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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 |
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