Topband: EZNEC Ground Errors

[John Kaufmann]

I have two receiving antennas on 160:  an 8-circle vertical array and a low
dipole up 10 feet.  I have been noticing that in the first part of the
evening, the dipole often hears Europe as well as, or nearly as well as, the
8-circle.  This appears to indicate that the signals are arriving at
relatively high angles.   This might also explain why a transmit dipole at a
moderate height can work well for DX.  Other times, the dipole is way down
from the 8-circle, and I would expect a vertical transmit antenna to do
better.

Occasionally in the mornings, around SR, the dipole also hears the DX as
well as or sometimes better than the 8-circle.

73, John W1FV

-----Original Message-----
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon.net at contesting.com] On Behalf
Of Artek Manuals
Sent: Friday, December 11, 2020 9:39 AM
To: topband at contesting.com
Subject: Re: Topband: EZNEC Ground Errors

OR

The propagation mode on 160 is not what we have popularly come to "Accept".

There is a growing body of evidence that particularly at gray line that 
signals often arrive at a higher angles. This is often attributed to 
"ducting" . Maybe a lot more of 160 intercontinental propagation is  due 
ducting rather than the more commonly thought of low angle earth to F 
layer hop/multi-hop stuff seen at higher frequencies?

Where do i get a pair of those glasses that lets me look at radio waves 
so I actually see them arrive

Dave
NR1DX

On 12/11/2020 8:58 AM, Roger Kennedy wrote:
> Guy I have ALWAYS thought that the various Computer-based modelling of
> Ground and its effect on Antennas is WAY off . . .
>
> And surely the errors are MOST significant on 160m, not just because
> Antennas are near the ground (in wavelength terms) . . . but also because
> even the ground 130 ft deep is still going to have an effect . . . and
there
> is no way EZNEC can possibly take that into account, even if you KNEW what
> was underneath your topsoil !
>
> In my particular case it's not the effect on Verticals on 160m that
interest
> me . . . it's the effect on a Low Dipole.
>
> Any DX stations I work on 160m will confirm I put out a pretty respectable
> signal . . . my signal reports around the world and more recently I am
able
> to compare my RBN Reports across NA and they tend to be very similar to
the
> other British DXers.
>
> However, most people are surprised to discover that for the last 50 years
I
> have always used a Horizontal Half Wave dipole on 160m, at around 50ft.
>
> BUT I believe that EZNEC plots showing that most of the RF is just very
High
> Angle is WRONG . . . that's because in practice the Ground underneath it
is
> rubbish . . . so the Dipole's effective height above Ground is much
higher.
>
> And in fact, it seems that most people who have Dipoles on 160m mounted
over
> or near a very comprehensive Radial system DO get poor results using them
> for DX . . . but that goes to confirm my theory (which is all based on my
> actual experience on Top Band)
>
> Roger G3YRO
>
> _________________
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Reflector

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