Surface participation ratio for combined ports #446
Description
When designing a lumped port might be represented as two entities, a mean value and a bias. The bias can have a negative inductance, but the combination with the mean will give an overall positive inductance. A negative inductance can result in SPR that are outside of [-1,1], but the combined effective inductance for mean and bias would still be in the range, as the overall energy of the pair would be net positive.
This could be possible by effectively placing extra parentheses in the calculation of the energy associated with a given port, to be that within multiple elements in a port. This would be an extension of the multi element port to allow specification of the impedance on each piece individually as opposed to in a combined mode.