Abstract: Methods of fabricating air-dielectric true-time-delay, continuous transverse stub array antenna. The first method uses conventional machining or molding techniques to fabricate layers of plastic with desired microwave circuit features. The plastic layers are then metalized, assembled (aligned) and joined together, such as by using ultrasonic welding techniques. Readily available metalization and ultrasonic welding techniques exist that may be used. The second method uses sheets of metal, into which microwave circuit features are fabricated, such as by machining. The layers are then assembled (aligned) and joined together, using one of several available processes, such as an inert gas, furnace brazing technique, for example.

Abstract: A planar array antenna having a switching matrix that couples an RF signal to two distributed ferrite scanning line feeds that feed a planar continuous transverse stub array antenna. The scanning line feeds couple RF energy to the antenna from opposite sides to form a total of four beams offset in space that each cover different angular scan sectors. The antenna has reduced complexity and lower design and production costs. The use of dual ferrite scanning line feeds, the switching matrix, and the continuous transverse stub antenna to obtain wide-angle scanning provides significantly improved performance. The present invention uses the two distributed ferrite scanning line feeds to obtain greater scan coverage at upper millimeter-wave frequencies, where realizable ferrite materials are less active and provide diminished scan capability. The scanning line feeds and planar array antenna may be designed so that the four scan sectors are contiguous, to increase the angular scan coverage of the antenna.

Abstract: An optical fiber having a conductive layer disposed therearound has sections removed therefrom that form gaps that expose the underlying optical fiber. Light manifolds are formed at each gap, such as are provided by Bragg gratings photoinduced in the core at each gap, and photoconductive material is disposed at each of the gaps. An opaque coating may optionally be disposed over the outside of the photoconductive material to ensure that it is activated by light propagating within the optical fiber. Light transmitted down the fiber may be controllably coupled output of the fiber at each of the gaps. The optical fiber thus provides multiple functions including electrical conductor, light manifold, and substrate on which the photoconductive material is deposited.

Abstract: A compact scanned antenna which includes a radiator, a rotatable tube and a line source. The radiator is formed by plating a shaped dielectric core. It generates an antenna beam at an output aperture in response to a microwave signal at an input port. The line source generates a radiation sheet which is directed across a signal plane to the input pot. The tube has a cylindrical wall which is positioned across the signal plane. As the tube rotates, refractive or diffractive transmission structures pass through the signal plane. The refractive structures include linear segments which refract the wavefront of the radiation sheet. Because the wavefront slope at the radiator's aperture is a function of the wavefront slope at its input port, the antenna beam is scanned. The linear contour segments have the same inclination but are not colinear. This arrangement reduces the thickness of the tube wall. Phase coherence is achieved by an appropriate radial spacing of adjacent ends of contour segments.

Abstract: Spatial thinning in no more than two dimensions is used in order to lower both the effective dielectric constant and the dielectric loss tangent of ferroelectric ceramics, while retaining a substantial fraction of their tunability. By not thinning in the third direction, along which the dc bias field is applied, the ferroelectric material maintains the connectivity between elements of the ferroelectric structure that is essential to retaining the tunability. Examples of one-dimensional structures (30) include small diameter columns (28, 32) of dielectric material embedded in a dielectric matrix (26, 34). Examples of two-dimensional structures (21) include square (22) and hexagonal (24) cells comprised of ferroelectric material filled with inert dielectric material or vice versa.

Abstract: A broadband antenna system utilizes multiple photonic bandgap crystals to achieve nearly 100 percent power efficiency over a larger range of frequencies than prior antenna systems. Multiple custom tailored photonic bandgap crystals form a substrate for the antenna system. Each of the crystals is designed to cover a specific range of frequencies. The multiple crystals are attached together to form a photonic bandgap substrate whose bandwidth varies as a function of location on the substrate. A broadband antenna that can cover a wide frequency range, and whose active region shifts to different portions of the antenna as a function of frequency, is formed on the substrate such that the active region of the antenna is always on a crystal that has a corresponding operating bandwidth. The photonic bandgap crystals provide a nearly 100 percent efficient reflector for radiation emitted into the substrate that would otherwise be trapped or dissipated therein.

Abstract: A dielectric material having a dielectric constant which varies inversely with frequency, and preferably with the second power of frequency, fills the space between a radiator and a reflecting groundplane. The back-directed wave is reflected back to the radiator in phase with the directly radiated wave over a wide frequency band, increasing the radiator efficiency.

Abstract: An electronic device operating in the microwave frequency range having components disposed in a plurality of planes, wherein the planes are stacked vertically. The electronic device is a T/R module or element forming a part of a subarray used in an active array radar. The T/R module or element comprises a transmit chip, a receive chip, low noise amplifiers, a phase shifter, an attenuator, switches, dc power supply, interconnects that interconnect the foregoing components and logic circuits to control the foregoing components. The components when stacked in a 3-D package are disposed behind a radiator or antenna, which transmits and receives the microwave signals. Behind the T/R module or element is a manifold which provides input and output to and from the T/R module or element. The microwave chips of the T/R module are monolithic microwave integrated circuit chips and control logic, which are disposed in an aluminum nitride substrate and coated with a conformal hermetic coating.

Abstract: A length of strip transmission line uses two symmetrically spaced center conductors between two groundplanes. These conductive strips produce an even-mode electric field between the two groundplanes when excited in-phase and an odd-mode electric field when excited in anti-phase relationship. For the latter case, the phase velocity of the odd-mode is significantly affected by the electric field in the gap region between the conducting strips. By varying the relative dielectric constant of a material located in the gap region, e.g., by means of a voltage-controllable dielectric such as barium-titanate compositions, the phase velocity and, hence, the phase shift of an RF signal propagating through the strip transmission medium can be controlled.

Abstract: A true time delay phased array is provided which includes a digital subarray interface in the transmit signal path. The digital transmit signal path interface includes a digital reference signal generation means and digital signal propagation means for supplying the digital reference signal to the subarray. Each subarray includes RF carrier signal generating means for generating an RF carrier signal phase coherent with the reference signal, a fiber optic true time delay circuit for applying an appropriate phase delay to the RF carrier and an appropriate true time delay to the modulation signal, and a waveform modulator for modulating the modulating signal onto the phase locked RF carrier signal to provide the transmit signal for the subarray. The present invention can be used in conjunction with existing digital interface technology for receive and control signal paths to provide an entirely digital subarray signal path interface.

Abstract: This invention discloses an antenna element (12) or an array of antenna elements (52) for use in multifunctional systems which exhibits wide bandwidth, small size, polarization diversity and conformality. In one preferred embodiment, an array of circular conductive patches (56,58) are formed on a dielectric substrate (54) in which adjacent patches are formed on opposite sides of the substrate (54). Each of the opposite conducting patches (56,58) are configured to form a dual flared slotline such that an electric field created between the two conductive patches (56,58) will exhibit a wide range of impedance matching to free space. By exciting the conductive patches (56,58), radiating electromagnetic waves having a polarization with respect to the orientation of the slotlines is produced. By this, a single array of antenna elements (52) can be used in a multifunctional system.

Abstract: A structure integrity monitoring apparatus and method for use with certain structures such as air-frame structures. A meandering transmission line (22) or serpentine coaxial cable is adhered to a dielectric substrate (20). The dielectric substrate may be a composite panel of the air-frame structure. A microwave signal is introduced at one end of the transmission line (22) or coaxial cable and absorbed at the other end by an appropriate signal absorbing device. For use of the meandering transmission line (22), generally two conductors (22, 24) are affixed on opposite sides of the dielectric substrate (20). In this manner, an electric field created by the two conductors (22, 24) by the microwave signals propagating through them is confined within the dielectric substrate (20). As the signals travel down the transmission conductors (22, 24), they will be reflected at crossover points along the way creating a signature reflection wave.

Abstract: A switched loop/180.degree. phase shift device is disclosed, having the additional capability of an aperture shutter that can be selected to produce either a noncorrelated reflection in one mode of operation, or to absorb RF energy that enters the radiating aperture port in the other mode.

Abstract: An improved serpentine feed and method of making same. The invention includes a block of conductive material having a primary microwave waveguide channel and at least one secondary channel. Each secondary channel has at least one broadwall common to the primary channel. A high performance coupler is provided in the common broadwall by which microwave energy communicates from the primary channel to the secondary channel.

Abstract: An antenna element including a microstrip radiating element having a microstrip feed line and a ground plane on opposite sides of a substrate, with at least one of a plurality as resonators on the same side of the substrate as the microstrip feed line, and a dipole radiator having an increased bandwidth and insulated from the feed line and from the plurality of resonators.

Abstract: An antenna element including microstrip having a microstrip feed line and ground plane on opposite sides of a substrate, a resonator on the same side of the substrate as the microstrip feed line, and a dipole insulated from the feed line and from the resonator.

Abstract: A non-dispersive antenna feed in which a length of strip transmission line (stripline) has two spaced center conductors supported on a dielectric sheet between two ground planes. These center conductors or conductive strips produce an even-mode electric field between the two ground planes when excited in-phase and an odd-mode electric field when the center conductors are excited in anti-phase relationship. A plurality of close-coupled quarter wave conductors parallel one of the center conductors, a feed strip extends substantially orthogonally from each such coupling strip to provide an antenna element feed externally. A four poor hybrid has two external ports and two additional ports for discretely feeding the stripline center conductors in-phase corresponding to excitation of one hybrid external port an in anti-phase corresponding to excitation of the other hybrid port. Each external hybrid port thereby corresponds to a different angle of antenna beam generation.

Abstract: A multiple-port loop-coupled commutating feed for a circular or cylindrical antenna array which is circumferentially scanned. A rotor assembly having a plurality of elongated coupling loops circumferentially spaced about an arc of its perimeter is fed from a stripline feed configuration excited at the driven central axis of the rotor. The rotor loops are formed by extension of printed circuit traces extant within the stripline feed about an arc of the rotor assembly. A plurality of elongated stator loops with essentially the same radial dimensions as the aforementioned rotor loops is provided, however the stator loops are distributed throughout the full 360.degree. of the circular perimeter of the device to continuously couple a changing fraction of the stator loops to the rotor as the latter is rotated. An output port is provided connected to each stator loop and these output ports may then be discretely connected to corresponding elements of a circular array or columns of elements of a cylindrical array.

Abstract: An annular rotary antenna feed coupler especially for around-the-mast use, as on shipboard. A housing in the general shape of a cylinder with a central axial opening essentially concentric with the axial center line of the housing contains a circumferential distribution of a number of fixed axially elongated, conductive loops each with a feed port. Radially spaced therefrom, a second, group of elongated conductive loops circumferentially distributed about a circle of different radius as compared to the aforementioned fixed loops is rotatably mounted. A corresponding plurality of ports, one for each rotating loop, is also provided, and input and output combiner/divider devices, one for the fixed and another for the rotating sub-assemblies serve to combine all ports into a single fixed and a single rotating port. Mechanically, the rotating combiner/divider rotates with the antenna array with which it operates.

Abstract: An integrated planar antenna array comprising at least two separate interleaved arrays separately controllable and responding to separate frequency bands. Both arrays operate with substantially the same phase center and substantially within the same effective aperture. The first array or subarray comprises spaced linear, slotted-waveguide arrays and the second subarray includes a meander line occupying the space between each of the waveguides of the first array. Scan systems are shown for independent operation of the two arrays. An alternative for the second subarray is shown in the form of slotted, square-coaxial, linear arrays in the spaces between the waveguides of the first subarray.