Abstract: An antenna is provided with a wire loop having a tapered end with the antenna perpendicular to a base plate. Insulating rods extend from the plate to lock the loop. Wire radials are directed horizontally and circumferentially from the metal base plate to metal stakes secured in a terrain. The base plate is part of a transmission line assembly that also includes a clamp, an S-shaped plate, an input jack and an L-shaped standoff insulator. The antenna is powered from the input jack to the loop. A beam pattern is generated by the loop section, base plate, wire radials and the Earth. Deviation of the beam pattern depends on soil properties of the terrain. To transfer power when the antenna is mounted on a terrain with unknown dielectric properties; a compensation network is provided.

Abstract: A buoy antenna assembly with a hub having a first conical cavity in a top portion and a second conical cavity in a bottom portion is provided. The first conical cavity aligns with the second conical cavity with a space between an apex of the first conical cavity and an apex of the second conical cavity. Each of the first conical cavity and the second conical cavity is plated with a conducting material. A plurality of vanes attaches at an angle to the hub. A transmission line attaches to plated portions of the first conical cavity and the second conical cavity. The dimensions of buoy antenna assembly are determined by selecting a center design frequency followed by a calculation of the corresponding wavelength in the material of the hub and the vanes.

Abstract: An antenna is provided which includes a base piece, a first arm, and a second arm. The first arm includes a first section extending vertically from the base piece. The first arm also includes a second section connected to the first section. The second section vertically extends orthogonal from the first section. The first arm further includes a third section extending linearly from the second section. The third section is bent at an angle out of the vertical plane. The second arm includes a first section vertically extending from the base piece. The second arm also includes a second section connected to the first section. The second section angularly extends from the first section in the vertical plane. The second arm further includes a third section extending linearly from the second section. The third section is bent at an angle out of the vertical plane.

Abstract: An antenna is provided as a dipole class radiator with a first bell-shaped element and a second bell-shaped element that extend from a feed gap and are mirror images to each other. Each of the elements has a contour with a combination of curvilinear segments sized to an overall impedance for needed radiation beam pattern properties. In detail, the feed gap with a feed port is between small spherical feed hubs with a larger spherical boss for each element extending away from each feed hub and the feed gap. A frusto-conical section and an adjacent cylindrical section extend from the larger spherical boss for each antenna. The antenna is capable of fitting within a cylindrical shell whose surface area-to-volume ratio is a minimum. The radiation field produced by the antenna is omnidirectional in a horizontal plane. The antenna occupies a minimum surface area-to-volume ratio; thereby, requiring less material.

Abstract: An antenna is provided with a plurality of spaced-apart interdigital back plates covered by a slotted plate having a longitudinal slot of varying rectangular parameters. A plurality of spacers are positioned between the interdigital back plates and the slotted plate. A support stiffener connects the interdigital back plates at a trough of each back plate with three rectangular stanchions extending perpendicular from the support stiffener to attach to the slotted plate. A feed point is positioned on a central rectangular stanchion and beneath a central slot of the slotted plate. A feed cowl protects the feed point. The sizing of a slot in the slotted plate depends on an operating wavelength.

Abstract: A tunable antenna includes a base supporting a support and hollow tube opposing and spaced apart from one another, and spaced-apart and parallel plates. Each plate is coupled only at one end thereof to one of the support and hollow tube. One of the plates located furthest from the base extends past the hollow tube and is spaced apart therefrom. A shaft extends through the hollow tube and the one plate extending past the hollow tube. A tuning plate is coupled to the end of the shaft. A tuning piston is coupled to the shaft and is adapted for movement within the hollow tube where such movement changes the resonant frequency of the antenna.

Abstract: An antenna is provided with conducting plates spaced apart from each other and the base to be in vertical alignment. A cross-shaped support extends perpendicular from a front section of the base to secure the conducting plates. An arm of the support indents to accommodate a conducting plate. A J-shaped support is fastened to a rear planar section of the base with extensions extending perpendicular to secure the conducting plates. A first conducting plate is J-shaped with a bend facing a width edge. A second conducting plate is also J-shaped with the plane of the plate perpendicular to the base and spaced apart from the first conducting plate. A third conducting plate is U-shaped and integral with an L-shaped section with a bend of the U-shape facing the width edge. The short leg of the L-shape section attached in the indentation of the cross-shaped support.

Abstract: A probe is provided for measuring permittivity of a dielectric material. The probe includes side electrodes and a pivotable center electrode with a bulbous tip to contact the material. A mounting harness supports the side electrodes and a feed connector with the center electrode soldered to the connector. The tip includes a contoured surface for measurement and rotation on the material. The bulbous tip can rest perpendicularly or in a pivoted position on the material without a loss of measurement accuracy. A saddle ensures that a measurement of the reflection coefficient is near the bulbous tip. In use, a voltage wave generated by a vector network analyzer is guided between the electrodes toward the tip and into the material. The material reflects this voltage wave back to the analyzer. The ratio of the reflected and forward voltages forms a reflection coefficient as a baseline for measuring permittivity.

Abstract: An antenna includes a base, and first and second supports coupled to the base and extending perpendicular therefrom. The first and second supports oppose one another and are spaced apart from one another. The antenna also includes a plurality of plates spaced apart and parallel to one another. Each plate is T-shaped to have a trunk and a top wherein a width of the trunk is less than a width of the top. Each trunk is coupled to one of the first support and second support, and extends perpendicular thereto wherein a corresponding top of the plate is spaced from an opposing one of the first support and second support to thereby generate a gap region that serpentines between the first support and second support and around the top of each of the plates.

Abstract: The invention as disclosed is a parallel plate antenna having a number of stacked horizontal plates and two vertical plates. Alternating ones of the horizontal plates are electrically coupled to one vertical plate such that the horizontal plates coupled to one vertical plate are interleaved with the horizontal plates coupled to the other vertical plate. The assembled antenna is mounted on a planar mounting flange. The height/width of the antenna is approximately 1/30th of a wavelength at the frequency of operation.

Abstract: A device for measuring electrical properties, including permittivity, of a material is disclosed. The device includes a first conduit and second conduit terminating at open ends and respectively connected to a first and second connector port. Annuli are formed by the open ends to encompass portions of a flange of the device. The flange as well the portions make firm contact with the material under test, permitting simultaneous measurements of the complex scattering parameters of the material when an electromagnetic field is transmitted through the first connector port. Electrical characteristics of the material can be computed using the measurements received at the first connector port and the second connector port. Shorting screws are used for calibration by selectively opening or shorting the conduits.

Abstract: A device for measuring electrical properties, including permittivity, of a material is disclosed. The device includes a first conduit and second conduit terminating at open ends and respectively connected to a first and second connector port. Annuli are formed by the open ends to encompass portions of a flange of the device. The flange as well the portions make firm contact with the material under test, permitting simultaneous measurements of the complex scattering parameters of the material when an electromagnetic field is transmitted through the first connector port. Electrical characteristics of the material can be computed using the measurements received at the first connector port and the second connector port. Shorting screws are used for calibration by selectively opening or shorting the conduits.

Abstract: An amphibious antenna for providing Near Vertical Incidence Skywave (NVIS) communication when grounded to a conductive fluid. The amphibious antenna has a support member for supporting a helix. The helix includes a first helical arm that is not insulated and grounded, when in use, through a conductive fluid into which the antenna is placed, and a second helical arm that is insulated from the conductive fluid.

Abstract: An apparatus including a gimbal and an antenna with a hollowed frustum having a closed end and an open end. The antenna includes a feed stem at the closed end extending as an internal rod into the hollowed frustum. The opposite end of the rod connects to a receiver section extending from an edge of the open end beyond a longitudinal axis of the antenna. The antenna is supported by the gimbal attachable to a container suitable for towing. A pivot at the open end in relation to the center-of-gravity of the frustum allows a swinging arc in relation to the attached gimbal in that the frustum moves by gravity toward the axes of the gimbal such that the receiver section maintains a facing position to the force of gravity.

Abstract: A slotted antenna comprises a plurality of loop structures and interconnecting conductors that define a slot. The antennas can operate in a single band or over multiple bands. Flexible or inflatable substrates enable easy storage aboard an underwater craft and facilitate deployment and towing behind an underwater craft with minimal chances of detection.

Abstract: An antenna including a feed tube with radial fins and circular plates at the ends of the tube and fins thereby forming a boundary for a plurality of resonant cavities. Curved plates, connected to the tube by switches of a switching system, partially encompass and subtend to the length of the tube. Interior to the tube, a transmission line from an end plate terminus conducts radio-frequency energy from the terminus to a hub and onto a switch of the switching system in which the switch is mechanically reactive to and actuated by a righting action of the curved plates when the curved plates encounter a sea state. When actuated, energy from the switch distributes to a proximate resonant cavity and curved plate to form a radiation pattern based on the difference in phase of the resonant cavity and curved plate.

Abstract: A wideband, low-profile, towable submarine antenna is provided. The antenna is formed with a metal cylinder having a longitudinal slot. The entire enna may be encapsulated in a tow body and towed horizontally on the surface of the water. The longitudinal slot is open at one end and closed, or shorted, at the opposite end. The location of the antenna feedpoint is placed along the slot so as to set up two sets of frequency resonances. This configuration provides two voltage standing wave ratio minimums, thereby extending the effective reception and transmission range over the entire military UHF frequency range (225-400 MHz).

Abstract: A broad passband pressure barrier arrangement is provided for insertion in circular waveguide between a source and a receiver of radio frequency (RF) energy with a spatially circumferential electric field characteristic of the TE.sub.01 mode. At least two cylindrical barrier regions are coaxially aligned and arranged symmetrically in mirror image fashion about a radial plane of the circular waveguide. The cylindrical barrier regions include at least one solid cylindrical plug region sealed in a cross-section of the circular waveguide and having a longitudinal thickness sufficient to withstand a predetermined pressure load. Each of the cylindrical barrier regions are defined by a characteristic impedance at opposing end faces thereof and a by characteristic impedance between the opposing end faces. A region-by-region impedance analysis process begins with an end face of the arrangement that is furthest from the source and is completed with an end face of the arrangement that is nearest the source.

Abstract: A broad passband pressure barrier arrangement is provided for insertion in circular waveguide between a source and a receiver of radio frequency (RF) energy with a spatially circumferential electric field characteristic of the TE.sub.01 mode. At least three abutting cylindrical barrier regions are coaxially aligned a arranged symmetrically in mirror image fashion about a radial plane of the circular waveguide. The cylindrical barrier regions include: at least one solid cylindrical plug region sealed in a cross-section of the circular waveguide and having a longitudinal thickness sufficient to withstand a predetermined pressure load, and at least one solid cylindrical tuning region having a radius less than that of the circular waveguide and further having a longitudinal thickness. Each of the cylindrical barrier regions are defined by a characteristic impedance at opposing end faces thereof and a by characteristic impedance between the opposing end faces.

Abstract: The invention is an apparatus for measuring the volume of water intrusion underwater cables without dissecting the cables. The apparatus comprises a novel arrangement of a capacitive test fixture and an electrical impedance analyzer to provide measurement of the volume of water in a cable based on cable capacitance. The capacitive test fixture measures the electrical capacitance along the cable as the cable is fed through the test fixture.