defining the excitation in HFSS ?

hi,

i have some doubt about defining the excitation in HFSS for a centre fed archimedean planar spiral antenna (800mhz - 3GHz). i am presently using a lumped port of driven terminal type inside the gap between the two arms in the centre on a rectangle that is connecting to both the arms on its either sides.


but i don't know whether that is correct or not.

so if anybody has any idea or examples, on how to do it correctly plz share ur views.

with regards
abhi

I think you need to post your design here. I want to talk a look at your port before giving you my response

Yes a lumped port can be used for this type of excitation. It will give the antenna input impedance across the feed gap.

A more rigorous model could include the type of feed (possibly with balun) that will be implemented. A slot spiral can be fed using a planar infinite balun. Metal spirals may use a coaxial feed with the shield connected to one arm and the center pin connected to the other. Also, some type of matching may be necessary to match the high feedpoint impedance of the spiral (~200 Ohms) to the feedline.

generally for wire structures, lumped ports are the best options.
just make sure you define your integration line correctly. if you use a flat sheet for the lumped port, start the integration line from the edge or ground to the other edge. Doing it halfway can cause problems.

For integration line highlight midpoint and simply use ur pointing device

Hey Peleda and Saifullah,
I can define integration line in two ways as shown in the attachment. Can u tell me which one of the integration lines is correct for feeding two arm archimedean spiral antenna?
Thanks

Hi ahsaan!

Can you pls tell me the design process of your antenna? I am facing difficult to make a spiral shape. My email address kamal14_kuet@yahoo.com