In the design of the terrestrial microwave links, it is important to know the atmospheric radio refractivity. Radio refractivity depends on temperature, pressure and vapor pressure that varies daily and seasonally by region. International Telecommunication Union (ITU) produced contour maps for radio refractivity using global metrological data for use in the design of microwave. However, ITU recommends using local data to get more accurate contour maps of radio refractivity. So, this study aimed to produce more precise contour maps which show the distributions of radio refractivity over Oman for all months of the year by using local data for Oman. Meteorological data from 39 locations in Oman covering ten years were used to compute radio refractivity using ITU formula to generate contours maps for refractivity. The results show that refractivity is changing geographically and seasonally. The highest values of the radio refractivity have been observed in coastal regions. Also, the values of radio refractivity during summer are higher than in winter. The maximum refractivity during the study period was about 400 N-unit recorded in Al-Hallanyyat during May, and the minimum was about 240 N-unit recorded in Saiq during December. These will contribute in helping local telecommunications companies in the design of terrestrial microwave links. Some terrestrial microwave links in Oman face fading problem more than others. This work also aimed to investigate the main causes which contribute to this problem by analyzing five links: Zakher-Shaleem, Ayn ALmasharfah-Bufshaighah (AlAshkharah), Kawther (Adam), Sahma-Zolyia (Hima) and Kuff-Yibal (Ibri). These links are located in different areas of Oman )not included in the previous 39 stations). This was achieved by correlating hourly and monthly variations of meteorological parameters (temperature, pressure and humidity) with refractivity computed from relevant daily and hourly meteorological data. This data was available only for the three years 2017-2019, their link profile and corresponding transmitted and received signal levels. Monthly rainfall was also used to investigate the fading problem. The results showed that fading occurs in these five links mostly during the summer season and from sunset till sunrise time because of high humidity, low temperature and fluctuations in refractivity. The duration of the fading lasted for about 11 hours. Rain is also one of the causes of fading. However, rainfall varied from link to link depending on the region. Its impact was showed mostly in Zakher-Shaleem link in Dhofar during the rainy season from May till August