A computational model for calculating the electric field strength of radio transmissions

This paper presents a computational model to calculate the electric field strength of radio waves due to a given transmitter. The developed software is based on ray optics theory and it can determine the field strength in double quick time and the electric field strength can be graphically illustrated. This model can also be used to predict the location of a new transmitter providing optimum coverage. By using this model we attempted to identify the field strength distribution in selected areas of the Rathnapura district, Sri Lanka, from a given transmitter. Good agreement was seen in the computed shadow areas and the areas where no radio signals were observed in the field strength measurements carried out by the Sri Lanka Broad Casting Corporation in 1997 for the Yatiyanthota and Radella transmissions. Where measurable signals were present, the measured and computed signal strengths were different. This is possible since atmospheric absorption, reflections from mountains among other effects were not considered in the computations. This computational model is useful in planning and operation of radio communication systems so as to optimize radio coverage and cost.