Study of scintillation and fadings of microwave signals with respect to tropospheric irregularities

Abstract

The basic aim of the present work is to receive the fade character information of microwave signal over selected terrains of Assam valley and then to analyse the fade/scintillation so recevied, in association with different atmospheric and environmental parameters to understand the system (atmospheric) responses towards the microwave propagation. The work is presented in six chapters. The subject matter included in each chapter is discussed very briefly in the following sections. Chapter 1 : quot Introduction And Scope Of The Present Investigation quot. Starting with a brief introduction on the need of utilising microwave frequencies in communications and the role of the troposphere towards propagation, this chapter presents a review of work done by different workers of the globe towards fading in microwave communication signal and the role of propagating media in generation of fading and scintillation. The chapter also highlights the importance of such studies over north eastern region of the Indian sub-continent. Chapter 2 : quotTheoretical Aspects Of The Microwave Propagation And Physics Of The Medium quot. This chapter encompasses the physics of the radio wave propagation with respect to varying properties of the propagating medium. Models associated with the scattering of microwaves in turbulent medium are also discussed here. The system gain parameters needed for reliable communication for specified fade margin over varied terrain conditions are presented in this chapter. The existing theoretical models for fade depth, fade rate and fade durations are discussed for normal (10 dB/decade of probability ) and strong fade conditions. Chapter 3 : quotExperimental Arrengment And Circuit Developmentquot The technical details such as radio receiving parameters and system informations like frequency, radiating power, fade margin, antenna height etc of the four links operating at 6/7 GHz are presented. The path profile for each link is drawn for K=4/3 and 2/3 conditions. The fresnel zone clearance for the links are examined for...