via the connector tube. Alternatively, the individual segments may be individually connected to one or more corresponding air pumps using one or more corresponding connector tubes. The individual segments may be arranged in any suitable pattern around the perimeter of the radome.

[0030] In some embodiments, the air knife and/or connector tube may be made of a rigid, non-flexible material such as, for example, metal or plastic. In some embodiments, the air knife and/or connector tube may be made of, or may be at least partially encased in, an insulating material, such as, for example, polystyrene. The insulation is particularly useful in embodiments that use heated air.

[0031] · In some embodiments, end caps may be used to cap the tube ends of the air knife and be the interfaces into which the above-described plugs and inlets are inserted. End caps may be, for example, machined, cast, or molded metal or plastic.

[0032] In some embodiments, the mounting lip may be different from the exemplary embodiments shown. In some embodiments, the mounting lip may be completely absent.

[0033] In some embodiments, different means may be used to attach and secure the air knife to the antenna and/or radome. For example, the antenna or antenna-shield perimeter may be shaped - e.g., recessed - so as to accept and/or secure the mounting lip of a corresponding air knife. [0034] In some embodiments, the air knife may be integrated with - i. e. , built into - the antenna or antenna shield. In some embodiments, the connector tube, or its equivalent, may be integrated into the antenna and/or antenna shield.

[0035] In some embodiments, the cross-section of the air carrier of the air knife is not circular. In some embodiments, the cross-section of the air carrier varies over the length of the air knife.

[0036] In some embodiments, the nozzles may be shaped, angled, or used in conjunction with grooves or other features in the air knife in order to further shape the generated air flow and, as a result, the sheet of air produced by the air knife. The nozzles may be, for example, elongated laterally along, or extended outwardly from, the air carrier.

[0037] In some embodiments, where the antenna system is vertically mounted, the air knife may be located on a side of the radome, so as to blow beads of moisture sideways. In some embodiments, the air knife may be located on the bottom of the radome.

[0038] In some embodiments, the connector tube is spliced into the body of the air knife rather than being inserted into an inlet fitting at one of the tube ends of the air knife. In some embodiments, a suitable interface other than an inlet fitting is used to interface between the connector tube and the tube end of the air knife.

[0039] Although circular antennas have been described, non-circular antennas - such as, for example, rectangular antennas - may also be outfitted with air knives in accordance with the invention. Rectangular antennas may use flexible air knives as described above or may instead use one or more rigid and/or linear air knives, including conventional air knives.

[0040] Any suitable air pump may be used and may be located anywhere on site with the antenna. One example of a suitable air pump is the Cyclone SSX-150 air pump from Septic Solutions, Inc., of Dieterich, Illinois. A typical antenna system is mounted on an antenna tower. For example, the air pump may be mounted together with the antenna and radome on the antenna tower. Or the air pump may be independently mounted nearby on the antenna tower. Or the air pump may be located in a ground-level utility shed on site with the antenna tower.

[0041] In certain embodiments of the invention, an antenna system comprises an antenna, a radome mounted on the antenna, and an air knife adapted to blow air on the surface of the radome.

[0042] Pursuant to further embodiments of the present invention, air knives such as any of the air knives described above may used in conjunction with antennas that do not include a shield or a radome. For example, in some cases, microwave dish antennas may be used without a radome. Fig. 10 illustrates a dish antenna system KA that includes such an air knife.

[0043] As shown in Fig. 10, the dish antenna system KA includes a dish antenna KB that does not include any antenna shield or radome. The dish antenna KB includes a feed structure in the form of a waveguide KC that supports a sub-reflector KD. The interior of the dish antenna KB and the sub-reflector KD are exposed to the elements since the antenna system KA does not include a radome.

[0044] As shown in Fig. 10, an air knife KE may be mounted around a portion of the perimeter of the dish antenna KB. In the depicted embodiment, the air knife KB is mounted on the rim of the dish antenna KA. The air knife KE may be identical to the air knife DE that is described above, or to any of the other air knives described herein.

[0045] The air knife KE has a tubular air carrier KF that has a plurality of nozzles KG that are directed generally toward the interior surface of the dish antenna KB. In some embodiments, air knife KE may be mounted along the top portion of dish antenna KB (e.g., along the top half of the rim) so that the air emitted from air knife KE blows downwardly onto the interior of the dish antenna KB. This downwardly blowing air, coupled with gravity, may blow any droplets of moisture that fall onto or condensate on the interior of the dish antenna KB downwardly and off of the antenna KB, thereby reducing or preventing the accumulation of ice on the dish antenna KB.

[0046] In some embodiments, the nozzles KG on air knife KE may be designed to blow air over a wider area (as compared, for example, to air knife DE above that is designed to blow air across a radome) in order to ensure that air knife KE blows air across substantially the entirety of the interior of the dish antenna KB. As noted above, the dish antenna KB includes a waveguide feed structure KC with a sub-reflector KD mounted thereon that is mounted within the interior of the dish antenna KB. The air knife KE may be designed to blow air onto both the interior surface of the dish antenna KB and onto the feed structure KC and/or the sub-reflector KD in order to also reduce or prevent the build-up Of moisture and/or ice on the feed structure KC and/or the sub-reflector KD. In some embodiments, the air knife KE may be configured to output a flow of air in a direction that is at a relatively small angle (e.g., less than 30 degrees) with respect to the surface of the interior of the dish antenna KB that the air impinges upon. This may facilitate creating a flow of air that travels along the interior surface of the dish antenna KB to remove moisture therefrom.

[0047] As noted above, in some embodiments, the air knife KE may be designed to not only blow air onto the interior of the dish antenna KB, but to also blow air onto a feed structure KC and/or sub-reflector KD of the dish antenna KB. In such embodiments, the air knife KE may optionally include nozzles KH that are specifically designed to direct air onto the feed structure KC and/or the sub-reflector KD. The nozzles KH may differ from the nozzles KG in, for example, size, shape, location and the like.

Claims

That Which is Claimed is:

1. An antenna system comprising:

an antenna; and

an air knife having at least one nozzle that is positioned to blow air onto one or more components of the antenna system.

2. The antenna system of Claim 1, further comprising a radome that is mounted on the antenna, wherein the air knife is mounted so that the at least one nozzle is adjacent the radome.

3. The antenna system of Claim 2, wherein the air knife is mounted on the antenna.

4. The antenna system of Claim 3, where the antenna comprises a reflector antenna and a cylindrical shield that extends forwardly from the reflector antenna, and wherein the air knife is mounted on the cylindrical shield.

5. The antenna system of Claim 2, wherein the air knife is mounted on the radome.

6. The antenna system of any of Claims 2-5, wherein the radome includes a hydrophobic coating.

7. The antenna system of any of Claims 2-5, wherein the at least one nozzle comprises a plurality of nozzles.

8. The antenna system of any of Claim 1, wherein the air knife comprises: an air carrier that includes the plurality of nozzles;

a compressed air source; and

a connector tube between the air source and the air carrier.

9. The antenna system of Claim 8, wherein the air knife further comprises: a plug that closes a first end of the air carrier; and

an inlet fitting mounted at a second end of the air carrier that connects the connector tube to the air carrier.

10. The antenna system of Claim 8, wherein the air carrier comprises a tubular structure having a plurality of holes that form the respective nozzles, and wherein the tubular structure comprises a flexible material.

11. The antenna system of atiy of Claims 1 , wherein the air knife is mounted to extend at least part of the way around a periphery of an upper half of the antenna.

12. The antenna system of Claim 10, wherein the air carrier further includes a mounting lip that extends from the tubular structure.

13. The antenna system of Claim 12, wherein the air carrier further comprises a shielding lip that extends from the tubular structure.

14. The antenna system of any of Claims 1-5, further comprising a thermostatic control system which controls the air knife to only operate when an ambient temperature is within one or more preset temperature ranges.

15. The antenna system of Claim 14, further comprising a hydrostatic control system that controls the air knife to only operate when an ambient humidity is within one or more preset humidity ranges.

16. The antenna system of any of Claims 1-5, wherein the air knife comprises a plurality of separately formed air knife segments.

17. The antenna system of any of Claims 1-5, further comprising a heater, the heater positioned to heat air that is input to the air knife.

18. The antenna system of any of Claims 1-5, further comprising a dehumidifier that dehumidifies air that is input to the air knife.

19. The antenna system of Claim 1, wherein the air knife is integrated into a reflector of the antenna or into a shield of the antenna.

20. An antenna system, comprising:

an antenna having an open end;

a radome mounted over the open end of the antenna; and

an air knife that has a plurality of air outlets, the air knife positioned so that air is adapted to blow air onto an exposed outer surface of the radome.

21. The antenna system of Claim 20, wherein the antenna includes a reflector dish and the air knife is mounted on the reflector dish.

22. The antenna system of Claim 20, wherein the antenna includes a reflector dish and a radio frequency shield mounted on the reflector dish, and wherein the air knife is mounted on the radio frequency shield.

23. The antenna system of Claim 20, wherein the air knife comprises:

a tubular air carrier that includes the plurality of air outlets;

a compressed air source; and

a connector tube between the air source and the air carrier.

24. A method of reducing moisture accumulation on an antenna system, the method comprising:

using an air knife to blow air across at least one component of the antenna system.

25. The method of Claim 24, wherein the antenna system includes an antenna and a radome, and wherein the air knife blows air across the radome.

26. The method of Claim 24, wherein the antenna system includes a dish antenna and the air knife blows air across an interior surface of the dish antenna.

27. The method of Claim 26, wherein the dish antenna includes a sub-reflector, and wherein the air knife further blows air across the sub-reflector.

28. The method of Claim 24, wherein the air knife comprises:

a tubular air carrier that includes the plurality of air outlets;

a compressed air source; and

a connector tube between the air source and the air carrier.

29. The method of Claim 25, further comprising heating the air before the air is blown across the radome.

30. The method of Claim 25, further comprising dehumidifying the air before the air is blown across the radome.

31. The method of Claim 24, further comprising controlling the air knife to only operate when an ambient temperature is within one or more preset temperature ranges.

32. The method of Claim 24, further comprising controlling the air knife to only operate when an ambient humidity is within one or more preset humidity ranges.

33. The method of Claim 24, further comprising varying a rate at which air flows through the air outlets

34. The method of Claim 25, further comprising modifying a chemical composition of the air before the air is blown across the radome.