Raytheon

About: Raytheon is a company organization based out in Waltham, Massachusetts, United States. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 15290 authors who have published 18973 publications receiving 300052 citations.

Inertially stabilized gimbal platform

Abstract: An inertially stabilized gimbal platform is disclosed wherein the gyros used in such system operate about their mechanical null positions and control the gimbal drive means through an electronic control section. The electronic control section includes a control signal which is combined with the gyro output to provide a drive signal for the gimbal drive means. The control signal is proportional to the offset between the electrical null position and the mechanical null position of the gyro. The control signal may be modified in accordance with platform command signals to orient the platform in a desired attitude.

Comparative study of high-performance GPS receiving antenna designs

Abstract: The FAA decision allowing the use of the global positioning system (GPS) as a radio navigation and landing help system in the United States commercial airports boosts the need for a high-performance GPS receiver which provides the demanded precision. The design of the receiving antenna is one of the most important parts in the design process, as it has to face significant challenges including uniform coverage of all satellites and the rejection of the multipath signals. The rejection of the multipath signals is accomplished by specifying restrictive criteria to the GPS antenna. This includes a high rejection of the cross-polarized signals and a radiation pattern with a sharp slope for low-elevation angles; that is, near the horizon. The feasibility of using different types of antennas to satisfy restrictive criteria such as dual-frequency coverage (L1 and L2 frequencies), -15 dB cross-polarization rejection, and a beamwidth of more than 130/spl deg/ is discussed. The antenna designs examined in this study include patch antennas, helical antennas, and conical spiral antennas. Two different receiver designs were also examined including a single-antenna system with a hemispherical coverage and an antenna array which may provide independent sectoral coverage or the desired beamwidth. It is shown that a design based on a conical spiral antenna backed with absorbing material may be used to satisfy all the desired specifications. This result was confirmed experimentally.

A rigorous yet simple method for determining stability of linear N-port networks [and MMIC application]

Abstract: The authors describe a technique for easily calculating normalized determinant function using return ratios. It is shown that an elegant yet simple relationship exists between the return ratios of each dependent source in a linear network and Platzker's normalized determinant function. Using this relationship, the stability (or instability) of linear N-port networks containing any number of active devices can easily be determined using commercially available circuit simulators. An example is shown where this new technique correctly predicts instability in a GaAs MMIC power amplifier. >

Wireless communication system with high efficiency/high power optical source

Abstract: An optical communication system is provided which includes an optical signal transmitter which communicates high bandwidth, high power frequencies. The optical signal transmitter includes a high efficiency/high power optical source such as an optical magnetron or a phased array source of electromagnetic radiation, and a modulator element. The modulator element may be within a resonance cavity of the high efficiency/high power optical source (intra cavity) or external to the cavity (extra cavity). The modulator element serves to modulate output radiation of the high efficiency/high power optical source to produce a modulated high frequency optical signal which may be transmitted through the air. The optical signal transmitter is particularly useful in providing the last mile connection between cable service operators and end users.