Tim - I thought this thread sounded familiar.. I also seem to remember a discussion on whether or not to add the gains of the two yagis together in passive mode - in reference to the effective +36db of the two yagis. Correct? Of course reductions here would just further prove the point..
D. > >From a previous mail of almost two years ago. :-) > > From: Tim Pozar <[EMAIL PROTECTED]> > To: Walter Bruce <[EMAIL PROTECTED]> > Cc: Tom Farrow <[EMAIL PROTECTED]>, [EMAIL PROTECTED], > [EMAIL PROTECTED], [EMAIL PROTECTED] > Subject: Re: [BAWUG] Re: Passive repeater net gain > Message-ID: <[EMAIL PROTECTED]> > References: <[EMAIL PROTECTED]> > <[EMAIL PROTECTED]> > <[EMAIL PROTECTED]> > In-Reply-To: <[EMAIL PROTECTED]>; > from [EMAIL PROTECTED] on Tue, Feb 12, 2002 at 01:23:21PM -0800 > Date: Tue Feb 12 14:08:01 2002 > X-Original-Date: Tue, 12 Feb 2002 14:07:48 -0800 > > On Tue, Feb 12, 2002 at 01:23:21PM -0800, Walter Bruce wrote: > > So, why did it work for Cringely? > > Hmm... Let's calculate it... > > He states in the article that he is using a WAP11 at his > house running at 100mW (too bad as a WAP11 splatters all up > and down the band in this mode and he is likely violating the > FCC's spectrum > requirements) into a 21dBi dish. The mountain top is 1.5 > miles away. He is using some sort of yagis on the mountain > top. The second path is 5 miles. He doesn't state the gain > of the yagis or what the antenna is at the ISP. But we can > make some assumptions... > > Ignoring cable/connector losses at his home he is doing 41dBm > EIRP out of his antenna (20dBm + 21dBi). The free space loss > at 1.5 miles is about 108 dB. Lets assume his yagis are 18dBi > and there is no loss on the cable connecting them together. > The 5 mile path will have a free space loss about 118dB and > we will assume he has a 24dBi gain antenna on the roof of the > ISP. Lets add this up... > > 41 dBm EIRP (20dBm + 21dBi) at his house. > - 108 dB Free space loss - first link > + 18 dBi antenna gain on the mountain. > + 18 dBi antenna gain on the mountain. > - 118 dB Free space loss - second link. > + 24 dBi antenna gain at ISP. > ========= > - 125 dBm > > Most cards will start to work about -90dBm so this is 35dB > below his receiver threshold. Unless my assumptions or > interpretation of his paths are are wrong, it doesn't look > like the numbers hold up his claim. > > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > > -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
