Inverted-L (was OT: Vertical antenna)

[ARDUJENSKI]

Going from loop to vertical involves two very different lob patterns. It  
was never mentioned if the antenna performance was to favor local or DX. Here
is  one which it does not matter as it adapts for both.
 
A nice compromise antenna which takes into account:
---high and low angle lobe patterns
---good match (resonant on 80m)
---small footprint
 
======DESCRIPTION===============================


 
 INVERTED-L: 33 ft vertical, 33 ft top wire, feed at base against 12 16ft  
 radials. I use Radio Shack low loss 300 ohm tv wire for feed
 
 According to calculations EZNEC had a 40ft top wire. In the field I
trimmed it until we got an  
 acceptable match on several bands
 
 For supports I have used the DK9SQ mast as the main and used the Black
Widow  20ft
 for the end support with great success
 ----------------------------------------------------
 I use RCA connectors for many of my antennas. I install male RCAs on wires
 
 and interconnect with using DOUBLE FEMALES. For 300 ohm TV wire I will
solder  
 short piece of speaker wire to each of the conductors and then securely
tape
 the  soldered area to the ribbon insulator body . To the end of each
speaker
 wire I  afix a MALE RCA. Generally I will make one speaker wire on each
end a
 little  shorter (3/4 inch) so I can tell easily identify which wire is
which.
 The RCAs  work great and it they break off in the field I carry wire nuts
for  
 emergencies
 ----------------------------------------------------
 I have EZNEC pattern (PDF) for several bands and also a sketch for the  
300
 ohm connection if you want more details
 ----------------------------------------------------
 Note at the QTH I have used this for 80 and 160m with good success  
including
 contacts with Japan on 160m. I am sure the key is the other fellows  has
HUGE
 arrays but it worked.
 
 Hope this helps
 
 Alan KB7MBI
 



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[Guy, K2AV]

(For the record, I am also addressing some off-reflector extensions of
this thread with a single post.)

We are still talking about an end-fed antenna for 80-10 which presents
unique problems.  Trimming the horizontal length of up 30, out 30 for
a good match will help a lot.  But that will not address avoiding an
up to 10 dB loss problem in the radial system that can make it perform
like a wet noodle dipole.

Although there really is not that much published on this, LOCAL
research, I repeat, RESEARCH, does indicate a lossy booby trap in what
is done at the base with radials. Adding the high bands to the radial
calculations takes away from using any insulated radials because the
radials (MEASURED, not modeled) can have velocity factors as low as 45
percent and as high as 80 percent laid on or notched into the ground.
A range of 54 to 76 was measured in a single back yard, just moving
the site and orientation of the measurement.  Picking and keeping an
anti-resonant length for insulated radials, as in the vertical length,
is an impossibility.

If any of you want to prove this yourself, put down a 151 foot (46
meter) dipole on the ground (DOG).  Insulate the ends so they don't
short to ground and measure the resonance point and feed resistance.
Use the handbook formulas to compute velocity factor.  Scan across 160
through 40 meters and make a graph of the varying readings.  Let it
lay on top of the grass, measure it, notch it in and re-measure.
Measure in wet weather, and measure after things have dried out.
Measure it in different places in your yard, note how it changes. Post
your measurements as you go. Put down a 151' BARE WIRE dipole and lay
it on top of the grass.  Measure. Water it with a garden hose and
remeasure. Now notch it into the ground (needs to be in contact with
the dirt all the way) and remeasure.  In particular note how the feed
Z measurement levels out over frequency, how the Z remains more or
less constant across the frequency range.  This exercise will help you
in thinking about getting on 160 meters. It should also make you
really suspicious of insulated radial claims for multiband
applications.

I have a list of call signs who are dismissive of these radial
concerns AND ALSO argue that 0.3 dB is significant on RX.  This
particular schizophrenia is really hard to understand.  I understand
the reverse, someone who considers 0.3 dB significant being a really
snotty radial purist.  He's sweating the little dB parts any place he
can dig them up.

Don't wonder if this is truthful or not, or worry that it's not the
common wisdom (whatever that is).  Just go out and measure it
yourself, and spend a contemplative cup of coffee at a quiet time
about how YOUR measured results will effect use of radial wires on/in
the ground. In analyzing this, remember that this scales to 30 feet on
10 meters quite nicely, that the competition is multi-element yagis,
and if anything, ground losses on 10 meters are MORE significant than
low bands where the enemy has more of the same constraints.

Now contemplate how the ENDS of insulated wires are going to corrode
and arc through (that's a voltage point at the wire ends) over time
and change the radial system behavior over time.

You could prove in this bad behavior on 160 (where radials are common
and an everyday issue) if you want by putting down 120 insulated 250'
radials and do a time study. You don't hear about this, proving it's a
disaster, because people want to spend their precious constructing
time and even scarcer construction dollars on something that will
work, not disproving an idea that won't work.  That's NOT a dig at
anyone, radial construction time and money when you're raising a
family and/or building a career IS precious.

Insulated radials are subject to resonance effects which depend on
today's ground moisture to set today's velocity factor over/in your
particular dirt and complicate the performance of the radials in the
same way that the length of the vertical complicates selecting lengths
there.  The difference is that you get it set for the vertical wire
and you are done.  This becomes a ridiculous moving target for
choosing a decent multi-band length with an insulated wire on the
ground.

If you're looking for some validation in the commercial world, the
simple commercial reality is that most people simply do not want to
deal with radials, will short-cut the procedure and then blame the
awful results on the antenna itself.  Radials are a total commercial
nightmare for the ham market.   All the commercial manufacturers avoid
this conundrum by using some counterpoise technique on the high bands.

If the radials are not dense, the vertical wire will get the blame. It
will get the blame regardless of whether it is straight up or an L.
But the 1000 pound gorilla in the room was always the radials.  I do
not know why hamdom seems so oddly dismissive of this.  Putting
radials down IS a real PITA.  But 60 bare wire radials buried just
under the sod are completely invisible from the start, and lack of
this commercial FCC grade treatment of the problem is why so many
installations of an otherwise great stealth antenna fail.

When you are stealth, you have to squeeze every last dB drop of blood
out of that ground turnip.

73, Guy.

On Mon, Dec 20, 2010 at 10:45 AM,  <[hidden email]> wrote:

> Going from loop to vertical involves two very different lob patterns. It
> was never mentioned if the antenna performance was to favor local or DX. Here
> is  one which it does not matter as it adapts for both.
>
> A nice compromise antenna which takes into account:
> ---high and low angle lobe patterns
> ---good match (resonant on 80m)
> ---small footprint
>
> ======DESCRIPTION===============================
>
>
>
>  INVERTED-L: 33 ft vertical, 33 ft top wire, feed at base against 12 16ft
>  radials. I use Radio Shack low loss 300 ohm tv wire for feed
>
>  According to calculations EZNEC had a 40ft top wire. In the field I
> trimmed it until we got an
>  acceptable match on several bands
>
>  For supports I have used the DK9SQ mast as the main and used the Black
> Widow  20ft
>  for the end support with great success
>  ----------------------------------------------------
>  I use RCA connectors for many of my antennas. I install male RCAs on wires
>
>  and interconnect with using DOUBLE FEMALES. For 300 ohm TV wire I will
> solder
>  short piece of speaker wire to each of the conductors and then securely
> tape
>  the  soldered area to the ribbon insulator body . To the end of each
> speaker
>  wire I  afix a MALE RCA. Generally I will make one speaker wire on each
> end a
>  little  shorter (3/4 inch) so I can tell easily identify which wire is
> which.
>  The RCAs  work great and it they break off in the field I carry wire nuts
> for
>  emergencies
>  ----------------------------------------------------
>  I have EZNEC pattern (PDF) for several bands and also a sketch for the
> 300
>  ohm connection if you want more details
>  ----------------------------------------------------
>  Note at the QTH I have used this for 80 and 160m with good success
> including
>  contacts with Japan on 160m. I am sure the key is the other fellows  has
> HUGE
>  arrays but it worked.
>
>  Hope this helps
>
>  Alan KB7MBI
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Vic K2VCO]

Your post is a little elliptical, but am I to understand that you are saying that there
are resonant effects noted with in-ground radials when the wire is insulated, but not when
it's bare?

If that's true it's interesting and I hadn't heard it before. Most writers on the subject
simply say that if the wires are in or on the ground to ignore the question of resonance
and just make them as long as possible -- and they don't mention the use of insulated or
bare wire.

I have always thought that the connection to ground from an in- or on- ground radial
system was primarily capacitive and that insulation or lack thereof was irrelevant.

I'm not challenging what you say, just interested in the idea. I've always used insulated
wire just to improve resistance to corrosion.

On 12/20/2010 9:28 AM, Guy Olinger K2AV wrote:

> (For the record, I am also addressing some off-reflector extensions of
> this thread with a single post.)
>
> We are still talking about an end-fed antenna for 80-10 which presents
> unique problems.  Trimming the horizontal length of up 30, out 30 for
> a good match will help a lot.  But that will not address avoiding an
> up to 10 dB loss problem in the radial system that can make it perform
> like a wet noodle dipole.
>
> Although there really is not that much published on this, LOCAL
> research, I repeat, RESEARCH, does indicate a lossy booby trap in what
> is done at the base with radials. Adding the high bands to the radial
> calculations takes away from using any insulated radials because the
> radials (MEASURED, not modeled) can have velocity factors as low as 45
> percent and as high as 80 percent laid on or notched into the ground.
> A range of 54 to 76 was measured in a single back yard, just moving
> the site and orientation of the measurement.  Picking and keeping an
> anti-resonant length for insulated radials, as in the vertical length,
> is an impossibility.
>
> If any of you want to prove this yourself, put down a 151 foot (46
> meter) dipole on the ground (DOG).  Insulate the ends so they don't
> short to ground and measure the resonance point and feed resistance.
> Use the handbook formulas to compute velocity factor.  Scan across 160
> through 40 meters and make a graph of the varying readings.  Let it
> lay on top of the grass, measure it, notch it in and re-measure.
> Measure in wet weather, and measure after things have dried out.
> Measure it in different places in your yard, note how it changes. Post
> your measurements as you go. Put down a 151' BARE WIRE dipole and lay
> it on top of the grass.  Measure. Water it with a garden hose and
> remeasure. Now notch it into the ground (needs to be in contact with
> the dirt all the way) and remeasure.  In particular note how the feed
> Z measurement levels out over frequency, how the Z remains more or
> less constant across the frequency range.  This exercise will help you
> in thinking about getting on 160 meters. It should also make you
> really suspicious of insulated radial claims for multiband
> applications.
>
> I have a list of call signs who are dismissive of these radial
> concerns AND ALSO argue that 0.3 dB is significant on RX.  This
> particular schizophrenia is really hard to understand.  I understand
> the reverse, someone who considers 0.3 dB significant being a really
> snotty radial purist.  He's sweating the little dB parts any place he
> can dig them up.
>
> Don't wonder if this is truthful or not, or worry that it's not the
> common wisdom (whatever that is).  Just go out and measure it
> yourself, and spend a contemplative cup of coffee at a quiet time
> about how YOUR measured results will effect use of radial wires on/in
> the ground. In analyzing this, remember that this scales to 30 feet on
> 10 meters quite nicely, that the competition is multi-element yagis,
> and if anything, ground losses on 10 meters are MORE significant than
> low bands where the enemy has more of the same constraints.
>
> Now contemplate how the ENDS of insulated wires are going to corrode
> and arc through (that's a voltage point at the wire ends) over time
> and change the radial system behavior over time.
>
> You could prove in this bad behavior on 160 (where radials are common
> and an everyday issue) if you want by putting down 120 insulated 250'
> radials and do a time study. You don't hear about this, proving it's a
> disaster, because people want to spend their precious constructing
> time and even scarcer construction dollars on something that will
> work, not disproving an idea that won't work.  That's NOT a dig at
> anyone, radial construction time and money when you're raising a
> family and/or building a career IS precious.
>
> Insulated radials are subject to resonance effects which depend on
> today's ground moisture to set today's velocity factor over/in your
> particular dirt and complicate the performance of the radials in the
> same way that the length of the vertical complicates selecting lengths
> there.  The difference is that you get it set for the vertical wire
> and you are done.  This becomes a ridiculous moving target for
> choosing a decent multi-band length with an insulated wire on the
> ground.
>
> If you're looking for some validation in the commercial world, the
> simple commercial reality is that most people simply do not want to
> deal with radials, will short-cut the procedure and then blame the
> awful results on the antenna itself.  Radials are a total commercial
> nightmare for the ham market.   All the commercial manufacturers avoid
> this conundrum by using some counterpoise technique on the high bands.
>
> If the radials are not dense, the vertical wire will get the blame. It
> will get the blame regardless of whether it is straight up or an L.
> But the 1000 pound gorilla in the room was always the radials.  I do
> not know why hamdom seems so oddly dismissive of this.  Putting
> radials down IS a real PITA.  But 60 bare wire radials buried just
> under the sod are completely invisible from the start, and lack of
> this commercial FCC grade treatment of the problem is why so many
> installations of an otherwise great stealth antenna fail.
>
> When you are stealth, you have to squeeze every last dB drop of blood
> out of that ground turnip.
>
> 73, Guy.

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[k6rb]

Another antenna for top band that's worth considering is a Double L (Don
Toman, K2KQ) www.yccc.org/Articles/double_l.htm  . It is essentially a
vertical dipole with the ends bent parallel to the ground and in the same
vertical plane. So, if you have, say, a 70 foot or higher tower, you can
raise the bottom horizontal wire up 10 feet off the ground and the top one
at 70 feet. The pattern is primarily influenced by the 60 foot (center
fed) vertical section (omni directional with decent low-angle lobes). I
find it works well both long-haul and close in. Because it is a vertical
dipole, the ground return is via the lower vertical/horizontal
(non-non-inverted L). So, no need for radials, just the one 105 foot
horizonal wire at 10 feet. I have mine hanging off the tower with bungee
cords at 72 and 10 feet. The vertical portion is parallel to the tower and
about 24 inches from it. Both horizontal portions go to the same tree (the
tree is not high enough, so the my antenna looks more like a pennant than
a true Double L). But, it does work. Compared with inverted Ls, half
slopers, and other antennas I've tried, this one has been the most
reliable.

Rob K6RB

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[Guy, K2AV]

Elliptical?  I suppose so.  But simply stating the facts seems to have
little effect and just gets bashed, where wading through the issues,
however elliptical, seems to give the nay-sayers some pause, and have
some effect.  Radials, even in 2010, 80 years after the last
definitive research, are still the undiscovered country, aside from
the FCC mandated treatment for commercial BC band antenna systems.

To answer your question, practically speaking, yes.  Go make yourself
an insulated 151' DOG and note how you can find a resonance. Repeat
with a notched into the ground bare wire version.  The primary
resonance is QUITE clear and pronounced on the insulated DOG. The
"third harmonic" dip on the insulated DOG is less pronounced than the
primary resonance and oddly skewed from a times three frequency. But
the resonance effects at even harmonics can move the field
cancellation effect  (or current return as some term it), one of the
benefits of radials, off optimum by moving the primary current max in
the radial wire away from the center. This last effect of "too long"
radials is documented by ON4UN in one of his older books, but not
related to it's possible consequences in a multiband use of a given
radial field. Though this is a very fuzzy figure, I don't see
insulated wires terminating in less than 500+.  Use of bare wire
notched into the ground minimizes the self-termination length for the
even harmonics of the effective.

It is a VERY elliptical connection, but needing to specify a length
for the intentionally insulated BOG receiving antenna to get good
front to back, and varying the termination resistance from typical
beverage, is a reverse proof of the same issue, e.g. that with
insulated wire on the ground, you have to pay attention to reflection
and resonance effects.  A 235' BOG is not long enough for
self-termination to take control of measurements.

73, Guy.

On Mon, Dec 20, 2010 at 12:46 PM, Vic K2VCO <[hidden email]> wrote:

> Your post is a little elliptical, but am I to understand that you are saying that there
> are resonant effects noted with in-ground radials when the wire is insulated, but not when
> it's bare?
>
> If that's true it's interesting and I hadn't heard it before. Most writers on the subject
> simply say that if the wires are in or on the ground to ignore the question of resonance
> and just make them as long as possible -- and they don't mention the use of insulated or
> bare wire.
>
> I have always thought that the connection to ground from an in- or on- ground radial
> system was primarily capacitive and that insulation or lack thereof was irrelevant.
>
> I'm not challenging what you say, just interested in the idea. I've always used insulated
> wire just to improve resistance to corrosion.
>
> On 12/20/2010 9:28 AM, Guy Olinger K2AV wrote:
>> (For the record, I am also addressing some off-reflector extensions of
>> this thread with a single post.)
>>
>> We are still talking about an end-fed antenna for 80-10 which presents
>> unique problems.  Trimming the horizontal length of up 30, out 30 for
>> a good match will help a lot.  But that will not address avoiding an
>> up to 10 dB loss problem in the radial system that can make it perform
>> like a wet noodle dipole.
>>
>> Although there really is not that much published on this, LOCAL
>> research, I repeat, RESEARCH, does indicate a lossy booby trap in what
>> is done at the base with radials. Adding the high bands to the radial
>> calculations takes away from using any insulated radials because the
>> radials (MEASURED, not modeled) can have velocity factors as low as 45
>> percent and as high as 80 percent laid on or notched into the ground.
>> A range of 54 to 76 was measured in a single back yard, just moving
>> the site and orientation of the measurement.  Picking and keeping an
>> anti-resonant length for insulated radials, as in the vertical length,
>> is an impossibility.
>>
>> If any of you want to prove this yourself, put down a 151 foot (46
>> meter) dipole on the ground (DOG).  Insulate the ends so they don't
>> short to ground and measure the resonance point and feed resistance.
>> Use the handbook formulas to compute velocity factor.  Scan across 160
>> through 40 meters and make a graph of the varying readings.  Let it
>> lay on top of the grass, measure it, notch it in and re-measure.
>> Measure in wet weather, and measure after things have dried out.
>> Measure it in different places in your yard, note how it changes. Post
>> your measurements as you go. Put down a 151' BARE WIRE dipole and lay
>> it on top of the grass.  Measure. Water it with a garden hose and
>> remeasure. Now notch it into the ground (needs to be in contact with
>> the dirt all the way) and remeasure.  In particular note how the feed
>> Z measurement levels out over frequency, how the Z remains more or
>> less constant across the frequency range.  This exercise will help you
>> in thinking about getting on 160 meters. It should also make you
>> really suspicious of insulated radial claims for multiband
>> applications.
>>
>> I have a list of call signs who are dismissive of these radial
>> concerns AND ALSO argue that 0.3 dB is significant on RX.  This
>> particular schizophrenia is really hard to understand.  I understand
>> the reverse, someone who considers 0.3 dB significant being a really
>> snotty radial purist.  He's sweating the little dB parts any place he
>> can dig them up.
>>
>> Don't wonder if this is truthful or not, or worry that it's not the
>> common wisdom (whatever that is).  Just go out and measure it
>> yourself, and spend a contemplative cup of coffee at a quiet time
>> about how YOUR measured results will effect use of radial wires on/in
>> the ground. In analyzing this, remember that this scales to 30 feet on
>> 10 meters quite nicely, that the competition is multi-element yagis,
>> and if anything, ground losses on 10 meters are MORE significant than
>> low bands where the enemy has more of the same constraints.
>>
>> Now contemplate how the ENDS of insulated wires are going to corrode
>> and arc through (that's a voltage point at the wire ends) over time
>> and change the radial system behavior over time.
>>
>> You could prove in this bad behavior on 160 (where radials are common
>> and an everyday issue) if you want by putting down 120 insulated 250'
>> radials and do a time study. You don't hear about this, proving it's a
>> disaster, because people want to spend their precious constructing
>> time and even scarcer construction dollars on something that will
>> work, not disproving an idea that won't work.  That's NOT a dig at
>> anyone, radial construction time and money when you're raising a
>> family and/or building a career IS precious.
>>
>> Insulated radials are subject to resonance effects which depend on
>> today's ground moisture to set today's velocity factor over/in your
>> particular dirt and complicate the performance of the radials in the
>> same way that the length of the vertical complicates selecting lengths
>> there.  The difference is that you get it set for the vertical wire
>> and you are done.  This becomes a ridiculous moving target for
>> choosing a decent multi-band length with an insulated wire on the
>> ground.
>>
>> If you're looking for some validation in the commercial world, the
>> simple commercial reality is that most people simply do not want to
>> deal with radials, will short-cut the procedure and then blame the
>> awful results on the antenna itself.  Radials are a total commercial
>> nightmare for the ham market.   All the commercial manufacturers avoid
>> this conundrum by using some counterpoise technique on the high bands.
>>
>> If the radials are not dense, the vertical wire will get the blame. It
>> will get the blame regardless of whether it is straight up or an L.
>> But the 1000 pound gorilla in the room was always the radials.  I do
>> not know why hamdom seems so oddly dismissive of this.  Putting
>> radials down IS a real PITA.  But 60 bare wire radials buried just
>> under the sod are completely invisible from the start, and lack of
>> this commercial FCC grade treatment of the problem is why so many
>> installations of an otherwise great stealth antenna fail.
>>
>> When you are stealth, you have to squeeze every last dB drop of blood
>> out of that ground turnip.
>>
>> 73, Guy.
>
>
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>

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[Don Wilhelm-4]

  Guy,

I know it is not equal to your statements, but in my mind you are making
a good case for the use of elevated (and tuned) radials.  L B Cebik
recommended them to me at FDIM several years ago over in-ground radials
and I have never done the work of burying the radials, so I have no
comparison.  Mine are supported on electric fence insulators in the
trees 10 feet up, and the monopole and radials are tuned together using
the techniques outlined in UN4ON's Low-Band DXing (page 9-23).
The radiator is the 40/80 vertical/160 inverted L BC-Trapper also
described in the same book. (yes, I have radials for 40 and for 80 and
for 160).

It works well for me, and no way did I want to dig through the tree
roots in the forest nor trip over wires on the ground when I wanted to
take a walk.

There are good reports of elevated radials, although some measurements
by Tom Rauch W8JI indicated some disagreement, but for my situation it
is the best solution despite any controversy.

73,
Don W3FPR

On 12/20/2010 12:28 PM, Guy Olinger K2AV wrote:
> (For the record, I am also addressing some off-reflector extensions of
> this thread with a single post.)
>
> We are still talking about an end-fed antenna for 80-10 which presents
> unique problems.  Trimming the horizontal length of up 30, out 30 for
> a good match will help a lot.  But that will not address avoiding an
> up to 10 dB loss problem in the radial system that can make it perform
> like a wet noodle dipole.
>
______________________________________________________________
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Steve Ellington]

Guy:
Very interesting....

Some of your comments were verified in a recent QST article.

Mar 2010 - QST (Pg. 30)

An Experimental Look at Ground Systems for HF Verticals
The author experimented with resonant vs nonresonant radials on the ground
and found performance improved when the radials were cut to electrical
resonance vs just measuring them with a tape.

Given this, it stands to reason that if the same radial field is used by a
multiband vertical on a higher frequency, the high current point would be at
some distance from the antenna's base thus reducing efficiency.

Now here's the question....
Folks assume ground radials to be (non resonant) but that isn't the case. So
what would be the best solution for a multiband antenna with ground radials?
Well if we follow this idea, we would need multiple 1/4 wavelength radials
for each HF band for best performance.

My inverted L is 50' up and 150' out. I use a separate elevated counterpoise
for each band. I've found that a ground rod and some buried radials have
virtually no effect. I just use them for lightning protection.

Steve
N4LQ

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[Phil Kane-2]

On 12/20/2010 1:48 PM, Don Wilhelm wrote:

> There are good reports of elevated radials, although some measurements
> by Tom Rauch W8JI indicated some disagreement, but for my situation it
> is the best solution despite any controversy.

  Elevated radials are great until the metal thieves get around
  to stealing them for scrap, as many broadcasters have found out
  even with buried radials.  Protection of ground systems against
  theft is a very hot topic in the broadcast engineering community.

--  73 de K2ASP - Phil Kane
    Elecraft K2/100   s/n 5402
    SBE Chapter 124 Vice-Chair
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[Mel]

It is a matter of loss or lack of it.  If you look at the takeoff patterns of a
vertical antenna on a perfect ground and then with increasing loss, the pattern
is modified to have increasing less energy on the horizon.  However, this is the
loss factor, not necessarily due to lack of resonance.  As one removes the
antenna network from direct ground, and substitutes radials, several things
happen.  IF, and that is a big IF, the amount of coupling to ground is
maintained with non resonant radials or resonant radials are used, eff and match
will remain .  Example, a mag mount antenna or a ground plane vertical with
three or four resonant radials works fine and any elevation.  Just a point of
thought.

Mel, K6KBE






________________________________
From: Steve Ellington <[hidden email]>
To: Guy Olinger K2AV <[hidden email]>; Vic K2VCO <[hidden email]>
Cc: [hidden email]
Sent: Mon, December 20, 2010 3:44:28 PM
Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna)

Guy:
Very interesting....

Some of your comments were verified in a recent QST article.

Mar 2010 - QST (Pg. 30)

An Experimental Look at Ground Systems for HF Verticals
The author experimented with resonant vs nonresonant radials on the ground
and found performance improved when the radials were cut to electrical
resonance vs just measuring them with a tape.

Given this, it stands to reason that if the same radial field is used by a
multiband vertical on a higher frequency, the high current point would be at
some distance from the antenna's base thus reducing efficiency.

Now here's the question....
Folks assume ground radials to be (non resonant) but that isn't the case. So
what would be the best solution for a multiband antenna with ground radials?
Well if we follow this idea, we would need multiple 1/4 wavelength radials
for each HF band for best performance.

My inverted L is 50' up and 150' out. I use a separate elevated counterpoise
for each band. I've found that a ground rod and some buried radials have
virtually no effect. I just use them for lightning protection.

Steve
N4LQ

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[Kok Chen]

On Dec 20, 2010, at 12/20    3:44 PM, Steve Ellington wrote:

> Some of your comments were verified in a recent QST article.
>
> Mar 2010 - QST (Pg. 30)

A more complete version of Rudy's study are in 6 parts in the 2009  
issues of QEX.

"Experimental Determination of Ground System Performance for HF  
Verticals," R. Severns, N6LF.

Part III (Mar/Apr issue) compared elevated radials with ground surface  
radials.

The 6 parts are in a single ARRL annual periodical CD-ROM for 2009 as  
PDF files.

http://www.arrl.org/shop/ARRL-Periodicals-on-CD-ROM/

73
Chen, W7AY

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CONTENTS DELETED

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[Don Wilhelm-4]

  Mel,

I personally would not consider elevated radials that are non-resonant -
but then all of my antennas are resonant.

I could consider something "balanced", like a 43 foot vertical having 43
foot elevated radials and being fed with parallel feedline to the
location of the tuner.  I would equate that to a dipole having 43 foot
elements on each side of the feedline, but oriented in a different
fashion to take advantage of things like the low angle radiation of a
vertical antenna.

I am not on the edge of salt water, so the great low angle "advantage"
of a vertical is not available to me.  I recently bought a (used) GAP
Titan DX antenna, and installed it - it pales in comparison to my modest
height resonant dipoles, and I have made comparisons with DX stations as
well as distant domestic stations - the horizontal dipoles always are
better.  I was expecting better results for the vertical on DX, but
failed to find it.  (anyone want to buy a GAP Titan DX for about half
the price of a new one?).

73,
Don W3FPR



On 12/20/2010 6:56 PM, Mel Farrer wrote:

> It is a matter of loss or lack of it.  If you look at the takeoff patterns of a
> vertical antenna on a perfect ground and then with increasing loss, the pattern
> is modified to have increasing less energy on the horizon.  However, this is the
> loss factor, not necessarily due to lack of resonance.  As one removes the
> antenna network from direct ground, and substitutes radials, several things
> happen.  IF, and that is a big IF, the amount of coupling to ground is
> maintained with non resonant radials or resonant radials are used, eff and match
> will remain .  Example, a mag mount antenna or a ground plane vertical with
> three or four resonant radials works fine and any elevation.  Just a point of
> thought.
>
> Mel, K6KBE
>
>
>
>
>
>
> ________________________________
> From: Steve Ellington<[hidden email]>
> To: Guy Olinger K2AV<[hidden email]>; Vic K2VCO<[hidden email]>
> Cc: [hidden email]
> Sent: Mon, December 20, 2010 3:44:28 PM
> Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna)
>
> Guy:
> Very interesting....
>
> Some of your comments were verified in a recent QST article.
>
> Mar 2010 - QST (Pg. 30)
>
> An Experimental Look at Ground Systems for HF Verticals
> The author experimented with resonant vs nonresonant radials on the ground
> and found performance improved when the radials were cut to electrical
> resonance vs just measuring them with a tape.
>
> Given this, it stands to reason that if the same radial field is used by a
> multiband vertical on a higher frequency, the high current point would be at
> some distance from the antenna's base thus reducing efficiency.
>
> Now here's the question....
> Folks assume ground radials to be (non resonant) but that isn't the case. So
> what would be the best solution for a multiband antenna with ground radials?
> Well if we follow this idea, we would need multiple 1/4 wavelength radials
> for each HF band for best performance.
>
> My inverted L is 50' up and 150' out. I use a separate elevated counterpoise
> for each band. I've found that a ground rod and some buried radials have
> virtually no effect. I just use them for lightning protection.
>
> Steve
> N4LQ
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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>
>
>
>
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[David Gilbert]

"I personally would not consider elevated radials that are non-resonant"


I guess I'm having a difficult time with that comment.  You can have a
resonant system without the elevated radials themselves being
"resonant"  ... i.e, any two of them acting like a resonant dipole.  If
the elevated radials are shorter than a 1/4 wavelength, all that is
required is that the vertical section be a little longer than a 1/4
wavelength to compensate.  If the radials are longer than a 1/4
wavelength, the vertical section needs to be shorter than a 1/4
wavelength for resonance.

Elevated radials are kind of like the lower half of a vertical 1/2
wavelength dipole except that it is "fanned out" for symmetry, and if
the radials are longer or shorter than half of a 1/2 wavelength dipole
the feedpoint simply behaves similarly to an off-center fed dipole.  You
can prove this to yourself with EZNEC ... start with a vertical section
longer than 1/4 wavelength and see what length radials you need to have
a resonant feedpoint.  Then do the same thing with different lengths of
vertical sections and see the effect on radiation pattern.   I can tell
you that it isn't a direct function of radial resonance.

I could be wrong, but I don't see any need at all for the radials to be
"resonant" on their own.  You want system resonance and generally
speaking, for radiation effectiveness you want as long a vertical
section as you can manage.  You might want to choose a vertical section
somewhat longer than a 1/4 wavelength and radials correspondingly
shorter than a 1/4 wavelength in order to take advantage of that
"off-center feed" aspect I mentioned in order to get a 50 ohm match.

The only situation where resonant radials might be required is if you're
trying to decouple whatever is on the other side of the radials.  In
that case, the radials act like a choke to keep current on the feedpoint
side of the resonant radials.  You can see that effect with EZNEC as well.

73,
Dave   AB7E




On 12/20/2010 5:25 PM, Don Wilhelm wrote:

>    Mel,
>
> I personally would not consider elevated radials that are non-resonant -
> but then all of my antennas are resonant.
>
> I could consider something "balanced", like a 43 foot vertical having 43
> foot elevated radials and being fed with parallel feedline to the
> location of the tuner.  I would equate that to a dipole having 43 foot
> elements on each side of the feedline, but oriented in a different
> fashion to take advantage of things like the low angle radiation of a
> vertical antenna.
>
> I am not on the edge of salt water, so the great low angle "advantage"
> of a vertical is not available to me.  I recently bought a (used) GAP
> Titan DX antenna, and installed it - it pales in comparison to my modest
> height resonant dipoles, and I have made comparisons with DX stations as
> well as distant domestic stations - the horizontal dipoles always are
> better.  I was expecting better results for the vertical on DX, but
> failed to find it.  (anyone want to buy a GAP Titan DX for about half
> the price of a new one?).
>
> 73,
> Don W3FPR
>
>
>
> On 12/20/2010 6:56 PM, Mel Farrer wrote:
>> It is a matter of loss or lack of it.  If you look at the takeoff patterns of a
>> vertical antenna on a perfect ground and then with increasing loss, the pattern
>> is modified to have increasing less energy on the horizon.  However, this is the
>> loss factor, not necessarily due to lack of resonance.  As one removes the
>> antenna network from direct ground, and substitutes radials, several things
>> happen.  IF, and that is a big IF, the amount of coupling to ground is
>> maintained with non resonant radials or resonant radials are used, eff and match
>> will remain .  Example, a mag mount antenna or a ground plane vertical with
>> three or four resonant radials works fine and any elevation.  Just a point of
>> thought.
>>
>> Mel, K6KBE
>>
>>
>>
>>
>>
>>
>> ________________________________
>> From: Steve Ellington<[hidden email]>
>> To: Guy Olinger K2AV<[hidden email]>; Vic K2VCO<[hidden email]>
>> Cc: [hidden email]
>> Sent: Mon, December 20, 2010 3:44:28 PM
>> Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna)
>>
>> Guy:
>> Very interesting....
>>
>> Some of your comments were verified in a recent QST article.
>>
>> Mar 2010 - QST (Pg. 30)
>>
>> An Experimental Look at Ground Systems for HF Verticals
>> The author experimented with resonant vs nonresonant radials on the ground
>> and found performance improved when the radials were cut to electrical
>> resonance vs just measuring them with a tape.
>>
>> Given this, it stands to reason that if the same radial field is used by a
>> multiband vertical on a higher frequency, the high current point would be at
>> some distance from the antenna's base thus reducing efficiency.
>>
>> Now here's the question....
>> Folks assume ground radials to be (non resonant) but that isn't the case. So
>> what would be the best solution for a multiband antenna with ground radials?
>> Well if we follow this idea, we would need multiple 1/4 wavelength radials
>> for each HF band for best performance.
>>
>> My inverted L is 50' up and 150' out. I use a separate elevated counterpoise
>> for each band. I've found that a ground rod and some buried radials have
>> virtually no effect. I just use them for lightning protection.
>>
>> Steve
>> N4LQ
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
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>>
> ______________________________________________________________
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[Don Wilhelm-4]

  Dave,

If you read the radial tuning procedure in Low-Band DXing, you will find
that it "all comes out in the wash".  Yes, your statements are correct,
and in fact that is how I did mine. Although  I did not resonate my
vertical monopole against any ground plane - I simply cut the lengths to
what was stated in the article, and then cut each radial to resonate
with that particular length of the "monopole".  If the result was
slightly "off-center fed", so be it, the impedance and the resonance
point obtained were a good match for 50 ohm coax, and I left it at that.

OK, so the ideal impedance of a vertical antenna is 32 ohms - I got
closer to 50 ohms which indicates a 15 ohm loss in signal efficiency.  
It matches my feedline nicely, and I an willing to accept the the 3%
loss in efficiency that represents.

The ground conductivity in my area is not the greatest, so I have
accepted the logical consequences of that fact.

73,
Don W3FPR


On 12/20/2010 8:06 PM, David Gilbert wrote:

> "I personally would not consider elevated radials that are non-resonant"
>
>
> I guess I'm having a difficult time with that comment.  You can have a
> resonant system without the elevated radials themselves being
> "resonant"  ... i.e, any two of them acting like a resonant dipole.  If
> the elevated radials are shorter than a 1/4 wavelength, all that is
> required is that the vertical section be a little longer than a 1/4
> wavelength to compensate.  If the radials are longer than a 1/4
> wavelength, the vertical section needs to be shorter than a 1/4
> wavelength for resonance.
>
> Elevated radials are kind of like the lower half of a vertical 1/2
> wavelength dipole except that it is "fanned out" for symmetry, and if
> the radials are longer or shorter than half of a 1/2 wavelength dipole
> the feedpoint simply behaves similarly to an off-center fed dipole.  You
> can prove this to yourself with EZNEC ... start with a vertical section
> longer than 1/4 wavelength and see what length radials you need to have
> a resonant feedpoint.  Then do the same thing with different lengths of
> vertical sections and see the effect on radiation pattern.   I can tell
> you that it isn't a direct function of radial resonance.
>
> I could be wrong, but I don't see any need at all for the radials to be
> "resonant" on their own.  You want system resonance and generally
> speaking, for radiation effectiveness you want as long a vertical
> section as you can manage.  You might want to choose a vertical section
> somewhat longer than a 1/4 wavelength and radials correspondingly
> shorter than a 1/4 wavelength in order to take advantage of that
> "off-center feed" aspect I mentioned in order to get a 50 ohm match.
>
> The only situation where resonant radials might be required is if you're
> trying to decouple whatever is on the other side of the radials.  In
> that case, the radials act like a choke to keep current on the feedpoint
> side of the resonant radials.  You can see that effect with EZNEC as well.
>
> 73,
> Dave   AB7E
>

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[Guy, K2AV]

Buried BARE radials of sufficient number will show far less "tuned"
behavior and self-terminate more rapidly.

BURIED bare wire radials and ON THE GROUND bare radials measure quite
differently.  This too is something you can verify by experimenting
with a bare wire DOG on top of the ground vs an entirely buried bare
wire DOG.  It is important to keep all the permutations cataloged and
separate in the discussion.

Many people are adopting a construction technique as primary over
performance considerations, e.g. lay out wire and hold them down with
lawn staples and let the grass grow up around them, holding them in
suspension OVER the dirt, rather than notching them DOWN INTO the
dirt. Grass supported bare wire radials will exhibit tuned
characteristics and a higher velocity factor than buried bare radials.
 As this is almost exclusively done for a single band antenna, it is
completely satisfactory for its intentions.  It's the MULTI-BANDING
that throws a monkey wrench into the works.

My original posting is specifies BURIED BARE WIRE radials, placed by
notching them into the dirt below the grass, (no laying them on top of
the grass).  These buried bare radials will be essentially self
terminating at frequencies where they electrically exceed a quarter
wavelength. and will exhibit a much lower velocity factor than those
supported in the grass weave.  On frequencies where the buried bare
radials electrically are shorter than a quarter wavelength (lower
bands), depending on the dirt, even buried bare radials can show some
of the tuned behavior of on-top or insulated radials because the
radials have not reached a self terminating length.

Insulated radials will always show significant tuned behavior.  With
the 151' insulated wire DOG, I can always find resonance, whether
buried or lightly strewn across the leaves touching nary even a single
blade of grass.

The controversy that I am aware of concerns purported RF current in
the ground itself and concentric zones of conduction set up by
interaction between the vertical element and the radial-induced
spreading ground current, similar to Fresnel zones.

73, Guy.

On Mon, Dec 20, 2010 at 6:44 PM, Steve Ellington <[hidden email]> wrote:

> Guy:
> Very interesting....
>
> Some of your comments were verified in a recent QST article.
>
> Mar 2010 - QST (Pg. 30)
>
> An Experimental Look at Ground Systems for HF Verticals
> The author experimented with resonant vs nonresonant radials on the ground
> and found performance improved when the radials were cut to electrical
> resonance vs just measuring them with a tape.
>
> Given this, it stands to reason that if the same radial field is used by a
> multiband vertical on a higher frequency, the high current point would be at
> some distance from the antenna's base thus reducing efficiency.
>
> Now here's the question....
> Folks assume ground radials to be (non resonant) but that isn't the case. So
> what would be the best solution for a multiband antenna with ground radials?
> Well if we follow this idea, we would need multiple 1/4 wavelength radials
> for each HF band for best performance.
>
> My inverted L is 50' up and 150' out. I use a separate elevated counterpoise
> for each band. I've found that a ground rod and some buried radials have
> virtually no effect. I just use them for lightning protection.
>
> Steve
> N4LQ
>

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[Tony Estep]

For those who wish to pursue the radials question further, here's one of the
many publications on the subject. This one is replete with numerous tables
and graphical representations of the incremental value of more and longer
radials in various types of soil:

http://www.ncjweb.com/k3lcmaxgainradials.pdf



Tony KT0NY
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[Guy, K2AV]

15 ohms miscellaneous in series with 32 ohm radiation resistance, only
3%?  Don't you mean 30%?

What were the lengths of the elevated radials and how many?

73, Guy.

On Mon, Dec 20, 2010 at 8:27 PM, Don Wilhelm <[hidden email]> wrote:

>  Dave,
>
> If you read the radial tuning procedure in Low-Band DXing, you will find
> that it "all comes out in the wash".  Yes, your statements are correct,
> and in fact that is how I did mine. Although  I did not resonate my
> vertical monopole against any ground plane - I simply cut the lengths to
> what was stated in the article, and then cut each radial to resonate
> with that particular length of the "monopole".  If the result was
> slightly "off-center fed", so be it, the impedance and the resonance
> point obtained were a good match for 50 ohm coax, and I left it at that.
>
> OK, so the ideal impedance of a vertical antenna is 32 ohms - I got
> closer to 50 ohms which indicates a 15 ohm loss in signal efficiency.
> It matches my feedline nicely, and I an willing to accept the the 3%
> loss in efficiency that represents.
>
> The ground conductivity in my area is not the greatest, so I have
> accepted the logical consequences of that fact.
>
> 73,
> Don W3FPR
>
>
> On 12/20/2010 8:06 PM, David Gilbert wrote:
>> "I personally would not consider elevated radials that are non-resonant"
>>
>>
>> I guess I'm having a difficult time with that comment.  You can have a
>> resonant system without the elevated radials themselves being
>> "resonant"  ... i.e, any two of them acting like a resonant dipole.  If
>> the elevated radials are shorter than a 1/4 wavelength, all that is
>> required is that the vertical section be a little longer than a 1/4
>> wavelength to compensate.  If the radials are longer than a 1/4
>> wavelength, the vertical section needs to be shorter than a 1/4
>> wavelength for resonance.
>>
>> Elevated radials are kind of like the lower half of a vertical 1/2
>> wavelength dipole except that it is "fanned out" for symmetry, and if
>> the radials are longer or shorter than half of a 1/2 wavelength dipole
>> the feedpoint simply behaves similarly to an off-center fed dipole.  You
>> can prove this to yourself with EZNEC ... start with a vertical section
>> longer than 1/4 wavelength and see what length radials you need to have
>> a resonant feedpoint.  Then do the same thing with different lengths of
>> vertical sections and see the effect on radiation pattern.   I can tell
>> you that it isn't a direct function of radial resonance.
>>
>> I could be wrong, but I don't see any need at all for the radials to be
>> "resonant" on their own.  You want system resonance and generally
>> speaking, for radiation effectiveness you want as long a vertical
>> section as you can manage.  You might want to choose a vertical section
>> somewhat longer than a 1/4 wavelength and radials correspondingly
>> shorter than a 1/4 wavelength in order to take advantage of that
>> "off-center feed" aspect I mentioned in order to get a 50 ohm match.
>>
>> The only situation where resonant radials might be required is if you're
>> trying to decouple whatever is on the other side of the radials.  In
>> that case, the radials act like a choke to keep current on the feedpoint
>> side of the resonant radials.  You can see that effect with EZNEC as well.
>>
>> 73,
>> Dave   AB7E
>>
> ______________________________________________________________
> Elecraft mailing list
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