On 29 May 2002 at 11:02, Tim Pozar wrote: > On Wed, May 29, 2002 at 10:44:59AM -0700, Tim Pozar wrote: > > As an example... > > If we had a 24 dBi antenna on both ends of a point-to-point link > > with the legal max power of .25 Watts (FCC 15.247) we would have a > > fade margin of 47.775 dB (with a 80 dBm RX threshold) over a 1 mile > > link. If we had a passive repeater connecting two 1 mile links we > > would have to multiply the pass loss of one link (104.2 dB) by 2 and > > the antenna gain (48 dBi) by 2. This would have a total path loss > > of 108.4 dB and would put the RX signal at -88.42 dBm. > Whoops... That should be 208.4 dB.
I believe you were closer the first time at 108.4 dB. dB are not a linear scale, and a doubling or halving of signal is a 3 db change. So, if you lose 104.2db on each leg, the total loss would be 107.2 db because you have doubled the loss - or added another 3 db of loss. If I missed the boat on my math, well, it's been a long time since high school or college. Mike -- Mike Avery [EMAIL PROTECTED] ICQ: 16241692 AOL IM: MAvery81230 Phone: 970-642-0282 * Spam is for lusers who can't get business any other way * A Randomly Selected Thought For The Day: Any minimum criteria set will be the maximum value used. -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
