impedance simulation

Hi, everyone. I have a question about how to use HFSS to find the Characteristic Impedance of a transmission line in the eigen-mode solver, such as microstrip line.

I remember in David Pozar's Microwave Engineering, the characteristic impedance can be defined by either power and current, or power and voltage, or voltage and current. And I think the HFSS port-only Driven Mode Solver provide a quick wave to calculate them.

My question is that whether the characteristic impedance can be gotten from the Eigen-Solver by doing "field calculator" integral. I am not sure whether I can integrate the E field along a line to find the voltage, integral H field along a close line to find the current, and then divide them to the characteristic impedance for the quasi-TEM mode.

Or do I need to integral the poynting vector for a surface to get the power?

Any information or examples are welcomed.

Thanks in advance.

Hi there !

The easiest way to find Impedance of tranmission line is just define port and calculate port only solution, imho. HFSS will give you the answer as Z0 value in Matrix Data
You can find it using eigen-mode solver as well. The Impedance will be equal (in general case) to a relation between maximums of tangential components of E and H fields along any line in z direction.
This relation is a constant and doesn't depend on line (x,y) position.

I think the characteristic impedance along the antenna seems to be a distributed variable along the z direction and may not be a constant. Of course, we usually consider that a constant.

Hi

can any one help to solve this problem of finding surface impedance, when we use eigen mode solver in HFSS.