That lit a light bulb (pun intended), How about the cover of one of the encased low energy compact fluorescent. lamps? I've seen them in both glass and plastic (possibly PET). Robert g8rpi.
--- On Mon, 6/9/10, Chuck Harris <[email protected]> wrote: From: Chuck Harris <[email protected]> Subject: Re: [time-nuts] GPS ceramic patch in what plastic housing? To: "Discussion of precise time and frequency measurement" <[email protected]> Date: Monday, 6 September, 2010, 16:38 I know, cut the top off of a 150W incandescent light bulb and use it to make a radome. -Chuck Harris jimlux wrote: > Predrag Dukic wrote: >> >> Bill, >> >> Pyrex ( and any other glass) could reflect too much. It is true that >> glass, >> >> depending on composition, is not absorbing microwaves, and does not >> heat itself in the owen, >> >> but how much it is transparent at 2.4 ghz should be checked somehow... >> >> P. Dukic >> >> >> > > I wouldn't use a glass jar/mixing bowl, what-have-you. > > A) glass is a bit lossy (even at 100-200kHz), but probably not enough to > be an issue.. (Now, if you were building kW scale capacitors for a tesla > coil, that's a different thing) > > B) A bigger problem: Glass has a (unevenly controlled) dielectric > constant of around 2.5.. > > So, you'll get reflections at both interfaces as well as some refraction > as the signal passes through the "radome" > > The whole radome design thing is much trickier than one might think for > a something where angle of incidence is important. There's a reason that > you see lots of hemispheres, and one tries to control the thickness of > the radome (in fact, sometimes, you make the shell from a honeycomb core > with 2 face sheets, although at L band, this would be tricky). > > So, either you use something simple, and accept whatever defects it > creates in your antenna pattern, or get fancy. > > Glass babyfood or canning jars will probably work, and will literally > last your life time. White painted plastic would also work. > > Watch out for things like appropriately venting it (so moisture doesn't > collect inside) and making sure it doesn't make a little solar oven > (gotta paint that clear glass, I suspect) > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
