MT-MR PLATINUM. POINT TO POINT AURAL RADIO RELAY SYSTEM
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Distances can be seen in the following Fig. # 4:
Fig. 4. DISTANCES FOR CALCULATION OF FRESNEL ZONES RADII.
In our illustrative Example, we can find the radius of the First Fresnel Zone in the point where it assumes a
maximum value, in the path midpoint between A and B.
Data: Wavelength of propagated signal will be:
f = 2038 MHz
d
1
= 20 Km
λ
= 300/2038 = 0.147 m
d
2
= 20 Km
d
3
= 40 Km
n = 1 Inserting numerical values in Expression (2) :
R(1) = 31.6 (0.147 x (20 x 20)/40)
½
R(1) = 38.3 meters
Now we can calculate and trace, from one kilometer to the next, the radius of First Fresnel Zone for the whole
propagation in the Profile Sheet shown in Fig. # 2, giving the results shown below, in Fig. # 5:
Fig. 5. FIRST FRESNEL ZONE FOR ILLUSTRATIVE EXAMPLE IN 2 GHz BAND
This profile, as can be seen, has absolute clearance both for First and Second Fresnel Zones because it's a typical
inter-mountain hop. In case of partially obstructed profiles, it's allowable a clearance of 70% of total area at
X
