Discussion Forum

Short description:

In Equation View I find the following definition of the S11 parameter:

emw.S11 = if(abs(emw.beta_1)>1.0E-7 * emw.intport1(emw.k)/emw.Area_1&&(abs(arg(emw.beta_1))<=0.25pi||abs(arg(emw.beta_1))>=0.75pi),emw.S1x * exp(-j*phase),0)

I can find all these functions, e.g. emw.beta_1, defined elsewhere in Equation View, but I cant see emw.S1x anywhere. Does anyone know what it is and what expression defines it?

Long description and context:

I am currently trying to re-write my own S-parameters in order to evaluate transmission and reflection on a surface inside my geometry, in contrast to the normal S-parameters that take readings from the ports that has to be placed on boundaries defining exit/enter locations of the electromagnetic waves.

My model is a simple waveguide with two ports on either end, where Port 1 excites the incident wave. I want to measure transmittance and reflectance very close to the center of the waveguide, but still need the ports to be placed sufficiently distanced from each other. So I cannot use e.g. the traditional abs(emw.S11)^2 as it reads the reflectance outside the region of interest.

My plan is to define my own variable, say comp1.S11_z0, that does the same as emw.S11 but instead of integrating over the area of Port 1 it integrates over a similar surface placed at z=z0, closer to the center (z=0) of the waveguide. It should also take into account material properties at z0 instead of at wherever Port 1 is. I attached an image of the waveguide. Marked are Port 1 and the surface closer to center. Unmarked are Port 2 and its corresponding surface.

In Equation View I find the following definition of the S11 parameter:

emw.S11 = if(abs(emw.beta_1)>1.0E-7 * emw.intport1(emw.k)/emw.Area_1&&(abs(arg(emw.beta_1))<=0.25pi||abs(arg(emw.beta_1))>=0.75pi),emw.S1x * exp(-j*phase),0)

I have written new variants of emw.beta_1, emw.k, emw.Area_1, emw.intport1() and their subsequent function emw.alphaport_1 to fit this new S11_z0, but I need to rewrite emw.S1x to complete the expression. I don't know what emw.S1x is and cannot find its definition anywhere. Anyone able to help out?

On a final note, I bet there is a simpler way to read reflection/transmission power on interior geometry. I am open for suggestions for other methods!