How do they determine relative permittivity & permeabili

how do they determine the relative permittivity, ε, and permeability, μ? How do they come up with such values?

Thank you.

Hello kae_jolie !

Here is an excellent application note of Agilent (c) about measuring those values.
Its includes a breif explanation about permittivity and test equipments!

Good Luck !

fill a resonator with the material whose permittivity is to be measured.
the cavity has a slot
it is joint with a transmission line.
one end of the line is a generator
on end a detector
u change freq
observation of a dip in detector indicator means a resonance
f, cavity dimensions are known
the unknown is :::: permittivity
the resonance freq(s) of a cavity are discrete.