Abstract: A structure (47) is rotatable 360.degree. about a vertical azimuth axis and 90.degree. or more about an orthogonal elevation axis. The structure (47) is mounted upon a rotating turret (6) in the general shape of an inverted pyramid, with a vertical generally cylindrical torque tube (11) protruding from the bottom of the turret (6). A drive wheel (12) is attached to the bottom of the tube (11) and provides a mechanical advantage for azimuthal rotation because it is larger than the wheel (25, 26, 30) connecting the top of the tube (11) with the bottom of the turret (6). The turret (6) rotatably turns about tripod base (46) by means of wheels (29) mounted beneath the rim (30) of said upper wheel (25, 26, 30). Elevational motion is provided by means of a lead screw (16) connecting rotating turret (6) with structure (47), which can be a modular mass-producible solar radiation reflector consisting of many identical reflective panels (1), each having the shape of a portion of the surface of a sphere.

Abstract: A microwave coupler for coupling microwave energy from a first waveguide to a second waveguide disposed side by side along a propagation length includes a common coupling means, and specifically, orifices along the propagation length wherein the coupling orifices are sized to promote coupling of a favored field mode of electromagnetic energy according to a Bessel function distribution of energy along the length of the waveguide. The Bessel function distribution provides for wideband, low-loss coupling of the favored field mode and maximal isolation from non-favored field modes. The invention is particularly useful for extracting a type TE.sub.21 circular mode signal from a signal containing TE.sub.11 and TE.sub.21 circular modes wherein the TE.sub.21 mode signals are used for generating elevational and azimuthal tracking signals.

Abstract: A bipolar metal-gas battery cell stack (1) eliminates the heavy bipolar plates (11) of the prior art by means of locating the series electrical connections (25, 27) between oppositely polarized electrodes (5, 7) of adjacent cells (3) external to the cells (3) in a dielectric frame (21, 23). As a result, the reliability of said electrical connections (25, 27) is improved, weight is saved, and reactant gas screens (15) and electrolyte reservoirs (13) can beneficially be made of compressible lightweight materials. Electrolyte is beneficially confined within each cell (3), and secondary (overcharge) gasses are beneficially confined within each cell (3) in a region (17) proximate the positive electrode (7). A hydrophobic barrier (29) and the frame segments (21, 23) prevent intercell migration of electrolyte and secondary gasses.

Abstract: A vacuum dewar for infrared detectors is disclosed, in which unitary Kovar leads are used to reduce heat load and improve reliability and ruggedness. The Kovar leads are encapsulated in the glass walls of the hollow stem which carries the sensor array and supplies cryogenic fluid for cooling the array. The Kovar leads extend throughout the entire length of the stem to form both the electrical feed-through and the contact points at each end of the stem for the attachment of wire leads or cables, and to form a reinforcing structure for the stem. A fabrication method is also disclosed, in which a unitary Kovar leadframe is held under tension while two concentric glass tubes, between which the leadframe is vacuum-sandwiched, are fused together to form a stem encapsulating continuous Kovar leads throughout its length, while preventing excessive oxidation of the Kovar leads.

Abstract: A double dielectric resonator (1) having lower and upper preferably cylindrical dielectric elements (3, 5, respectively) is used to stabilize an oscillator operating at microwave frequencies. The dielectric elements (3, 5) are separated by a distance (d) which is greater than zero but less than an amount that will eliminate magnetic coupling between the dielectric elements (3, 5), and preferably less than an amount that will push the oscillator into a nonlinear region of the frequency versus separation (d) curve. The major axes (43, 45, respectively) of the dielectric elements (3, 5) are aligned, or else parallel but offset slightly. The invention may be used with reflection type, parallel feedback, and series feedback oscillators.

Abstract: A guidance system for small spinning projectiles which is mechanically simple, has low power requirements, uses relatively unsophisticated electronics, and is capable of withstanding large gas pressures and accelerations. The system uses a one-piece fin assembly which is de-spun so that its guidance fins maintain a constant attitude with respect to the ground. The guidance fins and their hub can be nutated simultaneously and independently in two orthogonal planes by pivoting and translating a single control rod. The hub cooperates with the projectile body to reduce its base drag and thereby extend its range.

Abstract: An imaging radar seeker (8) for producing two-dimensional images of a target (2) is mounted on a missile (6) or other moving body, such as an automobile. A computer (40) directs the seeker (8) to operate sequentially in searching, tracking, and imaging modes. In the searching mode, a combination of circumferential rotation of antenna (12) of seeker (8) and frequency scanning of electromagnetic energy fed to antenna (12) enables seeker (8) to search for its target (2) over a conical field-of-view (16) or a wider, peripheral belt field-of-view (16). In the imaging mode, circumferential rotation of antenna (12) is stopped, and the tilt angle (A) of the linear array (32) of antenna (12) is stepped or continuously moved to compensate for radial movement of the radiated beam (14) caused by frequency stepping imparted by a frequency synthesizer (20). This keeps the beam (14) fixed in space and centered on target (2).

Abstract: A compact, low-profile broad-banded log-periodic antenna comprises a planar conductor (3) partially sandwiched by but electrically insulated from two substantially parallel spaced-apart ground planes (4, 8). The sandwich extends as far as an imaginary plane (15) that is orthogonal to conductor (3) and to the ground planes (4, 8). Conductor (3) comprises an alternating series of radiating loops (L(n)) and non-radiating transmission-line loops (L(j)). The non-radiating loops (L(j)'s) lie on the ground plane (4, 8) side of plane (15). The radiating loops (L(n)'s) lie on the other side of plane (15). Optional additional ground planes (6, 10) may be employed, in which case they lie in plane (15) and meet one of the primary ground planes (4 or 8, respectively) along a common edge. The length (d) of the loops (radiating or non-radiating), the spacing (D) between loops, and the height (h) and width (w) of the radiating loops (L(n)) are all scaled by a factor (S) which is less than 1 but greater than 0.

Abstract: Heat exchangers (2) with particular use as solar receivers are mass-produced by weaving on a textile loom a yarn of high modulus fibers (18, 20) into a repeating series of substantially flat preforms (4), forming a set of interconnected passageways (26, 30, 32) connecting one side of each preforms (4) with an opposite side thereof. The separated preform (4) are each wrapped around a mandrel to give each the shape of a cylindrical sleeve (2). The sleeve (2) is impregnated in a low modulus matrix, dried, and sintered for rigidization. In a first sealing embodiment, the outer sleeve surface (24) is sealed or weatherproofed, and the surfaces of the internal passageways (26, 30, 32) are sealed, but the radiation absorbing inner sleeve surface (22) is not sealed. In a second sealing embodiment, the outer surface (24), the radiation absorbing inner surface (22), and the exchanger ends (14, 34) are sealed, but the surfaces of inner passageways (26, 30, 32) are not sealed.

Abstract: A stable electromagnetic oscillator (30) comprises an amplifying element (3) in feedback association with a dual mode resonant cavity (12) that provides a double pole bandpass filter function. Two orthogonal modes (1 and 2) of electromagnetic energy resonate within the cavity (12). An output from the amplifying element (3) excitationally couples into the first mode (1), while the second mode (2) couples into the input of the amplifying element (3). The output (8) of the oscillator (30) is obtained from the first mode (1). Optional injection lock can be used for greater stability by means of coupling a stable a.c. reference (9) into the cavity (12) in alignment with the second mode (2). Optional electronic frequency tuning comprises a phase or frequency comparator (11) and a reference a.c. source (13), producing a d.c. feedback signal fed to varactor diodes (10). Coupling ports (4, 5, 6, 7) of the cavity (12) can be, e.g., irises, capacitive probes, coaxial probes, or any combination thereof.

Abstract: Transients and steady state error induced in maneuvering a satellite due to a disturbance torque caused by thrust mismatch or differential in the alignment of thrusters with respect to the center of mass are minimized by introducing a torque balancing bias at the input of a thrust modulator of the thrusters prior to sensing position or attitude error. The bias may instantly off-modulate the thruster control signal to cancel the effects of attitude transients before errors develop. Other axes thrusters may be on-modulated instantaneously to compensate for cross-axis torque. The bias may be introduced into the satellite control scheme by manual ground control or in automatic on-board compensation based on stored parameters obtained for example from calibration measurements. Specifically, the torque balancing bias may be developed by reference to thrust mismatch detected and stored during previous maneuvers, thus anticipating expected attitude error without actual detection thereof.

Abstract: A moving target detector for spinning bodies such as projectiles or missiles uses a linear detector array so mounted on the body as to periodically scan an arcuate target area during the spin of the body. Compensation for the resulting optical growth of the target area image as the body approaches the target is accomplished by serially reading the image information from the detector elements (in a direction radial of the target area) into a delay element chain at a variable rate, and dumping the delay chain contents in parallel into the image memory at a fixed rate. The readout rate variation is pre-programmed prior to launch, and feed-back loop may be provided to adjust the rate if the image evaluation circuits detect apparent radial movement of evidently stationary objects near the target.

Abstract: A structure (47) is rotatable 360.degree. about a vertical azimuth axis and 90.degree. or more about an orthogonal elevation axis. The structure (47) is mounted upon a rotating turret (6) in the general shape of an inverted pyramid, with a vertical generally cylindrical torque tube (11) protruding from the bottom of the turret (6). A drive wheel (12) is attached to the bottom of the tube (11) and provides a mechanical advantage for azimuthal rotation because it is larger than the wheel (25, 26, 30) connecting the top of the tube (11) with the bottom of the turret (6). The turret (6) rotatably turns about tripod base (46) by means of wheels (29) mounted beneath the rim (30) of said upper wheel (25, 26, 30). Elevational motion is provided by means of a lead screw (16) connecting rotating turret (6) with structure (47) which can be a modular mass-producible solar radiation reflector consisting of many identical reflective panels (1), each having the shape of a portion of the surface of a sphere.

Abstract: A laser radar transmitter (2) has, associated with a single active lasing region (11) and preferably in the same laser cavity (1) therewith, an amplitude modulator (21) and a frequency modulator (25), which may simultaneously place continuous AM and continuous FM on a single output beam (7). Amplitude modulator (21) is preferably an EO crystal having a high EO coefficient, low loss, and field-induced birefringence. Frequency modulator (25) is preferably an EO crystal having a high EO coefficient, low loss, and a field-induced index change. Applying a d.c. driving voltage to the AM crystal (21) and an a.c. driving voltage to the FM crystal (25) produces an output beam (7) having FM. Applying an a.c. driving voltage to the AM crystal (21) produces an output beam (7) having AM, independently of whether FM is added by means of applying an a.c. driving voltage to the FM crystal (25).

Abstract: A dynamic electronic switch (10) having n inputs (2) and m outputs (4), where n and m are any positive integers. The electromagnetic signal on any given input (2) may be switched onto any number of outputs (4), but any given output (4) may have no more than one input signal switched thereonto at any given time. Switching nodes (8), comprising at least one switching diode (11, 13, 15) and a directional edge coupler (17) embedded between two parallel ground planes (9, 1) in a planar mother board (5), perform switching at each intersection of an input (2) and an output (4). Each output (4) is mounted on a planar dielectric summer board (6) positioned orthogonal to the mother board (5).

Abstract: In a guided moving warhead (1) which can be a missile or a projectile containing a long rod penetrator (3), alignment wings (5) keep the rod (3) in alignment with the warhead's velocity vector, thus maximizing its destructive potential. Two pairs of wings (5) are coupled to the rod (3) by means of a two-axis gimbal (7). One pair of wings (5) pivots along one axis of the gimbal (7) while another pair pivots about a second orthogonal axis. Aerodynamic forces cause the wings (5) to align with the relative wind, and as a result, the rod (3) aligns with the warhead's velocity vector as desired. Orthogonal components of crossflow acting upon the wings (5) can be compensated out by means of gearing the shafts (11, 15) which connect the wings (5) with the gimbal (7). In the case where warhead (1) is a missile, it is often necessary to negate the lift force imparted by the wings (5) during early low velocity stages of flight.

Abstract: Disclosed is a method and apparatus estimating yaw error and roll and yaw disturbance torques from measured roll error and yaw momentum on a continuous on-orbit basis in an orbiting satellite. The information thus obtained can be used to continuously correct for the yaw error by means of, for example, activating a magnetic torquer. Two control loops are used in this invention, a fast loop to damp nutations by changing momentum wheel speed, and a slow loop of the Luenberger observer variety. The latter is a yaw error correction loop which also serves to unload yaw momentum. The satellite in which the invention was first incorporated is of the type having three momentum wheels, all situated in the plane orthogonal to the roll axis. In normal operation, two wheels, each having major momentum component along the pitch axis and minor momentum component along the yaw axis, are operable.

Abstract: A short-focus microwave reflector is located a short distance away from the feed horn and is positioned to reflect the beam of microwave radiation away from the feed axis and toward a large primary reflector antenna for transmission. A conical shield extends from the feed horn to the secondary reflector, joining them together as a unit and preventing sidelobe radiation. The beam of radiation emerges from the shield through an aperture in the sidewall thereof. The short focus of the secondary reflector causes the beam to be focussed approximately at the plane of the aperture, such that the beam diameter is small and the aperture can also be small, reducing stray radiation from the shield structure. Diffraction at the edges of the aperture is reduced by a radially surrounding choke structure which further suppresses sidelobe radiation.

Abstract: A leaky waveguide slotted traveling wave antenna having several elongated nonresonant slots (2) oriented with their long axes substantially orthogonal to the direction of propagation within waveguide (1) filled with a dielectric material having a dielectric constant greater than 1. The length (m) of each slot (2) gradually increases as one traverses the waveguide (1) along the direction of propagation, whereas the width (W) of the wall of the waveguide (1) in which the slots (2) are cut gradually decreases as one traverses the waveguide (1) along the direction of propagation. Any angle of radiation between 0.degree. and 135.degree., including endfire and broadside radiation, can be achieved. The width (w) of each slot (2) and the inter-slot spacing (d) can vary; the increase in slot length (m) can be non-uniform.

Abstract: A cover (1) for protecting the surface (23) of a lens (3) disposed at the rear surface (21) of a guided projectile (7) is fabricated of Teflon or other soft material. Lens (3) faces rearward to receive guidance signals used to keep projectile (7) on a chosen path. Cover (1) protects lens surface (23) from combustive gases and particulates generated during projectile (7) firing, but must be removed shortly after firing to permit lens (3) to receive its guidance signals. Cover (1) comprises at least one vacated chamber (15) for receiving, via holes (17), high pressure combustive gases during firing. Subsequent to firing, the greater pressure within chamber (15) compared with the pressure surrounding cover (1) produces a net force of removal between cover (1) and projectile (7), causing cover (1) to be removed therefrom as desired.