Radio visibility at microwave frequencies

Abstract

Radio visibility through water vapour has been studied over Calcutta at microwave/ millimetre wave frequencies. Due to large abundance of water vapour over Calcutta, the integrated water vapour content restricts the radio visibility approximately up to 5 km at different microwave/millimetre wave frequencies. The present study has been restricted to only the total absorption (dB) part of the propagation parameters of radio waves. The vertical layers of atmosphere have been divided into 10m slabs with the assumption that the meteorological parameters remain unchanged quantitatively within any of these slabs. The height at which the variation of total absorption (dB) is less than or equal to 1% of that of the immediate preceding height (which is one slab thickness less), is, here, defined as 1% height limit. It has been found that beyond this height the radio receivers at microwave/millimetre wave frequency suffer no appreciable change in the total absorption.