No abstract

The high-resolution FT interferometer of the Laboratoire d'Infrarouge at Orsay has been used to investigate the broadening of N(2)O lines in the 4- and 8-microm spectral regions. All data were taken at both room temperature and 220 K. The uncertainty of the measured values of linewidths was estimated to <4%. From these data, the exponent n of the temperature dependence of linewidths was experimentally determined for the first time, for the systems N(2)O-N(2)O, N(2)O-N(2), and N(2)O-O(2). In the first two cases, it was shown that n is nearly J-independent, whereas it seems to vary linearly for N(2)O-O(2). Finally the values of N(2)O air-broadened linewidths were derived for the two temperatures 295 K and 220 K representing the upper and lower boundaries of middle atmosphere temperatures.

The knowledge of directions of arrival (DOA) of waves is fundamental in understanding the physics of the mobile communications wide-band propagation channel. In this paper, we first present a measurement setup able to accurately measure these DOA. It is based on the evaluation of the channel complex impulse response at regularly spaced locations on a circle. We theoretically investigate a new approach for deriving DOA from this ring array. We then describe an experimental campaign, where such measurements were done on a building rooftop. We show that all the main paths are clearly retrieved and identified and that the ray theory is valid and applicable. The results emphasise the predominant role of UHF-wave specular reflection by walls in actual urban environment.

No abstract

No abstract