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[TowerTalk] Question re current dist. on 1/3 w. dipole

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Subject: [TowerTalk] Question re current dist. on 1/3 w. dipole
From: (Rob Atkinson, K5UJ)
Date: Thu Aug 7 20:39:05 2003
Hi everyone:

One of my antennas is a dipole ~30 feet up that's a 1/2 wave at around 5.3 
MHz (88' long).  I feed it with 600 ohm open wire feed and use it on 75 
meters where it's around 1/3 wave long.  One midday a few weeks ago, I 
transmitted a 10 - 15 watt carrier for several minutes in a dead part of the 
80 cw band and walked around under the dipole  with a cheap field strength 
meter.  While the whole undertaking was crude, it was pretty clear that the 
field was strongest at the ends of the dipole and weakest near the feed 
point.   I was not expecting this, mainly because with a 1/2 wave dipole I 
understand the current is max at the feedpoint.  while this antenna is 
shorter I did not think that would matter that much.  I was wondering if 
someone with modelling software could tell me (explain) the current 
distribution on a 1/3 w. dipole and if possible tell me the modelled swr for 
an 88' dipole at 30 feet, fed with 600 ohm open feed on 3.75 MHz and the 
resistance/reactance.  Since I've never used any of the antenna packages, I 
don't know if I'm asking a great deal or not, so if it's a big hassle I 
apologize--please disregard.  I use this antenna on 17-80 m.
tnx & 73,


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