Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

Agree with your points.  I've said for a couple of decades now that one 
of the least expensive ways to improve a modest station (assuming one 
has at least a decent antenna) is to add an amplifier.  Lots cheaper 
than a bigger tower and a bigger antenna.


Also, to your point about arrival angles ... HFTA calculates a "figure 
or merit" for several common paths.  N6BV (the author of HFTA) ran a few 
thousand simulations in VOACAP between various parts of the world for 
the parameter TANGLE ... the optimum takeoff angle for that path. He ran 
it for every month of the year over a full sunspot cycle (typical solar 
fluxes) for each path to generate a statistical profile of the 
normalized signal strength for each takeoff angle.  I believe the data 
for those profiles is included with the ARRL Antenna Book.  HFTA's 
"figure of merit" for a particular antenna over a particular terrain 
overlays the calculated radiation pattern over that VOACAP statistical 
profile of takeoff angles and sums the combination for each angle.


For example, N6BV ran 121 TANGLE calculations (12 months and 11 years) 
from W7 to Europe, compiling the signal strength at every degree of 
elevation for each of the 121 runs.  Adding up the strengths for each 
angle and dividing by 121 gives the statistical profile for the TANGLE 
calculation.  Overlaying the HFTA radiation pattern for the terrain 
profile pointing from W7 to Europe onto the TANGLE profile, and then 
adding up the result for each degree, gives the HFTA Figure of Merit.  
The net result gives an interesting assessment of the antenna/terrain 
for a particular path taking into account an entire sunspot cycle.


That being said, TANGLE is an empirically generated projection based 
upon actual data taken during the International Geophysical Year and 
other times, and one of the key scientists who worked on VOCAP and 
adapted it for general use (Greg Hand) has pointed out that of all the 
20 or so parameters that VOACAP can produce, TANGLE is probably the 
least rigorously substantiated.  Still, I think that HFTA Figure of 
Merit offers a useful assessment of the combination of horizontally 
polarized antennas and terrain for a desired path. I've used HFTA quite 
a bit, and my on the air results subjectively correlate quite well with it.


73,
Dave   AB7E



On 7/15/2016 12:16 PM, brian wrote:

Guys,

There is another issue here.

That is :

Just because ones antenna pattern is inferior to an optimum one by 5 
or even 20 db at the best arrival angle, that doesn't mean there is 
zero energy at the most important arrival angles.  It just means there 
is less.


QRPers often work the same stations as QRO guys. You see it all the 
time in contests. Likewise guys with high radiation angle antennas do 
work DX. Maybe just not always the really rare ones, or as many or as 
quickly.


-
It might be more interesting to discuss something like $/db to get to 
closer to optimum.  Going from low dipole to a higher one might cost 
zero to a couple hundred and gain 3 db at about $10-$100/db. Going 
from that higher dipole to something directive that picks up 4 db more 
might cost a couple kilobucks - $200-500/db.  Going from this 
directive array to something that picks up another 3 db might cost 5 
to 10 kilobucks. Now you're at > $1000/db.  Diminishing returns can 
happen quickly.


Desktop dB are near the cheapest. One can pickup 10 db (from 100 w) 
for about $100-200/db by buying a used amp.  Desktop dB can be easier 
to keep "in the air" too.

--
So what is that extra db worth to you?  Real world constrains besides 
money often limit what's possible too.


Paper and electricity is cheaper than hardware.  Learn how to use 
EZNEC or another antenna modeling program. Spend pennies/per bad new 
antenna design rather than big bucks.  Go after the cheap dB first.  
Debunk the myths about magic or folklore antennas that waste time and 
money.


Don't forget feedline loss.  One example was a local who was trying to 
work satellites using 50' of RG58 feedline.  Switching him over to 
LMR-400 doubled his uplink radiated power and improved reception by 
even more.


Read all you can. For example, K9YC's paper referenced in this thread 
illustrates how difficult it is to make a vertical work as well as 
even reasonable height dipole on the higher frequency bands. The 
ground reflection gain of a horizontal antenna (event a zig zag one) 
is hard to overcome.


73 de Brian/K3KO



On 7/15/2016 18:02 PM, Jim Brown wrote:

On Fri,7/15/2016 10:07 AM, Wes Stewart wrote:

shows an example where IONCAP says there is no (usable) path between
two stations, yet QSOs are made.


Wes,

There are exceptions to every generalization, even when the
generalization is good most of the time. I recall some well known person
who had come up poor but was no longer saying "I've been poor and I've
been rich, and rich 

Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Rick WA6NHC]

No.  That was a specific statement.  The general version would read 
"Most generalizations..."  Alan used 'All' which is a specific.


Ah the vagaries of language...

Rick nhc


On 7/15/2016 2:46 PM, Phil Wheeler wrote:

Including that one? :-)

Phil W7OX

On 7/15/16 2:06 PM, Alan Bloom wrote:

On 07/15/2016 11:02 AM, Jim Brown wrote:


There are exceptions to every generalization, even when the
generalization is good most of the time.


"All generalizations are wrong."

Alan N1AL


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Phil Wheeler]

Including that one? :-)

Phil W7OX

On 7/15/16 2:06 PM, Alan Bloom wrote:

On 07/15/2016 11:02 AM, Jim Brown wrote:

There are exceptions to every generalization, 
even when the

generalization is good most of the time.


"All generalizations are wrong."

Alan N1AL


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Alan Bloom]

On 07/15/2016 11:02 AM, Jim Brown wrote:


There are exceptions to every generalization, even when the
generalization is good most of the time.


"All generalizations are wrong."

Alan N1AL

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Jim Brown]

On Fri,7/15/2016 12:16 PM, brian wrote:
It might be more interesting to discuss something like $/db to get to 
closer to optimum.  Going from low dipole to a higher one might cost 
zero to a couple hundred and gain 3 db at about $10-$100/db. 



You will find exactly that analysis here.

http://k9yc.com/VertOrHorizontal-Slides.pdf

Also, several changes of a dB or two add up. Anyone who's ever tried to 
make QSOs over a difficult path in a contest can tell you that as little 
as 2dB can be the difference between making the QSO and the other 
station CQing in your face.. Years ago, our NCCC resident statistician, 
N6ZFO, even managed to assign a percentage increase in Sweepstakes 
scores to a dB. In my station, I've worked to squeeze every dB out if 
that I can -- everything from antenna height to a better feedline to 
more accurately reading TX power (I use N8LP's power meter, which allows 
me to get right to the limit, whether it's 1.5kW or 5W).


73, Jim K9YC

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[brian]

Guys,

There is another issue here.

That is :

Just because ones antenna pattern is inferior to an optimum one by 5 or 
even 20 db at the best arrival angle, that doesn't mean there is zero 
energy at the most important arrival angles.  It just means there is less.


QRPers often work the same stations as QRO guys. You see it all the time 
in contests. Likewise guys with high radiation angle antennas do work 
DX. Maybe just not always the really rare ones, or as many or as quickly.


-
It might be more interesting to discuss something like $/db to get to 
closer to optimum.  Going from low dipole to a higher one might cost 
zero to a couple hundred and gain 3 db at about $10-$100/db. Going from 
that higher dipole to something directive that picks up 4 db more might 
cost a couple kilobucks - $200-500/db.  Going from this directive array 
to something that picks up another 3 db might cost 5 to 10 kilobucks. 
Now you're at > $1000/db.  Diminishing returns can happen quickly.


Desktop dB are near the cheapest. One can pickup 10 db (from 100 w) for 
about $100-200/db by buying a used amp.  Desktop dB can be easier to 
keep "in the air" too.

--
So what is that extra db worth to you?  Real world constrains besides 
money often limit what's possible too.


Paper and electricity is cheaper than hardware.  Learn how to use EZNEC 
or another antenna modeling program. Spend pennies/per bad new antenna 
design rather than big bucks.  Go after the cheap dB first.  Debunk the 
myths about magic or folklore antennas that waste time and money.


Don't forget feedline loss.  One example was a local who was trying to 
work satellites using 50' of RG58 feedline.  Switching him over to 
LMR-400 doubled his uplink radiated power and improved reception by even 
more.


Read all you can. For example, K9YC's paper referenced in this thread 
illustrates how difficult it is to make a vertical work as well as even 
reasonable height dipole on the higher frequency bands. The ground 
reflection gain of a horizontal antenna (event a zig zag one) is hard to 
overcome.


73 de Brian/K3KO



On 7/15/2016 18:02 PM, Jim Brown wrote:

On Fri,7/15/2016 10:07 AM, Wes Stewart wrote:

shows an example where IONCAP says there is no (usable) path between
two stations, yet QSOs are made.


Wes,

There are exceptions to every generalization, even when the
generalization is good most of the time. I recall some well known person
who had come up poor but was no longer saying "I've been poor and I've
been rich, and rich is better." :)

Sure, there are times when a higher angle path is better than a low
angle path (or exists when the low angle path is not present). But
N6BV's statistical data for paths to various locations shows low angle
paths to be better far more often than higher angle paths. It also shows
high angle paths some smaller percentage of the time.

The HUGE problem with using the concept of "takeoff angle," and ONLY the
takeoff angle to describe and evaluate antenna performance is that by
looking at only one curve at a time, it fails to compare one antenna or
mounting height to another. Again, my work looking at the effects of
antenna height in a "flatland" QTH have all plotted the complete
vertical pattern ON THE SAME GRAPH, which clearly shows that for the
range of vertical angles where we can use the ionosphere, higher is
better! N6BV presents this quite well as a "figure of merit" for the
plots of his elevation studies in HFTA, while also showing the complete
vertical data.

73, Jim K9YC

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Jim Brown]

On Fri,7/15/2016 10:07 AM, Wes Stewart wrote:
shows an example where IONCAP says there is no (usable) path between 
two stations, yet QSOs are made.


Wes,

There are exceptions to every generalization, even when the 
generalization is good most of the time. I recall some well known person 
who had come up poor but was no longer saying "I've been poor and I've 
been rich, and rich is better." :)


Sure, there are times when a higher angle path is better than a low 
angle path (or exists when the low angle path is not present). But 
N6BV's statistical data for paths to various locations shows low angle 
paths to be better far more often than higher angle paths. It also shows 
high angle paths some smaller percentage of the time.


The HUGE problem with using the concept of "takeoff angle," and ONLY the 
takeoff angle to describe and evaluate antenna performance is that by 
looking at only one curve at a time, it fails to compare one antenna or 
mounting height to another. Again, my work looking at the effects of 
antenna height in a "flatland" QTH have all plotted the complete 
vertical pattern ON THE SAME GRAPH, which clearly shows that for the 
range of vertical angles where we can use the ionosphere, higher is 
better! N6BV presents this quite well as a "figure of merit" for the 
plots of his elevation studies in HFTA, while also showing the complete 
vertical data.


73, Jim K9YC

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Wes Stewart]

I'll make a few closing comments, as I suspect the moderator will be cutting 
this off soon.


When I used 45 degrees, that was a number out of a hat for illustrative purposes 
only.  The point being that we hams tend to think that we can "force" the TOA to 
be lower, and lower is always "better."  NM7M (SK) in his book, "The Big Guns 
Guide to Low-Band Propagation" mentions the case where a low angle signal (10 
degrees) can't penetrate the E-layer and needs many more hops than a higher 
angle signal that does penetrate and gets to the F-layer were fewer hops are 
necessary to cover the same path.


Eric, KL7AJ, has a couple of thought-provoking papers in QST that have a 
different take as well.  They are, "Gimme and X, Gimme an O", QST, Dec. 2010,
 pp 33-37 and "Three Wrong Assumptions about the Ionosphere", QST, Mar 2012, pp 
40-42.


Carl, K9LA, in a presentation 
(http://wwrof.org/webinar-archive/a-long-overdue-review-of-gray-line-propagation-on-the-low-bands-by-carl-luetzelschwab-k9la/) 
shows an example where IONCAP says there is no (usable) path between two 
stations, yet QSOs are made.


Wes



On 7/13/2016 5:48 PM, David Gilbert wrote:


I've played around with VOACAP a lot in the past.  Possibly you want to argue 
with it's validity, but I can tell you that the percentage of time it shows 
signals optimally arriving at 45 degrees is much less than the percentage of 
time they arrive closer to 10 degrees ... certainly for any kind of DX work 
and most of the time for domestic work here in the U.S.  That depends upon the 
band, of course, and also the time of the opening (optimum angles are lower at 
openings and closings versus mid-opening), but in general the best TOA's area 
lot lower than most hams assume.


If low takeoff angles weren't generally desirable our hobby has several 
generations of very misguided members who have squandered millions of dollars.


Dave   AB7E


On 7/13/2016 5:02 PM, Wes Stewart wrote:

Jim, I've looked at your stuff in the past.

But, "improvement" is in the eye of the beholder.  The ionosphere determines 
the optimum TOA, not the antenna. Taking heroic measures to get the max TOA 
down to 10 degrees (a near impossibility over dirt) when the signals are 
arriving at 45 degrees is hardly optimum.


Anecdotal evidence is mostly worthless but for what it's worth, I have 48 
entities worked on 160 meters from here in the desert using no more than 500 
watts into an inverted-V, apex at 45' ends at 6'.  Everyone "knows" that this 
can't possibly work because it radiates straight up.  (Except that it doesn't)


Wes


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Jim Brown]

That exactly proves my point about takeoff angle being an inappropriate 
measure. If you study the plots of my NEC models, it becomes clear that 
raising the antenna does much more than moving the peak of radiation 
lower -- it also increases the field strength at most angles below 
that.  See my family of plots of field strength vs height of horizontal 
antennas.


73, Jim K9YC

On Wed,7/13/2016 5:02 PM, Wes Stewart wrote:
Everyone "knows" that this can't possibly work because it radiates 
straight up.  (Except that it doesn't)



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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Phil Wheeler]

Dave,

Aside from the issue at hand, and perhaps sans the 
"misguided", I'm certain this "our hobby has 
several generations of very misguided members who 
have squandered millions of dollars." is true ;-)


73, Phil W7OX

On 7/13/16 5:48 PM, David Gilbert wrote:


I've played around with VOACAP a lot in the 
past.  Possibly you want to argue with it's 
validity, but I can tell you that the percentage 
of time it shows signals optimally arriving at 
45 degrees is much less than the percentage of 
time they arrive closer to 10 degrees ... 
certainly for any kind of DX work and most of 
the time for domestic work here in the U.S.  
That depends upon the band, of course, and also 
the time of the opening (optimum angles are 
lower at openings and closings versus 
mid-opening), but in general the best TOA's area 
lot lower than most hams assume.


If low takeoff angles weren't generally 
desirable our hobby has several generations of 
very misguided members who have squandered 
millions of dollars.


Dave   AB7E


On 7/13/2016 5:02 PM, Wes Stewart wrote:

Jim, I've looked at your stuff in the past.

But, "improvement" is in the eye of the 
beholder.  The ionosphere determines the 
optimum TOA, not the antenna. Taking heroic 
measures to get the max TOA down to 10 degrees 
(a near impossibility over dirt) when the 
signals are arriving at 45 degrees is hardly 
optimum.


Anecdotal evidence is mostly worthless but for 
what it's worth, I have 48 entities worked on 
160 meters from here in the desert using no 
more than 500 watts into an inverted-V, apex at 
45' ends at 6'.  Everyone "knows" that this 
can't possibly work because it radiates 
straight up.  (Except that it doesn't)


Wes

On 7/13/2016 3:07 PM, Jim Brown wrote:

On Wed,7/13/2016 12:03 PM, Wes Stewart wrote:
Ok, but I'm unclear about what "improves 
radiation pattern" means. 


Wes,

Take a look at the links I posted to my NEC 
studies. There can be no doubt as to the 
meaning of "improves radiation pattern."



BTW -- I do NOT agree that elevated radials 
have much to do with establishing the take-off 
angle. AND, more to the point, I view take-off 
angle as absolutely the wrong way to look at 
the vertical pattern of an antenna. A FAR 
better approach is the one I used in those 
antenna planning applications notes, for which 
I posted links a few hours ago.


73, Jim K9YC


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

I've played around with VOACAP a lot in the past.  Possibly you want to 
argue with it's validity, but I can tell you that the percentage of time 
it shows signals optimally arriving at 45 degrees is much less than the 
percentage of time they arrive closer to 10 degrees ... certainly for 
any kind of DX work and most of the time for domestic work here in the 
U.S.  That depends upon the band, of course, and also the time of the 
opening (optimum angles are lower at openings and closings versus 
mid-opening), but in general the best TOA's area lot lower than most 
hams assume.


If low takeoff angles weren't generally desirable our hobby has several 
generations of very misguided members who have squandered millions of 
dollars.


Dave   AB7E


On 7/13/2016 5:02 PM, Wes Stewart wrote:

Jim, I've looked at your stuff in the past.

But, "improvement" is in the eye of the beholder.  The ionosphere 
determines the optimum TOA, not the antenna. Taking heroic measures to 
get the max TOA down to 10 degrees (a near impossibility over dirt) 
when the signals are arriving at 45 degrees is hardly optimum.


Anecdotal evidence is mostly worthless but for what it's worth, I have 
48 entities worked on 160 meters from here in the desert using no more 
than 500 watts into an inverted-V, apex at 45' ends at 6'.  Everyone 
"knows" that this can't possibly work because it radiates straight 
up.  (Except that it doesn't)


Wes

On 7/13/2016 3:07 PM, Jim Brown wrote:

On Wed,7/13/2016 12:03 PM, Wes Stewart wrote:
Ok, but I'm unclear about what "improves radiation pattern" means. 


Wes,

Take a look at the links I posted to my NEC studies. There can be no 
doubt as to the meaning of "improves radiation pattern."



BTW -- I do NOT agree that elevated radials have much to do with 
establishing the take-off angle. AND, more to the point, I view 
take-off angle as absolutely the wrong way to look at the vertical 
pattern of an antenna. A FAR better approach is the one I used in 
those antenna planning applications notes, for which I posted links a 
few hours ago.


73, Jim K9YC 


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Wes Stewart]

Jim, I've looked at your stuff in the past.

But, "improvement" is in the eye of the beholder.  The ionosphere determines the 
optimum TOA, not the antenna. Taking heroic measures to get the max TOA down to 
10 degrees (a near impossibility over dirt) when the signals are arriving at 45 
degrees is hardly optimum.


Anecdotal evidence is mostly worthless but for what it's worth, I have 48 
entities worked on 160 meters from here in the desert using no more than 500 
watts into an inverted-V, apex at 45' ends at 6'.  Everyone "knows" that this 
can't possibly work because it radiates straight up.  (Except that it doesn't)


Wes

On 7/13/2016 3:07 PM, Jim Brown wrote:

On Wed,7/13/2016 12:03 PM, Wes Stewart wrote:
Ok, but I'm unclear about what "improves radiation pattern" means. 


Wes,

Take a look at the links I posted to my NEC studies. There can be no doubt as 
to the meaning of "improves radiation pattern."



BTW -- I do NOT agree that elevated radials have much to do with establishing 
the take-off angle. AND, more to the point, I view take-off angle as 
absolutely the wrong way to look at the vertical pattern of an antenna. A FAR 
better approach is the one I used in those antenna planning applications 
notes, for which I posted links a few hours ago.


73, Jim K9YC 


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Jim Brown]

On Wed,7/13/2016 12:03 PM, Wes Stewart wrote:
Ok, but I'm unclear about what "improves radiation pattern" means. 


Wes,

Take a look at the links I posted to my NEC studies. There can be no 
doubt as to the meaning of "improves radiation pattern."



BTW -- I do NOT agree that elevated radials have much to do with 
establishing the take-off angle. AND, more to the point, I view take-off 
angle as absolutely the wrong way to look at the vertical pattern of an 
antenna. A FAR better approach is the one I used in those antenna 
planning applications notes, for which I posted links a few hours ago.


73, Jim K9YC

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Mel Farrer via Elecraft]

On a slightly different take, controlling the vertical pattern, ie minimizing 
the minor lobes, will have a significant effect on gain as the major lobe now 
gets all of the energy.  Elevated radials have more to do in establishing the 
actual TOA above ground.  This is not easy.  Try modelling the vertical with 
radials in free space and see the TOA move around and the minor lobes move with 
the angle of the radials away for 90 degrees.  When you have the TOA where you 
want it, move the antenna to somewhere AGL and watch the pattern.  The ground 
losses will now start to absorb the lower portion of the major lobe.  The 
result will always be a higher TOA unless over VERY conductive ground.  

Mel, K6KBE


  From: David Gilbert <xda...@cis-broadband.com>
 To: elecraft@mailman.qth.net 
 Sent: Wednesday, July 13, 2016 1:24 PM
 Subject: Re: [Elecraft] Sloping Terrain vs Feedline Losses
   

Lowering takeoff angle.

Regarding the other part, I've stated it as clearly as I can about three 
times now.  If you disagree or can't follow the point, I don't think 
anything else I might say will change that.

73,

Dave  AB7E


On 7/13/2016 12:03 PM, Wes Stewart wrote:
> Ok, but I'm unclear about what "improves radiation pattern" means. To 
> paraphrase your other premise, "I'm not sure if it does or doesn't but 
> if it does, I'm sure it's big" has me wondering.  But I wonder about a 
> lot of things...
>
>
> On 7/13/2016 10:38 AM, David Gilbert wrote:
>>
>> No, I didn't mean that.
>>
>> If sloping ground improves radiation pattern, it's going to be worth 
>> more than 1 db.  Pattern changes of any sort typically have 
>> significant effect, whereas one db is almost trivial (notwithstanding 
>> my own experiments on that on my website).  I'm not saying that 
>> sloping ground actually has a significant effect ... only that if it 
>> has any effect at all it is likely to be greater than 1 db.
>>
>> Dave  AB7E
>>
>>
>>
>> On 7/13/2016 10:06 AM, Wes Stewart wrote:
>>> I hope you meant much less than 1 dB.
>>>
>>> On 7/13/2016 1:49 AM, David Gilbert wrote:
>>>>
>>>> Agree on the coax losses, but totally disagree on both of your 
>>>> other comments:
>>>>
>>>> 1.  Elevated radials will ONLY help reduce near field ground losses 
>>>> ... they will do nothing to help radiation pattern. The effects of 
>>>> ground conductivity determine far field pattern (given a particular 
>>>> profile) no matter what kind of radials he uses.
>>>>
>>>> 2.  If there is any gain benefit from the terrain profile at all, 
>>>> it will be much more than 1 db.
>>>>
>>>> Dave  AB7E 
>
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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

Lowering takeoff angle.

Regarding the other part, I've stated it as clearly as I can about three 
times now.   If you disagree or can't follow the point, I don't think 
anything else I might say will change that.


73,

Dave   AB7E


On 7/13/2016 12:03 PM, Wes Stewart wrote:
Ok, but I'm unclear about what "improves radiation pattern" means. To 
paraphrase your other premise, "I'm not sure if it does or doesn't but 
if it does, I'm sure it's big" has me wondering.  But I wonder about a 
lot of things...



On 7/13/2016 10:38 AM, David Gilbert wrote:


No, I didn't mean that.

If sloping ground improves radiation pattern, it's going to be worth 
more than 1 db.  Pattern changes of any sort typically have 
significant effect, whereas one db is almost trivial (notwithstanding 
my own experiments on that on my website).  I'm not saying that 
sloping ground actually has a significant effect ... only that if it 
has any effect at all it is likely to be greater than 1 db.


Dave   AB7E



On 7/13/2016 10:06 AM, Wes Stewart wrote:

I hope you meant much less than 1 dB.

On 7/13/2016 1:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your 
other comments:


1.  Elevated radials will ONLY help reduce near field ground losses 
... they will do nothing to help radiation pattern. The effects of 
ground conductivity determine far field pattern (given a particular 
profile) no matter what kind of radials he uses.


2.  If there is any gain benefit from the terrain profile at all, 
it will be much more than 1 db.


Dave   AB7E 


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Wes Stewart]

Ok, but I'm unclear about what "improves radiation pattern" means. To paraphrase 
your other premise, "I'm not sure if it does or doesn't but if it does, I'm sure 
it's big" has me wondering.  But I wonder about a lot of things...



On 7/13/2016 10:38 AM, David Gilbert wrote:


No, I didn't mean that.

If sloping ground improves radiation pattern, it's going to be worth more than 
1 db.  Pattern changes of any sort typically have significant effect, whereas 
one db is almost trivial (notwithstanding my own experiments on that on my 
website).  I'm not saying that sloping ground actually has a significant 
effect ... only that if it has any effect at all it is likely to be greater 
than 1 db.


Dave   AB7E



On 7/13/2016 10:06 AM, Wes Stewart wrote:

I hope you meant much less than 1 dB.

On 7/13/2016 1:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your other comments:

1.  Elevated radials will ONLY help reduce near field ground losses ... they 
will do nothing to help radiation pattern. The effects of ground 
conductivity determine far field pattern (given a particular profile) no 
matter what kind of radials he uses.


2.  If there is any gain benefit from the terrain profile at all, it will be 
much more than 1 db.


Dave   AB7E 


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Jim Brown]

On Wed,7/13/2016 10:29 AM, David Gilbert wrote:
I have no idea how or to what extent terrain affects a vertically 
polarized signal.  I am, however, pretty certain that if it does at 
all it would be worth more than 1 db.


N6BT presented excellent experimental work on the effect of terrain on 
vertically polarized antennas as his contribution to the Pacificon 
Antenna forum last fall. He's been working on vertical dipoles for 
several years now. This experiment included setting one up at various 
locations on a broad knoll with drop-offs in most directions. He made 
some measurements of vertical pattern using a drone, and also used the 
antennas at those various locations to make contacts on the air.  As I 
recall, he was operating on 20M, but I could be wrong about that.


The antenna location near a dropoff in the direction of SA yielded QSOs 
with SA, but none with JA. A location near a dropoff in the direction of 
JA yielded JA QSOs but no SA. And a setup in the center of the knoll, 
relatively far from the dropoffs yielded no QSOs with SA or JA. And his 
measurements with the drone showed vertical radiation increasing below 0 
degrees in the direction of the dropoff.


I've always wished we had a version of HFTA that handled vertically 
polarized antennas ... that would probably be enlightening.  I've also 
tried on occasion to use EZNEC+ for the same purpose since it allows 
you to specify at least two different zones around the antenna, but I 
didn't have much success with that.


The interaction of vertically and horizontally polarized signals with 
ground is quite different, so the math is quite different. Among other 
things, a primary determinant of ground interaction with vertical 
antennas is soil conductivity in the far field (that is, at the point of 
interaction). Height is also a factor. With horizontal antennas, soil 
conductivity is essentially insignificant, and the primary determinants 
are height and the elevation profile.




I'm one of those who had quite good luck with roof mounted verticals, 
but it's hard to say whether any improvement (if there was one) was 
the result of distance from lossy ground or simply the ability to 
shoot over lossy surrounding structures like trees and houses.


See my NEC study on this, which is in line with your observations. When 
I presented this material to an NCCC meeting a few years ago, the OT 
hams with solid engineering background were nodding their heads in 
agreement.


http://k9yc.com/AntennaPlanning.pdf
http://k9yc.com/VerticalHeight.pdf

I do think it is more than "folklore" that elevated radials have 
benefits over in-ground radials unless the in-ground radial system is 
reasonably extensive.  There have been some pretty decent studies on 
that.


Yep. N6LF has done lots of excellent work, which is on his website.

http://www.antennasbyn6lf.com/

I've used part of his work in my applications note/tutorial on antennas 
for 160M.


http://k9yc.com/160MPacificon.pdf

73, Jim K9YC

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

No, I didn't mean that.

If sloping ground improves radiation pattern, it's going to be worth 
more than 1 db.  Pattern changes of any sort typically have significant 
effect, whereas one db is almost trivial (notwithstanding my own 
experiments on that on my website).  I'm not saying that sloping ground 
actually has a significant effect ... only that if it has any effect at 
all it is likely to be greater than 1 db.


Dave   AB7E



On 7/13/2016 10:06 AM, Wes Stewart wrote:

I hope you meant much less than 1 dB.

On 7/13/2016 1:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your other 
comments:


1.  Elevated radials will ONLY help reduce near field ground losses 
... they will do nothing to help radiation pattern.  The effects of 
ground conductivity determine far field pattern (given a particular 
profile) no matter what kind of radials he uses.


2.  If there is any gain benefit from the terrain profile at all, it 
will be much more than 1 db.


Dave   AB7E



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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

Hi, Brian.

I have no idea how or to what extent terrain affects a vertically 
polarized signal.  I am, however, pretty certain that if it does at all 
it would be worth more than 1 db.  That's just the nature of proximity 
effects in general.  I suspect that one possible effect of sloping 
ground for a vertical antenna might be to move the lossy environment to 
where it has less effect on the signal (i.e., lower), and that might be 
more significant with poor soil conductivity than with good 
conductivity.  It seems reasonable to me to imagine that the pattern for 
sloping ground would shift at least to some minor extent toward that of 
a free space pattern, but I'm pretty sure that ON4UN and others have far 
more insight into this than I do.


I've always wished we had a version of HFTA that handled vertically 
polarized antennas ... that would probably be enlightening.  I've also 
tried on occasion to use EZNEC+ for the same purpose since it allows you 
to specify at least two different zones around the antenna, but I didn't 
have much success with that.


I'm one of those who had quite good luck with roof mounted verticals, 
but it's hard to say whether any improvement (if there was one) was the 
result of distance from lossy ground or simply the ability to shoot over 
lossy surrounding structures like trees and houses.  I do think it is 
more than "folklore" that elevated radials have benefits over in-ground 
radials unless the in-ground radial system is reasonably extensive.  
There have been some pretty decent studies on that.


But again, it is important to keep separate the effect of radials on 
feedpoint return loss from the effect of ground on radiation pattern.  
Radials reduce feedpoint loss but have minimal effect on radiation 
pattern unless you are able to go out several wavelengths.  On the other 
hand, the conductivity of the ground has much less effect on return loss 
than a decent radial system, but it is the ONLY determinant of far field 
radiation pattern (other than whatever effect the terrain profile itself 
may have).


73,

Dave   AB7E



On 7/13/2016 3:46 AM, brian wrote:

Hi Dave.

Care to comment on how much benefit vertically polarized antennas 
might gain from terrain sloping away from vertical?


For horizontally polarized antennas, where ground reflection gain is 
up to 6 dB, the sloping terrain can lower the effective take off angle 
a lot- 10's of degrees.  There was a program called YTAD that 
estimated this effect in one dimension.  It's results were quite 
enlightening.


Vertical antennas have no ground reflection gain.  Would one then 
expect sloping terrain NOT to alter their already low take off angle 
much?  On the other hand, folklore seems to indicate a benefit of roof 
top verticals with their "elevated" radials over ground mounted 
verticals with elevated radials/or in ground radials.


73 de Brian/K3KO



On 7/13/2016 8:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your other
comments:

1.  Elevated radials will ONLY help reduce near field ground losses ...
they will do nothing to help radiation pattern.  The effects of ground
conductivity determine far field pattern (given a particular profile) no
matter what kind of radials he uses.

2.  If there is any gain benefit from the terrain profile at all, it
will be much more than 1 db.

Dave   AB7E


On 7/12/2016 3:49 PM, Craig Smith wrote:

Ted …

I think you are overstating the coax losses.   Even stock RG-11 should
be perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. 
run.


Even so, I would probably gravitate toward the closer location.  With
the elevated radials, the effects of the ground conductivity should be
minimal.   Not sure if ON4UNs data assume elevated radials or many
on-ground radials.  It could be that his estimate of the sloping
ground advantage is for the later.   With the closer location, you
will have perhaps 1 dB stronger signal in all directions because of
the lower feedline loss.

73Craig   AC0DS


_

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Wes Stewart]

I hope you meant much less than 1 dB.

On 7/13/2016 1:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your other comments:

1.  Elevated radials will ONLY help reduce near field ground losses ... they 
will do nothing to help radiation pattern.  The effects of ground conductivity 
determine far field pattern (given a particular profile) no matter what kind 
of radials he uses.


2.  If there is any gain benefit from the terrain profile at all, it will be 
much more than 1 db.


Dave   AB7E



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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[brian]

Hi Dave.

Care to comment on how much benefit vertically polarized antennas might 
gain from terrain sloping away from vertical?


For horizontally polarized antennas, where ground reflection gain is up 
to 6 dB, the sloping terrain can lower the effective take off angle a 
lot- 10's of degrees.  There was a program called YTAD that estimated 
this effect in one dimension.  It's results were quite enlightening.


Vertical antennas have no ground reflection gain.  Would one then expect 
sloping terrain NOT to alter their already low take off angle much?  On 
the other hand, folklore seems to indicate a benefit of roof top 
verticals with their "elevated" radials over ground mounted verticals 
with elevated radials/or in ground radials.


73 de Brian/K3KO



On 7/13/2016 8:49 AM, David Gilbert wrote:


Agree on the coax losses, but totally disagree on both of your other
comments:

1.  Elevated radials will ONLY help reduce near field ground losses ...
they will do nothing to help radiation pattern.  The effects of ground
conductivity determine far field pattern (given a particular profile) no
matter what kind of radials he uses.

2.  If there is any gain benefit from the terrain profile at all, it
will be much more than 1 db.

Dave   AB7E


On 7/12/2016 3:49 PM, Craig Smith wrote:

Ted …

I think you are overstating the coax losses.   Even stock RG-11 should
be perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.

Even so, I would probably gravitate toward the closer location.  With
the elevated radials, the effects of the ground conductivity should be
minimal.   Not sure if ON4UNs data assume elevated radials or many
on-ground radials.  It could be that his estimate of the sloping
ground advantage is for the later.   With the closer location, you
will have perhaps 1 dB stronger signal in all directions because of
the lower feedline loss.

73Craig   AC0DS


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[David Gilbert]

Agree on the coax losses, but totally disagree on both of your other 
comments:


1.  Elevated radials will ONLY help reduce near field ground losses ... 
they will do nothing to help radiation pattern.  The effects of ground 
conductivity determine far field pattern (given a particular profile) no 
matter what kind of radials he uses.


2.  If there is any gain benefit from the terrain profile at all, it 
will be much more than 1 db.


Dave   AB7E


On 7/12/2016 3:49 PM, Craig Smith wrote:

Ted …

I think you are overstating the coax losses.   Even stock RG-11 should be 
perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.

Even so, I would probably gravitate toward the closer location.  With the 
elevated radials, the effects of the ground conductivity should be minimal.   
Not sure if ON4UNs data assume elevated radials or many on-ground radials.  It 
could be that his estimate of the sloping ground advantage is for the later.   
With the closer location, you will have perhaps 1 dB stronger signal in all 
directions because of the lower feedline loss.

73Craig   AC0DS


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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Vic Rosenthal]

You might also consider receive noise, which you can check in both spots 
(unless you are planning a dedicated RX antenna). 
As others said, loss for most coax will be much lower than one dB per 100 feet.

Vic 4X6GP

> On 13 Jul 2016, at 01:16, Dauer, Edward  wrote:
> 
> So long as antenna discussions on the reflector haven’t been met with the 
> “OT” cloture lately, I have an antenna question of a different sort.  I am 
> contemplating a ¼ wave vertical with four elevated radials for 80 meters.  My 
> choices for siting it are two – one is near the top of the property (about 
> 8,600 feet ASL), somewhat in the clear, and within 100 feet from the 
> operating position.  The other is in a meadow near the property boundary, 
> which is much more open and a just a bit higher – but it has two other 
> significant characteristics.  One is that the land slopes away from that 
> site, over about half the compass from NNW to SSE, at a slope of 10 to 15% 
> for about a half mile.  According to ON4UN’s text, that slope could give me a 
> significant gain in that part of the azimuth with no significant terrain 
> obstruction on the other half.  The second characteristic, however, goes the 
> other way – that site would require about 500 feet of feedline from the house 
> to the antenna feed point.  I have been looking at the loss factors in 
> hardline and in “direct burial” coax, which on 80 meters seem modest but not 
> irrelevant for a run of that length – maybe a dB or so per 100 feet.   What I 
> can’t quantify – because I don’t have enough life expectancy to learn how to 
> adapt antenna modelling software to a Mac or even to learn it if I could – is 
> whether the gain from the sloping near field would make up for the feedline 
> loss.  In case it matters, the ground likely has very poor conductivity.  
> It’s decomposed granite – a specialty in the Colorado mountains – with a very 
> thin layer of usually very dry soil.  (Our well has a static level of 142 
> feet, so there’s no ground water anywhere near the surface.)  Anyone have 
> opinions, guesses, estimates, advice, or whatever – should I accept the 
> feedline losses and enjoy the half-hemisphere low-angle gain?  Or would the 
> poor soil quality negate that advantage?
> 
> Ted, KN1CBR
> 
> 
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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Mel Farrer via Elecraft]

Elevated radials will do more by establishing a fixed array configuration on 
match and pattern.  The orientation of the ground is another issue but with a 
fixed orientation the pattern will be more subtle.  I run multiple antennas 
with vertical orientation and find that the ground conductivity has more to 
change the pattern than the radials.  That said, look at the ground 
conductivity in your area and see if it is constant over a year or widely wet 
to dry.  If the ground is highly variable, the elevated radials will help give 
you a more stable operating platform or match.  

Mel, K6KBE


  From: John Langdon <jlangd...@austin.rr.com>
 To: 'Craig Smith' <cr...@powersmith.net>; "'Dauer, Edward'" 
<eda...@law.du.edu> 
Cc: elecraft@mailman.qth.net
 Sent: Tuesday, July 12, 2016 6:36 PM
 Subject: Re: [Elecraft] Sloping Terrain vs Feedline Losses
   
The elevated radials should help reduce near field I2R losses, but the sloping 
terrain will help far field reinforcement and produce 'gain' in some 
directions, although at 80M it should slope for further than a mile away to 
really make a difference.  I do not think elevated radials will change the far 
field reflections from the sloping terrain in any way.

At 80M, even small hardline should have very low loss, so I would go for the 
location that has the better terrain profile.

73 John N5CQ


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Craig 
Smith
Sent: Tuesday, July 12, 2016 5:50 PM
To: Dauer, Edward <eda...@law.du.edu>
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Sloping Terrain vs Feedline Losses

Ted …

I think you are overstating the coax losses.  Even stock RG-11 should be 
perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.  

Even so, I would probably gravitate toward the closer location.  With the 
elevated radials, the effects of the ground conductivity should be minimal.  
Not sure if ON4UNs data assume elevated radials or many on-ground radials.  It 
could be that his estimate of the sloping ground advantage is for the later.  
With the closer location, you will have perhaps 1 dB stronger signal in all 
directions because of the lower feedline loss.

73    Craig  AC0DS

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Ken G Kopp]

Don't forget about scrap 72 ohm CATV aluminum hard-line -or- open wire to
feed the vertical.

73!

K0PP
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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[John Langdon]

The elevated radials should help reduce near field I2R losses, but the sloping 
terrain will help far field reinforcement and produce 'gain' in some 
directions, although at 80M it should slope for further than a mile away to 
really make a difference.  I do not think elevated radials will change the far 
field reflections from the sloping terrain in any way.

At 80M, even small hardline should have very low loss, so I would go for the 
location that has the better terrain profile.

73 John N5CQ


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Craig 
Smith
Sent: Tuesday, July 12, 2016 5:50 PM
To: Dauer, Edward <eda...@law.du.edu>
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Sloping Terrain vs Feedline Losses

Ted …

I think you are overstating the coax losses.   Even stock RG-11 should be 
perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.  

Even so, I would probably gravitate toward the closer location.  With the 
elevated radials, the effects of the ground conductivity should be minimal.   
Not sure if ON4UNs data assume elevated radials or many on-ground radials.  It 
could be that his estimate of the sloping ground advantage is for the later.   
With the closer location, you will have perhaps 1 dB stronger signal in all 
directions because of the lower feedline loss.

73Craig   AC0DS

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Re: [Elecraft] Sloping Terrain vs Feedline Losses

[Craig Smith]

Ted …

I think you are overstating the coax losses.   Even stock RG-11 should be 
perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.  

Even so, I would probably gravitate toward the closer location.  With the 
elevated radials, the effects of the ground conductivity should be minimal.   
Not sure if ON4UNs data assume elevated radials or many on-ground radials.  It 
could be that his estimate of the sloping ground advantage is for the later.   
With the closer location, you will have perhaps 1 dB stronger signal in all 
directions because of the lower feedline loss.

73Craig   AC0DS

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