loss tangent

dear....

what's the physical meaning of loss tangent ( tan δ)?
is loss tangent same with dissipation loss of dielectric?
what r the differences of loss tangent, dielectric loss and dissipation loss?
im confused when i read datasheet of roger's microstrip.


thanks a lot.

the full dielectric constant contains a real part and a image part.
Eps=Eps1-jEps2
so the Tanδ=Eps2/Eps1
and the tanδ is proportional to the dielectric loss,it means the EM energy
are converted to heat energy because of the dielectric are losy,
The dissipation loss means the radiation of energy when EM is propagating,
becasue the microstrip line is an open structure.

i see in a reference that loss tangent or tan δ is ratio of conduction current and displacement current

tan δ = σ/ωε

is it right?

Yes it's correct that tan δ = σ/ωε.

Loss tangent is the ration b/w the imaginary and real parts of the complex permittivity
where the complex permittivity can be defined as εc = ε-j (σ/ω)

The valie of the loss tangent describes how lossy a material is, if σ ? ω ε, it represents a very lossy material or a very good conductor