Transmission loss through materials depends on 2 factors. Loss tangent and
dielectric constant. Loss tangent is often the lesser of the problems, but
is simple exchange of the wave energy for heat caused by several possible
mechanisms. Look up the operating principles of microwave ovens.
Dielectric constant manifests itself as an impedance mismatch at each
surface, which causes reflections. At a specific frequency, this
characteristic can be used to make the material transparent, as in ceramic
radomes for spacecraft.

In your case, the loss tangent of polystyrene for RF is among the best if
there is no moisture trapped in the foam (closed cell type preferably), and
since the dielectric constant approaches that of air, then the loss at the
GPS frequency will be virtually nil.

--
Crazy George
Remove N O and S P A M imbedded in return address
"David Harper" wrote in message
m...
I was wondering what the general relationship between frequency and
its ability to transmit through various materials? For instance, 1GHz
and 1MHz obviously transmit differently through materials. I'm
curious as to what material properties are involved (i.e. dielectric
constant, density, etc?)

The main reason for this questions is I'm wondering how well 1+ GHz
(GPS) signals transmit through about 1.5 inches of expanded
polystyrene (styrofoam).

Thanks in advance for any insight!
Dave