Learning Forum

[Yi-Chen Lai]

I have read this article: Understanding field polarization in far field projections – Ansys Optics. In the example file, there is a case that compares two methods to calculate the far-field power. 

Method 2 integrated the intensity of the far-field electric field (|E|^2) at the spherical coordinate and multiplied 0.5*(sqrt(eps0/mu0)). I am confused about why we need to multiply 'sqrt(eps0/mu0)'. After searching for the reference, I find another article: Changing the far field refractive index analysis object – Ansys Optics. The bottom picture shows the words.

I remember the relationship between E & B is B=sqrt(eps0*mu0)*E. How does the magnetic field amplitude become sqrt(eps0/mu0)?

 

[Guilin Sun]

You may need to recheck some books, as H=E/eta for plane wave and farfield where eta is the impedance sqrt(u0/eps0).

I believe you know why there is 0.5 in front.