Microwave Design

Today I have been working my butt off in making my project for our Microwave Subject. First, we have to search for the appropriate map that we will use for our design. The map should be a topographical map with a scale of 1:50k. One requirement is that we should have at least 7 links that is at least 20 km apart. The locations should also be populated enough. I have used 6 topo maps to be able to meet all those conditions flawlessly while sacrificing my allowance. I'll be discussing some aspects when creating the path profile for each of the links.

The first one is the DISTANCE between the two sites. You must divide the total distance into two and let's name it D1 and D2 both in kilometers. For example, the total distance between the sites you have chosen is 32 km, D1 will start from the minimum distance which is the 0 km while D2 will start from the maximum distance which is the 32 km. You need to make a table with D1 and D2. D1 will increment 1 km in each cell it takes and D2 will decrement by 1 km in each cell it takes.

D1 (km)                       D2 (km)

   0                                    32

   1                                    31

   2                                    30

   3                                    29

   .                                      .

   .                                      .

   .                                      .

  32                                    0

Now that D1 and D2 are present, the Earth Bulge can now be computed. The formula is EB=(D1*D2)/17.

After gaining the result, place the values of the Earth Bulge corresponding to the value of D1 and D2 used in the formula.

D1 (km)                       D2 (km)                    EB (m)
   0                                    32                             0
   1                                    31                         1.8235                          
   2                                    30                         3.6294
   3                                    29                         5.1176                      
   .                                      .                               .
   .                                      .                               .
   .                                      .                               .
  32                                    0                             0

The next part of the table will be the Terrain of the path for each kilometer. It will be based from the topographical map and each type of terrain will have a corresponding value of Allowance that will be needed in graphing the profile.

Here are some types of terrain with their corresponding allowance:
Orchard- 6.10
Coconut Plantation-6.10 
Industrial- 50
Woods- 6.10
Rice Field - 0
Residential- 50

With the Terrain and Allowance done, the next one will be computing for the Fresnel Radius. The essential part of solving the Fresnel radius is the value of frequency you will be using. The formula for Fresnel Radius is  F1=17.3*SQRT(D1*D2/(Freq*Link Distance)). Link Distance is the sum of D1 and D2. Reading the F-Series ITU-R Recommendations is essential when selecting the value of frequency you will be using. When you have finally selected the frequency you will use, you have to assign a channel for each link your design has.When a certain site has for example, three links connected to it, you must avoid assigning adjacent channels for them to not interfere with each other.

After solving for the Fresnel Radius, the 0.6F1 will be the one used in the graph of the path profile and the formula is simply the 60% of the Fresnel Radius. After getting the product, the Total sum of the Earth Bulge, Elevation, Allowance, and the 0.6F1 needs to be solved.