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*Subject*: [amsat-bb] Coax Attenuation*From*: "william washburn" <billwashburn@xxxxxxxxxxxx>*Date*: Sat, 7 Jul 2001 10:05:36 -0700

Folks, I wasn't going to post this concept, but since there seems to be some discussion today about coax attenuation, I think I will anyway. I tried last week to develop (since I couldn't find one) a formula for calculating the attenuation of a known length of cable given the attenuation per 100 ft. For example, given an attenuation of 3dB per 100 feet, what is the attenuation of 50 feet of said cable in dB? Given 10 watts into 100 ft of this 3dB line, the ratio of input power to output power is 10/5 or 2 (3dB). For 50 ft, the power loss is half what it was before or 2.5W lost rather than 5W lost. The I/O power ratio of 50ft is 10/7.5 or 1.25dB. The scaling must be done with power ratios, not dB. I have seen, however, articles saying to halve the 3dB factor which gives 1.5dB not 1.25dB. This may seem a small difference, but for critical calculations it becomes important. I put the calculations into a spreadsheet but still would like to have an explicit equation for this calculation. If anybody knows of such a formula please post it. Thanks, Bill, WA6QGR ---- Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

**Follow-Ups**:**RE: Coax Attenuation***From:*Howard Long

**Re: Coax Attenuation***From:*Bob Nielsen

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