Multipath effects in indoor wireless communication systems exhibit a characteristic power delay profile (PDP) and can be a detriment to system performance. In this paper, we present a simplified model for calculating the decay rate of the PDP for propagation within rooms. This simplified model provides a time-efficient means of predicting system performance. Predictions of this in-room PDP model are compared to results obtained from a finite-difference time-domain (FDTD) model. Additionally, comparisons of the IPDP model to measured data are presented. The rms delay spread is the second central moment of the PDP of a propagation channel and is a measure of the communication link degradation due to multipath. We also show results of the estimated rms delay spread from this model and show comparisons to the measured data. This IPDP model can be used to investigate the effects of variable room size and properties of the surfaces (or walls) on the decay characteristics of the PDP.Index Terms-Channel modeling, delay spread, impulse response, multipath, power delay profile.

Zeeman splitting of O2 molecular states in the Earth's upper atmosphere leads to polarized emission spectra. A 61 GHz radiometer operated as part of the Millimeter‐wave Atmospheric Sounder (MAS), a core payload instrument of the NASA Space Shuttle ATLAS missions, observed such emissions. This instrument's high resolution spectrometer (200 kHz) allows us to verify for the first time Zeeman effect model calculations for the upper atmosphere in some detail. The results suggest some interesting new aspects for the research of the upper atmosphere.

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