VIEWS: 11 PAGES: 2 POSTED ON: 2/26/2011
Antenna coupling for high power microwave tubes ABSTRACT Microwave tubes are used for generation and amplification of high power (up to MW of pulsed/CW output power) and high frequency (0.3GHz to 1000GHz) electromagnetic waves. These tubes are in great demands for defense, communication, remote sensing, and for numerous industrial, scientific, and medical (ISM) applications. Input and output RF couplings in microwave tubes are very significant for efficient and reliable operation of these devices. Any coupler for a tube basically consists of four constituents: (i) probe, loop or slot for coupling e.m. waves from or into the RF structure, (ii) coaxial or waveguide impedance transformation section, (iii) glass or ceramic window to provide vacuum barrier and lossless transmission of rf power, and (iv) standard coaxial or waveguide output. Antenna probe is used to excite the waveguide output in case of coaxial transition. 3-dimensional e.m. field simulators like Ansoft HFSS and MWS-CST codes are used to achieve well matched and broadband design of the input and output couplers with the antenna probe. Standard mechanical codes like ANSYS, COSMOS are used to achieve thermal efficient and mechanically rugged design of the antenna coupling. Antenna couplings for some of the microwave tubes are presented in this paper. The Application of Self-Organising Neural Networks to Location Detection in 3G Systems Abstract A solution to mobile user location identification in 3G wireless systems based on a self-organising neural network architecture is presented. Radio signals from the mobile terminal's serving base stations are captured by the terminal, encapsulated and transmitted to the location detection server. These signals are fed to the neural network which translates the radio signals into neural coordinates, which are then triangulated to determine the user's location. Simulation results demonstrate that allowing a two meter error, the algorithm is capable of locating the user's position in 92% of the cases. Location Determination and Tracking Using Radio Beacons Abstract Location awareness is an important capability for a series of wirelessly-enhanced business and consumer mobile applications. Low-cost devices that can be incorporated into a broad range of business and consumer appliances can be used for location determination and tracking. In this paper, we demonstrate a radio beacon-based approach that suggests heterogeneous wireless networks can be joined together to provide wide area tracking capability. Our implementation is based on probabilistic and statistical techniques, where signal strengths measurements from cellular networks are used to estimate the user's location. Simulation results and field tests around Lancaster University campus show that these techniques can achieve good performance (accuracy less than 50 m) compared with traditional deterministic methods (i.e. triangulation).
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