[Top] [All Lists]

[TowerTalk] RF current in REF + DIR much ?

To: <>
Subject: [TowerTalk] RF current in REF + DIR much ?
From: "Jim Thomson" <>
Date: Wed, 22 Dec 2010 06:15:39 -0800
List-post: <">>
How much RF current typ flows in the REF + DIR  on a 3-el yagi ?     YO  just 
shows a 'relative'  scale  for the parasitic ele's. 
IE: just to simplify things,  let's  say we have 10A flowing into the 30 ohm 
feed-point of the DE  [3 kw] . [monoband yagi]
How much RF  current do we typ have at the center of the REF  +  DIR  ??   [as 
a percentage of the DE current]    10%, 30% ?? 

If the  REF + DIR used solid  fiberglass center insulator's and the shorting 
strap across em was removed, and an RF ammeter
was strapped across the insulator, what would I expect ?   Is that method  
valid ?   I was thinking a clamp on RF Ammeter
could also be used, but typ they are not calibrated..but are only relative.   
Has anybody ever tried to measure the RF current in the
center of the parasitic ele's ??      I downloaded 4NEC2 a few days 
it's  new to me..and at 1st glance,  I don't see any mention
of exact current flow in the parasitic els.   Now of course, this will all 
depend on the tuning and spacing of the parasitic ele's....and 
relative current flow in the parasitic ele's could vary  across the band.  

Tnx in advance.......  Jim   VE7RF

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>