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*Subject*: Re: [amsat-bb] Mir, SO-35, RS-18 stuff.]*From*: Anthony Monteiro <aa2tx@xxxxxxxxxxxxxxxxxxxxxxxxxxx>*Date*: Wed, 14 Jul 1999 01:56:25 +0000

>A fellow reported using a JPole with 50 watt, and failing. Using the >same calculations, here is his situation: > 50 watts pep > 1.75 db line and insertion loss (assumed) > 5.5 dbi antenna gain (again assumed) > 20.7 dbW EIRP > for an approximate ERP of 118 watts > A jpole is a really crummy antenna for transmitting to a satellite. Here are some better numbers for the jPole at 15 degrees elevation with bottom of the antenna at 25': +47dBm0 = 50W PEP tx power -1.75db = feed line loss 0dB = antenna gain at 15 degrees -6dB = average polarization mismatch loss (not median) EIRP = +40 dBm0 or about 10 watts on average >Commonly, portable users will use an ARROW (or similar) antenna and a 5 >watt HT: > 5 watt pep > 1.75 db line and insertion loss (assumed) > 8 dbi antenna gain (assumed) > 13.2 dbW EIRP > for an approximate ERP of 21 watts Notice that the 5 watt HT with a manually pointed ARROW is 3 dB better and doesn't have the deep fading problem. >If I required a fixed antenna for LEO use, I'd build (or buy) a QHA, >turnstile, eggbeater or Lindenblad antenna. A Lindenblad is an excellent fixed station antenna. Here is the same station with a Lindenblad at 15 degrees +47 dBm0 = 50W PEP -1.75 dB = feed line loss 3dB = antenna gain at 15 degrees -3 dB = average polarization mismatch loss EIRP = +45 dBm0 or about 33 watts The Lindenblad also does not have the deep fading problem but doesn't require manual pointing. Tony Tony AA2TX@amsat.org North Andover, MA ---- Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

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