investigating intresting parasitic resonance phenomena

[yefj]

Hello , I have a line geting closer to the line connected to the ports.
as the distancebetween them gets closer the S21 notches get deeper and deeper.
The difference between two peaks is 3GHz.
each notch represent a resonance on the floating line.
at 6Ghz we have two wavelength
at 9GHz three wavelength
at 12GHz we see four wavelength resonances.
given only this data is there a physical way to know that the floating line is 26mm?
Thanks.

 

[Baluncore]

The 26mm strip is a dipole, resonant at: 6G162, 9G159, and 12G120.
Those are not perfect harmonics, so some end effect is in play.
There will also be a resonance at about 3.163 GHz, λ = 94.75 mm in free space.
λ/2 = 47.38 mm in free space. The velocity factor is 47.38/26 = 1.822
Effective Er will therefore be about 1.822² = 3.32 ; but that seems a bit high without a ground plane, as most of the volume about the dipole is air with Er = 1.00

given only this data is there a physical way to know that the floating line is 26mm?

Yes.
Is there a ground plane ?
What is the thickness and Er of the dielectric ?
Then calculate backwards to find the line length.