Abstract: Methods and apparatus are provided for distributed polyphase spread spectrum communication and non-contiguous spectrum underlay. The method includes polyphase channelizing a direct sequence spread spectrum (DSSS) signal, determining available spectrum in an observed frequency range having a noise floor based on detection of polyphase users below the noise floor, distributing the polyphase channelized signal among the available spectrum, and interference mitigation using a combination of standard signal detection and cyclostationary feature detection methods.

Abstract: Waveguide phase shifter (200, FIG. 2 and 300, FIG. 3) uses piezoelectric ceramics to implement a voltage variable actuator (270, 370) for moving at least one dielectric vane (255, 355) relative to a reference surface (206, 306) in a waveguide cavity (285, 385). In this manner, the phase shift in waveguide phase shifters (200, 300) is controlled. In one embodiment, actuator (270) comprises first piezoelectric wafer (210), second piezoelectric wafer (220), first metallic layer (230), second metallic layer (240), third metallic layer (250), mating surface (272) and spacer (265). Actuator (270) uses a stack of piezoelectric materials to establish a lever arm mechanism to establish vertical movement (294) and move dielectric vane (255). Actuator (370) uses a stack of piezoelectric materials to establish vertical movement (394) and move dielectric vane (355). Waveguide phase shifters (200, 300) are used in phased array antenna (400) operating at microwave frequencies.

Abstract: An antenna system (10) capable of transmitting electromagnetic radiation using the technique of combining two quadrature signals for either right hand circular polarization or left hand circular polarization using a circularly polarized antenna (30), or alternately, either horizontal or vertical polarization using a linearly polarized antenna (36) while incorporating feedback for automatically correcting for amplitude and phase variations in the quadrature paths using a switch (12) which selects the sense of the polarization and electronic optimization of the transmit antenna (30, 36). The antenna system includes a control circuit having a polarization switch (12) for receiving a transmission signal. The switch (12) generates first and second output signals which are substantially similar to the transmission signal, and determines whether to apply the transmission signal to one of a first or a second switch output.

Abstract: An array (100) of voltage variable capacitors (110) is provided in which voltage variable capacitors (110) are fabricated with piezoelectric displacement devices (150). Voltage variable capacitors (110) have first plates (120) which are coupled to displacement devices (150). First plates (120) are dielectrically coupled to second plates (130). Displacement device (150) has a stack of metallic layers (154), voltage variable material blocks (152), and voltage supply terminals (170) and (180). Voltage differences are established across voltage variable material blocks (152) using voltage supply terminals (170) and (180). A voltage difference causes a voltage variable material layer to change thickness, and this causes first plate (120) to move relative to second plate (130). Voltage variable material is selected from a group of piezoelectric ceramics, which can include lead-titanate (PbTiO.sub.3), lead-zirconate (PbZrO.sub.3), barium-titanate (BaTiO.sub.3), and lead-zirconate-titanate (PbZr.sub.x Ti.sub.1-x O.

Abstract: A phased array antenna (1000) is formed using a number of independently controllable piezoelectric phase shifters (1300) which results in a low cost phased array antenna that is functional at microwave and/or millimeter wave frequencies. In addition, the independently controllable piezoelectric phase shifters (1300) have sufficient phase range to allow a single antenna to be steered over a wide angle field of view. Piezoelectric phase shifters (1300) comprise at least one-voltage variable capacitor (1310, 1320, FIG. 2). Typically, the piezoelectric material used in the voltage variable capacitors is selected from a group consisting of lead-titanate (PbTiO.sub.3), lead-zirconate (PbZrO.sub.3), barium-titanate (BaTiO.sub.3), and lead-zirconate-titanate (PbZr.sub.x Ti.sub.1-x O.sub.3), where x varies from zero to one.

Abstract: A variable oscillator controlled by a phase-locked loop to lock on to a received pulse of radio frequency waves, sample and hold circuitry sampling the control signal in the loop and storing the signal, and a timed switch disconnecting the oscillator from the loop and connecting it to the sample and hold circuit after a predetermined period of time so that the oscillator is locked on to the radio frequency after the single pulse ceases.

Abstract: A high power, pulsed microwave frequency converter for a microwave communications system including a phase locked loop with a voltage controlled microwave oscillator that provides at least five watts of pulsed RF output power, the components of the loop being designed to lock on the desired RF output frequency within approximately 20 nanoseconds or during the initial portion of each pulse so that the converter coherently converts two low level signals, one or both of which may be pulsed, into a higher level narrow pulse signal at the sum or difference of the frequencies of the two low level signals.