defining the port in grounded CPW in IE3D?

hi,

i have a basic doubt in defining the port in case of grounded CPW structure - in the IE3D manual it is mentioned that while defining port (advanced extension/extn. for MMIC) we should define port only to a part of the finite CPW ground for higher accuracy, but my question is that - wat should be the size of that part/segment where port is defined ( in say % ) with respect to finite CPW ground.

suppose, i have a grounded cpw structure on GaAs (350 micron thick) with signal line width = 50 micron , gap width = 70 micron and finite cpw ground width = 270 micron.wat should be the segment width for port on finite ground in this case?

eagerly waiting for replies.

with regards

abhi

Hi, Abhi:

Please define negative ports on the cpw ground with width about 50-70 um is good. The exact value is not very critical. You just need about the same size as the center conductor or slightly larger. Regards.