Learning Forum

[halamohmmed7]

Hello. Please I need help regarding how can I calculate the normal component of the Poynting vector directly from the far-field Electric fields ? I used the following script, but it did not work:
mon_name = "xz";
f = getdata(mon_name, "f");
# Get the electric field components in the far field
E_squared = farfield2d(mon_name, 1, 2000);
theta = farfieldangle("xz"); # Get angle data if needed for integration
# Calculate the normal component of the Poynting vector using pre-defined constants
epsilon0 = 8.854187817e-12; # Permittivity of free space
Poynting_normal = sqrt(epsilon0 / mu0) * E_squared;
# Integrate the Poynting vector over the specified solid angle
x=getdata(mon_name,"x");
z=getdata(mon_name,"z");
T2 = 0.5 * integrate(Poynting_normal); # Power in watts
# get power injected by source (Watts)
sp=sourcepower(f);
# Normalize to source power
T2 = T2 / sp;
?"Total Scattered Power: " + num2str(T2);
?"Source power (Watts): "+num2str(sp);

[Guilin Sun]

It is E cross conj(H) in near or farfield.

You will need first to get E field, and then use plane wave approximaiton, H=E/eta where eta is the impedance of the material usually it is n=1, and eta=120pi. or by farfield exact:  https://optics.ansys.com/hc/en-us/articles/360034914773-Calculating-magnetic-fields-in-far-field-projections

Please note that now farfieldexact can directly give H fields: https://optics.ansys.com/hc/en-us/articles/360034930733-farfieldexact3d-Script-command so you do not need to solve the discrete Maxwell equations.