MWS Energy Balance?

May someone please provide some information about the "energy balance" property of MWS. From what I understand this quantity is used to determine wether a two port system has reciprocity. But in the manual it says that "energy balance" must be equal to 1 for lossless systems. This seems rather interesting. Because even if your structure is lossless you may still have transmission+reflection not equal to one. There may be scattering losses, as is the case for photonic crystal. May someone please shed some light on on this issue.

Hi irfan1,

the energy balance is just the square Sum of the S-Parameter. For a lossless structure (no internal losses and no radiation) the balance has to be 1 becuase in the phsical world energy is conserved. Any energy lauched into the structure has to leave the structure again via the ports because it can not leave the strcuture thru another "exit" ....

I hope this makes it clear.

F.

Hi,
Actually my point is that, Consider a photonic crystal (in open space or rather in air) composed of simple lossless dielectric material and lets say you got horn antennas for excitation and for measurement. Then I beleive that the square sum of S-parameters will be generally different than 1. It may even be larger than one. On the other hand still the energy conservation holds (Poynting's theorem should hold). Or am I still missing something?

The energy balance correctly works only for closed structures. The radiation effects not takes into account. Only waveguide ports are considered. And quantum effects in photonic crystal not simulated by CST-MWS. If You simulate the photonic crystal based on classical EM-theory (quantum effects are not considered), the energy conservation law must works.

Regards,
Kit

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