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.

Effect of particle non-sphericity on satellite monitoring of drifting volcanic ash clouds

Abstract: Volcanic eruptions loft gases and ash particles into the atmosphere and produce effects that are both short term (aircraft hazards, interference with satellite measurements) and long term (atmospheric chemistry, climate). Large (greater than 0.5mm) ash particles fall out in minutes [Rose et al, 1995], but fine ash particles can remain in the atmosphere for many days. This fine volcanic ash is a hazard to modem jet aircraft because the operating temperatures of jet engines are above the solidus temperature of volcanic ash, and because ash causes abrasion of windows and airframe, and disruption of avionics. At large distances(10(exp 2)-10(exp 4) km or more) from their source, drifting ash clouds are increasingly difficult to distinguish from meteorological clouds, both visually and on radar [Rose et al., 1995]. Satellites above the atmosphere are unique platforms for viewing volcanic clouds on a global basis and measuring their constituents and total mass. Until recently, only polar AVHRR and geostationary GOES instruments could be used to determine characteristics of drifting volcanic ash clouds using the 10-12 micron window [Prata 1989; Wen and Rose 1994; Rose and Schneider 1996]. The NASA Total Ozone Mapping Spectrometer (TOMS) instruments aboard the Nimbus-7, Meteor3, ADEOS, and Earth Probe satellites have produced a unique data set of global SO2 volcanic emissions since 1978 (Krueger et al., 1995). Besides SO2, a new technique has been developed which uses the measured spectral contrast of the backscattered radiances in the 330-380nm spectral region (where gaseous absorption is negligible) in conjunction with radiative transfer models to retrieve properties of volcanic ash (Krotkov et al., 1997) and other types of absorbing aerosols (Torres et al., 1998).

Extremely low-phase-noise SAW resonators and oscillators: design and performance

Abstract: The authors describe prototype low-noise SAW (surface acoustic wave) resonator oscillators which have demonstrated state-of-the-art phase-noise performance not only at their fundamental operating frequencies in the 400- to 600-MHz range but also after 16* frequency multiplication to X-band as well. SAW resonator designs with overmoded cavities, very wide apertures, and dual apertures, as well as modified fabrication techniques, have been used to realize an overall reduction in an oscillator's phase-noise spectrum, i.e. white phi M, flicker FM, and random-walk FM. The S resonators can typically handle incident RF power in excess of +20 dBm, a key requirement to achieving an extremely low oscillator-phase-noise floor. A novel burn-in procedure at relatively high incident-RF-power levels (>27 dBm) was used to reduce both the flicker FM and random-walk FM phase-noise levels. Using these various techniques, a 5- to 15-dB improvement in the overall phase-noise spectrum for several prototype oscillators was demonstrated. >

Introduction to the design of transconductor-capacitator filters

Abstract: Preface. 1. Introduction. 2. Filter Topologies and Terminology. 3. Biquad Filters. 4. Gyrator Filters. 5. State-Variable Filters. 6. Dealing with Floating Capacitors. 7. The Non-Ideal Transconductor. Part I: Parasitic Capacitances and Mismatches. 8. The Non-Ideal Transconductor. Part II: Output Impedance. 9. The Non-Ideal Transconductor. Part III: Non-Linearity. 10. Tuning of Transconductors. 11. Design of the gm-C Integrator. 12. Design of a gm-C Filter. 13. Tuning of gm-C Filters. Index.

Fluid mixer with an integral fluid capture ducts forming auxiliary secondary chutes at the discharge end of said ducts

Abstract: A fluid mixer for mixing two fluid streams 40, 42 includes a set of main lobes 26 defining alternating primary and secondary main chutes 30, 32, one or more auxiliary lobes 28 intermediate two of the main lobes, and an auxiliary fluid capture duct 62. The auxiliary lobes are defined, at least in part, by the discharge end of the duct. In operation, the duct conveys secondary fluid to secondary chutes 36 defined by the lobes thereby improving the performance of the mixer despite the presence of an obstruction 18 that would otherwise impede thorough mixing of two fluid streams.

Highly integrated single substrate mmw multi-beam sensor

Abstract: A multiple beam array antenna system comprises a plurality of radiating elements provided from stripline-fed open-ended waveguide coupled to a Butler matrix beam forming network. The Butler matrix beam forming network is coupled to a switched beam combining circuit. The antenna can be fabricated as a single Low Temperature Co-fired Ceramic (LTCC) circuit.