14
l3 3 4 {len*l/2}
c2 4 0 {len*c}
l4 4 out2 {len*l/2}
* third conductor
r5 in3 5 {len*r+1u}
l5 5 6 {len*l/2}
c3 6 0 {len*c}
l6 6 out3 {len*l/2}
*mutual couplings
k1 l1 l3 {lm/l}
k2 l2 l4 {lm/l}
k3 l3 l5 {lm/l}
k4 l4 l6 {lm/l}
k5 l1 l5 {lm/l}
k6 l2 l6 {lm/l}
c4 2 4 {len*cm}
c5 4 6 {len*cm}
c6 2 6 {len*cm}
.ends
This model can be extrapolated to two, four, and five conductors.
A Limitation
To be able to decouple the inductance and capacitance matrices, LM < L and CM < C. Large values of
LM can lead to a negative eigenvalue when decoupling the matrix.
Rules Of Thumb For Choosing Between Lumped And Distributed Types
For short transmission lines the distributed model can slow down the simulation by imposing a
maximum time step of Td/2. For each line where Tr>Td/2, consider using a lumped model. Also, a
large number of lumps required can slow down the simulation - use largest lump size that still gives
accurate results
Asymmetric coupled lines should be simulated using lumped models due to assumptions in the model
[1] and [2].
RC (high loss tlines) must be simulated as lumped circuits.
