On Mon, 03 May 1999 15:30:19 GMT k2av@qsl.net (Guy Olinger, K2AV) writes:
> On Sun, 2 May 1999 17:55:44 -0400, you wrote:
>
> >
> >A tribander 20' above the guy station should not interact enough to
> cause
> >a problem except on a computer.
>
> Modelling getting good enough to handle a lot of things that can
> barely be measured. Unbroken wires 20' below a tribander can be
> either
> trivial or totally screw up the pattern, depending on lengths. If
> the
> SWR changes a couple of tenths, pattern is being messed with.
Good point and I agree.
>
> >This was supposed to be an excersise in reality, not
> >perfection...remember.
>
> The modelling has it's bad moments, it's weaknesses, it's occasional
> not-to-be-trusted results. HOWEVER, working within the limits, it
> gives valuable insight into the behavior of RF on conductors that is
> nearly impossible to measure with the equipment available to most of
> us.
I need to get a new program still trying to learn with early K6STI MN and
YO releases, computers are not my best area of comfort.
So, getting back to the original 60' of 45G where would be the best
location for a single uninsulated guy? This would attach at between the
40-45' level and be in the 60-80 % of height at the anchor point.
The antenna will be a 10-15-20M only tribander.
Any help appreciated.
>
> I modelled a 40m 45 degree sloping folded dipole, a matching section
> of 300 ohm twin lead to get a wideband match to the 450 ohm
> ladderline
> in use, so I could use a 9:1 transformer at the house end without
> worrying about the stuff that goes wrong with transformers operating
> away from design impedances.
>
> I cut the stuff to lengths specified by the modelling (EZNEC2 for
> this
> one), strung it up. 1.5:1 at the band edges, 1.2:1 in the middle,
> works great.
>
> THAT's an exercise in reality. Putting stuff up without trying to
> validate design with modelling is an exercise in denial of reality,
> unless you have an antenna test range and many K bux worth of
> measuring equipment.
>
>
> 73, Guy
> --. .-..
>
> Guy Olinger, K2AV
> k2av@qsl.net
> Apex, NC, USA
>
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