Abstract: An internal calibration system is provided for use with a direction finding interferometer which comprises a plurality of receiving antenna elements (A.sub.1, A.sub.2), a local oscillator (20), a master receiving channel means (41), a receiving channel means (42), and a phase meter (92). The internal calibration system comprises a master switch (22), a master power divider and switch assembly (31), a power divider and switch assembly (32), two transmission lines (M.sub.1, M.sub.2) connected to the master switch assemblies (31, 32), an inter-channel transmission line (T.sub.12) connected to the master power divider and switch assembly (31) and to the other power divider and switch assembly (32), and a plurality of couplers (51, 52).

Abstract: The present invention provides an improved microwave integrated circuit filter for electromagnetic waves. The filter includes a waveguide and three, four or more resonators spaced from one another and extending from the waveguide. Means, which may include a conductive ribbon, are provided electromagnetically coupling nonadjacent resonators.

Abstract: An electromagnetic filter assembly comprises a transmission line electromagnetically coupled to a dual mode resonator having a means for differentially tuning the two modes. The filter may be incorporated in a microwave integrated circuit, and the tuning means may be a movable dielectric slab asymmetrically disposed on the resonator.

Abstract: An enhancement-mode field effect transistor (ENFET) logic circuit providing greater fan-out capability. The logic circuit employs a conventional common-source inverter section, but additionally incorporates a current-driving section which drives the common-source inverter section. A current-driven inverter logic circuit is realized by employing a second ENFET transistor to drive the gate of the common-source inverter section. A current-driven NOR gate is realized by employing two ENFET transistors in parallel which drive the common-source inverter section. Also a current-driven NAND gate is realized by utilizing a single transistor having two gate inputs to drive the common-source inverter section. The use of sweep-out circuitry allows for control of the operational speed of the device. The logic circuit designs have high fan-out capability compared to the common-source inverter circuit alone.

Abstract: A biconical antenna, the halves of which are connected together at the apex by a pair anti-parallel diodes through a pair of parallel conductive whiskers or wires. A pair of quasi-optical lenses focuses energy from a local oscillator and from a submillimeter radio source, respectively, onto the diode pair in the end-fire and broadside direction, respectively. The diode pair spacing is equal to the half wavelength of the local oscillator energy. The local oscillator energy is common mode rejected and causes the incoming radio energy to be sampled by forward biasing the anti-parallel diode pair in synchronism with each zero crossing of the local oscillator energy. Accordingly, the local oscillator energy and noise virtually do not affect the current flow between the halves of the biconical antenna. The current flow represents an intermediate frequency signal corresponding to the difference in frequency between the incoming radio signal frequency and the local oscillator frequency.

Abstract: A compact power coupler comprises a first waveguide short-circuited at one end, a resonant cavity slot-coupled to the shorted end of the first waveguide, and a coaxial transmission line coupled to the resonant cavity. Power at 6 gigahertz is coupled from the waveguide to the transmission line in a unit that is 3.5 inches long. Alternatively, a second waveguide can be slot-coupled to a narrow-wall of the first waveguide (a quarter-wavelength from the short-circuit) to couple 4 gigahertz power, thereby forming a compact diplexer.

Abstract: A photoconductive film reader comprises a disc with a read head attached to its bottom surface at an edge point and rotated over the photoconductive film at a sufficiently high velocity so that the read head floats aerodynamically on the film, the read head having means for sensing the information stored as electrostatic charge on the film. The film has a reset strip of a predetermined amount of charge prerecorded along one of its edges, resetting of the read head electronics being coincident with the passage of the read head over the reset strip. The floatation of the read head on the film reduces the effect of film modulations on the film-to-read head spacing and allows the spacing to be well defined and controllable.

Abstract: Apparatus for controlling the pointing position of the payload platform of a dual-spin satellite. A torque motor which controls the relative position of the payload platform is controlled by means of a closed-loop feedback system which points the line-of-sight of the platform at a predetermined position on the earth. The control circuitry comprises position and rate sensing devices which monitor the relative position of the line-of-sight and the relative rotational rate of the payload platform. The line-of-sight of the platform is compared to signals indicative of the angular subtense of the earth. If the line-of-sight is pointed at the earth, then position command signals control the torque motor. If, however, the line-of-sight of the platform is not directed at the earth, then rate command signals are summed with the position command signals and subsequently applied to the motor.

Abstract: Apparatus for processing microwave signals at two predetermined frequencies. Signals at a first predetermined frequency are received or transmitted at one end (input port) of a microwave transmission line whose other end is utilized as a common output port for transmitting and receiving signals at both predetermined frequencies. A band rejection portion is provided which comprises first and second rejection resonators orthogonally disposed along the transmission line at two predetermined positions. A bandpass portion, comprised of a plurality of collinearly aligned bandpass resonators, is disposed at a third predetermined position along the transmission line. Signals at a second predetermined frequency are transmitted or received at a second input port which is part of the bandpass portion. All resonators are capacitively coupled together and to the transmission line.