Hughes Aircraft Company

Hughes Electronics Corporation

Harry T Wang

Jar Jar Lee

Gregory L Tangonan

Hui-Pin Hsu

Willie W Ng

Robert R Hayes

Irwin L Newberg

Ronald Regis Stephens

Ronald B Chesler

Adrian E Popa

John K Keigharn

Bill H Otoide

Wideband phased array antennas are provided that eliminate the need for phase shifters in the region of the array face. In addition, they generate less beam squint than conventional antennas. In one embodiment, they include an electronic signal generator, reference and scanning manifolds and an array of n radiative modules. The signal generator generates a variable-frequency scanning signal s.sub.s and a reference signal s.sub.r wherein the frequency of the reference signal s.sub.r is substantially a selected one of the sum and the difference of the frequencies of the scanning signal s.sub.s and an operating signal s.sub.o. The reference manifold receives and divides the reference signal s.sub.r into n reference signal samples which are progressively time delayed by a selectable one of m reference differential time delays .DELTA.t.sub.r. The scanning manifold receives and divides the scanning signal s.sub.o into n scanning signal samples which are progressively time delayed by a scanning differential time delay .DELTA.t.sub.s. Each of the radiative modules includes a mixing device, an electromagnetic radiator and a filter. The mixing device receives and mixes a respective one of the reference signal samples and a respective one of the scanning signal samples. The filter couples the mixing device to the radiator and is configured to pass the operating signal s.sub.o. Accordingly, an antenna beam is radiated from the array at m selectable scan angles with each of the scan angles varying in response to the frequency of the scanning signal s.sub.s. Multiband and two-dimensional embodiments are shown and described. The wideband characteristics of these antennas are especially suited for radar, electronic warfare and high data-rate communication applications.

Wideband phased array antennas and methods

A single transmission optical fiber is used to transmit RF signals of the same frequency but different polarization from a source to a polarization diversity receiver without introducing interference between the signals. The incoming signal of one polarization modulates a first laser transmitter operating at one wavelength, and the incoming signal of the other polarization modulates a second laser transmitter operating at a different, second wavelength. The two modulated optical beams are combined in an optical coupler whose output is connected to the transmission fiber leading to the polarization diversity receiver. At the receiver, a wavelength division multiplexing coupler is used to separate out the two modulated optical carriers. The two RF signals used to modulate the laser transmitters are separately recovered via photodiode detectors to provide inputs to the polarization diversity receiver.

Wavelength division multiplexed fiber optic link for RF polarization

A tethered vehicle such as a missile system comprises a tethered vehicle body having a control system and propulsion system therein, a control station for the tethered vehicle located outside of the tethered vehicle body, and an optical fiber data link extending from the tethered vehicle control system to the control station. The tethered vehicle system further includes a GPS positioning system for the tethered vehicle, which comprises a positioning signal receiving antenna mounted in the tethered vehicle, and a positioning signal amplifier mounted in the tethered vehicle, which receives a positioning signal from the antenna and produces an amplified positioning signal. A transmitter transmits the amplified positioning signal into the optical fiber data link at its end within the tethered vehicle, and a receiver receives the amplified positioning signal from the optical fiber data link at its end at the control station. A signal processor analyzes the amplifier positioning signal received from the receiver. The signal processor is located at the control station. Preferably, there is imposed a time-shift correction to the positioning signal to negate the effect of the separation between the antenna and the signal processor.

Tethered vehicle positioning system

A programmable fiber optic delay system employs multiple programmable fiber optic delay lines, and switches among the delay lines for inclusion in an overall delay path. Switching among the delay lines is coordinated with the programming of those lines so that only a delay line with a settled delay program is included in the overall delay path. Each delay line consists of a plurality of fiber optic segments of varying length. The line's delay is programmed by switching in particular segments whose aggregate lengths correspond to a desired delay period. The multiple delay lines are used to simulate target speed and distance for use in testing a radar system. The programming of each individual delay line and the switching between lines is preferably controlled by a computer resident in the target simulator.

Programmable fiber optic delay line, and radar target simulation system

Self-sustained oscillation of the atoms in a maser is achieved in a cavity of reduced size by in-phase feedback for cavity Q-enhancement. Cavity resonant frequency is stabilized using a small reactive element coupled to the maser cavity. The reactance of the small element is precisely controlled so that the resonant frequency of the cavity is stabilized with reference to the radiation frequency of the atoms inside the maser cavity by a feedback control loop using the maser radiation as a reference signal.

Q-Enhanced resonance-stabilized maser

In the free induction technique of this invention, the maser is externally stimulated to allow significant reduction of the size of the maser, and the stimulation is turned off and allowed to decay so that the maser output is free from the external stimulation before the signal is sensed to provide a clock frequency standard. As a result, the invention solves significant problems which otherwise have limited the accuracy of prior art atomic clocks, including the problem of frequency pulling due to amplitude drift in the stimulation signal.

Growing community of inventors

Thousand Oaks, CA, United States of America

Harry T Wang