Abstract: This specification discloses a polarization network for selectively converting between linear and circular polarization. The network includes a twistable waveguide having a generally rectangular cross section. Coupled to the twistable rectangular waveguide is a transducer waveguide which acts as an interface between the rectangular waveguide and circular waveguide. A polarizer having a generally circular cross section is coupled to the transducer waveguide and can convert transmitted electromagnetic waves between linear and circular polarization. A coupling means permits relative rotation between the transducer waveguide and the polarizer and selective securing at any of three rotational positions. A first position permits a linearly polarized signal to pass through the polarizer remaining linearly polarized. A second position converts between a linearly polarized signal and a right hand circularly polarized signal.

Abstract: A bit synchronous switching system is disclosed which has applicability in a space diversity system of digital telecommunications. Two versions of a signal waveform are received at two remote locations from the same signal source. The end user is able always to receive the more intelligible signal by means of instantaneous switching logic. An acquisition and tracking circuit, which can include a delay lock loop, keeps the two signal streams synchronized. One data stream is used as a reference and the time delay of the other is varied so that the time differential between the two streams is tracked out. The system features continuous tracking and does not require any frame synchronization to be superimposed on the data stream.

Abstract: The tracking signals of a monopulse satellite tracking system are optimized by aligning the phases of the azimuth and elevation channels (the "difference" channels) with the reference (or "sum") channel using an autophase controller and a simulated far field source in the near field. The autophase controller monitors the output of the tracking receiver and adjusts phase shifters along the transmission paths of the azimuth and elevation channels, in a manner to maximize the outputs of the receiver. The simulated far field source provides an alignment signal for the autophase controller. The simulated far field source consists of a signal generator, a near field probe, and near field phase compensators. The probe is positioned to avoid any nulls in the simulated tracking signal for the frequencies of interest. The probe is also positioned to limit the range of the phase shifts introduced by near field placement, for the frequencies of interest.

Abstract: The antenna system employs a parabolic reflector fed by an offset feed array of circular wave guides located substantially at the focus of the parabolic reflector, but offset from the axis thereof. A plurality of aperture tuning mechanisms disposed at the mouths of the circular waveguides of the waveguide feed array, and having physical lengths much shorter than one wavelength at the frequencies involved, are provided to reduce cross-polarization and mutual coupling between adjacent feeds. The short resonant length of these tuning mechanisms, and their shape which is chosen to generate the TM.sub.11 mode E-field contour line ensures that they are effective over a broad bandwidth of as much as 20% or more. Within this bandwidth, they act as inductive suppressors to control both cross-polarization and mutual coupling between adjacent feeds.

Abstract: An antenna system is disclosed comprising a paraboloidal reflector and a feed array having several substantially identical feed elements. The antenna produces a coverage pattern of transmitted radiation in the form of a shaped beam. The present invention permits the use of a smaller number of feed elements for a given size of the reflector's aperture by means of attenuating the sinusoidal ripple that is present in the shaped beam radiation pattern and caused by the size of the feed elements. A plurality of disks is placed in the focal plane of the paraboloidal reflector. The disks are selective with respect to one spatial frequency of the emitted radiation (which is at a constant electromagnetic frequency). The disks may be fabricated of a material which reflects the radiation, a material which absorbs the radiation, or a dielectric material of a certain thickness stipulated herein which changes the phase of the radiation by 90.degree..

Abstract: A single microwave-reflective antenna "dish" can be used in combination with a plurality of multiple-beam microwave feed arrays to generate or receive multiple-beam-path microwave radiation in several different frequency bands. Each of the feed arrays may operate in a discrete band of frequencies, with the combined radiations of all the arrays illuminating the reflector along a single axis. The optical system is based on the Newtonian model, such that the radiations from several arrays located off the principal axis may be combined by corresponding frequency-sensitive reflective surfaces located on the principal axis. Each of these reflective surfaces serves to direct the radiations from a single feed array toward the reflective antenna, and reciprocally, to direct radiation from the antenna to the associated feed array.

Abstract: A solar converter is disclosed which has particular applicability at the focal point of a parabolic concentrator. The converter absorbs solar thermal radiation in a cavity type receiver and transports the heat via a secondary fluid to a heat exchanger which contains a primary (i.e., working) fluid used for process heating or to power a heat engine employing either Stirling, Rankine, or Brayton thermodynamic cycles. The secondary fluid is boiled within the receiver by the trapped solar radiation and the released vapor rises along an elevated path to the heat exchanger. The vapor condenses on the surfaces of the heat exchanger, thereby transferring heat to the engine working fluid. The condensed liquid then flows by means of gravity back to the solar receiver. The walls of the cavity receiver are typically comprised of two concentric cylinders joined at one end in a half toroid and at the other end in concentric half spheres.

Abstract: An amplifier is disclosed which is capable of operation from 0 MHz to over 100 MHz with very low distortion over this entire range. Several inputs may be combined without affecting the gain of the amplifier. Several outputs may be combined without adding to the distortion products significantly. A pair of common-base symmetrically juxtaposed transistors drives a pair of symmetrical common-emitter transistors. An AC and DC feedback loop is provided along the line of symmetry. In addition, each symmetrical half of the set of four transistors has a DC feedback loop which balances current between stages of said half and inhibits overcurrent conditions in the transistors of that half.

Abstract: This device enables one to perform individual measurements, tests, and tuning of active elements in a circuit in which the active elements are combined using couplers. Typically, the active elements are amplifiers which are power combined using quadrature power dividers and combiners. The invention uses two additional quadrature couplers, one at the front and one at the back of the circuit. All the power is introduced into one input port of the first additional coupler. The action of the first two couplers results in power flowing through one of the active elements only. The action of the second pair of couplers results in the flow of power through one output port only. After testing, the additional couplers are removed. The invention enables the one step fabrication of components on the substrate followed by testing, rather than the more time consuming and complex separate assembly and testing of four substrates.

Abstract: A field effect transistor bias circuit is presented which exhibits a low impedance for small signals and a high impedance for large signals. This circuit uses an operational amplifier to provide a temperature compensated low impedance voltage source for the gate bias which is optimal for small signal operation. In the presence of a large signal, the gate begins to draw current. This causes the operational amplifier to saturate and transforms the bias circuit into a high impedance source, which is optimal for large signal operation.

Abstract: An impedance transforming coupler is disclosed which may be used as a power divider or power combiner at microwave frequencies. The power division or power combination ratio is arbitrary, and the impedance transformation ratio is arbitrary. These couplers may be used in a circuit to power-combine amplifiers. The insertion loss of the circuit is low and the bandwidth is improved by an order of two to one over prior art systems which had separate circuits for matching the impedance and providing power combining. The coupler is optimally a branch line coupler having four curved branches a quarter wavelength long at the center frequency. The output ports are 90.degree. out of phase. Simple formulas are given relating the desired admittances of each of the four branches to k, the desired power coupling ratio, and Y, the desired admittance transformation ratio.

Abstract: This multiplexer and demultiplexer features two transmission lines, one for conveying the data and a second for timing. The timing line controls both the shifting of data in the demultiplexer and the signaling for the beginning and end of data words. Synchronization of the bit shifting clock with the word shifting signal is accomplished by means of phase lock loop circuitry incorporated into the demultiplexer. The disclosed circuit uses low power CMOS design, directly interfaces with contact closure commands, and directly drives relay or lamp type loads. The demultiplexer contains a power-up delay circuit to avoid start-up ambiguities and false data transmission.

Abstract: A high bandwidth transversal filter is described having an input impedance matching network, a tapped delay line, a plurality of weighting amplifiers, a distributed summing circuit, and an output impedance matching network. The delay line is implemented with a transmission line. The input impedance of this transversal filter depends on the inductance and capacitance of the transmission line and the capacitance of the inputs of each of the FET's used as weighting amplifiers. The gates of the FET's provide high impedance low loss taps of the delay line. The weighting is accomplished by either varying the drain current of the FET's or by using capacitive voltage dividers to apportion the tapped signals. The resulting weighted signals are applied to a distributed summing circuit which provides both high bandwidth summing and additional delays. This summer is also implemented with a tapped transmission line.

Abstract: A method for joining a composite material shaft, such as a graphite epoxy or fiber glass driveshaft, to a metal end member is disclosed, wherein said joint is capable of withstanding large ranges of temperature and humidity, can handle high torque and has high resistance to fatigue. The design of parallel grooves on the end of a metallic sleeve concentrically aligned within the shaft is amenable to mass production. The first layer of fibers of the composite material shaft is preferably wound perpendicular to the orientation of the grooves. On the other end of the metallic sleeve is carved a scalloped pattern which facilitates concentric alignment of the sleeve on the tooling mandrel and helps to reduce shear stress between the sleeve and shaft. A method for mass production of shafts with metallic end joints attached employs an elongated spinning mandrel and pre-preg tape wound at high speed.

Abstract: Described herein is a method for bonding a skin member such as metal, plastic, perforated acoustic skin, or fiberglass or graphite reinforced plastic, to a honeycomb core support structure such as lightweight hollow hexagonally shaped tubes. Such a method can be used in the construction industry for making panels and walls and similar structures, and in the aerospace industry for making airplane and satellite structures, etc. The adhesive employed is an adhesive-coated fabric material which is partially cured onto the honeycomb and cooled down, following which most of the adhesive material is removed when the coated fabric is peeled away. This leaves an optimum amount of adhesive in the most effective locations on the wall edges of the honeycomb cells where it is needed for bonding the core to the skin. The skin member is then bonded to the honeycomb by bringing the adhesive to its final cure.

Abstract: The disclosed invention is a device and method for optimizing the weight and/or the heat transfer (conduction) capability of a heat transfer cylindrical sleeve. The sleeve is designed to fit around a cylindrical heat source. One particular application for this invention is where the heat source is a battery such as a metal gas battery in a satellite (where weight savings is important). Two sets of functional relationships are generated showing the relationship between the thickness of the sleeve at its top and bottom, an "area factor" (which is directly proportional to its heat transfer capability), the material thermal conductivity, and its volume per unit length (which is directly proportional to its weight). One can specify the desired heat transfer capability of the sleeve and optimize (minimize) its weight. Conversely, one can specify the desired weight for the sleeve and optimize (maximize) its heat transfer capability.

Abstract: This specification discloses a frontal reflector bracing wherein at least a portion of the support for a reflecting surface is positioned on the front side of the surface and the rearward most support is adjacent the reflecting surface. A natural structural rigidity minimizing weight can be achieved with a frontal truss arrangement including radial components.

Abstract: An apparatus for joining a composite material shaft, such as a graphite epoxy or fiber glass driveshaft, to a metal end member is disclosed, wherein said joint is capable of withstanding large ranges of temperature and humidity, can handle high torque and has high resistance to fatigue. The design of parallel grooves on the end of a metallic sleeve concentrically aligned within the shaft is amenable to mass production. The first layer of fibers of the composite material shaft is preferably wound perpendicular to the orientation of the grooves. On the other end of the metallic sleeve is carved a scalloped pattern which facilitates concentric alignment of the sleeve on the tooling mandrel and helps to reduce shear stress between the sleeve and shaft. A method for mass production of shafts with metallic end joints attached employs an elongated spinning mandrel and pre-preg tape wound at high speed.

Abstract: This device generates clock pulses which are synchronized with the bit data rate of an input antipodal bit pattern. The device can be used with multiple input data channels whenever such channels are synchronized, i.e., the periodicity of each channel is the same and the phase relationship between channels is fixed. For example, it can be used with QPSK modulation with two input basebands; or with biphase shift keying, frequency shift keying, or other types of modulation with only one baseband input. The circuit uses a form of delay lock loop which estimates the mean zero crossing instant of the input data stream. It compares the zero crossings with early and late gates which are generated on the basis of prior analysis of the input stream. A multiple transition detector circuit is employed when the operating environment is very noisy to inhibit the counting of multiple zero crossings during a combined early gate/late gate period.

Abstract: Described herein is a microwave radar system which employs heterodyned swept frequency at approximately two millisecond sweep intervals. The power source is a reliable solid state, low power device such as a Gunn diode. The heterodyned difference frequency signals are converted to digital form, transformed into the frequency domain by means of a Fourier power transform, and then averaged by computer processing. Performing the Fourier power transform before averaging enables the processing of quasi-incoherent data whereby signal-to-noise ratio improvement is a function of the square root of the average number of samples taken. High-speed processing is used to off-set the loss of statistical averaging of phase-coherent data which cannot be preserved because of target motion. Thus, the sequence of the power transform allows phase-less averaging over the entire collection period.