There is some industrial window tint that blocks wifi quite well. I know SeattleWireless had some issues with it when hooking up Alki Beach to the big black tower in Seattle - but a 24db parabolic and a homemade yagi easily made it past the windows and across the bay.
Tower (far right) http://loraksus.org/galleries/General/08-30-03/Seattle%20Scenery/Seatt le%20Panorama%2001.JPG The homemade yagi. http://loraksus.org/galleries/General/08-30-03/OnTheGround/Alki%20Setu p%2002.JPG Call a tinting place, ask for "metallic thermal tint" or something that might block wifi signals. They probably won't know what you are talking about, but they should know what metallic thermal tint is. I suppose any metallic tint should reflect a lot of signal. Test, test, test I suppose. Please post your results if you can on a wiki or webpage somewhere. The results would be really interesting. The tint might work as a better reflector from one side so keep that in mind. There might also be a product specially designed to block wifi / 2.4ghz. It doesn't sound like that big of a place, so installing + material should be fairly cheap. I suppose there is a minute chance of a problem showing up in signal reflections from the inside of the windows, but I'm not a physics guy by any means, so take the next two paragraphs with a lot of salt. I might be right, though I'm sure some PHD will utterly destroy me on this if they see it. Rightfully so, I might add. | \ / If you have a big "wifi mirror" on the opposite side of the windows (i.e. a big mirror) I suppose that could get a lot of signal bouncing. If I did my figures correctly, the frequencies are switched every 224 microseconds, light travels at ~304 meters a microsecond, so it would probably show itself as a bit of background noise (since it would of have bounced a few times since leaving the AP, and lost power with every bounce), but since you are cutting out the noise from outside, you will probably have a better SNR than before /shrug. If you're really worried about something like that, I suppose try setting up some aluminum / tin foil on the windows one day (after closing or whatever) get it stuck to the windows via static and try it with netstumbler. Also play with the various channels and see if that affects noise - it probably won't but 11 might be better than 1 or vice versa. Red = bad ;) BTW what does a caf� need a surveillance system for? Disgruntled guidos stealing grinders a la the Sopranos ;)? Get a dead webcam and put a blinking led hooked up to a 9v battery in it, should last you a good couple of months. . -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
