Hi Elia
From your other post it is clear you
are making (permittivity??) measurements.
A
lot depends on what is mixed with the water and
in what ratio. As I mention in my previous post
to you, I always used closed containers like coaxial
or waveguide transmission support, or resonant cavities,
and a Vector Network analyzer or other impedance
bridge methods. Containing the field makes the measurement
easier to set up and the results more accurate and
repeatable, and the errors calculable with confidence.
The open tank free space approach is obviously
important if the water is flowing and not static.
What are you considering for the Free Space
Method? There are 2 or 3 ways to approach it in
that case. What sort of frequency range are you
using?