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.

Microwave losses in strontium titanate above the phase transition

Abstract: The microwave losses in both pure and doped SrTi${\mathrm{O}}_{3}$ have been investigated as a function of frequency and temperature. It is found that the loss tangent is proportional to frequency in the range 3-36 kMc/sec. Above the phase transition at 112\ifmmode^\circ\else\textdegree\fi{}K, the temperature dependence of the loss tangent is well represented by $tan\ensuremath{\delta}={(T\ensuremath{-}{T}_{c})}^{\ensuremath{-}1}(\ensuremath{\alpha}+\ensuremath{\beta}T+\ensuremath{\gamma}{T}^{2})$, where the Curie temperature, ${T}_{c}=37\ifmmode^\circ\else\textdegree\fi{}$K. The parameter $\ensuremath{\alpha}$ is shown to be determined by lattice imperfections and vanishes for pure single-crystalline material. The parameters $\ensuremath{\beta}$ and $\ensuremath{\gamma}$, which are related to third-and fourth-order anharmonic terms in the interionic potential, are shown to be intrinsic properties of the perfect lattice and are unaffected by imperfections.

Low cost equipment for cleaning using liquefiable gases

Abstract: Precision cleaning of parts is performed with liquefiable gases, such as CO2, without the use of a complex and costly processor system Rather, simplified and reliable performance for small scale and "low end" cleaning applications is accomplished without the use of pumps and condensers The apparatus for removing undesired material from a chosen substrate comprises: (a) an enclosed cleaning chamber in a walled vessel for containing a liquid derived from a liquefiable gas and the substrate containing the undesired particulates and contaminants, the walled vessel adapted to withstand a maximum pressure of about 1,500 pounds per square inch (1054 kg/cm2) at ambient temperature; (b) means for supporting the substrate in the cleaning chamber; (c) ultrasonic energy-producing transducer means attached to the walled vessel within the cleaning chamber; (d) inlet means attached to the walled vessel for introducing the liquefiable gas into the cleaning chamber under a pressure less than about 900 pounds per square inch (633 kg/cm2); (e) temperature control means connected to the cleaning chamber for controlling the temperature within the chamber up to about 50° C; (f) reservoir means for providing the liquefiable gas to the inlet means; (g) means for changing the liquefiable gas to the liquid; and (h) outlet means in the chamber for removing the liquid from the cleaning chamber The liquid may then be further treated to remove particulates and organic contaminants and either recycled to the cleaning chamber or vented to the atmosphere The process is especially applicable for general degreasing and particulate removal processes, when high precision cleaning is not required

Annular slot antenna with stripline feed

Abstract: A stripline antenna having a radiating aperture in the form of an annular slot provided in one of its conducting plates and a pair of orthogonal narrow strip conductor feeds disposed between its two conducting plates and terminating under the central disk formed by the annular slot. Adjustment of the relative phase and amplitude of the electromagnetic energy applied to the strip conductor feeds permits radiation from the annular slot of circular, elliptical or orthogonal linear polarizations into space or into a waveguide.