Help needed with coupled lines in HFSS

Hello all

Does anyone know how to properly simulate two highly coupled microstrip lines in HFSS?

When two lines become too close to each other it seems that HFSS modal solution can not define the port fields properly.

Thank you in advance,
Mohammad.

But this is happened also in reality, not only in HFSS.

HFSS has no problems with coupled microstrip lines and their port fields. You need to correctly define the port.

u may try ADS For better results