RE: [BAWUG] Re: Passive repeater (Was: Cringely essay and my response)

[Casey Halverson]

Title: Re: [BAWUG] Re: Passive repeater (Was: Cringely essay and my response)

Calculating the SOM of any passive repeating device is a known science and has a nice little formula to go with it.   For this configuration, you'd calculate it like so:   power input + antenna gain - path loss + repeater antenna gain = passive repeater input power   passive repeater input power - connection losses + antenna gain = EIRP of passive repeater   EIRP of passive repeater - path loss + receiving antenna gain = estimated receive level   People are dumbfounded that a couple antennas connected via coax with "no power" could actually work, but it does.  Where the hell to people think multipath and relefections come from? ;)  Mountains, buildings, and urban clutter create a lot of unintentional "passive repeating".  It just so happens that our passive repeater is well tuned and aligned.   My g/f is harrassing me to get off the computer, so someone else run the cringly numbers if they wish .. i'd be interested to see what it comes out as. -----Original Message----- From: Jeff King [mailto:[EMAIL PROTECTED] Sent: Sun 1/11/2004 10:07 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Cc: Subject: Re: [BAWUG] Re: Passive repeater (Was: Cringely essay and my response) Passive repeating is all about aperture area.  Your passive repeater needs to capture enough energy to effectively reradiate any. That is why the most effective passive repeaters are very near one end of a link or the other. The worst place for a passive repeater (in general) is exactly in the center of a path. You want the energy leaving one site to be effectively coupled into the passive repeater dish, and the farther the energy travels, the more it disperses. Now, looking at the orginial story: http://www.pbs.org/cringely/pulpit/pulpit20020207.html we see cringly is 1.5 miles from the passive repeater, and his target is 5 miles from the passive repeater. He has optical line of sight to both locations, and one could surmise that he is out of the fresnal zones for both (since his site is on a hill). His hilltop Yagi's are ~ 14db gain http://www.oreillynet.com/cs/weblog/view/wlg/448 http://www.netscum.com/~clapp/wireless.html and he says at his home he has a 100mw WAP11 with a 21 db dish. So, I can't say if it worked, but their should be enough data here to determine if it could have worked, assuming panel antennas at Sonic net near the legal limit for erp