High-efficiency, 200-W Ku-band traveling-wave tubes for satellite communications downlinks
L-3 Communications Electron Technologies (L-3 ETI) has recently tested a unit from the production family of Ku-band TWTs, the 88151HXR S/N 110, up to 200-W RF output power in thermal vacuum. Performance data and thermal analysis from the testing will be presented.
Reliability and Cost Focused Optimization Approach for a Communication Satellite Payload Redundancy Allocation Problem
Abstract—A typical reliability engineering problem regarding communication satellites has been considered to determine redundancy allocation scheme of power amplifiers within payload transponder module, whose dominant function is to amplify power levels of the received signals from the Earth, through maximizing reliability against mass, power, and other technical limitations. Adding each redundant power amplifier component increases not only reliability but also hardware, testing, and launch cost of a satellite. This study investigates a multi-objective approach used in order to solve Redundancy Allocation Problem (RAP) for a communication satellite payload transponder, focusing on design cost due to redundancy and reliability factors. The main purpose is to find the optimum power amplifier redundancy configuration satisfying reliability and capacity thresholds simultaneously instead of analyzing respectively or independently. A mathematical model and calculation approach are instituted including objective function definitions, and then, the problem is solved analytically with different input parameters in MATLAB environment. Example results showed that payload capacity and failure rate of power amplifiers have remarkable effects on the solution and also processing time.
The Near Ultra-Violet Band-System (D-X) of Silicon Monosulphide
The rotational analysis of the near ultra-violet band-system, D1Π-X1Σ+, has been extended Twelve bands have been analysed, namely the 7,1, 6,0, 6,1, 5,0, 5,1, 4,0, 4,1, 3,0, 2,0, 1,0, 1,1 and 0,0 bands. The constants derived for D1Πare Bν' = 0.26647 - 0.00216 (ν' + ½); Dν' = [2.91 - 0.03(ν'+½)] ×10-7, Gν' = 513.12(ν' + ½) - 2.93 (ν' + ½)2, νe = 35026.86 cm-1, re' = 2.0589 A. A number of perturbations have been found in the upper state. They appear to arise from interactions with two electronic states, a 3Σ- state and a singlet state, 1Π or 1Δ. It has not been possible to determine the absolute numbering of the vibrational levels of the perturbing states, but in all other respects fairly complete information has been obtained about the 3Σ- state. The perturbations are similar to those already known in the spectrum of CO, and the analogy between the electronic states of the molecules is thus strengthened.