antenna coax length

I am simulating a mono antenna feed by coaxial line, and find that different length of coax line will lead to different S11 parameters. What length on earth should be? I have no idea to find the principle, Can anyone help me? Thanks very much!

In pricniple, mesh should be adjusted in such a way that it take at least three time steps for the wave to travel thoudh coaxial feed.

hi,

i also had the same problem while feeding a PIFA (a shorted probe fed microstrip patch antenna) in HFSS.

i am eager to know the answer

with regards
abhi

Can u upload ur design then i can check

Thanks

maybe adaptive meshing can be helpful!