Topband: 90 ft or 120 ft vert fer TB
herbs at vitelcom.net
Thu Feb 9 15:28:05 PST 2012
On 2/9/2012 7:01 PM, vk3pa at vk3pa.com wrote:
> Hi all,
> after loosing my 90ft top loaded vert (wind storm 120kph +++) fer
> TB, I find I have enough meteral to go to a max of 120foot vertical (
> 4 lengths @ 30 ft)
> Q is, if I base load will this be much better than my 90 ft top loaded
> vertical was?
> (108 dxcc wked/12 months)
> or Should I still go fer a 90ft top loaded 4 sq array?
> With a signal vert I run a triangle phased array HI-Z
A 120 vs. a 90 foot top loaded is a matter of choice since the RF
doesn't really care since the 90 foot top loaded can look exactly like a
120 foot unipole. The 90 footer, depending on the amount of top loading
most the current maximum up the tower near the top. The current
maximum never appears at the tip of a 120 footer. So the answer is to
do what ever is easier as it is the top loading that makes all the
difference, assuming the radial field is the same. Problem with a 120
foot tower is that when you start putting beams on top the feeding may
become more difficult as the tower at RF approaches 1/2 wave electrical.
Herb Schoenbohm, KV4FZ
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