Re: Topband: Low Dipoles

[Dave Cuthbert]

The radiation pattern plot shows the dipole end on. Rotate azimuth 90
degrees and the two antennas show the same gain at 30 deg elevation.

Dave KH6AQ

On Fri, Dec 11, 2020 at 10:51 AM VE6WZ_Steve  wrote:

> I know this thread has gone on-and-on-and on, but I felt I needed to add
> to the discussion.
>
> Regarding Roger G3YRO's 50 years of TB experience using a low dipole, I
> feel I need to support his observation from the DX side.
>
> This winter season since August I have had 56 QSOs with the UK, and worked
> 21 unique G callsigns. (Total this season is 775 EU QSOs)
> The top 3 UK repeat QSOs are:
>
> G3PQA 12 QSOs
> G3YRO 10 QSOs
> G4UFK 7 QSOs
>
> The truth is, I have heard Roger many more times than we have QSO’d since
> he seems to have a challenging RX location.
>
> Now, just working DX is not proof of good performance, BUT the FACT is
> Roger usually has a signal as good or better that the any of the other
> regular UK operators.
> This would seem to agree with his RBN observations.  I am also aware that
> these “QSO totals” could be just a function of Rogers activity, but I have
> listened to Rogers signal **at the same time** as other UK and EU are QRV,
> and he is as good as the rest.
>
> I love to build antennas and I do a lot of modelling.  I know exactly what
> the zenith and AZ plot a dipole at 50 feet looks like compared to a
> vertical antenna.  On paper it looks like the worst antenna possible for
> DX.  I am also aware of the concept that even though the dipole has a lot
> of energy radiated straight up, there is still some at lower angles.
> However, the gain from the low dipole compared to a vertical at these lower
> angles will still contradict what I copy from Roger.  Rogers signal
> “should” be much diminished compared to others in the UK (or anywhere in
> EU)  that are using vertically polarized radiators.
>
> Here is a screen shot from 4NEC2 showing a dipole at 50 feet overlaid with
> a vertical over average ground. (2.1 dBi).
>
> https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing
> <
> https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing
> >
> At best Rogers dipole should be a great vertical iono-sound for testing
> the ionosphere!  At a 30 deg wave angle the vertical has an 8.5 dB
> advantage !  That is a big number.
>
> So, I have fair-good copy on Roger one Wednesday night :-) while he is
> CQing with his dipole, and then he switches to a newly installed vertical.
> If indeed his signal bumped by 8.5 dB I think that would be pretty
> spectacular, and he would then be eclipsing the biggest signals out of EU.
> His RBN skimmer spots would also jump by 8.5 dB !?. He would probably be
> spotted by double the skimmers in NA too.
> In no way do I doubt what the modelling is showing us, but there is
> something else going on here.
>
> This really is an interesting study.
> Perhaps our propagation assumption about low-angle dominating is wrong?
> As Roger said and I can attest, most of my copy and QSOs have NOT been at
> his or my SR or SS.
>
> Roger, do you have a common mode choke on your dipole feed line?  If your
> feed line is radiating could it be emulating a vertical?
>
> 73, de steve ve6wz
>
> _
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> Reflector
>
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Re: Topband: Low Dipoles

[donovanf]

Several topbanders have had both horizontal dipoles at various heights 
-- including both very low and very high -- and high performing vertical 
antennas that we could compare on the air in real time. 


While there are always isolated cases when horizontal antennas 
might be the best transmitting antenna, in my experience they're 
isolated cases, usually occurring near sunrise. 


I long ago removed my 160 meter horizontal transmitting antennas 
and never regretted it... 


73 
Frank 
W3LPL 

- Original Message -

From: "VE6WZ_Steve"  
To: "topband"  
Sent: Friday, December 11, 2020 8:51:19 PM 
Subject: Topband: Low Dipoles 

I know this thread has gone on-and-on-and on, but I felt I needed to add to the 
discussion. 

Regarding Roger G3YRO's 50 years of TB experience using a low dipole, I feel I 
need to support his observation from the DX side. 

This winter season since August I have had 56 QSOs with the UK, and worked 21 
unique G callsigns. (Total this season is 775 EU QSOs) 
The top 3 UK repeat QSOs are: 

G3PQA 12 QSOs 
G3YRO 10 QSOs 
G4UFK 7 QSOs 

The truth is, I have heard Roger many more times than we have QSO’d since he 
seems to have a challenging RX location. 

Now, just working DX is not proof of good performance, BUT the FACT is Roger 
usually has a signal as good or better that the any of the other regular UK 
operators. 
This would seem to agree with his RBN observations. I am also aware that these 
“QSO totals” could be just a function of Rogers activity, but I have listened 
to Rogers signal **at the same time** as other UK and EU are QRV, and he is as 
good as the rest. 

I love to build antennas and I do a lot of modelling. I know exactly what the 
zenith and AZ plot a dipole at 50 feet looks like compared to a vertical 
antenna. On paper it looks like the worst antenna possible for DX. I am also 
aware of the concept that even though the dipole has a lot of energy radiated 
straight up, there is still some at lower angles. However, the gain from the 
low dipole compared to a vertical at these lower angles will still contradict 
what I copy from Roger. Rogers signal “should” be much diminished compared to 
others in the UK (or anywhere in EU) that are using vertically polarized 
radiators. 

Here is a screen shot from 4NEC2 showing a dipole at 50 feet overlaid with a 
vertical over average ground. (2.1 dBi). 
https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing
 

 
At best Rogers dipole should be a great vertical iono-sound for testing the 
ionosphere! At a 30 deg wave angle the vertical has an 8.5 dB advantage ! That 
is a big number. 

So, I have fair-good copy on Roger one Wednesday night :-) while he is CQing 
with his dipole, and then he switches to a newly installed vertical. If indeed 
his signal bumped by 8.5 dB I think that would be pretty spectacular, and he 
would then be eclipsing the biggest signals out of EU. His RBN skimmer spots 
would also jump by 8.5 dB !?. He would probably be spotted by double the 
skimmers in NA too. 
In no way do I doubt what the modelling is showing us, but there is something 
else going on here. 

This really is an interesting study. 
Perhaps our propagation assumption about low-angle dominating is wrong? 
As Roger said and I can attest, most of my copy and QSOs have NOT been at his 
or my SR or SS. 

Roger, do you have a common mode choke on your dipole feed line? If your feed 
line is radiating could it be emulating a vertical? 

73, de steve ve6wz 

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Re: Topband: EZNEC Ground Errors

[List Mail]

It's interesting how people's experiences differ, and how their perceptions 
of how something actually works, and how a computer model calculates how it 
should work. I have used MMANA-GAL to model designs, and it certainly helps 
to quantify my measurements, and is a good start. "Your Mileage May Vary" is 
a great disclaimer, after a system is described!


Also interesting is how DXing experiences vary from place to place, for 
example Roger's situation where he has a high density of activity to his 
east at medium range in Europe making difficulties, when he's looking for 
other medium to longer range DX in NA to his west. Those in USA east have a 
high density of local stations making it difficult to work DX. In VK/ZL most 
of our wanted DX is quite long range, with very few locals. Consequently, 
our receiving requirements differ.


My first DXing on 160 m was with a 160 m long doublet antenna, up about 20 m 
supported by trees. That whetted my appetite for the band, and so I 
constructed a top loaded vertical, over elevated radials. That worked, and I 
made DXCC. Next, the elevated radials went (then kept falling down anyway!) 
and I made the effort to bury 2000 metres of wire in 60 x 33 m radials. That 
appears to work, but I have no way of objectively comparing the elevated 
radial system to the buried radial system. But one aim of the buried 
radials, was to have a non-resonant ground radial field, as I also run 80 m 
over it. Next is to put up a 37 m high tower, so I have close to a quarter 
wave on 160 m. That is my project for the Christmas break. I'm hoping to 
have that up and running before the end of the summer DX in the mornings to 
EU.


73, Luke VK3HJ 


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Re: Topband: Low Dipoles

[donovanf]

The electron gyrofrequency (1.6 MHz or less) causes 160 meter signals 
propagating more-or-less east-west at mid-latitudes to strongly favor 
vertical polarization. 


80 meter propagation only slightly favors vertical polarization for 
more-or-less east-west propagation at mid-latitudes. Other factors 
such as ground reflection efficiency in the Fresnel zone are much more 
significant. 


The gyrofrequency doesn't affect horizontal or vertically polarized 
signals at 7 MHz and abovc. 


73 
Frank 
W3LPL 






- Original Message -

From: "K4SAV"  
To: topband@contesting.com 
Sent: Friday, December 11, 2020 10:17:39 PM 
Subject: Re: Topband: Low Dipoles 

Saying 160 propagation is complicated is an understatement. Otherwise 
someone would have already figured this stuff out. One other 
contributor that has to be added to the mix is the effect of Earth's 
electron gyrofrequency,. NEC knows nothing about this effect. It's 
also a function of where on this planet you live Some people get the 
benefit, other don't. Antenna polarization is important when 
interacting with the effects of Earth's gyrofrequency,. 

Jerry, K4SAV 

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Topband: Low Dipoles

[Roger Kennedy]

Yes Steve, I have a big custom 160m choke right at the feedpoint of my
Dipole . . even if I didn't, most of the feeder runs horizontally in my loft
at right angles to the dipole.

Thank you for your comments regarding my Signal on 160, and I think most
people I work regularly would say the same. (However, when I tried raising
this topic on a certain Forum a year ago, several people said I was clearly
lying - there's no way a low dipole could ever come close to a decent
vertical on 160m !)

As I said before, I personally think it's a combination of the two . . . a
low Dipole has more medium-angle radiation than EZXNEC suggests (as it
over-rates the effect of the ground on 160m) . . . plus most DX Propagation
on Top Band is NOT very low angle.

Regarding Receiving . . . sadly I live in an ordinary suburban house on the
edge of the city (with dozens of other houses within one wavelength) . . .
only one leg of my Dipole fits in my garden, so I certainly have no room for
Beverages !  I just try and do the best I can from an ordinary QTH.

73 Roger G3YRO


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Re: Topband: Low Dipoles

[K4SAV]

Saying 160 propagation is complicated is an understatement. Otherwise 
someone would have already figured this stuff out.  One other 
contributor that has to be added to the mix is the effect of Earth's 
electron gyrofrequency,.  NEC knows nothing about this effect.  It's 
also a function of where on this planet you live  Some people get the 
benefit, other don't.  Antenna polarization is important when 
interacting with the effects of Earth's gyrofrequency,.


Jerry, K4SAV

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Topband: Low Dipoles

[VE6WZ_Steve]

I know this thread has gone on-and-on-and on, but I felt I needed to add to the 
discussion.

Regarding Roger G3YRO's 50 years of TB experience using a low dipole, I feel I 
need to support his observation from the DX side.

This winter season since August I have had 56 QSOs with the UK, and worked 21 
unique G callsigns. (Total this season is 775 EU QSOs)
The top 3 UK repeat QSOs are:

G3PQA 12 QSOs
G3YRO 10 QSOs
G4UFK 7 QSOs

The truth is, I have heard Roger many more times than we have QSO’d since he 
seems to have a challenging RX location.

Now, just working DX is not proof of good performance, BUT the FACT is Roger 
usually has a signal as good or better that the any of the other regular UK 
operators.
This would seem to agree with his RBN observations.  I am also aware that these 
“QSO totals” could be just a function of Rogers activity, but I have listened 
to Rogers signal **at the same time** as other UK and EU are QRV, and he is as 
good as the rest.

I love to build antennas and I do a lot of modelling.  I know exactly what the 
zenith and AZ plot a dipole at 50 feet looks like compared to a vertical 
antenna.  On paper it looks like the worst antenna possible for DX.  I am also 
aware of the concept that even though the dipole has a lot of energy radiated 
straight up, there is still some at lower angles. However, the gain from the 
low dipole compared to a vertical at these lower angles will still contradict 
what I copy from Roger.  Rogers signal “should” be much diminished compared to 
others in the UK (or anywhere in EU)  that are using vertically polarized 
radiators.

Here is a screen shot from 4NEC2 showing a dipole at 50 feet overlaid with a 
vertical over average ground. (2.1 dBi).
https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing
 

At best Rogers dipole should be a great vertical iono-sound for testing the 
ionosphere!  At a 30 deg wave angle the vertical has an 8.5 dB advantage !  
That is a big number.

So, I have fair-good copy on Roger one Wednesday night :-) while he is CQing 
with his dipole, and then he switches to a newly installed vertical.  If indeed 
his signal bumped by 8.5 dB I think that would be pretty spectacular, and he 
would then be eclipsing the biggest signals out of EU.  His RBN skimmer spots 
would also jump by 8.5 dB !?. He would probably be spotted by double the 
skimmers in NA too.
In no way do I doubt what the modelling is showing us, but there is something 
else going on here.

This really is an interesting study.
Perhaps our propagation assumption about low-angle dominating is wrong?
As Roger said and I can attest, most of my copy and QSOs have NOT been at his 
or my SR or SS.

Roger, do you have a common mode choke on your dipole feed line?  If your feed 
line is radiating could it be emulating a vertical?

73, de steve ve6wz

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Re: Topband: I need help proofing an Inverted L model I made please. 40

[Jim Brown]

On 12/11/2020 3:55 AM, Rob Atkinson wrote:

The only thing about this I advise in the way of a change is something
W1BB recommended,


Again, I refer to N6LF's monumental work.

73, Jim K9YC
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Re: Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Jim Brown]

On 12/11/2020 2:02 AM, Artek Manuals wrote:
However I have always wondered about elevated radials . The NEC ( both 2 
and 4) models (not that those are to always be trusted) show very little 
(if any) improvement beyond four elevated radials, you have any theories 
on why that is? Intuitively (also not to be trusted) that is a lot of 
real estate in the spaces between


I refer you to N6LF's definitive work.

73, Jim K9YC
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Re: Topband: 160 L and radials

[Richard (Rick) Karlquist]

On 12/11/2020 6:49 AM, w3...@roadrunner.com wrote:


Bought three acres in the country here in central Ohio, where the
general ground conductivity articles feel we have good midwestern loam
soil. Well, MY soil is more like semi clay but it is agricultural
land. Corn and soy farming in particular.


I frequently see descriptions like the above that seem to
be saying that the suitability of soil for agricultural use
is somehow an indicator of its RF conductivity.  This is not
reliable.  For example, Yolo county California shows a
conductivity of 30 on the FCC map.  The soil is pure clay that
goes down 40 feet.  Except for growing rice, this soil is
fairly useless agriculturally, rated class 4 (the lowest possible
rating for farming).  Even weeds don't grow well.  Of course, YMMV.

73
Rick N6RK
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Re: Topband: Best conditions of the season

[John Kaufmann via Topband]

We got a piece of the action, too, in New England.  I worked JH1HDT, HL5IVL, 
and VK6LW just before my SR.  HL5IVL peaked up to 579 right at SR.  We only get 
propagation to HL very infrequently here in W1.  JA7BXS was in there but he 
first fired up on the disturbance on 1825 and was being obliterated by it.  He 
later moved to 1820 but a BCB spur took him out there, too. 

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Ron Spencer via Topband
Sent: Friday, December 11, 2020 8:11 AM
To: topband
Subject: Topband: Best conditions of the season

160 was excellent this morning. Early (1138 with sunrise at 1214) heard, and 
worked, Tad, JH1HDT. Not long after worked Kim HL5IVL. Kevin VK6LW answered my 
CQ as did AL7JI (not in that order). Worked Adrian, VK2WF.  Worked Takar, 
JA7BXS too even though he was zero beat on 1820 with a BC signal making it 
difficult. Almost 20 minutes after SR still hearing Kim and Tad. Hope we have 
more of these kind of days! Thanks all for the Qs. 



Ron

N4XD

Sent using https://www.zoho.com/mail/
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Re: Topband: Best conditions of the season

[David Raymond]

Agree totally with Ron's assessment.  160 this morning was the best I've 
heard this season to Asia and VK.  When HL5IVL called in this morning I 
first thought he was a stateside caller.  Four VKs in the log this 
morning (including VK6LW), 5 JAs, 2 HL plus an HL w/all time new call 
sign that could not hear me (can't remember his call) and 2 KL7.  
Hopefully some of this good prop will carry over to EU.


73. . . Dave, W0FLS

On 12/11/2020 7:11 AM, Ron Spencer via Topband wrote:

160 was excellent this morning. Early (1138 with sunrise at 1214) heard, and 
worked, Tad, JH1HDT. Not long after worked Kim HL5IVL. Kevin VK6LW answered my 
CQ as did AL7JI (not in that order). Worked Adrian, VK2WF.  Worked Takar, 
JA7BXS too even though he was zero beat on 1820 with a BC signal making it 
difficult. Almost 20 minutes after SR still hearing Kim and Tad. Hope we have 
more of these kind of days! Thanks all for the Qs.



Ron

N4XD

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Re: Topband: Best conditions of the season

[VE6WZ_Steve]

Strong DX Ron!
It’s great to hear you guys out east working the trans-pacific path.

de steve ve6wz

> On Dec 11, 2020, at 6:11 AM, Ron Spencer via Topband  
> wrote:
> 
> 160 was excellent this morning. Early (1138 with sunrise at 1214) heard, and 
> worked, Tad, JH1HDT. Not long after worked Kim HL5IVL. Kevin VK6LW answered 
> my CQ as did AL7JI (not in that order). Worked Adrian, VK2WF.  Worked Takar, 
> JA7BXS too even though he was zero beat on 1820 with a BC signal making it 
> difficult. Almost 20 minutes after SR still hearing Kim and Tad. Hope we have 
> more of these kind of days! Thanks all for the Qs. 
> 
> 
> 
> Ron
> 
> N4XD
> 
> Sent using https://www.zoho.com/mail/
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Topband: EZNEC Ground Errors

[Roger Kennedy]

Oh that's something else I forgot to mention . . .

A couple of years ago I built a 160m Receiving Loop, which is Vertically
polarised.

It behaves very differently to my Dipole, I can see huge differences on
European signals, depending on how far away they are, and the Propagation at
the time.

However . . . on DX there is usually no difference between the two antennas
(although the QSB is often "out of phase") . . . which again makes me think
DX Signals are arriving at a Medium Angle, rather than a High or Low angle.
(If they were Low angle they would definitely be stronger on the Loop).

And again, this is NOT at Grey Line times . . . it's pretty much all the
time, both on TX and Rx.

Years ago, when conditions were always much better, I used spend dozens of
hours on SSB getting comparison reports from stations right across America
with my good friend Mike G3SED.  We lived quite close to each other at the
time, he had a 100 ft vertical (with 60 radials), I had a Half Wave Dipole.

When we were running the same power, most of the time our reports were the
same !

These days I have set up RBN to show ALL G stations CW reports from any
American station . . . and again I notice that my signals are generally on a
par with all the Gs running verticals.

Roger G3YRO


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Re: Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Grant Saviers]

Rudy Severns has many plots of elevated radial numbers, lengths, and 
elevations on his web site  antennasbyn6lf.com


My "T" showed the expected change in feedpoint Z as I added 125ft long 
10ft elevated radials from 2 to the current 8.  The last two made no 
measurable difference.  From Rudy's analysis they could/should be a bit 
shorter than 125ft.


Another experiment with a prototype shorty vertical showed a big 
reduction in Z when two 128' radials were raised from 4ft to 9ft, 
confirming the NEC4 modeling.


Poor dirt here but a little bit better in winter when the ground is 
totally water saturated. Also, the T is pretty much surrounded with 
100ft plus firs and cedars absorbing RF.  Another reason to love 
verticals on the beach :) .


Grant KZ1W

On 12/11/2020 02:02, Artek Manuals wrote:

Jim et all

I agree with what you say on all points when it comes to radials on the 
ground and salt water affects.


However I have always wondered about elevated radials . The NEC ( both 2 
and 4) models (not that those are to always be trusted) show very little 
(if any) improvement beyond four elevated radials, you have any theories 
on why that is? Intuitively (also not to be trusted) that is a lot of 
real estate in the spaces between


Dave
NR1DX

On 12/11/2020 4:37 AM, Jim Brown wrote:

On 12/10/2020 11:14 PM, Raymond Benny wrote:
With said, I believe my ground absorption is very high so I feel the 
higher
numbers of radials helps greatly with my vertical efficiency and 
radiation.


Hi Ray,

The soil affects us in two important ways. First, poor soil burns 
transmitter power underneath the antenna and it's near field. We use 
radials to shield the soil from the field, and to supply a low 
impedance path for return current. Magnetic fields produced around 
each radial by virtue of current flow couples loss in the earth into 
the radials in the form of series resistance. Loss in each radial is 1 
squared R; each time we double the number of radials the current in 
each is divided by two, so the power coupled to the earth by each 
divides by four. So the more radials, the less power is coupled to the 
earth. THAT'S why more is better. The result of all this is that loss 
in the soil under the antenna reduces the total strength of our signal 
by that amount.


The second effect of soil is in the far field, where we field radiate 
hits the earth and is reflected by it to form the vertical pattern. 
The better the conductivity THERE, the our pattern will be both 
stronger and at a lower angle. An antenna with its base just above sea 
water is the extreme example of this -- the reflection is extremely 
strong, and it is at a VERY low angle.


We can help the first of these two effects with a good radial system, 
but the only thing we can do about the second (the far field 
reflection), is to move where there is better soil. Most of us live 
where we do because we like living there for reasons other than radio. 
And that includes me and my XYL.


73, Jim K9YC

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Re: Topband: EZNEC Ground Errors

[Grant Saviers]

For a literal "pair of radio wave glasses":

Given the vertical gain of a practical 160 dipole is pretty much cloud 
burner and a decent 160 vertical is pretty much low angle, IF you know 
the actual real gain patterns, then it is possible to compare signal 
amplitudes (probably real time considering QSB) and deduce approximate 
arrival angles.


At least one analysis of 80m arrival angles on the West Coast from EU 
was derived this way.


Grant KZ1W

On 12/11/2020 06:38, Artek Manuals wrote:

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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Re: Topband: EZNEC Ground Errors

[John Kaufmann via Topband]

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@contesting.com] On Behalf
Of Artek Manuals
Sent: Friday, December 11, 2020 9:39 AM
To: topband@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
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
Reflector

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Topband: EZNEC Ground Errors

[Roger Kennedy]

Well I agree with that too Dave . . .

To me, it's a kind of "Urban Myth" that 160m DX is all Low Angle
propagation.  

Sure, on 80m it nearly ALWAYS is . . . You MUST have a Vertical to work DX
well on 80, a Dipole is rubbish (even though my 80m dipole is effectively
twice as high as my Top Band one)

I actually think that many "experts" PRESUMED that because that is the case
on 80m (and on 40m), it MUST be so on 160m too.

But I know that simply isn't the case, from 50 years of my own experience
DX-ing on 160m. 

And not just at Grey Line either . . . for example, I find my best reports
from NA these days are currently between 0100 and 0300Z . . . that is way
after your Sunset, and long before our Sunrise.

So in practice, I have come to the conclusion that it must be a combination
of the two . . . 160m DX isn't very low angle (must be ducting or multi-hop)
. . . and a low dipole on 160m isn't just high angle.

Roger G3YRO


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Topband: 160 L and radials

[W3HKK]

Interesting thread. 

Bought three acres in the country here in central Ohio, where the
general ground conductivity articles feel we have good midwestern loam
soil. Well, MY soil is more like semi clay but it is agricultural
land. Corn and soy farming in particular.

When I moved here I had already sold off my tower and yagis (204BA and
KT36XA) , so was stuck with one 20 ft walnut tree as my highest
support. So I cut a 1/4 wave piece of #12 wire. shot it over the tree
and pulled it out to the east, sloping back to the ground.

I added one ground rod. Then slowly added several 130 ft #12 pvc
jacketed radials on the ground.

That season I worked LZ, 4X4, and a JA which opened my eyes to what
could be done on 160, a new band for me.

Over subsequent years I kept adding radials, and noticed each one
raised my swr. So I kept adding radials, eventually going to #17
aluminum fence wire, and shortening them to around 70 ft. The
proximity of the north PL forced me to use shorter wires...as short as
35 due due north and progressively longer to the NE and NW. 

But at 28 radials, the swr no longer changed. so I stopped there.
Also, as the walnut tree kept growing, I was able to use 4'x 1.5" mil
surplus aluminum masts sections to push the vertical wire up to 52 ft.
So, today, the c. 130 ft INV-L ( pvc insulated #12 solid copper wire)
wanders up through multiple tree branches, to the top of the 52'
supporting mast, and slopes out to the ENE, terminating about 15 ft
above ground level. And that original ground rod now has 28 radials to
go with it. 

W3HKK DXCC totals are now 175 worked/154confirmed.

A home brew coke bottle inductor shunts across the antenna-ground
connection and is played like an accordion to lower swr to nearly 1:1
during winter season when the radials are laid out across the grass;
and adjusted for the summer lawn mowing season when the radials are
coiled up and hung from the walnut tree to enable mowing without
chopping them up.(voice of experience. )

Five years back I added the SAL30 Rx antenna which I now use as my de
facto rx antenna on 160-40m.

Note: with the exception of a 5 el yagi at 15 ft, W3HKK uses an
all-wire antenna farm. The other antennas consist of monoband 1/4 wave
ground planes ( wires) with 4-8 elevated radials on 40--30-20-17-10m.
Seeking more oomph, on 40 and 20m, those GPs have been converted to 2
el vertical phased arrays. The 40m PA beams ENE and WNW, while the 20m
PA beams Asia (330 degrees) and SSE. ( in search of those final 10
remaining DXCC entities.) 

I should add that wandering along beside the 160m INV-L is a second
INV-L, this one for 80m. However only about 8 ft of it is bent over,
so it is almost a qtr wave vert, and performs very well.

Most of my activity is in the 160m cw contests and in the WWDX-cw
contests, plus Dxing for the few rremaining new ones. .

Im not sure how to significantly improve the 160m L's performance at
this point. I am unable to raise the vertical leg any higher, and at
age 79 am definitely slowing down. Some thought has been given to
adding a couple of wires as a top hat but have been waiting for the 52
ft support mast to fall down on its own before attempting to make
changes.

Dont think any more radials are making a significant difference. since
the swr is not affected in a measurable way, per my AA54 antenna
analyzer. So guess this will have to do.

Thoughts?


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Re: Topband: EZNEC Ground Errors

[Artek Manuals]

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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Topband: EZNEC Ground Errors

[Roger Kennedy]

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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Topband: condx last days

[Andree DL8LAS via Topband]

 Hey topbanders,the last two days the condx were very good after two weeks of  
poor 160m band.Thursday morning worked 29 NA (17 first time) and today 23 
NA.Now I worked 677 NAs from 1. June.The new end-fire array works well.

https://www.dl8las.com/last-dx-on-160m
www.dl8las.com

Hope to work more  DX next days.73 Andy DL8LAS/DR5X



www.swing-company-bigband.de/
www.uni-big-band-kiel.de/
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Topband: Best conditions of the season

[Ron Spencer via Topband]

160 was excellent this morning. Early (1138 with sunrise at 1214) heard, and 
worked, Tad, JH1HDT. Not long after worked Kim HL5IVL. Kevin VK6LW answered my 
CQ as did AL7JI (not in that order). Worked Adrian, VK2WF.  Worked Takar, 
JA7BXS too even though he was zero beat on 1820 with a BC signal making it 
difficult. Almost 20 minutes after SR still hearing Kim and Tad. Hope we have 
more of these kind of days! Thanks all for the Qs. 



Ron

N4XD

Sent using https://www.zoho.com/mail/
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Re: Topband: I identified signal on 1.825 MHz this morning

[Don Kirk]

Correction, it stopped at 7:54 EST.

73,
Don (wd8dsb)

On Fri, Dec 11, 2020 at 8:00 AM Don Kirk  wrote:

> Hi Topband Gang,
>
> Thanks to everyone that reported reception of the signal.  It stopped at
> 7:54am EDT.  Based on preliminary data which probably did not have enough
> resolution it looked like it was originating from Ohio or Pennsylvania.
> Hopefully it does not reappear.
>
> 73,
> Don (wd8dsb)
>
> On Fri, Dec 11, 2020 at 7:31 AM Don Kirk  wrote:
>
>> Hi Dave,
>> Thanks and glad others are hearing it too.  I just looked at it on an SDR
>> receiver and it has a bandwidth of 400 Hz, and it's using two different
>> frequencies spaced 200 Hz apart.  Very Strong here near Indianapolis.
>> Peaking 25 dB over my noise floor.
>>
>> Just FYI,
>> Don (wd8dsb)
>>
>> On Fri, Dec 11, 2020 at 7:15 AM David Raymond 
>> wrote:
>>
>>> Signal bearing from central Iowa/EN21 is about 70 degrees based on some
>>> interpolation from the 8 circle array.
>>> On 12/11/2020 6:06 AM, Don Kirk wrote:
>>> > I’m hearing a very strong pulsating signal that sounds like it might be
>>> > some kind of digital communications and it’s bearing is approximately
>>> 73
>>> > degrees from my QTH near Indianapolis and wonder if others are hearing
>>> it
>>> > at at what heading and does anyone recognize what it is? It’s on right
>>> now
>>> > at 7:06 AM
>>> >
>>> > Don wd8dsb
>>> > _
>>> > Searchable Archives: http://www.contesting.com/_topband - Topband
>>> Reflector
>>> _
>>> Searchable Archives: http://www.contesting.com/_topband - Topband
>>> Reflector
>>>
>>
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Re: Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Guy Olinger K2AV]

Over really good dirt there isn’t too much difference.

The other problem is that the NEC ground approximation coding usually
underestimates loss. This is because the ground approximation in the model
uses a monolithic ground. Same stuff 100 feet down as at the surface. Real
dirt never is. Water tables, etc, yada yada. Or farm dirt plowed, dug for
the first two or three feet down, below that undisturbed and thoroughly
packed for hundreds of thousands of years. That's not monolithic. Nor are
many properties that were leveled for construction, or in ancient lands,
built on construction rubble accumulated for millennia. Simple velocity
factor measurement of a 152' dipole on ground is monstrously variable,
sometimes just varying orientation in the same back yard.

That doesn't account for lots of trees, roots where the only way to reduce
the increased counterpoise loss from dielectric losses is to reduce the
fields from the counterpoise. That's where the FCP comes from.

NEC uses monolithic ground in its ground approximation because more
complexity results in monstrous increases in run time. And we have to
remember that NEC is from a period where mainframe run times cost a lot of
money, and some computational methods could result in jobs not completing
in a month.

Reality skeptics sure of underestimated NEC ground loss include W7EL, EZNEC
author.

One way to get a better idea is to set ground characteristics in EZNEC to
gawd awful (in all compared designs) and rerun. As in (.005,1).  I do that
routinely on a design to stay away from designs that are more sensitive to
poor grounds.

E.g. set ground characteristics to (.005,1), then run a ground plane with 4
radials. Repeat with 8. Note the difference. Run at various radial heights.

Poor ground qualities happen and definitely appear to be the majority
rather than the exception. Designing for least sensitivity to poor ground
will protect the poor soul that has gawd awful ground in their backyard and
don't know it.

We spend thousands of dollars on transceivers and amplifiers and then go
cheep, cheep on radials? On 160, ground loss is the two ton elephant in the
room. Clean up after the elephant and send it to the zoo before you put
down new carpet.

73, Guy K2AV


On Fri, Dec 11, 2020 at 5:02 AM Artek Manuals 
wrote:

> Jim et all
>
> I agree with what you say on all points when it comes to radials on the
> ground and salt water affects.
>
> However I have always wondered about elevated radials . The NEC ( both 2
> and 4) models (not that those are to always be trusted) show very little
> (if any) improvement beyond four elevated radials, you have any theories
> on why that is? Intuitively (also not to be trusted) that is a lot of
> real estate in the spaces between
>
> Dave
> NR1DX
>
> On 12/11/2020 4:37 AM, Jim Brown wrote:
> > On 12/10/2020 11:14 PM, Raymond Benny wrote:
> >> With said, I believe my ground absorption is very high so I feel the
> >> higher
> >> numbers of radials helps greatly with my vertical efficiency and
> >> radiation.
> >
> > Hi Ray,
> >
> > The soil affects us in two important ways. First, poor soil burns
> > transmitter power underneath the antenna and it's near field. We use
> > radials to shield the soil from the field, and to supply a low
> > impedance path for return current. Magnetic fields produced around
> > each radial by virtue of current flow couples loss in the earth into
> > the radials in the form of series resistance. Loss in each radial is 1
> > squared R; each time we double the number of radials the current in
> > each is divided by two, so the power coupled to the earth by each
> > divides by four. So the more radials, the less power is coupled to the
> > earth. THAT'S why more is better. The result of all this is that loss
> > in the soil under the antenna reduces the total strength of our signal
> > by that amount.
> >
> > The second effect of soil is in the far field, where we field radiate
> > hits the earth and is reflected by it to form the vertical pattern.
> > The better the conductivity THERE, the our pattern will be both
> > stronger and at a lower angle. An antenna with its base just above sea
> > water is the extreme example of this -- the reflection is extremely
> > strong, and it is at a VERY low angle.
> >
> > We can help the first of these two effects with a good radial system,
> > but the only thing we can do about the second (the far field
> > reflection), is to move where there is better soil. Most of us live
> > where we do because we like living there for reasons other than radio.
> > And that includes me and my XYL.
> >
> > 73, Jim K9YC
> >
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> > Reflector
>
> --
> Dave manu...@artekmanuals.com www.ArtekManuals.com
>
> --
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> Searchable Archives: http://www.contesting.com/_topband - 

Re: Topband: I identified signal on 1.825 MHz this morning

[Don Kirk]

Hi Topband Gang,

Thanks to everyone that reported reception of the signal.  It stopped at
7:54am EDT.  Based on preliminary data which probably did not have enough
resolution it looked like it was originating from Ohio or Pennsylvania.
Hopefully it does not reappear.

73,
Don (wd8dsb)

On Fri, Dec 11, 2020 at 7:31 AM Don Kirk  wrote:

> Hi Dave,
> Thanks and glad others are hearing it too.  I just looked at it on an SDR
> receiver and it has a bandwidth of 400 Hz, and it's using two different
> frequencies spaced 200 Hz apart.  Very Strong here near Indianapolis.
> Peaking 25 dB over my noise floor.
>
> Just FYI,
> Don (wd8dsb)
>
> On Fri, Dec 11, 2020 at 7:15 AM David Raymond 
> wrote:
>
>> Signal bearing from central Iowa/EN21 is about 70 degrees based on some
>> interpolation from the 8 circle array.
>> On 12/11/2020 6:06 AM, Don Kirk wrote:
>> > I’m hearing a very strong pulsating signal that sounds like it might be
>> > some kind of digital communications and it’s bearing is approximately 73
>> > degrees from my QTH near Indianapolis and wonder if others are hearing
>> it
>> > at at what heading and does anyone recognize what it is? It’s on right
>> now
>> > at 7:06 AM
>> >
>> > Don wd8dsb
>> > _
>> > Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>> _
>> Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>>
>
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Re: Topband: I identified signal on 1.825 MHz this morning

[Bill Stewart]

Hearing it in NC on an Inverted L...peaking S4-5 with noise floor at abt an S1.
Now sending a pulsing xmsn...1235Z(7:35 EST).
73 de Bill K4JYS

- Original Message -
From: "Don Kirk" 
To: "topband" 
Sent: Friday, December 11, 2020 7:06:40 AM
Subject: Topband: I identified signal on 1.825 MHz this morning

I’m hearing a very strong pulsating signal that sounds like it might be
some kind of digital communications and it’s bearing is approximately 73
degrees from my QTH near Indianapolis and wonder if others are hearing it
at at what heading and does anyone recognize what it is? It’s on right now
at 7:06 AM

Don wd8dsb
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Re: Topband: I identified signal on 1.825 MHz this morning

[Jon Zaimes via Topband]

It is 10db over S9 here in central Delaware, peaking on NW Beverages. Much 
weaker  spur from it covering 1823.5 as well (strong enough to cover HL5IVL).

Jon P. Zaimes, AA1K
Tower climber for hire
http://www.aa1k.us/
Cell: 302-632-2353

Reviews of AA1K tower work on eham website: 
http://www.eham.net/reviews/detail/12922

Hug your favorite tower every day, and always stay connected to it.

-Original Message-
From: Topband  On Behalf Of 
Don Kirk
Sent: Friday, December 11, 2020 7:07 AM
To: topband 
Subject: Topband: I identified signal on 1.825 MHz this morning

I’m hearing a very strong pulsating signal that sounds like it might be some 
kind of digital communications and it’s bearing is approximately 73 degrees 
from my QTH near Indianapolis and wonder if others are hearing it at at what 
heading and does anyone recognize what it is? It’s on right now at 7:06 AM

Don wd8dsb
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Re: Topband: I identified signal on 1.825 MHz this morning

[Don Kirk]

 Hi Dave,
Thanks and glad others are hearing it too.  I just looked at it on an SDR
receiver and it has a bandwidth of 400 Hz, and it's using two different
frequencies spaced 200 Hz apart.  Very Strong here near Indianapolis.
Peaking 25 dB over my noise floor.

Just FYI,
Don (wd8dsb)

On Fri, Dec 11, 2020 at 7:15 AM David Raymond 
wrote:

> Signal bearing from central Iowa/EN21 is about 70 degrees based on some
> interpolation from the 8 circle array.
> On 12/11/2020 6:06 AM, Don Kirk wrote:
> > I’m hearing a very strong pulsating signal that sounds like it might be
> > some kind of digital communications and it’s bearing is approximately 73
> > degrees from my QTH near Indianapolis and wonder if others are hearing it
> > at at what heading and does anyone recognize what it is? It’s on right
> now
> > at 7:06 AM
> >
> > Don wd8dsb
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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Re: Topband: I identified signal on 1.825 MHz this morning

[John Kaufmann via Topband]

Here in the Boston area it was peaking from the SW on my 8 circle array.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of w...@w5zn.org
Sent: Friday, December 11, 2020 7:24 AM
To: David Raymond
Cc: topband@contesting.com; Topband
Subject: Re: Topband: I identified signal on 1.825 MHz this morning

Signal is ~45 degrees from EM45 Arkansas. running about 15 dB above my 
noise floor.

73 Joel W5ZN


On 2020-12-11 05:15, David Raymond wrote:
> Signal bearing from central Iowa/EN21 is about 70 degrees based on
> some interpolation from the 8 circle array.
> On 12/11/2020 6:06 AM, Don Kirk wrote:
>> I’m hearing a very strong pulsating signal that sounds like it might 
>> be
>> some kind of digital communications and it’s bearing is approximately 
>> 73
>> degrees from my QTH near Indianapolis and wonder if others are hearing 
>> it
>> at at what heading and does anyone recognize what it is? It’s on right 
>> now
>> at 7:06 AM
>> 
>> Don wd8dsb
>> _
>> Searchable Archives: http://www.contesting.com/_topband - Topband 
>> Reflector
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector
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Re: Topband: I identified signal on 1.825 MHz this morning

[w5zn]

Signal is ~45 degrees from EM45 Arkansas. running about 15 dB above my 
noise floor.


73 Joel W5ZN


On 2020-12-11 05:15, David Raymond wrote:

Signal bearing from central Iowa/EN21 is about 70 degrees based on
some interpolation from the 8 circle array.
On 12/11/2020 6:06 AM, Don Kirk wrote:
I’m hearing a very strong pulsating signal that sounds like it might 
be
some kind of digital communications and it’s bearing is approximately 
73
degrees from my QTH near Indianapolis and wonder if others are hearing 
it
at at what heading and does anyone recognize what it is? It’s on right 
now

at 7:06 AM

Don wd8dsb
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Reflector

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Reflector

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Re: Topband: I identified signal on 1.825 MHz this morning

[David Raymond]

Signal bearing from central Iowa/EN21 is about 70 degrees based on some 
interpolation from the 8 circle array.

On 12/11/2020 6:06 AM, Don Kirk wrote:

I’m hearing a very strong pulsating signal that sounds like it might be
some kind of digital communications and it’s bearing is approximately 73
degrees from my QTH near Indianapolis and wonder if others are hearing it
at at what heading and does anyone recognize what it is? It’s on right now
at 7:06 AM

Don wd8dsb
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Topband: I identified signal on 1.825 MHz this morning

[Don Kirk]

I’m hearing a very strong pulsating signal that sounds like it might be
some kind of digital communications and it’s bearing is approximately 73
degrees from my QTH near Indianapolis and wonder if others are hearing it
at at what heading and does anyone recognize what it is? It’s on right now
at 7:06 AM

Don wd8dsb
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: I need help proofing an Inverted L model I made please. 40

[Rob Atkinson]

> IMHO, for that number, on-the-ground radials do not need to be anywhere near 
> that long.  Personally, I subscribe to the same-length-as-the-vertical 
> guideline.

The only thing about this I advise in the way of a change is something
W1BB recommended, which was that the radials on the ground going out
underneath the horizontal L wire should be as long as the horizontal
wire.  My horizontal component has some bends in it and I routed
around 10 radials under it to follow it.  It probably doesn't make
much difference, but it isn't that hard to run a few that are under
the wire all the way out.

73

Rob
K5UJ
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Re: Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Artek Manuals]

Jim et all

I agree with what you say on all points when it comes to radials on the 
ground and salt water affects.


However I have always wondered about elevated radials . The NEC ( both 2 
and 4) models (not that those are to always be trusted) show very little 
(if any) improvement beyond four elevated radials, you have any theories 
on why that is? Intuitively (also not to be trusted) that is a lot of 
real estate in the spaces between


Dave
NR1DX

On 12/11/2020 4:37 AM, Jim Brown wrote:

On 12/10/2020 11:14 PM, Raymond Benny wrote:
With said, I believe my ground absorption is very high so I feel the 
higher
numbers of radials helps greatly with my vertical efficiency and 
radiation.


Hi Ray,

The soil affects us in two important ways. First, poor soil burns 
transmitter power underneath the antenna and it's near field. We use 
radials to shield the soil from the field, and to supply a low 
impedance path for return current. Magnetic fields produced around 
each radial by virtue of current flow couples loss in the earth into 
the radials in the form of series resistance. Loss in each radial is 1 
squared R; each time we double the number of radials the current in 
each is divided by two, so the power coupled to the earth by each 
divides by four. So the more radials, the less power is coupled to the 
earth. THAT'S why more is better. The result of all this is that loss 
in the soil under the antenna reduces the total strength of our signal 
by that amount.


The second effect of soil is in the far field, where we field radiate 
hits the earth and is reflected by it to form the vertical pattern. 
The better the conductivity THERE, the our pattern will be both 
stronger and at a lower angle. An antenna with its base just above sea 
water is the extreme example of this -- the reflection is extremely 
strong, and it is at a VERY low angle.


We can help the first of these two effects with a good radial system, 
but the only thing we can do about the second (the far field 
reflection), is to move where there is better soil. Most of us live 
where we do because we like living there for reasons other than radio. 
And that includes me and my XYL.


73, Jim K9YC

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Re: Topband: I need help proofing an Inverted L model I made please. 40’ x 143’, four 100’ radials, #14 wire.

[Jim Brown]

On 12/10/2020 11:14 PM, Raymond Benny wrote:

With said, I believe my ground absorption is very high so I feel the higher
numbers of radials helps greatly with my vertical efficiency and radiation.


Hi Ray,

The soil affects us in two important ways. First, poor soil burns 
transmitter power underneath the antenna and it's near field. We use 
radials to shield the soil from the field, and to supply a low impedance 
path for return current. Magnetic fields produced around each radial by 
virtue of current flow couples loss in the earth into the radials in the 
form of series resistance. Loss in each radial is 1 squared R; each time 
we double the number of radials the current in each is divided by two, 
so the power coupled to the earth by each divides by four. So the more 
radials, the less power is coupled to the earth. THAT'S why more is 
better. The result of all this is that loss in the soil under the 
antenna reduces the total strength of our signal by that amount.


The second effect of soil is in the far field, where we field radiate 
hits the earth and is reflected by it to form the vertical pattern. The 
better the conductivity THERE, the our pattern will be both stronger and 
at a lower angle. An antenna with its base just above sea water is the 
extreme example of this -- the reflection is extremely strong, and it is 
at a VERY low angle.


We can help the first of these two effects with a good radial system, 
but the only thing we can do about the second (the far field 
reflection), is to move where there is better soil. Most of us live 
where we do because we like living there for reasons other than radio. 
And that includes me and my XYL.


73, Jim K9YC

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector