In the case of metal, even a thin film or mesh can block RF signals if any openings are smaller than the wavelength of the signal. Look up "Faraday cage".
-- John F. Eldredge -- j...@jfeldredge.com "Reserve your right to think, for even to think wrongly is better than not to think at all." -- Hypatia of Alexandria -----Original Message----- From: "Dave F." <dave...@madasafish.com> Date: Tue, 16 Feb 2010 17:46:21 To: John Smith<deltafoxtrot...@gmail.com> Cc: OpenStreetMap talk mailing list<talk@openstreetmap.org> Subject: Re: [OSM-talk] fwd: Two thirds of mobile users want driving ANDwalking navigation John Smith wrote: > On 17 February 2010 01:40, John F. Eldredge <j...@jfeldredge.com> wrote: > >> Frequently you can't get a position fix at all, if the building has much >> metal in its structure. I can't get a position fix from inside my house >> unless I am near a south-facing window, probably due to a metallic-foil >> vapor barrier in the attic. >> > > It has little to do with the material it's made of, it's all about how > much mass an object has, the more mass the more it will absorb RF. Is this correct? I assumed the reason I had trouble getting reception on board trains because of what their roofs were screened with. I can't believe they'd put much mass up there. Cheers Dave F. _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
