Patent Application
20130342412
In general, in order to transmit or receive signals included in electromagnetic waves, a transmitter and/or receiver is connected to an antenna. The antenna converts transmitted electrical signals into electromagnetic waves and received electromagnetic waves into electrical signals. There are many types of antennae depending on the use, such as vertical and dipole antennae. However, in order to improve the signal reception, such antennae can include a beam-forming element. One example of such a beam-forming element is a parabolic reflector which focuses the electromagnetic waves at a focal point.
Another type of antenna is a horn antenna. In general, the horn antenna is a flaring metal waveguide which directs electromagnetic waves in a beam. As such, the smaller end of the horn antenna is connected to transmission/reception electronics and the flared end is open. Horn antennas are used as directive antennas for such devices as radar guns, automatic door openers, microwave radiometers, as well as to calibrate gain in other antennas. Horn antennas are also useful to feed electromagnetic waves for larger antenna structures, such as parabolic antennas used for satellite communications, detection of signals from space, etc. In this context, the horn antenna is called a feedhorn antenna and is placed at or near the focal point of the parabolic reflector. The feedhorn antenna conveys electromagnetic waves between the transmitter and/or receiver and the reflector.
While a horn antenna can be used within a protective structure, when the horn antenna is located in an outdoor environment, there is a need to protect the horn portion of the antenna from environmental contamination. For instance, when mounted to a parabolic reflector as used in a satellite dish, the feedhorn antenna would necessarily be located in places where water, yard debris, and animals or insects could cause harm to the feedhorn antenna and degrade its performance. Therefore, the opening of the horn antenna needs to be closed.
The closure of the opening can be accomplished using epoxy to glue a cover to the opening, the cover can be press fit onto the horn antenna, or the cover could snap on to the opening. However, these methods still result in defective seals, such as where the epoxy is not sufficiently thick or the cover does not snap on or press fit securely. As such, the closure may be insufficient to prevent long term environmental damage in a real world environment.
According an aspect of the invention, an antenna for use with electromagnetic waves includes a waveguide body having an open end and first threads; and a cap having second threads which interface with the first threads to press the cap against the open end, the cap comprising a cover which covers the open end when the cap is screwed onto the open end using the first and second threads while allowing the electromagnetic waves to pass through the cover.
According an aspect of the invention, a reflector antenna includes a reflector which receives the electromagnetic waves and focuses the received electromagnetic waves at a focal point; an antenna which includes a waveguide body having an open end and first threads and a cap having second threads which interface with the first threads to press the cap against the open end, the cap comprising a cover which covers the open end when the cap is screwed onto the open end using the first and second threads while allowing the electromagnetic waves to pass through the cover; and a feed support which supports the antenna relative to the reflector such that the electromagnetic waves are received at the open end after passing through the cover.
According an aspect of the invention, a method of assembling an antenna for use with electromagnetic waves includes aligning a waveguide body having an open end and first threads with a cap having second threads which interface with the first threads; and screwing the cap to the open end using the first and second threads until the cap is attached to the waveguide body and a cover of the cap covers the open end, wherein the cover is transparent to the electromagnetic waves.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
While not limited thereto, an embodiment of the invention shown in
As shown in the system of
In the shown embodiment, the satellite 130 would be in geosynchronous orbit about 22,000 miles above the earth. However, it is understood that in other aspects, the orbiting satellite 130 could instead be in a non-geosynchronous orbit or at other altitudes, or could be an aircraft which relays ground signals between terrestrial stations. Moreover, while shown as a single satellite 130, it is understood that the satellite 130 could be part of a larger system of satellites which interact with each other to provide communication services.
The satellite 130 receives the request from the satellite dish 120 and transmits the request to the Network Operations Center (NOC) 140. The NOC 140 accesses the requested website on a server 150 via a network, such as the internet. The NOC 140 transmits the accessed website to the satellite 130, which in turn beams the website back to the computer 110 via the satellite dish 120. As such, while not limited thereto, the satellite internet system uses a satellite dish 120 which is capable of both transmission and reception.
While other shapes can be used in other aspects, the dish 220 has a parabolic shape designed to capture incoming electromagnetic waves. At substantially a focal point of the dish 220 is a feedhorn 240. The feedhorn 240 is a waveguide, usually shaped in the form of a cylindrical structure. The feedhorn 240 is supported relative to the dish 220 by a feed support 230. As shown, when transmitting (such as when there is a request for the website sent as in
As shown in
A cap 340 covers the horn 320 in order to separate an interior of the horn 320 from the elements, such as by keeping moisture out of the horn 320. The cap 340 is transparent to the electromagnetic waves transmitted from or received at the horn 320. While not required in all aspects, the cap 340 can also be transparent to other spectra, such as visible light to allow inspection of the horn 320 when the cap 340 is installed. While not limited thereto, the cap 340 could be made of plastic, such as polypropylene or polycarbonate.
Further, the shown cap 340 has grips 345 to allow the cap 340 to be screwed onto the horn 320 using the threads 350, 360. In this way, when the cap 340 is screwed onto the horn 340, there is a compressive connection between the cap 340 and the horn 320 which is easy to create during manufacture without special equipment or delays, such as occur when using epoxy or press fitting. Such an arrangement also allows the cap 340 to be removed after assembly in aspects of the invention which is also not easily done when a cover is connected using an epoxy or press fitting. While not shown, it is understood that an additional seal could be used, such as a sealant at the threads 350, 360.
Additionally, while shown as having threads 350 at the exterior of the horn 320 and the threads 360 at the interior of the cap 340, it is understood that the threads 350, 360 can be otherwise disposed. For instance, the threads 350 could be at the interior of the horn 320 and the threads 360 on the exterior of the cap 340. As such, aspects of the invention are not limited to the location of the threads 350 relative to an interior or exterior of the horn 320.
Moreover, the location of the threads 350 relative to the end of the horn 320 can be varied. For instance, if the cap 340 edge was elongated, the threads 350 could be on the cylindrical waveguide portion 330 or at the mount 310. As such, aspects of the invention are not limited to the location of the threads 350 relative to an edge of the horn 320.
Also, while shown as helical threads 350, 360, it is understood that the threads 350, 360 need not be helical in shape, can have horizontal elements, need not be identical in shape and/or be other interlocking but complimentary members. While not limited thereto, the threads 350, 360 could interlock using a bayonet mount, by which one of the threads 350, 360 is a pin, and the other of the threads 350, 360 is an L-shaped slot which receives the pin in one direction as the cap 340 is connected and holds the cap 340 when the cap 340 is twisted in a second direction.
The cap 340 includes a cover 370 which separates the exterior environment from the interior of the horn 320. The cap 340 need not be of the same material as the horn 320, such as where the horn 320 is made of aluminum and the cap 340 is made of plastic, but the invention is not limited thereto. Further, the cover 370 could further be transparent to visible radiation, thereby allowing visible inspection of the horn 320. This transparency could be created by the cap 340 being made of a transparent plastic material, or through the cover 370 including a window portion.
While not required in all aspects, an edge of the horn 320 could include an O-ring groove which receives an O-ring to prevent a further seal to prevent any damage due to environmental factors. A matching O-ring could be installed in the cap 340, or could be separately placed on the horn 320. Such an O-ring would be made of a sealing material, such as a rubber or plastic, which would add a further layer of seal. However, the invention is not limited thereto.
According an aspect of the invention, when attaching the cap 340 to the horn 320, the threads 350 are aligned with the threads 360, and the cap 340 is screwed onto the horn 320 such that the cover 370 covers the horn 320. The attachment could occur during an inspection, in which case the cap 340 was unscrewed from the horn 320, or during manufacture. For instance, where an environmental test is performed during manufacture, the cap 340 could be left off to allow direct access to the horn 320. On completion, the cap 340 would be screwed onto the horn 320, and the feedhorn 240 could be attached to the feed support 230. However, it is understood that the invention is not limited to the particular time or order for connection of the cap 340 to the horn 240. It is understood that, while described in terms of attachment using a rotation screwing motion, the invention is not limited to any particular clockwise or counterclockwise direction or to a rotational motion as any connection would depend on the shape of the threads 350, 360.
While described in terms of a satellite dish, it is understood that the feedhorn antenna could be used in other situations, such as a horn antenna used without a parabolic reflector dish or where used as a feedhorn antenna in other shape reflectors. Moreover, while described in terms of prevent environmental contamination in the context of moisture, it is understood that the seal strength could be made to vary depending on the need, such as where the feedhorn would be used underwater or in space. In this context, the strength of the seal could be varied through adjustment of the number of threads 350, 360. Also, while shown as being solid, it is understood that the cap 370 could be made porous in other aspects, such as where moisture is less of a concern than foreign object debris.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
