# Chapter 4: Radio Wave Propagation¶

## Example 4.1, Page 97¶

In :
import math
#Variable Declaration

El=50  #Elevation Angle(degrees)
h0=0.6 #Earth station altitude(km)
hr=3   #Rain height(km)
R01=10 #Point Rain Rate(mm/hr)
f=12   #frequency(GHz)
ah=0.0188
bh=1.217
av=0.0168
bv=1.2
#Calculation
Ls=(hr-h0)/math.sin(El*3.142/180) #Slant path length(km)
LG=Ls*math.cos(El*3.142/180)      #Horizontal projection(km)
r01=90/(90+4*LG)      #Reduction factor
L=Ls*r01              #Effective path length(km)
alphah=ah*R01**bh     #Specific Attenuation
alphav=av*R01**bv   #Specific Attenuation

#Results

print"Rain Attenuation for given conditions and horizontal polarization is",AdBh,"dB"
print"Rain Attenuation for given conditions and vertical polarization is",AdBv,"dB"

Rain Attenuation for given conditions and horizontal polarization is 0.89 dB
Rain Attenuation for given conditions and vertical polarization is 0.77 dB


## Example 4.2, Page 99¶

In :
import math
#Variable Declaration
ah=0.0188
bh=1.217
av=0.0168
bv=1.2
R01=10  #Point Rain Rate(mm/hr)
L=2.8753812  #Effective path length calculated in Example 4.1(km)

#Calculation

#Factors depending on frequency and polarization
ac=(ah+av)/2 #a for circular polarization
bc=(ah*bh+av*bv)/(2*ac) #b for circular polarization

alpha=ac*R01**bc  #Specific Attenuation(dB)

The Rain Attenuation for circular polarization is 0.83 dB