Abstract: A method of providing secure tactical communications between a submerged submarine and an airborne platform using a pulse-modulated blue-green laser beam. During an initial acquisition mode, the airborne transceiver sends out a downlink laser beam to the ocean surface and below using a predetermined IFF code to identify the transceiver to the submarine. In the preferred embodiment the transmit optics spread the beam out into an elongated elliptically-shaped pattern to maximize coverage of the search area. When the downlink beam energy is within range of the submarine, an optical receiver on the submarine detects the beam, filters out the background light with a very narrow-band filter, and converts the light pulses to equivalent electrical pulses. A signal processor in the submarine receiver decodes the electrical pulses and verifies the IFF code to prevent the submarine from responding to a laser beam from an unfriendly source.

Abstract: An articulated element for an antenna such as a log-periodic dipole antenna having an elongated boom comprises an inner tubular section secured to the boom and an outer tubular section movable relative to the inner section between an extended or operative position colinear with the inner section to a folded or inoperative position transversely of the inner section. The element sections are interconnected by spring means which is always in tension and exerts a compressive force between the two sections for good electrical conductivity when in the operative position while permitting the outer section readily to be pivoted to the stowed position. A T-shaped sleeve secured to the inner section has slotted longitudinal and transverse legs which releasably clamp and provide strong mechanical support of the outer section in both positions.

Abstract: An integrated erectable antenna system comprises a mast pivotally mounted for rotation between a horizontal stowed position and a vertical operative position, and a log-periodic antenna assembly longitudinally slidably and pivotally mounted on the mast for movement between stowed and operative positions. The pivoted end of the mast has an extendible arm connected by cable to a hand operated winch. The antenna assembly comprises an elongated boom having many articulated transverse dipoles connected thereto over its length and foldable for stowing without disconnecting the dipole parts. The boom is hinged to the mast about one axis transverse to the latter for pivoting from a stowed position parallel to the mast to an operative position perpendicular to the mast and about another axis parallel to the boom for orienting the dipoles in either horizontal or vertical planes when the mast is in the vertical position.