A survey of different techniques of determining the refractive parameters

Refraction over the troposphere is one of the key propagation phenomena of wireless radio signals. Different types of refraction prevail in the atmosphere, due to its non-homogeneous nature. The variation in refractive behavior of the wireless radio signal is primarily influenced by change in meteorological conditions, which vary with geographical coordinates, height and time of day/year. One basic parameter is refractivity, from which other factors like effective earth radius factor, refractivity gradient in lowest 100m and 65m of atmosphere, sea level surface refractivity and others can be derived. There can be three main techniques of determining the values of refractivity; One is by the use of radiosonde, second is using a refractometer and the third technique is using different weather stations. This study performs a survey of these techniques, highlighting their pros and cons. The study concludes with a case study of parameters determined using the different techniques, and compares their results. This will aid in communication link planning and propagation modeling.