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Re: [TowerTalk] 80 meter antenna advice. (NY6DX)

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 80 meter antenna advice. (NY6DX)
From: jimlux <jimlux@earthlink.net>
Date: Tue, 11 Feb 2020 13:17:34 -0800
List-post: <mailto:towertalk@contesting.com>
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.


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