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.

Unified AC model for the resonant tunneling diode

Abstract: A physics-based model is shown to yield the small-signal equivalent circuit of the resonant tunneling diode (RTD) including an analytic expression for both the quantum inductance and capacitance. This model unifies previous models by Brown et al. for quantum inductance and by Lake and Yang for quantum capacitance, and extends the RTD SPICE model of Broekaert. The equivalent circuit has been fit to both current-voltage and microwave S-parameter measurements of AlAs-InGaAs-InAs-InGaAs-AlAs RTDs from 45 MHz to 30 GHz and over biases from 0 to 0.81 V. Good agreement between the model and measurement is shown.

Solar Hard X-Ray Bursts and Electron Acceleration Down to 8 keV

Abstract: In 2 days that were typical of solar maximum (1991 October 1-2), the CGRO/BATSE Spectroscopy Detectors observed more than five solar X-ray bursts per hour above 8 keV [8-13 keV flux greater than 0.4 (cm2 s keV)-1]. Only approximately one-third of these were detected above 25 keV [25-59 keV flux greater than 1.7 × 10-3 (cm2 s keV)-1] by the BATSE Large Area Detectors (LADs). Most of the >8 keV bursts are impulsive and similar to solar hard X-ray bursts observed above 20 keV—the bursts occurred on the most rapid rise of the GOES thermal soft X-ray burst, and the ratio of 8-13 keV to greater than 13 keV flux for the impulsive bursts fitted a power-law spectrum [dJ/d(hν) ~ (hν)-γ] with γ = 3-7. More than half of the bursts that should be detected by the LADs if the power law extends to high energies are not detected, indicating that the spectrum steepens or cuts off above ~25 keV. These findings suggest that the acceleration of electrons occurs for essentially all impulsive energy releases but may only be detectable at low energies in smaller releases. The burst occurrence frequency varies with energy W(>8 keV) in accelerated electrons as dn/dW ~ W-1.6 above W ~ 1029 ergs, with an average rate of energy deposition of ~1026 ergs s-1, about 100 times that above 20 keV. Comparison with the occurrence frequency of the energy content in active region transient brightenings (ARTBs) detected by the Yohkoh soft X-ray telescope suggests that accelerated electrons may provide a significant fraction of the total energy in ARTBs.

Web-based risk management tool and method

Abstract: The present invention provides a risk management tool and method for creating an improved initial risk management process that captures, assesses, and prioritizes risks and implements mitigation plans to more effectively manage risk in large-scale development projects. A web-based system allows users and management to share and access risk information to more readily identify and assess risks, develop mitigation plans and track the risk management process. The tool and specifically the Pf and Cf tables are tailored to each project to more accurately calculate and prioritize risk factors RF and thus anticipate and minimize or eliminate risks before they occur. The demonstrated value of the tool is found in timely deliveries and a reduction of cost overruns as well as an increase in customer enhanced award fees.

Remotely powered transponder having a dipole antenna array

Abstract: A transponder having a novel circuit for the extraction of power from an incident interrogating beam of electromagnetic energy, the extracted power being utilized to operate a digital coding circuit. The transponder further comprises an oscillator circuit for developing a train of pulses of electromagnetic energy with successive pulses occurring in a coded format in accordance with a digital code imparted by the digital coding circuit. The transponder is of sufficiently small size to be affixed in the form of a tag to automobiles, personnel, containers and other objects to be identified. An interrogation system for utilizing the electronic tag is also disclosed.

Mixed technology mems/sige bicmos digitizing analog front end with direct rf sampling

Abstract: A digitizing analog front end (DAFE) (50) using mixed technology on a single substrate is described. SiGe BiCMOS technology is implemented for the semiconductor components, which include a low noise amplifier (64) and an analog-to-digital converter (68). Micro Electro Mechanical System (MEMS) switches are used to change the filtering characteristics of several filters, including an anti-aliasing filter (66) and a pre-select and anti-jamming filter (62).