Abstract: The invention is a buoyant cable antenna that is towed on the surface of a body of water by a submerged underwater vehicle to allow communication coverage in an omnidirectional pattern in the VHF frequency range and that is also compatible with existing buoyant cable antenna deployment and retrieval systems. The antenna of the present invention comprises a floating cable having four identical antenna elements that are arranged in a cross configuration. The antenna is designed with a system of four shielded inductor units connected in series with the antenna elements to reduce the losses to seawater by the submerged elements and to tune the exposed vertical element and its feed-cable capacitance to resonance which results in greatly increased radiated power at the design frequency of approximately 10-30 MHz.

Abstract: A current probe system includes a toroid made from a magnetic material and a wire made from an electrically-conducting material that forms at least one winding about a portion of the toroid. A current is induced in the winding(s) when a time-varying magnetic field is present in the toroid. A float coupled to the toroid floats the system at a water's surface. In use, a buoyant cable antenna is fed through the toroid and the system is moved along the antenna.

Abstract: A transmit antenna system includes active transmit electronics. A transistor has its gate coupled to a pulse generator for receiving the voltage pulses produced thereby. A coupled inductor is coupled to the transistor's drain. A tuning capacitor is coupled to the coupled inductor. An antenna is coupled to the coupled inductor and tuning capacitor. A choke inductor is coupled to the coupled inductor and a direct current voltage source. During each of the voltage pulses of the pulse generator, a resonant circuit is defined where parameters of the resonant circuit include resistance and capacitance of the antenna, capacitance of the tuning capacitor, inductance of the coupled inductor, and capacitance of the transistor. The resonant circuit is configured such that a resonant frequency thereof is equal to the pulse frequency of the pulse generator.

Abstract: A system and method are provided to control the power output, fuel efficiency and gas emissions of an internal combustion engine using an exhaust gas recirculation system. A recirculation loop containing a heat exchanger and an accumulator is installed between the exhaust ports and intake ports of the cylinders of the internal combustion engine. Diverter valves are used to control the amount of exhaust gas directed into the recirculation loop and the proportion of exhaust gas entering the intake ports. Controlling the amount of re-circulated exhaust gas and proportion of exhaust gas in the intake ports thereby controls the power output of the internal combustion engine.

Abstract: A combined antenna transmitter joined for transmitting a message signal includes a switching signal source modulated by the message signal. The switching signal is provided to a transistor at an operating frequency. The transistor switches a high voltage input through the transistor, a choke inductor and a boost inductor. A bypass capacitor is provided between the inductors for shielding the high voltage input. An antenna is connected between the boost inductor and the transistor for transmitting a radio frequency signal at the operating frequency. There is thus provided a compact, efficient transmitter and antenna assembly for transmitting modulated message signals.

Abstract: A Wireless Underwater Video System for obtaining live video/audio data to profile a designated area of an ocean bottom is described. The system includes a video camera enclosed in a water tight housing which produces video and audio signals which are transmitted to a transmitting buoy having a power source, electronics for conditioning the video/audio signals and a position stablizer. The conditioned video signals are then transmitted from the buoy to an observer on a platform over a radio frequency link.

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: An antenna adapted for surface deployment is provided. A coaxial feedline, erminated at one end thereof at a feedpoint, has a center conductor and a shield at ground potential. A continuous length of antenna wire having first and second ends is electrically connected at its first end to the center conductor at the feedpoint. A first portion of the continuous length is spooled adjacent the first end. A second portion of the continuous length is deployed from the first portion by means of tension at the second end. The second portion extends to the second end along a substantially straight line away from the first portion. The second portion is typically at least as long as the first portion. The first portion serves as a variable tuning inductor for the antenna as the second portion is deployed therefrom.

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 system for sensing motion of an object in an underwater environment is vided. The system has a circuit board, a light-emitting diode, an infrared filter, an integrated circuit, and an acrylic transparent housing. The light-emitting diode and the integrated circuit are mounted on the circuit board. The integrated circuit has a photoelectric transducer and a low-noise amplifier. The housing surrounds and seals the diode, the filter, the integrated circuit, and the board from exposure to the underwater environment. The housing also provides a convex lens on one end which corresponds with the direction in which the diode emits infrared radiation. The convex lens spreads the radiation emitted from the diode. The emitted radiation approaches and reflects back from the moving object. The convex lens also spreads this reflected radiation. The infrared filter screens unwanted radiation. The photoelectric transducer converts the filtered radiation into an electrical signal which the low-noise amplifier amplifies.

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.