rectangular coaxial line in circuit simulator

Hi.
Does anybody here know any circuit simulator have rectangular coaxial line component. As far as I know ansoft designer have round coaxial line components in the circuit simulator. But I have to model a low pass filter with coax line of retangular cross section. Can anyone have idea where to find this model?

Try to check Microwave Wizard from Mician. www.mician.com

Bye

You can easily model this line with Ansoft HFSS.

There is however no pre-formatted model. This sounds like an easy one to accomplish.