Abstract: A multimode low-profile avionics antenna is disclosed for use in Automatic Direction Finder (ADF) systems. The low profile antenna generates a steerable cardioid radiation pattern having a minimum bandwidth of 30% and an unusual degree of independence from mutual coupling and coupling to ground-plane currents. The antenna includes two resonant cavity-backed slot antennas. The upper cavity, which backs a directional crossed-slot antenna, is the larger of the two cavities. The shallow lower cavity is actually a short-circuited radial transmission line employing a stepped inner radius and band-switching to extend the operating bandwidth to the required 30%. The crossed-slot antenna elements are configured orthogonally and the slot ends are folded over the side of the cylindrical cavity to minimize the resonant cavity diameter for the requisite slot length.

Abstract: A method and system for avoiding ground collision through pilot warning messages which is implemented in aircraft having a plurality of sensors, onboard inertial navigation units, and altimeters for measuring aircraft performance or flight characteristics. Data is collected through a digital interface unit from data buses connected to these sources, transferred to one or more storage locations and a data validation unit for determining the validity of current altitude data. A series of data processing elements use the aircraft data to extrapolate an aircraft altitude path forward during a predetermined period of time as a function of the aircraft flight data. The extrapolated altitutde allows extrapolation of an aircraft flight path as a function of predicted terrain variations and changes in altitude in response to recovery from various aircraft maneuvers such as rolling, banking, diving, climbing, or accelerating.

Abstract: An apparatus and method for identifying sidelobe transmitted and/or received radar signals. The apparatus is utilized in a radar system having a transmitter for generating at least one detection signal, an antenna system defining a mainbeam and sidelobe radiation pattern for transmitting each detection signal and for receiving electromagnetic signals including echo signals each corresponding to a reflection from an object of a transmitted detection signal, and a receiver system for processing each received echo signal. The apparatus is embodied as a system for identifying each echo signal received upon the antenna system sidelobe and each received echo signal having a corresponding detection signal transmitted on the antenna system sidelobe.

Abstract: To permit boring with replaceable cutter elements (10, 10a, 10b), particularly into materials where, upon withdrawal of the boring tool from a bore hole (40), grooves or scratches are to be avoided, two cutter elements are positioned on a fluted cylindrical body (1), the cutter elements being so located that the inner cutter element (10b) is positioned on the body so that an effective cutting edge (19) thereof is radially inwardly of the theoretical circle (33) formed by the outer cutter element (10a) upon rotation of the tool, the cutting corner of each cutter element is formed as a relieved or chamfered corner (15) and forms a chopped corner cutting edge (22).

Abstract: A system for discriminating between signals received on the mainbeam of an antenna system and signals received on the sidelobe of the antenna system. The system utilizes a main antenna and multiple auxiliary antennas. The signals received on the main antenna are coincident on one or more of the auxiliary antennas. The auxillary antenna signals are multiplexed separated for single channel processing. The main antenna signal is compared with each of the multiplexed auxiliary antenna signals. The result of these comparisons are used to determine whether the signal received on the main antenna was received on a mainbeam or a sidelobe.

Abstract: A system for correcting phase errors in a space based radar system utilizing probes located in front of an array of lens elements of a phased array antenna. Included is a mechanism for supplying a stored perfect value signal indicative of the distance between the probes and lens elements for a perfect, nondeformed array, and the mechanism for receiving radiated pilot signals to supply an actual value signal indicative of the actual distance between the probes and the lens elements to determine an amount of structural deformation. A mechanism is provided for measuring the difference in phase between the perfect value signal and the actual value signal to supply a deformation phase correction signal to adjust the beam steering command to correct for phase error introduced as a result of the measured structural deformation. Further disclosed is a system and method for effecting phase coherence across the array by utilizing a radiated reference pilot frequency pulse to each lens element.

Abstract: A scanning antenna comprises a non-magnetic, electrically conductive radiation horn defining an antenna opening having a predetermined central line of focus, and at least one magnetically switchable conductive element such as a reed relay mounted to extend across the antenna opening perpendicular to and spaced from the central line of focus. A magnetic field generator such as an electromagnet is positioned to generate a magnetic field to control switching of the conductive element between its conductive and non-conductive states, and a control circuit controls operation of the magnetic field generator.