Dear Sim4Life-community,

in an EM FDTD simulation, I am trying to model a situation in which I have microwaves of known frequency (915MHz) and heat up a phantom. It is heated up by a machine that has a known power out (e.g. 12W). In the simulation however, I can only enter a resistance and a voltage. Is there a straightforward way to simulate such a situation, or how do I calculate the correct power output from the voltage?

I am already aware of the manual (especially the chapter "Power Waves"), and have tried to calculate the power from the provided theory, but so far, my attempts have not been successful. Here is one of my attempts:

I used the Thevenin equivalent and calculated Z_i=(U_0^2/P)-Z_0, where U_0 and Z_0 are the quantities that can be entered into the simulation, and P is the EM input power that can be found in the analysis. Having the internal resistance Z_i of the system, I can enter it into the equation to predict a correct power output P with other values of U_0 and Z_0. Yet the result never matches my predictions.

Can someone help me?