Abstract: An antenna for transmitting electromagnetic signals having a frequency less than 500 Hz includes a beam of dielectric material and a conductive sheet wound in a helical pattern around the beam of dielectric material. The antenna further includes a core fabricated from a silicon and iron alloy, the cote disposed between the beam of dielectric material and the conductive sheet. With such an arrangement, a magnetic dipole antenna is provided capable of providing a magnetic moment of approximately 10.sup.6 to 10.sup.7 Am.sup.2.

Abstract: A radar system is shown to include a transmitter for transmitting a pulsed electromagnetic signal having a frequency less than 500 Hz and a receiver for receiving a (scattered) reflected signal provided from the pulsed electromagnetic signal (scattered) reflected from an anomaly below the surface of the water. The radar system further includes a switch for inhibiting the receiver from receiving a reflected signal provided from the pulsed electromagnetic signal reflected from the surface of the water and a signal processor for controlling interoperability of the transmitter, the receiver and the switch. With such an arrangement, a radar system is provided for detecting anomalies such as a wake of a moving vessel (if and when this produces a conductivity anomaly), or a plume of oil beneath the surface of water.

Abstract: There is disclosed a system by which a satellite is connected by means of a long tether, typically a wire 100 km or more in length, to a powered spacecraft. The spacecraft may be the Space Shuttle, and two basic equilibrium positions of the system are discussed. The wire is gradually released from a storage drum aboard the powered spacecraft, and the gravity gradient established along with atmospheric drag provide the force for deployment. The system can be used repeatedly by reeling back onto the drum. The wire, once deployed, can then be left in orbit for use in future shuttle missions and (once reeled back) can be returned to earth for repair or replacement. The tethered system finds utilization in the broad areas of upper atmosphere measurements, gravity gradient measurements and radio physics research.

Abstract: A lithospheric electromagnetic telemetry system specifically adapted for telemetry of oil well drilling parameters from well bottom to surface of the earth. Sensors measure such parameters as pressure, temperature, salinity, direction of well bore, bit conditions, as well as the standard well logging parameters. The sensor outputs are converted to digital form and stored in a local memory until they are transmitted upon a triggering signal from a surface station. Transmission is accomplished by phase shift modulating an ELF (Extra Low Frequency) or ULF (Ultra Low Frequency) carrier, preferably in the range of 1-30 Hz. Repeater stations which delay and retransmit the signal are spaced along the oil well drill pipe as required. Both the well bottom station and repeaters are mounted inside the oil well drill pipe without substantially decreasing clearance for mud flow.