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Two novel designs of planar elliptical slot antennas are presented. Printed on a dielectric substrate and fed by either microstrip line or coplanar waveguide with U-shaped tuning stub, the elliptical/circular slots have been demonstrated to exhibit an ultrawideband characteristic. The performances and characteristics of the proposed antennas are investigated both numerically and experimentally. Based on these analyses, an empirical formula is introduced to approximately determine the lower edge of the 10 dB operating bandwidth. It is also shown that these antennas are nearly omnidirectional over a majority fraction of the bandwidth.Index Terms-Coplanar waveguide (CPW), microstrip line, printed antenna, slot antenna, ultrawideband (UWB).

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A finite element model has been established and used to predict the temperature history of direct laser fabricated (DLFed) Ti-6Al-4V thin wall samples. The effects of laser power and the effect of location within a sample on its temperature history have been modelled and compared with temperatures measured during DLF using thermocouples. The thermal history of the material has been correlated with the observed differences in the microstructures obtained at different locations in a given sample or for a given location in samples obtained at different laser powers.