Abstract: The present invention is drawn to an antenna having a reconfigurable length, and a method of reconfiguring an antenna. The antenna can comprise an enclosed composition capable of forming plasma operable as an antenna; an energy source configured for applying variable energy levels to the composition to thereby form variable plasma configurations; and an enclosure containing the composition. The enclosure can have a proximal end, wherein upon application of a first energy level to the composition, a first plasma length with respect to the proximal end is formed, and upon application of a second energy level to the composition, a second plasma length with respect to the proximal end is formed.

Abstract: An antenna assembly for mounting on a backstay of a sailboat. An insulative support apparatus includes a slotted center tube that can be forced over the backstay for mounting thereon. First and second outer tubes are attached on opposite sides of the center tube for holding first and second elongated radiators. Proximal ends of the radiators are electrically joined together and to a lead in-wire for connection to a receiver and/or transmitter. Distal ends of the radiators are secured at distal ends of the outer tubes by attachment to eyelets on the bottoms of plugs inserted into the distal ends of the outer tubes, which serve additionally to prevent water from entering the tubes. The outer tubes each include a water drainage channel to allow moisture accumulating to run out a bottom, proximal end of each tube.

Abstract: A compact antenna transmits and receives broadband electromagnetic energy signals over a 180° hemispherical pattern in air at the ocean's surface. The antenna has an elongate semi-cylindrical shell and a circular end disc connected to one end, and a semi-circular end disc connected to the other end to form a half-cylinder cavity. A curved plate is connected to the circular end disc and a curved body portion has a curved end extending parallel with the semi-cylindrical shell. A vertical stem has an upper portion connected to the curved plate. The semi-cylindrical shell, circular end disc, semi-circular end disc, and vertical stem are made from a material that is conductive of electromagnetic signals, and they can be differently dimensioned to change the center frequencies to embrace different broadband ranges. The antenna is deployed and retrieved from a submarine in a tow body.

Abstract: A plasma antenna is provided having an ionizer, which when energized, generates a bounded or unbounded plasma column extending along a vertical axis. When ionization is initiated, the difference in the diffusion characteristics of ions and electrons and the resulting gas plasma produce a current pulse in a first direction. As the plasma extinguishes, the difference in relaxation times for the ions and electrons in the plasma produces a second current pulse of opposite direction. The alternating current pulses generate an electric field that radiates from the plasma column.

Abstract: A novel retractable antenna which enables dual-band operation in two different positions of the antenna is described. Further, the novel retractable antennas are couple to a variety matching circuit arrangements according to various embodiments of the present disclosure to eliminates the use of electrical or mechanical switching of two different matching circuits.

Abstract: The present invention provides an outboard test facility that is operable for testing a ship's direction finding antenna system in all directions as the ship circles while receiving test signals from the outboard test facility. The test facility provides a computer control operable for monitoring and storing signal power produced by any selected patch interconnections between a plurality of antennas, a plurality of radio frequency amplifiers and a plurality of signal generators at the outboard test facility. The computer control permits a single operator to monitor a signal analyzer to determine the optimum signal power for each of a list of signal frequencies to be broadcast to the ship based on the selected patch interconnection.

Abstract: An above deck unit for an AIS (automatic identification system) is externally installed on a ship. The above deck unit includes a radio circuit and an associated antenna for transmitting and receiving a message, a position detector and an associated antenna, associated controller and power supply, and a container for storing these elements. An inboard transmission path, e.g., a cable, connects the outdoor unit for the AIS and an AIS display serving as an interface means for the crew. A signal to be transmitted through the inboard transmission path is a processed, for example, an amplified signal, rather than an unprocessed output of a VHF antenna. Therefore, problems of signal loss or degradation along the inboard transmission path are unlikely to occur. Because the unit is incorporated within a single container, it can easily be installed and transferred. With this antenna complex, it is also possible to suppress interference between antennas.

Abstract: An antenna extension system for extending an antenna from an underwater vehicle. The system comprises a housing disposed wholly within the vehicle and a plurality of telescopically connected tiers extendible from a base tier disposed within the housing, an innermost of the tiers being adapted to support the antenna. A cable extends from a base portion of the housing and is fixed at a distal end to the antenna. A plurality of telescopically connected fairings are extendible from the housing and are disposed around the tiers and the cable. A cap is fixed to a distal end of a distalmost of the fairings for enclosing the antenna. Extension of the telescopically connected tiers from the base tier moves the antenna from wholly inside the housing to a position extending outwardly from the vehicle, and extends the cable and fairings with the tiers.

Abstract: An antenna extension system for extending an antenna from an underwater vehicle. The system comprises a housing disposed wholly within the vehicle and a plurality of telescopically connected tiers extendible from a base tier disposed within the housing, an innermost of the tiers being adapted to support the antenna. A cable extends from a base portion of the housing and is fixed at a distal end to the antenna. A plurality of telescopically connected fairings are extendible from the housing and are disposed around the tiers and the cable. A cap is fixed to a distal end of a distalmost of the fairings for enclosing the antenna. Extension of the telescopically connected tiers from the base tier moves the antenna from wholly inside the housing to a position extending outwardly from the vehicle, and extends the cable and fairings with the tiers.

Abstract: An above deck unit for an AIS (automatic identification system) is externally installed on a ship. The above deck unit includes a radio circuit and an associated antenna for transmitting and receiving a message, a position detector and an associated antenna, associated controller and power supply, and a container for storing these elements. An inboard transmission path, e.g., a cable, connects the outdoor unit for the AIS and an AIS display serving as an interface means for the crew. A signal to be transmitted through the inboard transmission path is a processed, for example, an amplified signal, rather than an unprocessed output of a VHF antenna. Therefore, problems of signal loss or degradation along the inboard transmission path are unlikely to occur. Because the unit is incorporated within a single container, it can easily be installed and transferred. With this antenna complex, it is also possible to suppress interference between antennas.

Abstract: A flexible antenna cable is deployed or retrieved by movement along a helical path through an enclosure passage formed between internal surfaces of an assembly within which a plurality of cable pulleys are disposed in contact with the cable for exercising drive control over cable movement. A plurality of solid inserts shaped to occupy spaces between the pulleys within the helical passage, preclude buckling of the antenna cable during deployment and thereby prevent jamming.

Abstract: A detection system for small water craft, such as a kayak. Radar reflective material is incorporated in the surface of the kayak or other water craft, and also is incorporated in surface areas of water craft accessories, such as cushion, life vest or paddle. When the smaller water craft is in the vicinity of a larger aircraft which may be radar equipped so that there is danger of a collision or where the water craft is in a position where it would want detection as part of a rescue effort or the like, the water craft is oriented so that the radar reflective surface would reflect radar back to the sending source, thus better enabling detection. Also, the paddle or other water craft accessory could be positioned so as to reflect the radar waves. Further, the paddle or other accessory could be oriented to reflect the radar waves back to the source, or do so intermittently, in the event that the radar system is programmed to ignore a constant reflective signal.

Abstract: The invention described herein relates to an antenna system which makes use of the waveguide properties of sea ice. The antenna system broadly includes at least one antenna wire extending along and preferably in contact with a sea ice surface for transmitting and receiving substantially vertically polarized radio waves. In a first embodiment, the antenna system has a single antenna wire connected to a tuner at one end and grounded to seawater at a second end. The antenna system also has a second length of wire attached to the tuner. The second wire passes through a hole in the sea ice and is also grounded to the seawater beneath the sea ice. In an alternative embodiment, only the second wire is grounded to the seawater beneath the sea ice. The single antenna wire in this embodiment is ungrounded. In yet another embodiment, the antenna system comprises a dipole antenna wire laying on the surface of the sea ice and being connected to a radio for transmitting and receiving radio signals.

Abstract: A collision avoidance system mountable on an aircraft for providing to the pilot of that aircraft an early warning of the presence of another nearby threat aircraft within the surrounding air space. The system operates autonomously from that aircraft and does not require the presence of any matched system on board the threat aircraft. The system includes an omni-directional L-band microwave antenna formed by a dielectric sphere cut into eight equal “orange wedge” sectors covering eight distinct beam patterns. Eight L-band microwave signals are transmitted simultaneously from all eight dielectric sectors to provide a sphere of detection around the aircraft. The sectors also act as receivers for detecting a microwave signal reflected back from the threat aircraft, and indicating means provides information to the pilot regarding the direction, closeness and rate of closure of the threat aircraft.

Abstract: A submarine antenna assembly comprises a tubular body having a removable end cap, a mast stowable in the body and extendible therefrom and having elements mounted thereon, a penetrator stowable in the body and movable therefrom by the mast upon removal of the end cap, the penetrator being adapted to bore through an ice layer, and an inflatable ring stowable in the body and movable therefrom by the mast upon the removal of the end cap. First and second capsules are in the body for retaining and releasing gas, the first capsule being adapted upon opening thereof to pressurize the body to blow off the end cap to permit movement of the mast, the ring, and penetrator out of body, and the second capsule being adapted to inflate the ring to hold the penetrator in engagement with an undersurface of the ice layer. An electronics assembly is disposed in the body and includes message retention and transmitting means in communication with the mast, and timer means in communication with the capsules.

Abstract: An antenna arrangement comprising an antenna reflector (10) and a transceiver horn (11) combined to form a compact unit (10-11) includes a dynamic vibration-dampened suspension device (16), first (12) and second (15) rotation frames, and first (13) and second (15) elevation frames. The frames are rotatably mounted at the periphery of respective suspension device or frame, with the first rotation frame (12) mounted on the periphery of the suspension device and with the second rotation frame (15) mounted on the periphery of the second elevation frame (14) and functioning as an attachment for the compact antenna unit (10-11). The requisite bearing points are hereby moved to the periphery of the antenna arrangement and space is made available for accommodating the compact antenna unit (10-11) in the center of the suspension device.

Abstract: A high dielectric is fixed to the side of an opening of a casing made from a good electroconductive material or is fixed to the side of an opening of an outer shell made from an insulator such as ferrite, and an antenna element is fixed on the back surface of the high dielectric. A material body, which has a small relative dielectric constant such as air is stored in the casing or the outer shell. The antenna element is sandwiched between the material body having the small relative dielectric constant and the high dielectric. The high dielectric is formed from a material having a relative dielectric constant that is close to the relative dielectric constant of a medium material such as clay, sand, water and the like in the underground or the underwater.

Abstract: A method for controlling the navigation of a towed linear acoustic antenna. Birds equipped with variable-incidence wings are fixed onto the antenna. Through a differential action, the wings allow the birds to be turned about the longitudinal axis of the antenna so that a hydrodynamic force oriented in any given direction about the longitudinal axis of the antenna is obtained. Power and control signals are transmitted between the antenna and the bird by rotary transformers. The bird is fixed to the antenna by a bore closed by a cover. The bird can be detached automatically as the antenna is raised so that the antenna can be wound freely onto a drum. This method allows the full control of the deformation, immersion and heading of the antenna.

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 device (10) for mounting a radar antenna to a support structure such as a mast (M) includes a generally U-shaped frame (12). A proximal end (14) of the frame is adapted for securement to the support structure while the frame extends generally horizontally outward from the support structure and terminates at a closed distal end (16). A radar antenna mounting platform assembly (20) has a longitudinal axis (L) and is pivotally connected between the support structure and the distal end of the frame at a position within the U-shaped frame. The device includes means (60) for selectively pivoting the radar platform bi-directionally about its longitudinal axis. The platform is preferably pivotable at least 20.degree. in either direction from horizontal to define an overall arc of at least 40.degree.. The pivoting means is remotely operable, e.g.

Abstract: A plasma antenna is provided. An ionizer generates an ionizing beam in a nded or unbounded plasma column extending along a vertical axis. An amplitude or frequency modulating signal is applied to an electro-optical crystal that amplitude, phase, or frequency modulates the ionizing beam. The resulting changes in the ionizing beam produce gradients in the plasma that cause ions and electrons to oscillate in a vertical path that generates alternating current having the frequency of the modulator. These currents generate an amplitude- or phase-modulated electromagnetic field that radiates from the plasma column.

Abstract: An antenna arrangement for a submerged submarine includes an independently unctioning underwater vehicle free of any tethered connection to said submarine, a buoy member having a hydrodynamic shape, an antenna mounted on the buoy member, the antenna enabling collection and transmission of at least global positioning data and radio frequency communications, a releasable connector for securing the buoy member to said underwater vehicle in a primary non-deployed position, and a tether connection the buoy member to the underwater vehicle in a secondary deployed position. Release of the connector deploys the buoy member and the antenna such that the hydrodynamic shape of the buoy member raises the buoy member to a data collection and transmission position at a surface of the water.

Abstract: The highly-stiffened, dual-axle antenna tracking pedestal improves tracking performance, reduces manufacturing and installation costs and increases safety during field assembly, maintenance and operation of the pedestal. The reinforced concrete counterweights affect the natural frequency of the pedestal system and reduce vibrational effects from wind loads during antenna slew. Reduction of the number of structural components and pouring concrete counterweights at the job site simplifies fabrication, as well as reducing shipping and handling costs. The use of a dual-axle mount provides antenna slewing without problems associated with conventional azimuth-elevation pedestal systems. The pedestal mount has a structure and drive system that is simple and inexpensive. The drive system has two orthogonal rotational axes, one oriented east-west and the other north-south. The two rotational degree-of-freedom arrangement allows smooth tracking over the entire sky.

Abstract: The invention provides a hydrodynamically and stealth shaped suite of antas and sensors mounted above a hydrodynamically and stealth shaped mast. The mast is configured to extend from the sail of a submerged vessel to the surface so as to provide the vessel with satellite communications capabilities. The hydrodynamic shape of the mast minimizes the surface wake and the stealth shape of the antenna suite and mast minimizes the radar cross section of the system, lessening detection by hostile forces. To obtain a stealth shape, the radar suite utilizes a conformal phased array antenna. In addition, electro-optical sensors in the antenna suite provide visual, environmental and other sensing capabilities to the system. Further, structurally embedded ESM antennas provide ESM and radar capabilities.

Abstract: A buoyant loop antenna, deployable along a cable, includes a core region prising a plurality of annular ferrite beads. These annular shaped beads include a center hole and generally concave first end and a generally convex second end. The ferrite beads are aligned with the concave end of one bead against the convex end of another bead. This allows the cable to flex while the beads maintain contact with each other, providing flexibility and resistance to crushing. The core region has a loop wire wrapped helically around it, forming the loop antenna. The loop wire element starts and ends at the same end of the core region, forming a loop. This loop allows transmission and reception in and athwart (side to side) direction. This novel wire loop antenna can be combined with a straight wire antenna (which provides reception in a fore and aft direction) to provide an omni-directional cable antenna assembly.

Abstract: A support base fabricated with a heat exchanger for use in supporting an enna mast which contains heat generating electronic components. The base is attached to the faired mast of a submarine and the mast structure is attached to the support base. A cooling fluid is circulated through passageways within the mast adjacent to the electronic components to remove excess heat. The passageways are connected to the heat exchanger within the base. The heat exchanger consists of heat conductive exterior outer walls and an internal partition spaced inwardly from the outer wall forming a reservoir on the interior of the partition. The heated cooling fluid circulates through a serpentine passageway formed between the outer wall and the inner partition. Heat is dissipated through the outer wall into the surrounding medium. The passageway opens into the reservoir where the cooled fluid is returned to the electronic components.

Abstract: A submarine buoyant cable antenna having positive buoyancy comprising a cunications antenna electronics package encased in a polymer composition, the polymer composition comprising from about 80 percent to about 85 percent by weight of a room temperature curable thermosetting polymer having a viscosity, before curing, in the range of from about 700 to about 900 centipoise, and from about 15 percent to about 20 percent by weight of microballoons of a size ranging from about 20 to about 100 microns in diameter, the specific gravity of the composition being in the range of from about 0.51 to about 0.65 grams per cubic centimeter to provide the positive buoyancy.

Abstract: A Gaussian-beam antenna invention comprises a transmitting circuit or a receiving circuit, a resonator consisting of a pair of reflecting mirrors, which consist of a spherical mirror and a planar mirror or two spherical mirrors, and a transmission line which transmits a high-frequency signal between the aforesaid transmitting circuit or receiving circuit and the resonator, one reflecting mirror of the resonator having an electromagnetic wave coupling region constituted as a circular partially transparent mirror surface region having its center on the optical axis.

Abstract: A lightweight deployable antenna system capable of operating at two frequies concurrently, includes a canister providing an elongated chamber and mast therewithin. A conductor extends into the mast to provide radio signals to an antenna assembly and three broadband coaxial cables, which are coiled about a spacer and are electrically connected to the antenna assembly. The antenna assembly comprises four antenna elements of resiliently deflectable wire spaced at 90 degree intervals. Each antenna element has a generally helical coil and an elongate arm with a copper tape flag disposed on the distal end thereof. Pairs of the elongate arms form dipoles which are of differing lengths so that each pair of antenna elements resonates at a frequency which differs from the frequency at which the other pair resonates. Each elongate arm is adapted to extend downwardly in the canister in a non-deployable position and at a 45.degree. angle to a horizontal plane in a deployed position.

Abstract: A deployable antenna assembly includes a canister providing an elongated mber and an elongated hollow mast with a mounting member on its upper end. A coaxial cable extends into the hollow mast to provide radio signals to the antenna assembly of four antenna members of resiliently deflectable members spaced at 90 degree intervals about the periphery of a mounting plate. In the non-deployed position elongated arms extend downward along the inner wall of a canister. A resonant circuit having an inductive coil and a capacitor are located at an intermediate position on the arms. A smooth material is placed between the resonant circuit and the wall of the canister to prevent scraping and damage to the resonant circuit upon deployment. Each opposed pair of antenna element comprises a dipole. A pair of baluns are formed by the arrangement of coaxial cable. A hybrid circuit forming a phase shifter is securely affixed to a mounting plate.

Abstract: A buoyant antenna for providing sufficient transmission time windows for munication at ultra-high and extremely-high frequencies. The antenna is configured to float on the surface of a body of water and is connected to a vessel through a communications cable. The buoyant antenna has a length and a stabile or rotation resistant cross-section which minimizes wash over when deployed in a manner which essentially eliminates in line tension on the antenna. The antenna is cylindrically shaped with sensor elements offset from the centerline. A high density mass is placed diametrically opposite the sensor elements and a high buoyancy foam fills out the remaining cylindrical shape. The high density mass creates a righting moment to maintain the sensor elements above the water line. The absence of in line tension during communication periods serves also to eliminate any detectable wake during those communication periods.

Abstract: An antenna mount for a vehicle includes a two axis gimbaled mounting which allows the antenna to rotate in two axes. A pendular mass is provided to maintain the antenna in a particular orientation in the absence of any externally applied acceleration. A chamber is provided attached to the pendular mass for holding a viscous dampening fluid. The dampening fluid allows the antenna mount to rotate in response to an externally applied acceleration but serves to dampen any oscillations induced by an externally applied acceleration. The antenna mount maintains the antenna in substantially a predetermined position despite the influence of externally applied accelerations. Shock absorbers may be supplied to the gimbal mounting to aid in the dampening of large accelerations.

Abstract: Improved marine VHF radio antennas systems are provided that can be installed on sailboats to position a whip antenna or other radiation unit aloft from the boat deck, even while underway. The antenna system includes an elongated flexible plastic extrusion that internally carries the coaxial cable for the radiation unit and has a longitudinal channel accessed through a side slit. The radiation unit when slideably installed on the boat's backstay is then carried aloft on the backstay as the extrusion is threaded on it via the side slit until the extrusion channel is completely filled by the backstay. The system is completed by electrical connection of the lower end of the coaxial cable to a hand held, battery operated transceiver or other electronic device.

Abstract: A passive, active or mixed platform type antenna orienting apparatus mounts on a vehicle such as a small-sized vessel or an automobile, which is subject to turns and complex vibrations, traces a target such as a communications satellite with a directive antenna. Between a rotational shaft connected to a platform supporting an antenna and a stationery shaft connected to base to be carried on a vehicle, there is interposed as electric rotary coupling for transmitting power and signals necessary for a transmission signal and an attitude control, so that the platform 43 supporting the antenna 1 may continuously rotate with respect to the vehicle 27. Midway of a post 41, moreover, there is disposed a horizontal damping mechanism 70 which includes a laminate 75 and facial pressure apply means 76 for applying a facial pressure to a laminate 75, to effect a damping action which is excellent in durability and even in the horizontal direction.

Abstract: A marker beacon deployable by being launched through overhead foliage is able of landing atop and settling on the foliage for visual and infrared detection. A tether limits the flight range of the beacon and operates a switch to the electronic portion of the device to initiate radio signalling. The radio information assists in initial detection of the beacon by a seeking craft. Received signals from the seeking craft activate a flare stored within the beacon unit to further assist in locating the beacon. The beacon is also deployable by launch at sea, and by both place-and-leave and hand-held means on land and sea.

Abstract: The invention provides a controller for moving a boat mounted pole device, such as a marine antenna, from a normally vertical orientation to a substantially horizontal orientation so as to avoid interference with a bridge or other structure under which the boat is passing. The antenna is mounted to a rotatable shaft which is held by a control arm. When the antenna is vertical, the control arm is held by a latch. When necessary to move the antenna to a horizontal orientation, a mechanical actuator connected to the control arm and the latch first opens the latch and then moves the arm so as to rotate the shaft and the antenna. An electrical circuit is provided to sequentially actuate multiple antennas and avoid possible contact between adjacent antennas during movement.

Abstract: A stabilized antenna mount system is described which includes an antenna subassembly, a means for allowing the subassembly to rotate in three dimensional planes, and a means for stabilizing the subassembly. The subassembly rotates by means of a multi-axis bearing and is stabilized with an inertia mass attached to its lower portion. The inertia mass has a weight approximately six times the combined weight of the subassembly and the multi-axis bearing.

Abstract: A floating antenna system which can be deployed and retrieved by an underwater diver is equipped with a pressure proof radome atop an elongated support stalk carrying a lobed, inverted pyramidoidal flotation collar below the radome which can be folded and wrapped transversely around the support stalk like an umbrella when deflated. The air supply for inflation is carried in a pressurized canister inside the support stalk. The collar is inflated via an inflation line from the canister controlled be a manually operated pushbutton valve. The antenna inside the radome is connected to a long tether cable which can be connected to a separate receiver or transmitter below the surface. The tether cable can be manipulated to control deployment and retrieval of the floating antenna.

Abstract: A satellite television receiver antenna for use on seaborne vessels comprises a Cassegrain antenna including a parabolic main reflector, and a hyperbolic sub-reflector mounted at an angle slightly opposite from the center axis of the parabolic reflector, the sub-reflector being driven by a motor to rotate so as to cause the antenna reception pattern to perform a conical scan around the main axis of the parabolic reflector. The rotational speed is an even multiple of the frequency of any amplitude modulation of the received signal, or of any electrical interference, and the received signal is measured at points rotationally spaced apart 180 degrees, so that the effects of modulation and/or electrical interference are cancelled. The measured signal strength at four positions spaced rotationally by 90.degree. is used to derive power signals to drive pulse width modulation control azimith and elevation motors.

Abstract: A stabilized antenna mount system is described which includes an antenna subassembly, a means for allowing the subassembly to rotate in three dimensional planes, and a means for stabilizing the subassembly. The subassembly rotates by means of a multi-axis bearing and is stabilized with an inertia mass attached to its lower portion. The inertia mass has a weight approximately six times the combined weight of the subassembly and the multi-axis bearing. Optionally, to counter the effects of the wind, a set of fins, with or without an aerodynamic upper housing, or a protective shield may be attached.

Abstract: An apparatus is provided for erecting and stowing a communications antenna rom an underwater buoyant cable. In its stowed position, the antenna is approximately parallel to the cable. In its erected position, the antenna is approximately perpendicular to the cable. A hinge, spring biased to maintain the antenna in its stowed position, is connected to the cable and to one end of the antenna. A shape memory alloy actuator is connected to the cable and the antenna. The actuator overcomes the spring bias of the hinge to raise the antenna to its erected position when energy of activation is supplied thereto. Further, the actuator allows the spring bias of the hinge to return the antenna to its stowed position when the energy of activation is removed therefrom.

Abstract: A water-deployable whip antenna is extendable from a shortened configuration to a lengthened configuration. The body of the antenna is made up of a plurality of hollow frusto-conical segments which are slidably nested inside each other when the antenna is in its shortened configuration. To telescope the segments and thereby place the antenna in its lengthened operational configuration, a compressible container is housed within the segments. When the container is filled with pressurizing gas, the container expands to telescope the segments relative to each other. Additionally, a weighted ballast and electronic control circuitry are attached to one end of the antenna. In order to float the antenna in a vertical orientation, an air-filled stability bag is disposed around the antenna near the antenna's weighted end.

Abstract: A submarine radar antenna mast extension, retraction and rotation mechanism comprises a ball drive screw attached to the mast with a ball drive nut threaded to the screw. A rotary tube surrounds the mast with the mast keyed for translation within the rotary tube and prevented from rotation with respect to the rotary tube. An outer tube surrounds the rotary tube and effects a static hull penetration seal with respect to the submarine. The rotary tube rotates within the outer tube, but is prevented from translation with respect thereto. A brake/indexing assembly geared to the rotary tube selectively releases the rotary tube for rotation or locks the rotary tube to an indexed position for extension and retraction. A single bi-directional hydraulic drive motor geared to the ball drive nut effects mast extension and retraction by applying the brake to prevent rotary tube rotation. The drive motor effects mast rotation by releasing the brake.

Abstract: The mount disclosed herein facilitates the mounting of a radar antenna on a sailboat subject to heeling. A pivotable bracket providing a single horizontal axis of rotation only is supported on the upper end of a tube which surrounds the lower portion of the usual sailboat backstay, the tube preventing rotation around the backstay. The antenna is mounted with its center of gravity below the pivot axis and viscous damping is provided to prevent uncontrolled swinging of the antenna.

Abstract: A deployable antenna assembly includes a canister providing an elongated chamber and an elongated hollow mast with a mounting member on its upper end. A coaxial cable extends into the hollow mast to provide radio signals to the antenna assembly and four antenna members of resiliently deflectable wire spaced at 90 degrees intervals about the periphery of the mounting plate comprise a generally helical coil and elongate arms extending downwardly along the inner wall of the canister, and each opposed pair comprises a dipoles. A pair of baluns are connected to the coaxial cable and disposed adjacent the mounting member, and a phase shifter are connected between the coaxial cable and one of the baluns. Connectors conductively connect the central conductor of the balun to the coil of one of the antenna members of a dipole, and the conductive shield to the coil of the other antenna member of a dipole. A sealing medium is provided about the baluns, and phase shifter.

Abstract: An apparatus for mounting an antenna at the upper end of a mast. The antenna has a first electrical connector extending downward from its lower end. The mast has a second electrical connector extending upward from its upper end and is interengageable with the first connector. The apparatus comprises a head moveably adjustable on the upper end of the mast. The head has a skirt surrounding the mast and an upper surface. The upper surface has an opening therein dimensioned for passage of the connectors. The head is movable downwardly on the upper end of the mast to a lowered retracted position and movable upwardly on the upper end of the mast to a raised extended position. When the head is in its retracted position the second connector extends up through the opening above the upper surface for connection of the connectors.

Abstract: A high frequency (HF) communications buoy that employs HF surface wave, and sky wave, communication and spread spectrum modulation to suppress multipath fading and to decrease the undesired detectability of transmitted signals. The buoy comprises a water-tight floatable enclosure that may be deployed from a flying vehicle or a submerged vessel. An HF communications transceiver is disposed within the enclosure that is capable of transmitting and receiving signals employing high frequency (HF) band surface wave and sky wave propagation. The transceiver further comprises spread spectrum modulation and demodulation circuitry for modulating transmitted signals utilizing spread spectrum modulation and for demodulating received signals encoded by means of spread spectrum modulation. The spread spectrum modulation and demodulation circuitry is provided to suppress multipath fading and decrease the probability of detection of transmitted signals.

Abstract: An antenna mounting for use on a ship and which can be oriented in bearing and in elevation and has passive stabilization, which antenna mounting comprises, in combination,: (a) a frame which can be attached to a ship; (b) a support which can be oriented in bearing around an axis (bearing axis) in relation to said frame; (c) an intermediate device which is mounted on said support to oscillate around an intermediate axis at right angles to said bearing axis and whose center of gravity is below such intermediate axis; (d) an antenna support mounted on said device and which can be oriented around an axis of elevation at right angles to said intermediate axis; and (e) means comprising a pendular body mechanically connected to said support and said intermediate device and acting therebetween to maintain said intermediate device in a required orientation relative to horizontal.

Abstract: A ship borne antenna using a gimballed mount for establishing a two degree of freedom unstabilized structure. A ring is mounted for rotation on a radome and carries an antenna mounted for rotation relative to the ring. The ring antenna are respectively driven by stepper motors. Variations in stability occurring by pitch, yaw or roll of the ship are corrected on a real time basis using a microprocessor that dynamically drives the ring and the antenna to maintain lock-on with a satellite.

Abstract: A VLF-VHF broadband in-line amplifier forms a portion of a towable buoyant able antenna system that is deployed in seawater from submarines. The amplifier is located between an antenna system and a coaxial cable. The coaxial cable is connected to the submarine. The VLF-VHF broadband in-line amplifier provides substantially uniform amplification for the frequency range of 10 kHz-160 MHz on signals received from the antenna system. The amplified signals are then transmitted to the submarine over the coaxial cable.