"which is why your house is not a total RF shielded faraday cage :)" It's NOT even close for well into the VHF and UHF range I'm afraid to inform you ... I think you've read one too-many ill-informed text book on this subject ... I've been there - and done most of this - from AM Broadcast freqs through VHF and UHF 2-way radio including cellular/cell site propagation studies ***and*** actual crane tests/firld strength measurements with the highest freq worked at being Ku band on a RADAR project ... other projects included some original GPS gear - we at TI did one of the original HDUE (High Dynamic User Equipment) receivers for the military during GPS field trials in 1978 ... .. so, please, - *do* spare me the lecture about the black arts. The black arts are what I deal in, what I have dealt in and will continue to deal in ... (Okamura - where are you?) Investigation of Modified Hata/Okamura Propagation Models: http://www.aca.gov.au/frequency/spps/0102spp.pdf Jim ----- Original Message ----- From: "Alan B. Pearce" To: Sent: Thursday, July 18, 2002 3:35 AM Subject: Re: [OT]: BGMicro GPS recievers > > "Any timber is a good absorber of RF signals, even > > down to HF." > > > >Any truth to the rumor that old hams used to use > >wood sticks dipped in parafin (sp?) as spacers > >on their open-wire twin-lead feedlines? > > Well a couple of sticks of timber to support an antenna is a considerable > amount less thann a whole forest of trees with the antenna down among them. > As I understood it the parafin was a water proofing treatment. :) > > >I guess there're no thruth to the rumor that lumber > >used in construction if kiln-dried to some single-digit > >moisture value either ... > > > >I need an explnation, too, as to how I can pick up SW > >as well as AM broadcast band signals equally inside > >and outside inside of my house too. > > > >(It seems that 'mother nature' is un-informed as to the > >proper behavior of EM waves in an urban environemnt.) > > Again the amount of timber is a lot less than a forest of trees, and growing > trees have a fair amount of moisture in them - part of the reason that house > timber needs to be kiln dried :) > > >Your example involving 'pine forests' involves a > >LOT more in the way of lossy material which a > >typical land-mobile 2-way system would and see > >using terrestrially-bound just barely above > >the surface-of-the-earth signals. > > Exactly, there is an almighty amount of lossy material in a forest, and IIRC > I said there was a noticeable loss of signal strength, but this does not > mean a total loss at HF, which is why your house is not a total RF shielded > faraday cage :) > > But the fact still remains that the higher you go in frequency, the more > likely losses will arise from sources you do not expect, which is one part > of the reason that good RF engineers are regarded as dealing in black magic > by those who are not initiated into the inner circle :))) > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.