Re: Topband: Low Dipoles

[Wes]

I have no separate RX antennas here. Still, I believe I have parity between TX 
and RX performance, at least at my 500W power level.


Generally speaking, I think I have a reasonably quiet location and despite 
having two acres, the siting of my house, an existing tower, the TX vertical and 
neighbor's homes (noise sources) I'm left with few to no locations for an RX 
antenna.  Maybe something like a K9AY but that's about it.


Now suppose I install a K9AY with its relatively broad frontal lobe.  From my 
location in the far southwest of the US, the major DX center, EU, is a path over 
the continental land mass of the US. With good nighttime propagation atmospheric 
noise in that direction is propagated as well as signal and a "low-noise" 
antenna offers no improvement, the SNR is set by the path.  The back of such 
antenna is looking at the day lit Pacific Ocean.


At my sunrise, for the most part I'm looking west to NW for DX.  Noise and QRM 
from the east is attenuated by sunshine and I don't need directivity.


So that's my case, again at my power level and location.  My good friend Larry, 
N7DD, might argue with me but he runs a lot more power than I and has room for 
much more directive RX antennas.  As the realtors say, location, location, location.


Wes  N7WS



On 12/19/2020 10:02 AM, Fred Moeves wrote:

...
I'm more surprised when I hear that some stations are receiving on the 
inverted L.

Here in my location it's very noisy listening on my inv L is a waste of time.

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Re: Topband: Low Dipoles

[Fred Moeves]

Billy,

I was a little off on my guesstimate the K9AY loop center is 138' from 
the center of my inverted L.

It is however about 40' from my north Beverage.
When testing my K9AY I can see many instances where I can tune in one 
station switch directions and tune in a completely different MW station.

I don't see this much when talking about amateur stations.

I mostly see about 3 to 6 s-units switching away from a station.
But sometimes it is much greater...I'm sure this has something to do 
with the angle of the signal received.

It is almost never better then my north 300' Beverage.

I used the loop in one of the RTTY contests this year on 40m and it made 
a world of difference in receive from Eu stations...this day anyway..
This morning on 40m it was not very good on the Australian stations and 
the West short Beverage was better.
Beverage output is stronger then the loop output so maybe a preamp would 
level the field??


As has been said it's good to have several antennas to switch between.

I did one north Beverage 580' this summer but it was bent.
I just started to use/test it and something chewed up the RG-6 I 
replaced it twice then gave up.(photos below)
There's some sort of coax eating monster that lives in the woods behind 
my house.


I didn't have much time using this bent Beverage but it didn't look to 
good ...to much of a bend I think.

https://www.riverbendphotos.com/UnlistedGalleries/Web-Photos/n-mMvp3/i-8CDRqq7/A
https://www.riverbendphotos.com/UnlistedGalleries/Web-Photos/n-mMvp3/i-bvKTBWQ/A

I'm not that surprised that Rodger's Dipole does so well.
I'm more surprised when I hear that some stations are receiving on the 
inverted L.
Here in my location it's very noisy listening on my inv L is a waste of 
time.


I can tell when one neighbor is on his treadmill and when the other is 
doing the laundry...Crazy..
My XYL will poke her head in the radio room and say "I'm going out to 
see the kids I'll be back later" then heads to the laundry room and 
turns on the our Washer...


To me any rx antenna is worth a try...maybe any antenna is worth a try??

73
Fred KB4QZH
On 12/18/2020 10:40 PM, Billy Cox wrote:

Thank You Fred!

Do you still "see" the expected pattern and
any F/S-F/B there when switching directions?

MC es HNY!

Billy, AA4NU


On 12/18/2020 3:30 PM fmoeves  wrote:

  
BillyI would guess it's about 50' - 60'.I will measure it when I get a chance. Most of my antennas are to close to each other on a on a slope. You work with what you have. 73 Fred KB4QZH

 Original message From: Billy Cox  Date: 12/18/20  2:46 PM  (GMT-05:00) 
To: Fred Moeves  Subject: Re: Topband: Low Dipoles Good Afternoon Fred,Might I ask how 
close your K9AY loop is to your Inverted L please?Pondering if it is worth doing here, as the spacing will be 
close.TU!Merry Christmas and Happy New Year,Billy, AA4NU> On 12/18/2020 12:57 PM Fred Moeves 
 wrote:> I really didn't see a big improvement until I went to a inverted L > over 
a good number of radials.> And the addition of receive antennas.> K9AY loop and Beverages even short 
Beverages work.
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Topband: Low Dipoles

[Roger Kennedy]

Well to try and reply to some of the comments . . . (and apologies that I am
repeating myself, but clearly some haven't read all my posts on this
subject)

I'm certainly NOT trying to suggest that a decent Vertical isn't a good DX
antenna for 160m.

And my own observations certainly show that a decent Vertical is ESSENTIAL
to work DX on 80m.  To me, that proves that DX Propagation on 80m is almost
always quite Low Angle.

However, I also believe that most of the "Experts", even those that have
written books on the subject, have come down from 80m, and believe that 160m
DX Propagation is the same . . . whereas my own experience of working DX on
Top band for the past 50 years convinces me that is NOT the case !

I'm pretty sure that it's probably at a kind of Medium Angle most of the
time . . . maybe 30 or 40 degrees, due to being reflected between layers, or
multi-hop.  That's regardless of whether the stations are 3,000 miles, 6,000
miles or 10,000 miles apart.

As I have repeatedly stated, I have done hundreds of signal comparisons
against various British DXers over the decades with DX Stations, and found
that most of the time there is little to choose between my horizontal
Half-waves and their Verticals.

Maybe it's something unique about this country, the ground, it's position on
the globe . . . I really have no explanation.

And there's certainly nothing special about my current Dipole. The centre is
mounted on a pole on the roof of my house which is 50ft to the top, one end
goes to a tree, the other to another building. It's fed with LMR400 and a
big choke balun, so no vertical radiation from it. And I have had similar
antennas at 6 different QTHs at different ends of England over the past 50
years, all of which have worked much the same.

But the whole point is that it's not just these days that I can easily
compare my signals against other Gs with DX by using RBN . . . I have done
direct comparisons on SSB with hundreds of DX stations for decades.  Heck,
25 years ago there was a group of us coming on every morning for months
working a bunch of VKs and ZLs on SSB, so it was easy to compare reports.
All the other Gs had big verticals with 40+ radials - some had Inverted Ls,
a couple had 120ft towers.  But they were amazed that I was consistently as
good a signal as they were . . . and I was often receiving even better !

And even since starting this discussion on here, I've had lots of direct
emails from North American stations telling me that I am consistently as
good a signal as the other English DXers (all running Verticals).

So perhaps you can understand why I get a little angry when anyone suggests
that I am somehow kidding myself, or that the results should be taken with a
pinch of salt !

I can't explain why some of you guys get poor DX results using Dipoles . . .
I can only recount my own experiences and direct comparisons against people
using Verticals.

73 Roger G3YRO


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Re: Topband: Low Dipoles

[fmoeves]

BillyI would guess it's about 50' - 60'.I will measure it when I get a chance. 
Most of my antennas are to close to each other on a on a slope. You work with 
what you have. 73 Fred KB4QZH 
 Original message From: Billy Cox  Date: 
12/18/20  2:46 PM  (GMT-05:00) To: Fred Moeves  Subject: Re: 
Topband: Low Dipoles Good Afternoon Fred,Might I ask how close your K9AY loop 
is to your Inverted L please?Pondering if it is worth doing here, as the 
spacing will be close.TU!Merry Christmas and Happy New Year,Billy, AA4NU> On 
12/18/2020 12:57 PM Fred Moeves  wrote:> I really didn't see a 
big improvement until I went to a inverted L > over a good number of radials.> 
And the addition of receive antennas.> K9AY loop and Beverages even short 
Beverages work.
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Re: Topband: Low Dipoles

[Mike Waters]

Hi Roger,

Like the others, I never once thought that you were lying. Respectfully,
could you please tell us a little more about your dipole, tower, etc.? For
example:

 - How is the dipole oriented?
 - How is it fed?
 - Are you near a body of water?
 - Could there possibly be some vertically-polarized radiation from your
installation?
 - Any other antennas?
 - I assume that it is a center-fed, λ/2 wire dipole?

73 Mike
W0BTU

On Thu, Dec 17, 2020, 3:28 PM Roger Kennedy 
wrote:

>
> I do take offence at people suggesting that I am somehow lying about the
> results I have always had with a 160m Dipole at 50ft !
>
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Re: Topband: Low Dipoles

[Jim Brown]

On 12/18/2020 4:28 AM, Rob Atkinson wrote:

I invite you to come to the middle
of North America, Nebraska let's say, and set up the exact same
antenna in a rural location and report how it performs after a full
winter operating season.


Or to Northern California, and report on how many EU stations you hear.

73, Jim K9YC
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Re: Topband: Low Dipoles

[Fred Moeves]

Plenty of more experienced operators have already gave their insight.
But... here's my 2 cents..

When I started back in the 80s.
I first tried Dipole on 160 worked a few local stations out to 200-300 
miles.
I then tried to load short tower I really didn't know what I was doing 
so that failed.


I then tried a low full wave loop it received well but wasn't any better 
then the low Dipole.


I really didn't see a big improvement until I went to a inverted L over 
a good number of radials.

And the addition of receive antennas.
K9AY loop and Beverages even short Beverages work.

And a side note just before the weather here in Ky turned bad.
I tried a DHDL and could not get it to work.
I probably had it to close to my north Beverage.
I try again when it warms up.

I think you just have to have fun a build a few different antennas and 
see what works.
If I would have had an Elmer back then I might not have tried the Loop 
or Dipole...Maybe..


 Fred KB4QZH

On 12/18/2020 10:09 AM, cl...@gm3poi.com wrote:

Mike,
all antennas work, some better than others, a choice of one maybe not ideal.
Without an A/B comparison impossible to judge and I would add if any
vertical system is less than a quarter wave high it puts additional pressure
on the ground system to be even better. As per Lewis, Brown Epstein.  73
Clive GM3POI


-Original Message-
From: Topband  On Behalf Of
Mike Tessmer K9NW
Sent: 18 December 2020 14:40
To: topband@contesting.com
Subject: Re: Topband: Low Dipoles

Sometimes stuff just works.

73, Mike K9NW
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Re: Topband: Low Dipoles

[donovanf]

Its a fool's errand to use only antenna modelling software to evaluate 
the complexity of topband transmitting antenna performance. 


Why is that? Antenna models do not take into account polarization 
mismatch loss, a fact of life because the electron gyrofrequency 
is so close to 160 meters. See K9LA's excellent article: 


https://k9la.us/Polarization.pdf 


Antenna models also do not consider the lossy ground reflection 
in the Fresnel zone in front of the antenna. The Fresnel zone isn't a 
thin line along the ground in the direction of the distant receiving 
antenna, rather it has an elliptical shape with significant width. 
That's why HFTA analysis should always include ray traces at 
multiple azimuth angles in front of the antenna, unless the reflection 
zone has uniform terrain, such as several square miles of prairie or 
seawater. 


The classic reference on this topic is: 


https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote139.pdf 


While the NBS publication primarily addresses horizontally polarized 
antennas, its general conclusions also apply to topband vertical 
antennas. 


More than half of the low angle radiation from a 1/4 wavelength 
160 meter vertical is formed in an approximately 500 foot wide 
zone in the direction of propagation from the transmitting antenna 
to the intended receiver. 


The far edge of the Fresnel Zone is several miles away for low angle 
radiation from a 1/4 wavelength 160 vertical, especially if the 
vertical is installed on a highly conductive surface such as sea water, 
salt marsh or wet marshy soil. 


The far edge of the Fresnel zone is much closer when a 160 meter 
1/4 wavelength vertical is installed over poorly conducting dry, 
chalky or sandy soil. 


A specific worked example: 


For a 10 degree elevation angle more than half of the radiation from 
a 160 meter 1/4 wave vertical is formed in an area approximately 
500 feet wide in the desired direction of propagation. The near 
edge of the reflection zone is approximately 3000 feet in front 
of the vertical and the far edge is about three miles from the 
the vertical 


Its obvious that an extensive radial system has no affect at all 
of the efficiency of the ground reflection in the Fresnel Zone. 
Radials affect only the efficiency of the antenna itself. 


73 
Frank 
W3LPL 





- Original Message -

From: "K4SAV"  
To: topband@contesting.com 
Sent: Friday, December 18, 2020 4:48:20 PM 
Subject: Re: Topband: Low Dipoles 

On 12/18/2020 10:18 AM, Mike Waters wrote: 
> A few words of wisdom about 160m antennas from W8JI, ON4UN and others... 
> 
> https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html 

After you read W8JI's comments, put these two antennas on EZNEC. It 
will say the dipole smokes the vertical at all elevation angles. I 
trust W8JI's information because of his experience and his attention to 
detail when running tests like this. NEC is not telling you the whole 
story. 

Jerry, K4SAV 


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Re: Topband: Low Dipoles

[K4SAV]

On 12/18/2020 10:18 AM, Mike Waters wrote:

A few words of wisdom about 160m antennas from W8JI, ON4UN and others...

https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html


After you read W8JI's comments, put these two antennas on EZNEC.  It 
will say the dipole smokes the vertical at all elevation angles.  I 
trust W8JI's information because of his experience and his attention to 
detail when running tests like this.  NEC is not telling you the whole 
story.


Jerry, K4SAV


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Re: Topband: Low Dipoles

[Mike Waters]

Well said, Clive! :-)

On Fri, Dec 18, 2020, 9:10 AM  wrote:

> All antennas work, some better than others, a choice of one maybe not
> ideal.
> * Without an A/B comparison impossible to judge* and I would add if any
> vertical system is less than a quarter wave high it puts additional
> pressure
> on the ground system to be even better. As per Lewis, Brown Epstein.  73
> Clive GM3POI


73, Mike
W0BTU
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Re: Topband: Low Dipoles

[Mike Waters]

A few words of wisdom about 160m antennas from W8JI, ON4UN and others...

https://web.archive.org/web/20180815141931/http://w0btu.com/160_meters.html

73 Mike
W0BTU
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Re: Topband: Low Dipoles

[CUTTER DAVID via Topband]

I read a comment some while ago that our impressions of what is required for 
our low bands is distorted by the original works done in the 30s for medium 
wave broadcast transmitters in USA, in that, broadcast needs are different 
because they are servicing a "local" population and thus need a high "local" 
field intensity in day time at least and want to *avoid* dx. So, the short 
vertical and massive ground systems are de rigueur for those transmitters.  In 
those days it was probably most popular for folks receiving MW broadcasts to 
use a low horizontal wire.   

What would be interesting in this discussion would be recorded occasions when a 
low dipole is used at each end of the QSO.

David G3UNA/G6CP
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Re: Topband: Low Dipoles

[clive]

Mike,
all antennas work, some better than others, a choice of one maybe not ideal.
Without an A/B comparison impossible to judge and I would add if any
vertical system is less than a quarter wave high it puts additional pressure
on the ground system to be even better. As per Lewis, Brown Epstein.  73
Clive GM3POI 


-Original Message-
From: Topband  On Behalf Of
Mike Tessmer K9NW
Sent: 18 December 2020 14:40
To: topband@contesting.com
Subject: Re: Topband: Low Dipoles

Sometimes stuff just works.

73, Mike K9NW
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Re: Topband: Low Dipoles

[Mike Tessmer K9NW]

Sometimes stuff just works.

73, Mike K9NW
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Re: Topband: Low Dipoles

[KØKX Mark]

PleaseNebraska would be too easy as the propagation is quite good there.
Try central Minnesota and trust me the only EU stations worked will be just
a few in mid to late December.
This is 50 years of me operating from Minnesota speaking with a rather good
160 transmit antenna.
Thank you Rob for the reality check.

Merry Xmas
Mark
K0KX

On Fri, Dec 18, 2020 at 6:28 AM Rob Atkinson  wrote:

> > I do take offence at people suggesting that I am somehow lying about the
> > results I have always had with a 160m Dipole at 50ft !
>
> I don't think anyone believes you are lying, but perhaps instead, that
> you seem to imply that your experience can be generalized and that you
> are therefore, misguided.  This is because your results run counter to
> decades of experience and observations by countless others when it
> comes to antennas and 160 meters.  I invite you to come to the middle
> of North America, Nebraska let's say, and set up the exact same
> antenna in a rural location and report how it performs after a full
> winter operating season.
>
> Merry Xmas
> Rob
> K5UJ
> _
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> Reflector
>
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Topband: Low Dipoles

[Rob Atkinson]

> I do take offence at people suggesting that I am somehow lying about the
> results I have always had with a 160m Dipole at 50ft !

I don't think anyone believes you are lying, but perhaps instead, that
you seem to imply that your experience can be generalized and that you
are therefore, misguided.  This is because your results run counter to
decades of experience and observations by countless others when it
comes to antennas and 160 meters.  I invite you to come to the middle
of North America, Nebraska let's say, and set up the exact same
antenna in a rural location and report how it performs after a full
winter operating season.

Merry Xmas
Rob
K5UJ
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Re: Topband: Low Dipoles

[Jim Brown]

On 12/17/2020 1:27 PM, Roger Kennedy wrote:


I do take offence at people suggesting that I am somehow lying about the
results I have always had with a 160m Dipole at 50ft !


I don't see where anyone is saying you're lying, Roger.

 In terms of people doing their own DIRECT comparisons against a 
Vertical at

the same QTH, I believe the problem is that the Dipole is usually above (or
near) a decent Radial system. That will have the effect of lowering the
Antenna, and therefore making it only fire at very high angles.


A radial system would be only a small part of the story for a horizontal 
wire, potentially reducing loss in the soil under the antenna; the major 
contribution of height is formation of the pattern from the reflection 
in the far field.


A Dipole that is above poor ground, and without any wires underneath it, I
believe will "think" it's much higher


The property that aligns with that thinking is the Skin Depth at the 
frequency of interest. W8JI has noted that can be in the range of 60 ft 
(don't recall the specific numbers he cited -- it's a long time since I 
read it). I haven't studied the relationship between soil conductivity 
and skin depth.


, and probably therefore be more

efficient at lower radiation angles.


The strength of the first reflection increases with increased soil 
conductivity. The shape of the resulting vertical pattern depends on 
both the strength of that reflection and the electrical height of the 
antenna, taking skin depth into account. Lousy soil where that 
reflection is formed would weaken its strength.


I'd be interested to hear Frank's thoughts on this from an analytical 
point of view. But the bottom line for situations such as yours (and 
mine when I lived in Chicago) is that any antenna is better than no 
antenna, but the reason we study how antennas work is to make the most 
of our situation, which includes, but is not limited to, real estate, 
our surroundings, available or possible skyhooks, local noise, and our 
resources (money, friends to help, physical and mental abilities).


73, Jim K9YC


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Topband: Low Dipoles

[Roger Kennedy]

I do take offence at people suggesting that I am somehow lying about the
results I have always had with a 160m Dipole at 50ft !

Several people on this Forum have already stated how my current Signal on
160m compares favourably with other regular British DXers, all of whom use
decent Vertical Antennas.

If you don't believe them, then you can compare my signal reports on NA RBN
sites with all the other Gs on the band at the same time. (I have set up my
RBN to do that automatically) Again, you will see that, on average, there is
very little difference between mine and theirs. (sometimes I am a little
stronger, sometimes they are)

Equally the good results I have always had working DX stations in Contests,
or getting through Pileups to DX-peditions speak for themselves.

And there's nothing special about my current QTH or Antenna. I have been
working all over the world on Top Band since 1969, and ALWAYS with either a
Horizontal Half Wave Dipole or an End Fed Half Wave, at around 50ft.

In terms of people doing their own DIRECT comparisons against a Vertical at
the same QTH, I believe the problem is that the Dipole is usually above (or
near) a decent Radial system. That will have the effect of lowering the
Antenna, and therefore making it only fire at very high angles.

A Dipole that is above poor ground, and without any wires underneath it, I
believe will "think" it's much higher, and probably therefore be more
efficient at lower radiation angles.

Roger G3YRO


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Re: Topband: Low Dipoles

[Jim Brown]

On 12/17/2020 12:28 PM, Mike Smith VE9AA wrote:

I've had low (30-40' up) 160m dipoles in essentially 3 QTH's.and always had
inverted L's to do A/B realtime comparisons.


I'd define a dipole as "low" if it were less than 1/4 wavelength; I had 
one at 120 ft, less than a quarter wave. The virtue of having it lower 
than that, of course, is that it further suppresses low angle, 
potentially reducing local noise.


73, Jim K9YC
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Re: Topband: Low Dipoles

[Mike Smith VE9AA]

I've had low (30-40' up) 160m dipoles in essentially 3 QTH's.and always had
inverted L's to do A/B realtime comparisons.

 

.Here up on a good sized hill (660'ASL), rocky excuse for soil. (14+
yrs)

.At previous QTH, 30' ASL, wet swampy soil in most directions. (12+
yrs)

.At CY9AA, surrounded by salt water in 360* (< 2 weeks of operation)

 

In ~30 years of Topbanding, only *once*, at the swampy QTH did the low
dipole outperform my inverted L's on transmit.

There was one greyline opening to 9M6 that he was 539 or something on the
low dipole and inaudible on the inverted L.

 

Even on St. Paul's (N.) island-CY9AA (1997) completely surrounded by salt
water mere feet away from the antenna, it sucked really bad on 160m and the
balloon vertical kicked its butt 100% of the time.

 

At this ridgetop QTH where I've been extremely active the past 16+ yrs
contesting and DXing at no time did I see various 'low' dipoles ever
outperform inverted L's on 160m transmit. (every once in a blue because of
an arcing transformer or someone welding in the local area, the dipole might
be quieter on RX, but it's exceedingly rare)

 

I tend to view peoples claims about low dipoles with a huge grain of
salt.especially when they have no antenna to compare it to.

 

YMMV

 

CU (all of a sudden) (in the RAC Winter? in the Stew?)

 

Mike VE9Antenna Antenna

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

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Re: Topband: Low Dipoles

[m.r.c.]

at XZ0A the situation was a bit different -  high in the solar cycle so the polar oval was in the way for 
a lot of paths.  The signals we could hear in the first couple of hours at sunset arrived out of some 
kind of duct and were dumped down on us at a high angle.  We could not hear anything on the beverages ( 
not very good ones,  BOGs on uneven paths- beverages never the less) or the TX quarter wave until way 
past dark by a couple of hours.  Our signal arrived into the eastern US from the southwest


so, that dipole accounted for a lot of contacts.  I am not sure I can put a signal ratio number on it, 
but its got to be more than 10 dB as it was hear and copy signals versus hear nothing


RX noise level was not zero even though we were on an island that had diesel generator power -  we could 
hear the typical buzz from shore several miles away at noon-  common in Asia.  at night the propagated 
sum of zillions of Asia power leaks was not trivial.  the dipole helped with that as it did not hear the 
lower angle noise sources


Robin


- Original Message - 
From: 

To: 
Sent: Tuesday, December 15, 2020 10:03
Subject: Re: Topband: Low Dipoles



I have a "really low" NVIS dipole that is at 40ft elevation - ends at 20 ft.
I put it up for very local communication and to experiment with DX angles.



I have only found it to be "okay" at sunset to maybe 30 - 45 mins after,
where, at times, its equal to my 2 el T top phased array to EU.  Its NEVER
stronger to EU that I have seen so far.



I have observed it being 10db stronger during that same period than my omni
directional T vertical to stations about 500 miles out.  But within an hour,
it loses out to the vertical.



73



Ed  N1UR

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Re: Topband: Low Dipoles

[sawyered]

I have a "really low" NVIS dipole that is at 40ft elevation - ends at 20 ft.
I put it up for very local communication and to experiment with DX angles.

 

I have only found it to be "okay" at sunset to maybe 30 - 45 mins after,
where, at times, its equal to my 2 el T top phased array to EU.  Its NEVER
stronger to EU that I have seen so far.  

 

I have observed it being 10db stronger during that same period than my omni
directional T vertical to stations about 500 miles out.  But within an hour,
it loses out to the vertical.

 

73

 

Ed  N1UR

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

Re: Topband: Low Dipoles

[Wes]

I don't know what you used on 75 meters but I worked you on SSB with an 
inverted-vee up only 45 feet at the apex and just a few feet at the ends.  I 
worked my first 80 countries on 160 using the same antenna with some extensions 
on the ends.


Wes  N7WS


On 12/14/2020 3:24 PM, m.r.c. wrote:
At XZ0A we would not have made about 50% of our NA contacts if we had not 
installed a low receiving dipole.  It was the ONLY antenna that could hear NA 
stations for the hours at sunset and just after. These were clearly skew paths 
as the NA stations all had to use antennas aimed to the SW in order to hear 
us.  This during the solar maxima.  We did not transmit on the low dipole 
because it was too low, several hundred feet away, not fed with transmit grade 
cable, and portions were supported by the all encompassing wet brush.  It 
would have been a nice experiment if we had been able to transmit on that 
antenna.


Robin
WA6CDR
XZ0A-XZ1N-VP6DX 


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

Re: Topband: Low Dipoles

[m.r.c.]

At XZ0A we would not have made about 50% of our NA contacts if we had not installed a low receiving 
dipole.  It was the ONLY antenna that could hear NA stations for the hours at sunset and just after. 
These were clearly skew paths as the NA stations all had to use antennas aimed to the SW in order to hear 
us.  This during the solar maxima.  We did not transmit on the low dipole because it was too low, several 
hundred feet away, not fed with transmit grade cable, and portions were supported by the all encompassing 
wet brush.  It would have been a nice experiment if we had been able to transmit on that antenna.


Robin
WA6CDR
XZ0A-XZ1N-VP6DX

- Original Message - 
From: "Bill Tippett" 

To: "topband" 
Sent: Monday, December 14, 2020 05:31
Subject: Re: Topband: Low Dipoles



W3LPL wrote:
"I've never found them to be more effective receiving antennas than Beverages
or arrays of short verticals at sunset or at any time during the night"

I have a inverted-V with apex at 100' and ends at 30' that I specifically
put up for high angle conditions.  I also have a quasi-4SQ Tx antenna about
300' away.  The Eznec plot below shows the breakeven TOA is around 45
degrees.  I usually see +10 dB in favor of the 4SQ which you can see on the
plot happens at TOAs below 15 degrees.

https://photos.google.com/photo/AF1QipM_OgfeUmNPr7fPJL2YApvxE5HaQbajJDfYlD-M


Most (>99%) of the time what Frank says is true.  However there are rare
occasions when the inv-V is stronger than the 4SQ indicating high angles.
Normally I receive on Beverages and TX on the 4SQ but the tipoff to check
for high angles is when Beverages lose directivity.  When this happens it
indicates high angles, so I then switch to both TX/RX on the inv-V.  For me
this most often occurs just after sunset and only lasts 30 minutes or so.
However in contests I've had significant runs of deep z16 and even deeper
stations which have significantly added to my points and mult totals.
Sunrise also shows peaks but not as pronounced as sunset.  High angles can
also occur during significant solar events but this is more rare than at
sunset/sunrise.

"You can never have too many antennas!"

73,  Bill  W4ZV
_
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_
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Re: Topband: Low Dipoles

[John Harden, D.M.D.]

I am all for multiple receiving antennas for 160..

I have:

1) Hi-Z 8 down by the creek.

2) Hi-Z 2 up on the hill.

3) BOG to NW going down the hill.

4) Waller FLAG on 40 foot boon (2 loops) at 95 feet on a TIC Ring Rotor.

    The Waller FLAG appears to outperform all of the others (especially 
when the polarization is horizontal).


    It works well on the long path. It was #2 from N4IS. 100 ohm 
Twin-Ax to tower base. Then 100 ohm to 50 ohm transformer


    with Times Microwave LMR-600 to shack.

73,

John, W4NU


On 12/14/2020 8:31 AM, Bill Tippett wrote:

W3LPL wrote:
"I've never found them to be more effective receiving antennas than Beverages
or arrays of short verticals at sunset or at any time during the night"

I have a inverted-V with apex at 100' and ends at 30' that I specifically
put up for high angle conditions.  I also have a quasi-4SQ Tx antenna about
300' away.  The Eznec plot below shows the breakeven TOA is around 45
degrees.  I usually see +10 dB in favor of the 4SQ which you can see on the
plot happens at TOAs below 15 degrees.

https://photos.google.com/photo/AF1QipM_OgfeUmNPr7fPJL2YApvxE5HaQbajJDfYlD-M


Most (>99%) of the time what Frank says is true.  However there are rare
occasions when the inv-V is stronger than the 4SQ indicating high angles.
Normally I receive on Beverages and TX on the 4SQ but the tipoff to check
for high angles is when Beverages lose directivity.  When this happens it
indicates high angles, so I then switch to both TX/RX on the inv-V.  For me
this most often occurs just after sunset and only lasts 30 minutes or so.
However in contests I've had significant runs of deep z16 and even deeper
stations which have significantly added to my points and mult totals.
Sunrise also shows peaks but not as pronounced as sunset.  High angles can
also occur during significant solar events but this is more rare than at
sunset/sunrise.

"You can never have too many antennas!"

73,  Bill  W4ZV
_
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_
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Re: Topband: Low Dipoles

[Jim Brown]

On 12/14/2020 9:44 AM, donov...@erols.com wrote:

Bill's excellent: "You can never have too many antennas!"


For 160M contests, N6RO patches many components of his extensive antenna 
farm to the operating desk for use as RX antennas.



is often quoted with my important corollary:


"unless they interfere with each other"

which they all too often do...


Yes. When I added a 120 ft tower and sloping wire 160 verticals to it 
about ten years ago, N6BV and NI6T each told me in separate 
conversations that I should look for interactions with the tower, those 
sloping wires, and an existing Tee vertical about 200 ft away. I had 
already discovered the interaction between the Tee and coax feedlines to 
my high dipoles, and added ferrite chokes to suppress it.


I spent much of a summer studying those interactions in NEC, discovering 
that if I terminated unused feedlines for the 160 antennas, I could make 
the Tee a reflector for the sloping wires and the sloping wires plus the 
tower a reflector for the Tee, yielding me about 2 dB switchable to EU, 
JA, and to the south.


73, Jim K9YC

_
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Re: Topband: Low Dipoles

[donovanf]

Topband Guru W4ZV wrote an excellent comparison of the relative 
merits of vertical and horizontal antennas on 160 meters. 



Bill's excellent: "You can never have too many antennas!" 
is often quoted with my important corollary: 


"unless they interfere with each other" 

which they all too often do... 


73 
Frank 
W3LPL 


- Original Message -

From: "Bill Tippett"  
To: "topband"  
Sent: Monday, December 14, 2020 1:31:40 PM 
Subject: Re: Topband: Low Dipoles 

W3LPL wrote: 
"I've never found them to be more effective receiving antennas than Beverages 
or arrays of short verticals at sunset or at any time during the night" 

I have a inverted-V with apex at 100' and ends at 30' that I specifically 
put up for high angle conditions. I also have a quasi-4SQ Tx antenna about 
300' away. The Eznec plot below shows the breakeven TOA is around 45 
degrees. I usually see +10 dB in favor of the 4SQ which you can see on the 
plot happens at TOAs below 15 degrees. 

https://photos.google.com/photo/AF1QipM_OgfeUmNPr7fPJL2YApvxE5HaQbajJDfYlD-M 


Most (>99%) of the time what Frank says is true. However there are rare 
occasions when the inv-V is stronger than the 4SQ indicating high angles. 
Normally I receive on Beverages and TX on the 4SQ but the tipoff to check 
for high angles is when Beverages lose directivity. When this happens it 
indicates high angles, so I then switch to both TX/RX on the inv-V. For me 
this most often occurs just after sunset and only lasts 30 minutes or so. 
However in contests I've had significant runs of deep z16 and even deeper 
stations which have significantly added to my points and mult totals. 
Sunrise also shows peaks but not as pronounced as sunset. High angles can 
also occur during significant solar events but this is more rare than at 
sunset/sunrise. 

"You can never have too many antennas!" 

73, Bill W4ZV 
_ 
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_
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Re: Topband: Low Dipoles

[Bill Tippett]

W3LPL wrote:
"I've never found them to be more effective receiving antennas than Beverages
or arrays of short verticals at sunset or at any time during the night"

I have a inverted-V with apex at 100' and ends at 30' that I specifically
put up for high angle conditions.  I also have a quasi-4SQ Tx antenna about
300' away.  The Eznec plot below shows the breakeven TOA is around 45
degrees.  I usually see +10 dB in favor of the 4SQ which you can see on the
plot happens at TOAs below 15 degrees.

https://photos.google.com/photo/AF1QipM_OgfeUmNPr7fPJL2YApvxE5HaQbajJDfYlD-M


Most (>99%) of the time what Frank says is true.  However there are rare
occasions when the inv-V is stronger than the 4SQ indicating high angles.
Normally I receive on Beverages and TX on the 4SQ but the tipoff to check
for high angles is when Beverages lose directivity.  When this happens it
indicates high angles, so I then switch to both TX/RX on the inv-V.  For me
this most often occurs just after sunset and only lasts 30 minutes or so.
However in contests I've had significant runs of deep z16 and even deeper
stations which have significantly added to my points and mult totals.
Sunrise also shows peaks but not as pronounced as sunset.  High angles can
also occur during significant solar events but this is more rare than at
sunset/sunrise.

"You can never have too many antennas!"

73,  Bill  W4ZV
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Low Dipoles

[donovanf]

Horizontally polarized receiving antennas should be very low, so that 
they discriminate very effectively against both local vertically polarized 
RFI as well as atmospheric noise propagated via the ionosphere at low 
angles. They can occasionally work very well near sunrise when 
high angle DX signals are most likely to occur. 


I've never found them to be more effective receiving antennas than 
Beverages or arrays of short verticals at sunset or at any time during 
the night 


73 
Frank 
W3LPL 

- Original Message -

From: "Jim Brown"  
To: topband@contesting.com 
Sent: Saturday, December 12, 2020 10:55:47 AM 
Subject: Re: Topband: Low Dipoles 

On 12/12/2020 2:53 AM, Jim Brown wrote: 
> I fully agree with observations that DX can arrive at higher angles. 

I should have added that low dipoles can be better RX antennas for high 
angle arrivals, since efficiency doesn't matter on RX, but it matters a 
LOT on TX. 

73, Jim K9YC 
_ 
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Re: Topband: Low Dipoles

[Rodman, David]

Growing up, Jim Lawson W2PV (SK) was my local antenna mentor.  He addressed 80m 
dipoles for DX in a conversation with me one day with the following statement, 
paraphrasing Jim, "If you can't put up a more elaborate or directional antenna 
for 80, just use a high dipole, say 120 feet or so.  It really isn't a bad 
antenna choice."  I believe this echos the comments on normalizing patterns, 
etc.


Dave


---
David J Rodman MD
Assistant Clinical Professor
Department of Ophthalmology
SUNY/Buffalo

Office 716-857-8654
_
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Re: Topband: Low Dipoles

[VE6WZ_Steve]

Hi Dave,
Indeed you are correct. Sorry about that.
However, broadside I still see a 4.5 dB advantage to the vertical, but of 
course this can vary wildly up OR down depending on ground quality in the near 
field for efficiency and the far-field of the vertical.
A new plot showing both Zenith, and AZ plot at 30 deg wave angle:
https://drive.google.com/file/d/1OaQI0-2hLUjaG3cyoqp27d6qVURRMixC/view?usp=sharing
 


Steve, ve6wz


> On Dec 11, 2020, at 11:07 PM, Dave Cuthbert  wrote:
> 
> 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
>  
> 
>  
>   
> >
> 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
> 
> _
> Searchable Archives: http://www.contesting.com/_topband 
>  - Topband Reflector

_
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Re: Topband: Low Dipoles

[Jim Brown]

On 12/12/2020 2:53 AM, Jim Brown wrote:

I fully agree with observations that DX can arrive at higher angles.


I should have added that low dipoles can be better RX antennas for high 
angle arrivals, since efficiency doesn't matter on RX, but it matters a 
LOT on TX.


73, Jim K9YC
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Low Dipoles

[Jim Brown]

On 12/11/2020 6:28 PM, donov...@erols.com wrote:

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.


Some years ago, I did a disciplined modeling study of horizontal dipoles 
for 40 and 80M at heights incrementing at 5-10 ft from about 30 ft to 
about 130 ft, plotting all vertical patterns on the same graph. It 
clearly showed that a higher antenna produced great field strength at 
all elevations up to about 70 degrees. This disproved universally 
believed fallacy that low antennas are better at high angles, which is 
the result of normalizing all to their maximum field strength, as ARRL 
plots default to. It also disproves the myth that an antenna must be low 
for NVIS. The same physics applied to 160M, scaled by wavelength. The 
fundamental reason is ground losses for the lower antennas.


http://k9yc.com/AntennaPlanning.pdf  (NCJ)
http://k9yc.com/VertOrHorizontal-Slides.pdf

By definition, almost ANY dipole we can rig for 160M is a low dipole as 
a fraction of a wavelength. An exception is one that W8JI rigged at 300 
ft or so. I had one at 120 ft, which I abandoned about ten years ago.


I fully agree with observations that DX can arrive at higher angles.

73, Jim K9YC
_
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Re: Topband: Low Dipoles

[clive]

Same here Frank, I have tried low dipoles (90FT) and never did one of those 
antennas measure up to my vertical system.
I put mine all down to the ground system, which is far greater than mr average 
would consider, covering 4.5 acres with a 130 radials for a single top loaded 
T. BTW I used around 5 ft of wire on the radials.
A 500mile contact typically shows -6db on a dipole compared to the T. A dipole 
of course helps if you have noise.
73 Clive GM3POI/GM3X 


-Original Message-
From: Topband  On Behalf Of 
donov...@erols.com
Sent: 12 December 2020 02:28
To: topband 
Subject: Re: Topband: Low Dipoles

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

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

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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