Abstract: A method of testing the impedance of an IMPATT diode operating as a pulsed oscillator at a predetermined pulse repetition frequency is shown to comprise the steps of alternately applying through different, but known, paths, a test signal to the bias line to such diode and observing the change in the test signal as reflected from the IMPATT diode.

Abstract: An arrangement is shown to process mainlobe echo signals and range sidelobe signals in the receiver of a pulse compression radar by first converting such signals to a set of digital numbers and then correlating, number by number, such set with a set of reference numbers describing the mainlobe echo signals and the negative of selected range sidelobe signals.

Abstract: A method of operating a Doppler radar to track a target when main beam clutter is present is shown to comprise the steps of: (a) forming, from all signals exceeding a predetermined amplitude that are received by the pulse Doppler radar during a predetermined period, a range/Doppler matrix having NXM cells, where N is the number of range bins and M is the number of Doppler bins, with a digital one in any cell representative of a return signal with a given Doppler shift frequency from a reflector at a given range; (b) sequentially reading, in accordance with a predetermined program, the contents of the cells in the range/Doppler matrix to form digital numbers with digits indicative of the presence or absence of a reflector in adjacent cells; (c) comparing each digital number to a digital number representative of a target return signal; and (d) generating a frequency control signal when the comparison step indicates a target return signal to adjust a local oscillator in the pulse Doppler radar to effect tracking

Abstract: An improvement in a microwave oscillator using a GaAs FET as the active element is shown to include a phase detector responsive to a portion of the positive feedback signals applied to a resonator having a high Q and to a portion of the signals out of the GaAs FET, shifted by 90.degree., to obtain signals to degenerate noise internally formed in the GaAs FET.

Abstract: A radar antenna is shown in a first embodiment to have a ground plane and a feed line on opposite sides of a dielectric sheet and a ring-shaped antenna element on another dielectric sheet to form a microstrip assembly wherein such antenna element is capacitively coupled to the feed line. In a second embodiment the radar antenna has a parasitic antenna element on still another dielectric sheet, such parasitic antenna element being in register with the ring-shaped antenna element.

Abstract: An arrangement for determining the rotational position of the rotor of an electrical gyroscope is shown to include:(a) at least one sensor including a Hall effect crystal having a rotating magnetic field applied thereto, such field being synchronous with the field causing rotation of the rotor;(b) a phase-lock loop, responsive to square wave signals corresponding to signals out of the Hall effect crystal and a voltage-controlled oscillator to provide a signal approximating the rotational position of the rotor; and(c) a phase detector, responsive to negative going transitions of the square wave and to reference pulses to synchronize the rotational position of the rotor with the reference pulses.

Abstract: An improved microwave amplifier is shown to comprise an IMPATT diode in a coaxial circuit coupled to a section of double-ridged waveguide forming a resonant cavity with a low Q, such cavity in turn being coupled to outside circuitry through a compound iris.

Abstract: An improved round for a mortar is shown to include a streamlined, jettisonable nose covering a hemispherical infrared (I.R.) dome incorporated in a gyroscopically stabilized I.R. seeker, deployable wings and a jet control arrangement; during the initial phases of flight the streamlined nose is in place and the deployable wings are deployed so that the aerodynamic characteristics of the round are similar to those of a conventional round, but, in the terminal phase of flight, when the nose is jettisoned the jet control arrangement may be operated in response to commands from the I.R. seeker to direct the round to impact on the top of a selected target.

Abstract: A frequency discriminator having a wide capture band is shown to comprise, in addition to a conventional phase detector having two channels fed by a signal whose frequency is to be determined (the first one of the channels containing a tuned circuit operative to shift the phase of the signal in accordance with the difference between the frequency of the signal and the center frequency of the tuned circuit and the second one of the channels containing a phase shifter operative to shift the phase of the signal by 90.degree. regardless of the frequency of the signal), a compensating circuit operative substantially to equalize the amplitudes of the signals applied to the phase detector, the compensating circuit including an amplifier in the first one of the channels to amplify the signal out of the tuned circuit, the gain of the amplifier being controlled by a signal indicative of the difference between the amplitudes of the signals fed to the phase detector.

Abstract: A space fed antenna with a folded path to reduce the distance between a phased array and the focal point of such array is shown to be made up of: (a) a first plurality of vertically polarized antenna elements incorporated in the phased array; (b) a second plurality of cross-polarized antenna elements disposed to form a polarization-twisting screen at a distance from the first plurality of vertically polarized antenna elements equal to one-third the focal length of such elements; and (c) a third plurality of latching circulators connected between selected pairs of cross-polarized antenna elements in the polarization-twisting screen so that such pairs also may function as a feed array for the space fed antenna.

Abstract: A method of producing a control signal for a range gate in a pulse Doppler radar, the method encompassing the steps of periodically determining the range slip of a selected target and then changing the position of a range gate during each range sweep in accordance with the determined range slip.

Abstract: In a control circuit for a voltage-controlled oscillator including the combination of: (a) a source of D.C. power, the voltage out of such source being adjustable in discrete steps to provide a coarse frequency control signal; (b) a control loop, responsive to the signal out of the voltage-controlled oscillator, to provide a fine frequency control signal; and (c) a summer to combine the coarse and fine frequency control signals into a single frequency control signal for the voltage-controlled oscillator, an improvement is shown wherein the control loop comprises an interferometer wherein noise extant on the signal out of the voltage-controlled oscillator is degenerated by dividing a portion of such signal into a reference path, a delayed path and a parallel path, the signals in the latter two paths being processed to produce an amplitude corrected signal for combination with the signal, shifted by 90.degree., in the reference path, finally to produce the fine frequency control signal.

Abstract: An improved combiner of microwave power out of a plurality of coaxial diode oscillators is shown to be made up of a circular cylindrical cavity dimensioned to operate in the TM.sub.020 mode at a selected microwave frequency, with such oscillators being disposed about the periphery of both end planes of such cavity and each individual one of such oscillators being reentrant at an angle of 180.degree. so as to double the number of such oscillators as compared with the number of straight coaxial diode oscillators that may be disposed about the periphery of such cavity.

Abstract: Chaff for protecting a ballistic missile from detection by radar during re-entry into the atmosphere is shown to be made up of a plurality of dart like elements, each fabricated from pyrolytically formed graphite and shaped so as to follow a ballistic path through the atmosphere upon release from said missile and to appear as a resonant dipole to interrogating signals from a radar.

Abstract: A power combiner using a circularly cylindrical cavity, dimensioned to support the TM.sub.020 mode, to combine the power from coaxial diode oscillators is shown to comprise: (a) a first plurality of such oscillators disposed about the periphery of such cavity; (b) a second plurality of such oscillators disposed in coincidence with the first spatial null in the electric field in such cavity; and (c) a plurality, similar in number to the second plurality of such oscillators, of electrically conductive bridges interposed between the top and bottom walls of the cavity in-between the center conductors of the coaxial diode oscillators in the second plurlaity of such oscillators.

Abstract: A solid state transmitter/receiver operating at 94 GHz is shown to comprise an injection-locked pulsed oscillator for transmitting interrogating pulses and a first local oscillator for heterodyning with received signals to produce an intermediate frequency (I.F.) signal, both such oscillators being phase-locked to a master oscillator operating at a frequency below 94 GHz.

Abstract: A miniature rate-integrating gyroscope is shown to comprise: an electrical motor (whose rotor, when rotating, constitutes a gyroscopic mass) mounted in a single degree of motion gimbal within a cylindrical case; a motion sensor to determine any rotation of such gimbal with respect to such case, such sensor including a transformer having a primary winding and a secondary winding movable with respect to each other so that the phase difference between alternating signals in the primary and secondary windings is analogous to such rotation; phase detecting circuitry to produce a control signal representative of such phase difference; a torque generator responsive to the control signal to null any rotation of such gimbal; and a fluid damper to critically damp any rotation of such gimbal.

Abstract: Circuitry for controlling a phase-lock loop using a charge-pump phase detector is shown to comprise a phase detector network in combination with an operational amplifier connected to selected output signals from such network to produce a bipolar D.C. signal indicative of the phase difference between signals applied to such network, one of the signals being at a frequency half that of the other.

Abstract: A gimbal assembly for a monopulse antenna gyroscopically stabilized on a moving vehicle is shown to comprise a tripartite bearing having a fixed spherical inner section, an annular central section, connected through a helical spring to the moving vehicle, mounted on the spherical inner section and an annular outermost section rotatably mounted on the central section to form a gyroscopic mass that may be precessed.

Abstract: A method of controlling antiaircraft fire is described in which an aircraft is tracked continuously during the flight of a burst of projectiles and the probability of a hit is continuously revised according to the latest target maneuver as the projectiles proceed to the intercept point. If, before all of the projectiles reach the aircraft, the probability of a hit falls below a specified level, another burst of projectiles is fired. As this second burst proceeds to target its computed probability of hit is combined with that of the previously fired burst to determine the cumulative probability of hit of the two bursts taken together. If, before the second burst reaches the target, the cumulative probability falls below the specified level then a third burst is fired. This activity repeats until the cumulative probability of hit is driven up and kept up above the specified level.