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//Chapter 15: Antennas for Special Applications
//Example 15-14.1
clc;
//Variable Initialization
fre = 4e9 //Frequency (Hz)
T_sys = 100 //System Temperature (K)
S_N = 20 //Signal to Noise ratio (dB)
bandwidth = 30e6 //Bandwidth (Hz)
P_trans = 5 //Satellite transponder power (W)
dia = 2 //Satellite parabolic dish diameter (m)
sat_spacing = 2 //Spacing between satellites (degrees)
r = 36000e3 //Downlink distance (m)
k = 1.38e-23 //Boltzmann's constant (J/K)
c = 3e8 //Speed of light (m/s)
//Calculation
wave_lt = c/fre
s_n = (wave_lt**2)/(16*(%pi**2)*(r**2)*k*T_sys*bandwidth)
s_n = 10*log10(s_n) //Signal to noise ratio for isotropic antennas (dB)
Ae = 0.5*%pi*(dia**2)/4 //Effective Aperture (m^2)
Gs = 4*%pi*Ae/(wave_lt**2)
Gs = 10*log10(Gs) //Antenna Gain (dB)
Ge = 20 - s_n - Gs - 10*log10(P_trans) //Required earth station antenna gain(dB)
Ae_e = (10**(Ge/10))*(wave_lt**2)/(4*%pi) //Required earth station effective aperture (m^2)
Ap = Ae_e*2 //Required Physical aperture (m^2)
De = 2*sqrt(Ap/%pi) //Required diameter of earth-station antenna(m)
hpbw = 65/(De/wave_lt) //Half power beam width (degree)
bwfn = 145/(De/wave_lt) //Beamwidth between first null (degree)
//Results
mprintf("The Required parabolic dish diameter of earth station antenna is %.1f m",De)
mprintf("\nThe Half power beamwidth is %.1f degrees",hpbw)
mprintf("\nThe Beamwidth between first null is %.1f",bwfn)
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