By a News Reporter-Staff News Editor at Electronics Newsweekly -- Raytheon Company (Waltham, MA) has been issued patent number 9397400, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.
The patent's inventors are Crouch, David D. (Corona, CA); Kato, Keith G. (Alta Loma, CA).
This patent was filed on September 25, 2015 and was published online on July 19, 2016.
From the background information supplied by the inventors, news correspondents obtained the following quote: "As is known in the art, antenna elements (or more simply 'elements') constituting a phased array antenna have used electric dipoles, for example half-wave dipoles, or coupling slots to transfer energy from a travelling wave within a waveguide mode into the slot and, thereafter, to free space. A topologically deformed version of the half-wave dipole is a patch antenna element having a thin circular plate standing off one-quarter-wavelength (including intervening dielectric materials) from a reflecting plate. The circular plate can be energized by providing radio frequency (RF) signals to multiple input ports. The phase relationship between the ports determines whether a linearly polarized, elliptically polarized, or circularly polarized electromagnetic signal or wave is launched from the plate.
"The patch antenna element has a low dimensional profile, but the thinness of the circular plate has a limiting electric field due to edge enhancement effects, even if contoured Rogowski surfaces are used.
"Slotted arrays using waveguide must cope with the physical dimensions of the waveguide itself. Since the entire generated power must exist in the waveguide at some point, the waveguide must be insulated (e.g. by creating a vacuum in the waveguide) to prevent breakdown of the extremely high waveguide fields (i.e. high power) within the waveguide. Thus vacuum pumps must be included as part of the system design.
"Hence, a need exists for an antenna element that coherently combines the RF outputs from multiple sources and radiates at high peak power levels without inducing air breakdown at an antenna aperture."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "The concepts, systems and techniques described herein find application in high power microwave (HPM) directed energy system architectures for which HPM is generated locally at multiple nodes, but with frequency and phase control characteristics to allow the total power so generated to be combined in free space rather than within a smaller structure such as a waveguide or resonant cavity. While this architecture appears similar to a standard phased array antenna, the power generated at each node can be several tens of megawatts, thus producing a total power-aperture product for the HPM system to be at the gigawatt level--much higher than a standard phased array.
"One advantage of a system utilizing the concepts described herein is the resultant higher power handling capability per node, as opposed to similar architectures using an electric field 'patch' antenna element. Another advantage of a system utilizing the concepts described herein is the reduction of the unit of manufacture to a single quasi-'tile' which can then be emplaced in a field pattern of many tiles. Yet another advantage of a system utilizing the concepts described herein is the elimination of vacuum structures used to prevent breakdown from HPM-level electric fields.
"The concepts, systems, and techniques described herein illustrate a particularly simple scheme to use emerging waveform-generating technology to launch electromagnetic wave energy directly off an antenna aperture surface. The most common method of launching electromagnetic energy into a structure such as a cavity, waveguide, or antenna element, is to use electric field coupling.
"The concepts, systems and techniques described herein, however, use magnetic rather than electric field coupling. This approach allows the construction of a relatively simple, and modular, launching structure. Such a launching structure has an intrinsic power-handling capability which is relatively high compared to launching structures used with electric field-coupled schemes. This is because magnetic coupling utilizes current loops which do not rely on small, high-field gaps as do most electric-field coupling structures.
"In accordance with the concepts described herein, a multiple input loop antenna comprises one or more half-loop antennas disposed above a ground plane. The plane of each half loop is perpendicular to the ground plane. In one exemplary embodiment, coaxial transmission lines feed both ends of each loop in a push-pull configuration, i.e., the input signals feeding opposite ends of each loop are of approximately equal amplitudes and are 180.degree. out of phase. It should be appreciated that while embodiments described herein use 180 degree phasing and equal amplitude input signals it is possible to design a multiloop antenna in which opposite inputs have phase differences other than 180 degrees. Also, one example in which equal amplitude would not be used is in an N>4 linearly polarized antenna wherein half-loops are connected at a common point where the loops converge.
"In accordance with a further aspect of the concepts, systems and techniques described herein, a four-input antenna comprising two loops can be used to combine the outputs from four separate radio frequency (RF) sources, and can radiate either linear or circular polarization, depending upon the relative phases of the signals driving each loop. The radiated polarization can be changed dynamically by appropriately shifting the phases of the input signals. The reflected power at each input contains a direct contribution due to the discontinuity at the feed point, and a contribution due to cross-coupling from other inputs. By properly configuring the antenna geometry, the direct and cross-coupled contributions to the reflected signal can be made to cancel. It should be appreciated that regardless of the number of inputs, by adjusting selected geometric parameters it is possible to force the reflections to partially cancel at the desired operating frequency or over a desired frequency range. A person of ordinary skill in the art will understand which geometric parameters to choose and will be capable of optimizing the antenna geometry via simulation with any of a number of commercial EM simulation tools.
"Unlike most other array elements, the multiple input loop antenna is a three-dimensional structure and electromagnetic waves are radiated from points on the surface of the volume occupied by the antenna rather than from a flat two-dimensional surface. Electromagnetic energy enters the antenna via multiple inputs, avoiding the high concentration of energy that is realized with only a single input. The radiating structure itself avoids sharp edges that can cause air breakdown via edge enhancement. For these reasons, the multiple input loop antenna can radiate levels of peak power without inducing excessive air breakdown which are higher than levels radiated by conventional antennas having comparable transverse dimensions.
"With this particular arrangement, a multiple input loop antenna having high power handling capability, polarization agility, modular unit of manufacture, ability to create an aperture field of arbitrary size and graceful degradation of performance with the loss of a single element is provided. Furthermore, each multiple input loop antenna can be used as an element in an array. Using a plurality of multiple input loop antennas in an array allows quick replacement of a damaged single element."
For the URL and additional information on this patent, see: Crouch, David D.; Kato, Keith G.. Multiple Input Loop Antenna. U.S. Patent Number 9397400, filed September 25, 2015, and published online on July 19, 2016. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9397400.PN.&OS=PN/9397400RS=PN/9397400
Keywords for this news article include: Electronics, Electromagnet, Raytheon Company.
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