On 14 Jun 2004 09:06:12 -0700, (David Harper)
wrote:
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).

Hi Dave,

Such material at that frequency is often used to construct a
di-electric lens. That is, when the di-electric constant (which is
analogous to index of refraction) is taken into account of curvature
which, in turn, is of sufficient size with respect to wavelength; then
you have the means to construct lens of the common shape you encounter
for light lenses. This means both follow the same characteristics
given the same shape. For a slab of Polystyrene, it would be
equivalent to plate glass (no gain/magnification).

As long as your di-electric is free of impurities, then for all
intents and purposes it is as clear to RF as glass is to light. Add
impurities and you stand the chance of making sunglasses for your
antenna (unfortunately the analog of sunlight would be your precious
RF).

Optical lenses are hundreds to thousands to millions of wavelengths
across. On the other hand, RF lenses stand to be much smaller in
relation, and as such there is a minimum size whereby no advantage may
be found (don't expect to build an effective, but sloppy quarterwave
lens).

73's
Richard Clark, KB7QHC