Antenna systems provide the interface for both transmission and reception of radio frequency signals. Radio frequency signals cover a broad radio frequency spectrum, such that antennas can vary in size. Antennas may be full wave, half wave, quarter wave, or other fractional sizes of the particular wavelength of the frequency transmitted or detected. In addition, there are various types of antennas ranging in sizes and shapes. Antenna technology is a highly specialized art that requires a high degree of expertise to obtain efficient, workable antenna systems.
An embodiment of the present invention may comprise a patch antenna on an airplane that does not substantially alter aerodynamic characteristics of the airplane comprising: an insulating layer disposed on a portion of the airplane having a dielectric constant that is sufficiently low, and a thickness that is sufficiently great, to function as a spacing element for the patch antenna; an antenna element disposed on the insulating layer, the antenna element having a size that is related to a frequency of a radio frequency signal that is either received or transmitted by the patch antenna, the antenna element and the insulating layer having a combined thickness that does not substantially alter aerodynamic characteristics of the airplane.
An embodiment of the present invention may further comprise a method of forming a patch antenna on an airplane comprising: placing an insulating layer of an insulating material on at least one surface of the airplane, the insulating layer having a dielectric constant that is sufficiently low and a thickness that is sufficiently great, to function as a spacing element in the patch antenna; providing at least one antenna element on a surface of the insulating layer, the antenna element having a size that is related to a frequency of a radio frequency signal that is either received or transmitted by the patch antenna, and the at least one antenna element and the insulating layer having a combined thickness that does not substantially alter aerodynamic characteristics of the airplane.
An embodiment of the present invention may further comprise a patch antenna that is placed on a body of an airplane that uses the body of the airplane as a ground plane.
An embodiment of the present invention may further comprise a method of placing a patch antenna on a body of an airplane so that the patch antenna uses the body of the airplane as a ground plane.
The insulating layers 104, 114, 120, illustrated in
Another insulating sheet that can be used that has a low dielectric constant is biaxially-oriented polyethylene terephthalate (BoPET), which is otherwise known as Mylar. BoPET is a polyester film made from stretched polyethylene terephthalate (PET). BoPET has high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and is an electrical insulator. BoPET (Mylar) has a dielectric constant of 3.1. Biaxially-oriented BoPET film can be metalized by vapor deposition, creating a thin film of evaporated aluminum, gold or other metal. The metalized BoPET film can be laminated with a layer of polyethylene, which provides sealability and improves puncture resistance. Other coatings, such as a conductive indium tin oxide (ITO), can be applied to the BoPET film by sputter deposition. Again, the coated metalized mylar can be attached to the airplane 102 using a contact adhesive, or other curing adhesive, directly onto the desired portion of the body of the airplane 102. The metalized layer that forms the antenna elements 106, 112, 118 can be vapor deposited or sputtered onto a single sheet of mylar, or can be formed in separate individual sheets, for attachment to plane 102. Of course, any plastic sheet, film, or plastic layer can be used as an insulating layer, as long as the plastic sheet, film or layer functions as an insulator and has a sufficiently low dielectric constant, so that the insulating layer functions as an adequate spacing element in a patch antenna.
In that regard, there are a number of other low dielectric insulating materials that can be used as the insulating layers 104, 114, 120, illustrated in
As illustrated in
The antenna elements 106, 112, 118 of antenna arrays 108, 110, 116, respectively, can be placed on the insulating layers 104, 114, 120 using various techniques. For example, a conductive paint, or conductive cladding, can be sprayed or otherwise applied to the insulating layers 104, 114, 120 to create the antenna elements 106, 112, 118. Various other application techniques can be used to apply the antenna elements 106, 112, 118 to insulating layers 104, 114, 120. In that regard, various masking techniques can be used, including silk screening techniques, for applying the antenna elements 106, 112, 118 to the insulating layers 104, 114, 120. For example, a conductive-type of paint or cladding can be silk screened directly onto the insulating layers 104, 114, 120 to create the conductive antenna elements 106, 112, 118. Various types of paints can be used, that contain conductive materials, such as carbon, copper, or other conductive materials immersed in high concentrations in the paint, so that the painted antenna elements are conductive. Other techniques, such as photolithography, can also be used to form antenna elements 106, 112, 118. Alternatively, the thin insulating layers 104, 114, 120 can be formed in sheets, which can then be coated with the conductive material that forms the antenna elements. Either one single sheet, or a number of individual sheets, can be used for multiple antenna elements. The insulating sheets can be coated with a conductive material to form the antenna elements using various techniques, including sputtering, photo deposition, silk screening, electroplating, painting, or any desired method known to those skilled in the art. The insulating layer sheets 104, 114, 120 may be coated with an adhesive, so that the flexible insulating sheets can be applied directly to the aluminum surface of the airplane. The outside surface of the conductive layers can also be covered to protect the patch antenna.
The antenna elements 106, 112, 118 can form both Euclidean and non-Euclidean shapes. Non-Euclidean shapes can be used to match the surface of the body or wing of the airplane 102. Various curvatures of the conformal antenna elements can be used to match the surfaces of the body and wings of the airplane 102. These curvatures may affect the directionality and shape of the transmitted and received beams. Further, the elements can be formed in various curved, non-Euclidean shapes, including hyperbolic shapes and elliptical shapes. In fact, the antenna elements can take any desired curved shape to match portions of the body and wings and other portions of the airplane 102.
Patch antennas, such as patch′antennas 234, 236, are also known as rectangular microstrip antennas. Patch antennas are a type of radio frequency antenna that has a low profile. As illustrated in
The patch antennas disclosed in
Patch antennas inherently provide structures that can easily operate at microwave frequencies. For example, half wavelength antennas for 110 MHz are approximately 1.3 meters, which results in an antenna element which is slightly less than approximately 1.3 meters. A 4 GHz radio wave has a half wavelength of approximately 7.5 cm, which results in an antenna element that is slightly less than 3.75 cm. Accordingly, the physical size and shape of the antenna elements is such that the antenna elements can be easily formed using simple screening or masking techniques, in the manner described above. While square shaped antenna elements create a linearly polarized beam, rectangular shaped antenna elements create a beam that is fan shaped. The bandwidths of a fan beam created by a rectangular shaped antenna element vary from the orthogonal to the parallel direction of the antenna element. Circular polarization of a patch antenna can be created by having two feeds on adjacent sides of the antenna element using phased delayed signals. For example, a 90° hybrid coupler can be used to create a 90° phase shift in one of the orthogonal signals. In addition, various types of polarization can be created, including circular polarization, by the addition of slots in the antenna element. For example, a diagonal slot in an antenna element may create circular polarization by the redirection of current along the surface of the antenna element. Circularly shaped antenna elements may assist in creating circular polarization using these diagonally oriented slots. A circular antenna element having a single feed will create linear polarized radiation. If a circular antenna element is perturbed into an ellipse and fed properly, a circular antenna can create circularly polarized electromagnetic waves with a single feed.
Further, by coupling multiple antennas at the same frequency in the multiple antenna arrays, additional directivity can be achieved. In that regard, the phase of each of the antennas at the same frequencies can be adjusted to adjust the directivity of the combined beam in a manner similar to phased array antennas, so that the directional beam or lobe of the three different antennas at the same frequency form an array that can be directed and moved in accordance with the desired direction of the antenna beam. For example, the half wave 1.3 meter antenna elements in each of the antenna arrays 108, 110, 116 may be phase adjusted so that the combined signal forms a lobe that is directed in a forward-looking direction to monitor transmissions that emanate from the forward path of the direction of flight of the plane. Restricted air space exists in various geographical locations, and planes cannot fly into these restricted air spaces. The lobe of the combined beam can be directed to the side of the plane, so that the plane can fly adjacent to a restricted airspace and still detect radio frequency emissions from within the restricted air space. Again, this is simply done by adjusting the phases of the signals received by the antennas having the same frequency in the various antenna arrays, so that the combined beam has a lobe that is directed in the desired direction. Transmitted waves can also be directed in this manner.
Accordingly, simple patch antennas, such as patch antenna 234 and patch antenna 236, can be fabricated on the surface of an airplane using inexpensive techniques that have an extremely low profile that does not significantly affect the aerodynamic shape and qualities of the airplane 102. In that regard, any slight change in the thickness of the surface of an airplane may slightly affect the aerodynamic qualities of the airplane. Accordingly, it cannot be said that patch antenna do not affect the aerodynamic qualities of the airplane at all, since very slight changes may cause these changes. For example, re-painting a plane may affect the aerodynamic qualities of a plane. These aerodynamic effects may not even be detectable by a pilot, since they are so slight. On the other hand, thicker patch antennas may more significantly affect the aerodynamics of an airplane, especially if the patch antennas are placed on an important aerodynamic surface, such as the upper or lower portions of the wing. Accordingly, the term not “substantially” is used to indicate that some aerodynamic effect may be created by the patch antenna, and some effects may or may not be noticeable. However, the term not “substantially” does not include effects that are so great that the aerodynamic characteristics of a plane would cause the plane to be unflyable.
The patch antennas disclosed herein do not have significant weight and do not substantially or significantly affect the aerodynamic characteristics of the airplane 102. These patch antennas can be easily modified to transmit and receive various types of polarized microwave signals at a wide range of frequencies using an extremely low cost structure. The airplane 102 is ideally suited for the patch antenna structure, since the airplane body creates a large ground plane that increases the directivity and the gain of the patch antenna.
The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.
This application is a non-provisional application of U.S. Patent Application Ser. No. 61/782,428, entitled “Airplane Patch Antenna,” filed by Donald M. Bishop on Mar. 14, 2013. The entire contents of the above mentioned application are hereby specifically incorporated herein by reference for all they disclose and teach.
Number | Date | Country | |
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61782428 | Mar 2013 | US |