Hi Hadeel,
Here is an example of Signal Attenuation Due to Rainfall:
c = physconst('lightspeed');
rr = 20.0;
freq = [1:1000]*1e9;
L = rainpl(10000,freq,rr);
wavelength = c./freq; % wavelength calculated by speed of light/frequency
semilogx(wavelength,L)
grid
xlabel('Wavelength (m)')
ylabel('Attenuation (dB)')