Abstract: The signal-to-noise enhancer can be used in frequency memory loops to prevent loop capture by noise. If a frequency selective limiter is incorporated in the loop, more than one signal can be stored simultaneously because the limiter prevents the loop amplifier from saturating. At present, the limiter must be a separate device. The frequency selective signal-to-noise enhancer/limiter apparatus comprises an enhancer apparatus and a limiter apparatus on a single substrate, using a single pair of magnets to bias both units.

Abstract: A microwave gas discharge apparatus for use as a limiter or TR device or the like and employing a primary discharge arrangement which has a single resonator used for priming the discharge device and determining the priming energy frequency.

Abstract: A high power halogen-filled vial stage receiver protector utilizing an RF priming source in conjunction with a pair of circular guides to provide a continuous supply of priming free electrons to the halogen gas-filled plasma limiter vial.

Abstract: The plasma switching stage of a radar receiver protector is simplified and improved by the utilization of a halogen gas filled quartz container and a "keepalive" electron source. The container is configured as a capillary stem filled with low pressure chlorine gas and provides the active switching element in the signal waveguide portion of the receiver protector. An enclosed r.f. energy source in combination with the capillary stem creates a copious and steady free electron supply. The r.f. exciting field used to activate the "keepalive" plasma is enhanced by a coaxial re-entrant cavity located on the top wall of the receiver protector waveguide.

Abstract: A circuit injects the signal from a stable localized oscillator past a pin diode switch through a first circulator to a waveguide, a second circuit injects a noise signal from a generating diode through a second circulator to the first circulator to the waveguide, a switching system causes the diodes to function in a coordinated manner.

Abstract: A microwave circuit network which combines a number of signal-to-noise enhancers of the magnetostatic wave excitation type, utilizing ferrite material, to extend the signal-to-noise enhancement frequency bandwidth beyond that which is offered individually by any one of the enhancers being combined while reducing substantially any signal interaction between the signal-to-noise enhancement operations thereof is disclosed.

Abstract: An iris for a stage of a receiver protector is described incorporating a metal plate having a slot opening wherein the electric field across the slot opening is enhanced by tapering or beveling the edges of the slot.The invention overcomes the problem of high firing threshold and high recovery time of a gas plasma by providing metal in close proximity to the gap for providing free electrons.

Abstract: A receiver protector is described incorporating a waveguide containing several isolation stages followed by at least one iris plate filter.The invention overcomes the problem of RF or microwave leakage power of out-of-band frequencies some of which may be generated by non-linear elements in the prior isolation stages of the receiver protector.

Abstract: A coaxial line, wide dynamic range, ferrite limiter having optimal frequency selectivity for microwave frequencies is provided by a stepped ferrite rod with disks of varying volumes and dielectric constants controlling the operating frequency and threshold level for each step segment.

Abstract: A microwave discharge gap receiver protector includes a radioactive ignitor of the nuclear decay type to provide an auxiliary source of electron priming therefore, the radioactive ignitor comprising a radioactive plate for emitting beta particles therefrom, and a tubular enclosure to channel the flow of emitted beta particles therethrough. In operation, a portion of the channeled emitted beta particles collide with the inner walls of the enclosure which are comprised of a material having a high secondary emission characteristic to generate additional electron particles as a result of secondary emission. Another portion of the beta particles in the channel of the tubular enclosure collide with existing gas particles to generate a second source of auxiliary electrons. The combined sources of auxiliary electrons result in an increased particle concentration which is emitted at an exit end of the enclosure and directed to the discharge gap of the receiver for priming purposes.

Abstract: PIN diodes of decreasing base region thicknesses, wherein the thickest base region diode functions as a quasi-active limiter with turn-on bias supplied by detected RF current in a Schottky barrier diode with a discharge resistor providing fast recovery; and the thinnest base region PIN diode being a zero bias punch-through type, with a dc sensitivity time control, functioning as a passive limiter during transmit and controlled attenuator during receive provides an improved radar receiver protector circuit. The operation of the PIN diode is enhanced by a unique mounting on a gold-plated copper puck in the circuit board and tuning the signal leads to the diode.

Abstract: The passive receiver protector, AGC attenuator and sensitivity time control functions of a radar are combined in a single device which performs the functions in front of the radar low noise amplifier with relatively low loss. The receiver protector utilizes semiconductor diodes which operate as a power limiter during transmit and as precision attenuators during receive.

Abstract: Two sectoral radial resonators coupled at their centers of radii by a strip transmission line and doubly loaded with opposing ferrimagnetic spheres between the said strip transmission line and the ground planes provides a frequency selective power limiter.

Abstract: A high power pre-TR switch utilizes hot pressed boron nitride to form a vial. The vial contains a halogen gas such as chlorine.

Abstract: Frequency agility may be added to fire control radars by replacing the conventional receiver-protector/stationary-filter combination located between the duplexing circulator and the receiver input with a passive high power ferrite limiter and YIG tracking filter combination.

Abstract: An improved microwave device for filtering and power limiting is described incorporating a yttrium-iron-garnet (YIG) sphere and a transmission line wherein coupling between the YIG sphere and the transmission line is enhanced by placing the YIG sphere in a groove in a ground plane under the transmission line. The current induced in the groove of the ground plane results in enhanced coupling.

Abstract: A ferrimagnetic sphere that is biased to the subsidiary resonance mode and placed within a microwave slotted resonant structure functions as a frequency selective microwave power limiter. When the power level of a signal at the input port exceeds a threshold level, the device prevents the power level at the output port from increasing further. A weak signal present simultaneously passes with relatively little attenuation if it is slightly offset in frequency.

Abstract: A signal processing system for simultaneously transmitting a plurality of rrier frequencies and receiving certain of said frequencies to the exclusion of others. In a radar system employing the disclosed technique, a CW carrier and pulsed modulated carrier are transmitted simultaneously from a single antenna. The CW carrier and the echo frequency from the modulated carrier are received by a receiver protector circuit which passes the low power echo of the pulse modulated carrier to receiver processing circuitry while suppressing the CW carrier having a power level above a predetermined threshold. The receiver protector enables the use of plural carrier frequencies in a frequency agile system with decreased frequency separation.

Abstract: An FM/CW radar system which uses a single duplexed antenna, in which high degree of isolation of the transmission signal from the receiver is provided by passive power limiter devices employing the subsidiary resonance mode of narrow linewidth ferrite materials. In devices which are magnetically biased for operation in the subsidiary resonance mode, strong r.f. fields resonantly couple to spin waves, thus causing power absorption for signals at the frequency of incidence which exceed a predetermined threshold. A signal exceeding the threshold is attenuated over a narrow band at the frequency of incidence while the weak FM/CW target echo return signals are transmitted to the receiver with very low loss, provided their frequency displacement is of the order of 15 MHz from the frequency of incidence.

Abstract: The subject of the invention is a waveguide-type, multi-stage, receiver protector. It combines the use of all-chlorine gas discharge stages and a radioactive primer discharge stage having a semi-inert gas medium in a way to retain the protection benefits of the radioactive primer device, while providing the fast recovery time of the chlorine stages. The apparatus includes an r.f. limiting diode section which aids in attaining the combined benefits of the other two types of stages.