Abstract: An antenna system includes a plurality of antenna elements arranged in an array having a plurality of array elements. Each antenna element has a radiator extending from a radiator feed end to a radiator terminal end, where a first straight-line distance from the radiator feed end to the radiator terminal end is less than ?/4, ? being a longest wavelength of a bandwidth of the antenna element. Each antenna element also includes a counterpoise extending from a counterpoise feed end to a counterpoise terminal end, where a second straight-line distance from the counterpoise feed end to the counterpoise terminal end is less than ?/4. The counterpoise feed end is spaced apart from the radiator feed end. The radiator and the counterpoise diverge at an acute angle from an area encompassing the radiator feed end and the counterpoise feed end.

Abstract: An antenna includes two radiators that are co-planar and exhibit mirror symmetry about an axis. Each radiator includes a half-Vivaldi sub-radiator bounded by a first curved edge and a first straight edge adjacent to the first curved edge. Each radiator also includes a curved monopole sub-radiator that is bounded by a second curved edge and a second straight edge adjacent to the second curved edge. The first and second straight edges coincide such that the first and second curved edges are continuous. When the antenna is driven at relatively high frequencies, the half-Vivaldi sub-radiators cooperate to act like a planar Vivaldi antenna. At lower frequencies, the curved monopole sub-radiators cooperate to act like a planar dipole antenna. Two of these antennas may be fabricated on circuit boards that intersect to form a dual-polarization antenna system.

Abstract: A pair of radar nodes, each with full azimuthal coverage, cooperate to identify the position of an object without explicit measurements of the object's azimuthal coordinate. A first radar node, operating within a first azimuth field of view (FOV), measures a first elevation angle and a first slant range of the object. A second radar node, operating within a second azimuth FOV, measures a second elevation angle and a second slant range of the object. The second radar node transmits the data to the first radar node, which identifies, based on the first and second azimuth FOVs, an object half space within which the object is located. The first radar node then calculates the position of the object without an ambiguous solution. Alternatively, the first radar uses the first and second azimuth FOVs to identify and reject the ambiguous solution.

Abstract: A method for controlling an antenna array includes determining, based on a beamstate, an initial weight vector of excitations. The initial weight vector is transformed into an active-impedance vector. When the modulus of any element of the active-impedance vector exceeds a threshold, the initial weight vector is unsafe. In this case, a substitute weight vector is identified such that (i) the initial and substitute weight vectors have a similarity measure that exceeds a similarity threshold and (ii) the substitute weight vector is safe. The antenna array may then be driven according to the substitute weight vector to emit radiation having a radiation pattern that approximates that of the beamstate. The substitute weight vector may be found by searching a library of safe weight vectors or by adjusting the excitations of the initial weight vector until a safe alternative is found.

Abstract: An antenna feed for a stackable antenna system includes a polarization converter that continuously surrounds an omnidirectional antenna. Electromagnetic radiation emitted by the omnidirectional antenna and having an initial polarization passes through the first polarization converter, which converts the initial polarization into a non-vertical linear polarization. A feedline located outside of the first polarization converter forms a helix that wraps around the first polarization converter such that it runs perpendicularly to the non-vertical linear polarization. When the width of the feedline is sufficiently small, electrons in metal of the feedline will not be excited by the radiation, and the radiation will transmit through the feedline with minimal impact on the omnidirectional antenna's gain profile. The feedline may be used to feed a second antenna located vertically above the omnidirectional antenna.

Abstract: A filtering power divider includes a first partial transmission line having a first electrical length, a second partial transmission line having a second electrical length, and a third partial transmission line having the second electrical length. The first, second, and third partial transmission lines connect to form a T-junction, and a sum of the first and second electrical lengths is ninety degrees. Thus, the first and second partial transmission lines cooperate to act as a quarter-wave transmission line. Similarly, the first and third partial transmission lines cooperate to act as a quarter-wave transmission line. Additional transmission lines may be connected to the first, second, and third partial transmission lines to implement a filter between an input port and each of two output ports.

Abstract: An array antenna with dual polarization elements is provided. Each dual polarization element comprises a first sub-element and a second sub-element, each of which comprises a radiator that is embodied in and/or on a planar member and a balanced feed for the radiator that divides the radiator into two sections that that are mirror images of one another relative to a plane that passes through the balanced feed structure and is perpendicular to the planar member. Further, the radiator of the first sub-element is positioned to lie in an isolation plane associated with the second sub-element. Two such elements are positioned with respect to one another so that the planar members associated with the first elements are coplanar.

Abstract: The invention is directed to an antenna structure for producing a horizontally polarized beam. In one embodiment, the antenna structure includes a first quarter-wave patch antenna and a second quarter-wave patch antenna that are positioned such that the ground planes of the patch antennas or a ground plane shared by the patch antennas is disposed between the patches of the two antennas and the shorting structures associated with the antennas are substantially aligned. In operation, the antenna structure is capable of processing an omni-directional, horizontally polarized beam.

Abstract: An embodiment of the invention is directed to a method for manufacturing a radiator structure for a conical helical antenna that includes: (a) processing a piece of metal so as to produce a first metal structure with conical exterior and interior surfaces, and (b) processing the first metal structure to remove material between the conical exterior and interior surfaces to yield a radiator structure with a conical helical shaped conductor that can be combined with a ground plane to produce a conical helical antenna. In one embodiment, the radiator structure includes a matching structure and a cap with the conical helical conductor, matching structure, and cap being a single piece of metal.

Abstract: The invention is directed to an antenna array comprised of conical helical antennas with at least one of the antennas being a tilted conical helical antenna. In one embodiment, a tilted conical helical antenna in the array comprises an electrically conductive wire that follows a helical path on a frustum of an oblique elliptical cone in which the axis of the cone is tilted relative to the planar base surface of the cone (i.e., not perpendicular or parallel to the surface) in a plane defined by the axis and a phase center axis of the array. Each of the tilted conical helical antennas in an array is spaced from the phase center axis of the array. The degree of tilt increases the farther an antenna is located from phase center axis.

Abstract: The invention is directed to a dual-frequency stacked patch antenna. In one embodiment, the antenna comprises a pair of electrically conductive, nested, tub-like structures and a feed surface. The edges of the tub-like structures and the feed surface define a surface that is adapted to be conformal to an application surface that defines a cavity in which the antenna is positioned. The edges of the tub-like structures and the edge of the feed surface define a pair of slots for receiving and/or transmitting two signals with different center frequencies. Located and extending throughout each of the slots is a slot modification structure comprised of inter-digitated fingers that provide capacitive loading and enhance the low observability of the antenna.

Abstract: The invention is directed to a crossed-dipole antenna structure that, in one embodiment, is comprised of: (a) a first planar dielectric substrate with a feed portion and an antenna portion that supports a first dipole antenna and (b) a second planar dielectric substrate that supports a second dipole antenna or substantial portion of such an antenna. The first and second planar dielectric substrates are positioned substantially perpendicular to one another and so as to form a crossed-dipole antenna from the first and second dipole antennas. The feed portion of the first planar dielectric substrate is electrically and mechanically connected to the second planar substrate by a plurality of solder joints established in the corners defined by the intersections of the first and second planar dielectric substrates.

Abstract: A broadband antenna system is disclosed. The antenna system relates to a cylindrical structure, wherein the feed region comprises segmented radiators with tapered feed points, distributed around the circumference of the structure, and a balun that is co-planar with the cylindrical structure. This allows a plurality of feed lines, cables, piping, or other structures to be run through the center of the antenna without interfering with the performance of the antenna system. Segmentation of the radiators permits the integration of a corporate feed network, suppresses overmoding, and permits operation without the need for a ground plane. The invention further relates to a stacked broadband antenna system wherein additional antenna elements or devices may be stacked collinearly on the antenna structure and operated via the plurality of feed lines or other structures. The overall system thus provides a wide range of transmitting, receiving, sensing and other capabilities over a virtually infinite bandwidth.

Abstract: The present invention is directed to a monopole/dipole symmetric radiator structure that includes a symmetric planar radiator. When the symmetric radiator is part of an operative monopole or dipole antenna, the antenna exhibits a wide or broad bandwidth, a VSWR of less than about 3:1, a relatively constant gain perpendicular or broad-side to the plane of the radiator, and is vertically polarized. In one embodiment, the symmetric planar radiator has an outer edge that is bilaterally symmetrical. In another embodiment, the outer edge of the symmetric planar radiator is bilaterally symmetric and a closed inner edge of the radiator that defines a void is also bilaterally symmetric.

Abstract: The present invention is directed to a monopole/dipole asymmetric radiator structure that includes an asymmetric planar radiator. When the asymmetric is part of an operative monopole or dipole antenna, the antenna exhibits a wide or broad bandwidth, a VSWR of less than about 3:1, a relatively constant gain perpendicular or broad-side to the plane of the radiator, and is vertically polarized. In one embodiment, asymmetric planar radiator has an outer edge that is bilaterally asymmetrical. In another embodiment, the outer edge of the asymmetric planar radiator is symmetric and a closed inner edge of the radiator that defines a void is bilaterally asymmetric.

Abstract: The present invention is directed to an antenna system that includes a broadband free-space antenna (i.e., an antenna that does not utilize a ground plane to create a resonant structure) and a high-impedance backing that allows the antenna to be positioned adjacent to a conductive surface that but for the high impedance backing would adversely affect the broadband operation of the antenna. The high-impedance backing substantially preserves the bandwidth of the antenna while also allowing the antenna to be positioned within ?/4 of the conductive surface and accommodate a predetermined amount of power.

Abstract: The present invention is directed to an antenna system comprising two rigid portions, an electrical conductor located between the two rigid portions, and a connector that extends between the two rigid portions and: (a) allows the position of one of the rigid portions relative to the other rigid portion to be altered when a force is applied to one of the rigid portions, such as when one of the rigid portions encounters an obstacle, and (b) maintains the altered position until a subsequent force is applied. In one embodiment, the connector comprises a ball-and-socket joint with the spring force produced by the socket causing sufficient frictional force between the ball and socket so that the position relationship of the ball to the socket is maintained when only gravity is being applied to the rigid portions and the connector but allowing the positional relationship to be altered when an additional force is applied.

Abstract: The present invention is directed to fuze system for munition that produces a height-of-burst (HOB) signal using two Global Positioning System (GPS) signals, the first signal being from a particular GPS satellite (the direct GPS signal) and the second signal being the GPS signal from the same GPS satellite after the signal has been reflected from the surface adjacent to the target. In one embodiment, the HOB signal is generated when there is a substantial correlation between the reflected GPS signal and direct GPS delayed by an amount of time that is indicative of the desired HOB.

Abstract: A radar system having orthogonal antenna apertures is disclosed. The invention further relates to an antenna system wherein the orthogonal apertures comprise at least one transmit aperture and at least one receive aperture. The cross-product of the transmit and receive apertures provides a narrow spot beam and resulting high resolution image. An embodiment of the invention discloses orthogonal linear arrays, comprising at least one electronically scanned transmit linear array and at least one electronically scanned receive linear array. The design of this orthogonal linear array system produces comparable performance, clutter and sidelobe structure at a fraction of the cost of conventional 2D filled array antenna systems.

Abstract: A broadband antenna system is disclosed. The antenna system relates to a modified conical structure, wherein the feed region of the cone is cut away to form a hollow “coneless” cylinder, and the distribution of one or more tapered feed points around the circumference of the cylinder allows a plurality of feed lines, cables, piping, or other structures to be run through the center of the antenna without interfering with the performance of the antenna system. The invention further relates to a stacked broadband antenna system wherein additional coneless elements, as well as other types of antennas or devices, may be stacked collinearly on, or disposed coaxially to, the cylindrical antenna structure, and fed, powered or operated via the plurality of feed lines, cables, piping or other structures. The overall system may thus provide a wide range of transmitting, receiving, sensing and other capabilities.