The QTH is in NY? That sure sounds like a "challenging environment" for
any 80m beam. A 4SQ will be a rock star from NY (contesting point of
view) and will have only about 1% of the environmental survival issues
to deal with that a beam would have.
Around here (Kansas) we call 80m beams "stuff you mow around." Called
that - because when the ice storm or wind event or whatever comes along
that brings that once-lovely beast back to ground level, the owner is so
heart-broken and disgusted that he tends to leave it lay as it fell.
And from then on out, he just mows around it. Eventually the pile gets
overgrown and you can't see the beam anymore. ha ha
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 2/11/20 3:59 PM, Jim Brown wrote:
On 2/11/2020 1:17 PM, jimlux wrote:
On 2/11/20 11:30 AM, Jim Brown wrote:
On 2/10/2020 8:41 PM, Grant Saviers wrote:
I think 4sq vs 2L beam tradeoff depends on the beam height vs
ground conductivity and thus the 4sq gain/pattern.
Yes. Several years ago, I did a modeling study of horizontal and
vertical antennas vs height and ground conductivity. It's here.
http://k9yc.com/Multi-Station.pdf
N6BT (original Force 12 designer/owner) recently published the
results of a ground-breaking study he did of verticals and terrain.
Tom is a very smart engineer.
https://ncjweb.com/features/mayjun19feat.pdf
I wonder what you'd get if you modeled the vertical as slanted
(relative to vertical) using NEC, as if you had a vertical antenna on
a sloping surface.
You're not going to be able to model things like a cliff, or a slope
down to the beach with NEC, but a 12 degree downslope should be
modelable.
I think a lot of the handwaving about vertical pol and models is
because for H-pol, the ground is pretty much a mirror and the
incidence angle isn't super important, nor is the precise soil
properties. But for a V-pol it really depends, and it's highly angle
dependent. That's what Dean N6BV says is why HFTA is Hpol only - it
was too complex to add in the Vpol calculations.
I suspect that these days, one could build an equivalent of HFTA that
handles both pols and a terrain model (such as that for RadioMobile
for VHF and up). However, you're still stuck with the significant
variability in soil properties.
Yes. I talked to Dean about doing that about ten years ago. He
responded that he'd recently contracted Parkinson's, so no longer felt
up to the task. I've since encouraged several others who I thought
might have the engineering chops to do something for vertical
polarization, but so far, none have taken the bait. One of the
problems is likely to be data for soil conductivity, which a colleague
told me is considered valuable (and thus costly) because of its
usefulness in prospecting for oil and various minerals. That was 10
years ago, so that may have changed.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|