%Dobson's model to calculate the real and imaginary part of moist soil
%[1] Dobson, M. C., et al. (1985), Microwave Dielectric Behavior of wet
%Soil-Part II: Dielectric Mixing Models, IEEE Trans. Geosci. Remote Sens.,
%GE-23(1), 35-46.
%[2] Peplinski, N. R., et al. (1995), Dielectric properties of soils in the
%0.3-1.3-GHz range, IEEE Trans. Geosci. Remote Sens., 33(3), 803-807.
%[3] Klein, L., and C. Swift (1977), An improved model for the dielectric
%constant of sea water at microwave frequencies, IEEE Trans. Antennas
%Propag., 25(1), 104-111.
%[4] Stogryn, A. (1971), Equations for Calculating the Dielectric Constant
% of Saline Water, IEEE Trans. Microwave Theory Tech., 19(8), 733-736.
function [dcsr dcsi]=Dobson(f,T,smc,bd,vsand,vclay)
alpha=0.65;
dcs=4.7;
sd=2.65;
dc0=0.008854;
dcw0 = 88.045-0.4147.*T+6.295e-4.*T.^2+1.075e-5.*T.^3; % Refer to [3]
tpt=0.11109-3.824e-3.*T+6.938e-5.*T.^2-5.096e-7.*T.^3; %2*pi*tao, Refer to [4]
dcwinf=4.9;
if f>=1.4
   sigma = -1.645+1.939*bd-0.0225622*vsand +0.01594*vclay; % Refer to [1]
else
   sigma = 0.0467+0.2204*bd-0.004111*vsand +0.006614*vclay;% Refer to [2]
end
dcwr=dcwinf+((dcw0-dcwinf)./(1+(tpt.*f).^2));
dcwi=(tpt.*f.*(dcw0-dcwinf))./(1+(tpt.*f).^2)+sigma*(1.0-(bd/sd))./(8.0*atan(1.0)*dc0.*f.*smc);% Refer to [1]
betar=1.2748-0.00519*vsand-0.00152*vclay;
betai=1.33797-0.00603*vsand-0.00166*vclay;
dcsr=(1.0+(bd/sd)*((dcs^alpha)-1.0)+(smc.^betar)*(dcwr^alpha)-smc).^(1/alpha);% Result real part
dcsi=(smc.^(betai/alpha)).*dcwi;%Result imaginary part
% dcst=sqrt((dcsr)^2+(dcsi)^2);

end