A novel traveling-wave antenna array with bent conductors as elements can give circularly polarized radiation. An expression for the far-field has been derived, from which the lengths and bending angle of the conductors can be calculated for circular polarization. A useful application would be printed circuit m-icrowave antenna for different purposes. Antennas have been made and work well over reasonable large bandwidths. They can also function on their broadside frequency.
A frequency scanning satellite payload concept for aeronautical passenger communication at Ka-band is presented. Aeronautical passenger communications services via satellite at Kaband have been frequently considered, but no practical system has yet been implemented because of the high required RF power and of the satellite antenna complexity. If the coverage area is limited to the North-Atlantic or to Europe instead of the whole Earth, frequency scanning seems to offer a very attractive solution.
NTRODUCTIONFrequency allocations for fixed and mobile satellite services exist in the 30/20 GHz bands. Use of such high frequencies by surface mobiles is difficult due to the high attenuation caused by rain, but this attenuation does not exist for aeronautical users flying above the clouds. Therefore an air passenger communication system implemented at 30/20 GHz or at higher frequencies can be attractive, Bjdrnstr6m (1), Markus and Roederer (2), Sohn (3).Since such high frequencies are already in use for military space communications, LNA and HPA technology, as well as other components, are available from several sources. On the mobile terminal side, as a result of using Ka-band, a significant antenna gain can be obtained even from a small dish. This implies that a proper pointing mechanism is required. On the satellite, the higher gain footprint is preferable since it proportionately reduces the required size of mobile antenna, but on the other hand higher gain footprint means a narrower spot beamwidth, requiring a larger number of spots to provide the same extent of satellite coverage. If the covered area is limited to the North Atlantic or Europe, the number of spot beams and the gain footprint are still reasonable.The baseline for this study assumes a satellite that uses 40 beams to cover the North Atlantic with an edge of coverage (EOC) gain of 38.0 dBi and a terminal antenna diameter of 15 cm. The satellite position over the North Atlantic Ocean was chosen with the observation that the transoceanic flights between the North America and Europe constitute one of the biggest market share in the airline industry. Link budgets for the forward and return mobile links show that about 1 W RF power per channel is required to provide a good quality voice service for the forward mobile link. Assuming a payload supporting 300 channels this would mean that a total RF power of 300 W is required. For the return link, about 1 W of RF power is required from the terminal. Use of coding and improved front end technology would reduce the required RF power.
Enhanced leakage current through the gate oxide insulator and degraded oxide breakdown voltages were observed following hexode reactive ion etching and magnetically enhanced reactive ion etching (MERIE) of poly-Si electrodes over thin gate oxides. The degradation was seen to occur along the edges of the etched poly-Si gates and was not aggravated by the amount of poly-Si charge collection area (antenna) over a thick field oxide. Defect densities ranging from 0.02 to 0.3 per meter of perimeter were observed so that significant yield losses could be expected in deep submicron ultralarge scale integrated circuit chips. Interestingly the defect density, as measured at a fixed voltage, was not markedly affected by the gate oxide thickness down to 7 nm. Comparisons of results from the two etching systems showed that the degradation was three times greater in MERIE than with the hexode.
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