Shift of millimeterwave window frequencies in relation to tropospheric radio meteorological parameters

In view of wide application areas of the millimeterwave frequency band (18–300 GHz) in recent years for various civil and defence applications including radar and communications, remote sensing and radio astronomy, we were prompted to undertake a theoretical estimate of the variation of specific attenuation (dB/Km) with radio meteorological parameters in clear weather conditions. The results of the estimation of the attenuation in this frequency band for some major locations in India from available radio meteorological data from NOAA, USA are presented in this paper. An appreciable amount of shift, which is mainly a function of the atmospheric pressure, temperature and relative humidity was noticeable in each of the window frequencies around 35, 94, 140 GHz and 220 GHz.