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//Chapter 15: Antennas for Special Applications
//Example 15-21.1
clc;
//Variable Initialization
dia = 1000 //Diameter of asteroid (m)
prc = 0.4 //Power reflection coefficient of asteroid (unitless)
f = 4e9 //Frequency (Hz)
P = 1e9 //Power (W)
s = 20e3 //Asteroid speed (m/s)
ast_dis = 0.4 //Distance of asteroid (AU)
au = 1.5e11 //Astronomical Unit (m)
c = 3e8 //Speed of light (m/s)
k = 1.38e-23 //Boltzmann's constant (m^2 kg s^-2 K^-1)
Tsys = 10 //System temperature (K)
B = 1e6 //Bandwidth (Hz)
snr = 10 //Signal to noise ratio (dB)
eap = 0.75 //Aperture efficiency (unitless)
sigma = prc*%pi*s**2 //Radar cross section (m^2)
ast_dm = au*ast_dis //Astroid distance (m)
lmda = c/f //Wavelength(m)
d4 = (64*(lmda**2)*(ast_dm**4)*k*Tsys*B*snr)/((eap**2)*%pi*(sigma)*P)
d = d4**(0.25) //Diameter of dish (m)
delf = 2*s/lmda //Doppler shift (Hz)
delt = 2*(ast_dm)/c //Time delay (s)
timp = ast_dm/s //Time before impact (s)
//Result
mprintf("The diameter of the dish is %.0f m",d)
mprintf("\nThe doppler shift is %.1f Hz",delf)
mprintf("\nThe time delay for the radar signal is %d s", delt)
mprintf("\nThe time before impact is %d s", timp)
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