> Some plastics are transparent to microwave RF.   For some reason
> I remember the term "polycarbonate" although I forget whether
> that was good or bad.  <pause>  A quick web search suggests that
> this is the good stuff and it doesn't block RF.   Note you
> can buy many a receiver that has the antenna inside.
>
> If in doubt about your enclosure, set it on top of the antenna
> and see what it does to the signal strength.


A simple test for transparency to RF at 2.4 GHz is to place a piece in a (n
operating :-) )  microwave oven. Any heating suggests you should find
another plastic. While this is not necessarily representative of how the
material will act at other frequencies it often gives a fair indication.
(Note that water has an absorption line at ~2.4 GHz which is why they use
that frequency. )

Testing for a minute or so is probably worthwhile. Having some other "load"
in the oven at the same time is necessary if you value your magnetron.


        RM

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