# Drawing concentric circles that correspond to free space loss formula?

I want to be able to draw a circle with 50km radius and then fill the circle with values corresponding to the free space loss formula below:

FSPL(db)=20 log10(d)+20log10(f)+32.44

a circle of 50km around the "west Myara site" and then for every pixel(I guess) I would like to know its corresponding FSPL value and have it colored accordingly.

would I have to convert the polygon to a raster and then use the raster calculator to produce the values of each cell/pixel? if thats the case I would need to find the distance of the pixel/cell from the center point (in this case "west of Myara site" point) and how would I do that ?

• What f and d represent ? – nickves Jul 19 '16 at 2:08
• @nickves F=frequency(in MHz)and D=distance(in Km), so distance would be the distance between the cell and the centre point "West Myara..." and Frequency would be any of these 5,6GHz,8GHz,11GHz, and so on(any Microwave tech) – Ashan Lazarus Jul 19 '16 at 3:10
• How are you going to specify freq? How are they displayed when there are multiples? – BradHards Jul 19 '16 at 3:41
• I will perform the analysis for each of those frequencies. ultimately I would like to produce such circles for each of our sites(1000's) for each frequency – Ashan Lazarus Jul 19 '16 at 3:53
• You have a QGIS tag but make no mention of what you have tried to do with that software to answer your question prior to posting it. – PolyGeo Jul 22 '16 at 8:10