[TenTec] Radial Research
d.e.warnick at comcast.net
d.e.warnick at comcast.net
Sat May 19 07:08:57 PDT 2012
I can't help myself. I've got to reply. Billy, everything that you point out is correct & is necessary to understand if one is to maximize his/her antenna system. However, you have ignored Rick's premise that I have left in his post at the end of this.
The statement that Rudi's work is excellent should not be ignored. Rick further points out that he is addressing the ham with little real estate, etc. Qui te frankly, for many of us, this is a hobby, not an avocation. We are fully capable of understanding most of what Rudi has written. True engineering & design of antenna systems (or anything else) is the application of the learned facts (not ham lore) in a given situation. That includes QTH, time available, desire to expend countless hours measuring & pruning, etc.
I would love to be a big gun with multiple rotating towers & stacks of beams. That has not, & will not, happen. I'm on 1.6 acres. I have done a lot with Rx loops & am looking at a 4-square solution. However, There is no way, based on the layout of the property, that I can string all of the radials that I would need to improve my system. I can tell you that in my situation, based on actual trials, my 1/ 4 wave 80 M vert & my 160 M Tee, each with 2 raised 1/4 wavelength long radials & both fed with Davi s Bury-Flex perform better than did my 300+ ft dipole at 65 or 80 feet (I've got some really tall trees). Yes, I did a lot of calculations & measurements & adjustments to get it where it is now. By perform better, I mean that I am now working more DX and have added to my DXCC total. That's my goal, not building an antenna that is a few db hotter at the expense of lots of $ & time that can be better spent (for me) by operating.
One of my fears (based on some of my early ham experiences) is that the ham who is new to all of this will be turned off by all of the 'hype' that you cannot have a working vertical antenna unless you have 40 to 160 radials & spend endless hours pruning it. Yes, it would be better, but 40 years ago, I did not experiment with verticals largely because all of the technical data showed that it would be too complex for me to handle. Then I read a book by W6SAI ( Bill Orr, SK). He knew more than I ever will, but he presented it to the layman. He also made clear that it was OK to try things that didn't work as well as those built by some of the 'experts'. While I'm sure that it is not your intent, I fear that we may turn off some of our new hams with our insistence that anything but perfection is unacceptable.
Thanks for the bandwidth to rant. There's no disrespect intended in anything I've written
----- Original Message -----
From: "Billy Cox" <aa4nu at ix.netcom.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Saturday, May 19, 2012 7:35:02 AM
Subject: Re: [TenTec] Radial Research
Once again, I would suggest that we are tossing out
"ham lore" without an accurate basis of support, see
below please and let's walk through your statements
Rick, I tend to agree with most of your posts over
the years, but am going pushing back on some statements
made in this post, not on a personal basis, rather with
a trend in our hobby for sadly what seems to be a loss
of technical accuracy, my reply is simply an attempt to
change the tide and help others to better understand
HOW all this really works.
OK, can we agree on that focus please? I hope so.
Certainly each of us makes do with the best we can,
however to make broad statements without any real
technical support is at best misleading, and worst
are outright falsehoods to those who are interested.
There are solid technical reasons the majority of
broadcast stations have not abandoned their ground
radial systems in favor of elevated radials.
So let's look at what we DO agree on first.
Do elevated radials systems "work"? Yes.
Are they "better" than no antenna? Yes.
How "well" do they really work in most cases?
Here I am afraid we may be on different walks
in the land of RF. Why would our answers vary?
No one knows UNLESS they do their diligence!
N6LF did such, and then some decided to make
their up their own skewed conclusions, which
then lead to his follow-up letter saying WHOA,
it's not that easy to replicate 100% acceptable
results, especially with only 4 elevated radials
QSL so far?
Now how many are going to PROPERLY replicate his
effort needed for 10-12 elevated radials? And
what did he say, and then restate about simple
systems or systems built without measurements?
Despite inaccurate postings, there is still no free
lunch as to our antennas and how they work best.
For someone to read a posting that says elevated
radials are THE WAY to go and then run and do their
best to just build such in their backyard thinking
WOW I will have low losses, this is really going to
be better than jelly on a hot biscuit ... and then
they wonder why it does not play as expected?
Such is sad, because the RF devil is in the details!
And shame on us for not accurately sharing what is
going to be required for such performance. I am
not speaking of trying to find the last tenth of a
dB, rather the dBs of loss for not understanding
what is required for the system to work properly.
A radial being at resonance as a sign of efficiency
is not correct. My dummy load also appears to have
resonance, but that unit is a very very poor antenna!
The statement was made saying, "Considering that,
when someone says if I don't get it perfect, I will
have 2 to 3 dB pattern distortion and 1 to 2 dB of
additional loss. hey, let's get real."
Hey, I agree, let's get real. You just posted what
I label "ham lore". You and I really DO NOT know
that the loss for WX0ABC in his back yard will only
be the numbers you tossed out, do we? No, we do not.
Due to houses, trees, other wire antennas, towers,
power lines, etc. ... it could just as well be stated
as 20 to 30 dB pattern distortion and 10 to 20 dB
of additional loss. We can't promise WX0ABC that if
he or she does what we do, it will play 100% exactly
as what we might have done in our 100 acre field
with no objects to cause losses in the pattern.
Or what if WX0ABC lives on a lot where he can hear
and see the ocean's waves because he is that close
to the salt water and his back yard verses the little
dirt and much rock here at my Tennessee QTH?
Could we agree that the same exact 'system' installed
at WX0ABC's beach front property is NOT going to
perform the same as it would in my backyard here,
or at your side of hill location there in Germany?
Why, because there are fundamental differences that
cannot be ignored, but many want to overlook such.
Posts suggesting exactly that are made frequently
despite what the data, go re-read N6LF's details, is
actually telling us to be aware of the losses when
we don't carefully replicate and measure the results.
His website contains some excellent real world
data, especially as to tower interactions and
verticals, all very good material to review.
Honestly Rick, how much real time do you have using
both ground mounted and elevated radial systems
to support your statements? I have used the various
configurations with my 4x arrays for years and it
NOT quite as easy or simple as you infer here.
Low SWR on the main feedline is NO indication that
the vertical antenna array is working as it should
and I have the burned up parts to prove this point!
Arrays tend to multiply the real losses of any single
vertical, so the comparison holds very true here.
Again, having "pattern" or Front to Back, is NOT an
indication that an antenna is not really lossy.
How about another real world example?
OK, RX antennas, consider the Beverage as an example,
we don't use them for TX do we? Why? Because of their
overall losses, so no, we don't even consider such.
So let's narrow the focus here and look closer at
>It is fundamental to understand that a good working
>vertical on the low bands is typically 2 to 3 S-Units
>stronger at a distance DX station than your 40' high
>horizontal dipole. *** This is 12 to 18 dB improvement.***
Really? That's "ham lore"! Again let's dig into
the details that might support such a statement.
1. What's is your definition of a "good working vertical"
my friend? That's not going to be the typical 4 stray
elevated radials, hung willy nilly in the yard and without
proper feedline isolation and no idea of what the currents
are as to being balanced.
This means most setups are really "the luck of the draw",
are not repeatable and flunk the first part of your statement.
They in reality are NOT "good working verticals". Which is
also exactly the caution stated and re-stated by N6LF.
Somehow, perhaps due to "ham lore", the take away has
become "few elevated radials = GREAT performance. That
is NOT a true statement, without proper qualifications.
OK, let's move on ... as I am still looking for this
12 of 18 dB of improvement? But I have not found it yet.
2. Which low band are you speaking of here for the "12 to 18
dB" improvement using a 40' dipole? Trying to make such a
broad statement, without qualification is wrong and a distortion,
as 40m (with a dipole at 40') performance and 160m with the
same height and dipole are NOT going to be the same.
Again, "ham lore" begins with statements without accurate
qualification and then it gets repeated and accepted as
being 100% truthful. So I disagree with your statement.
A. Even a low dipole may have 6 to 8 dB of ground reflection
gain, that the vertical will not, be it 10m or on 160m.
B. You are UNDER-estimating the ground losses here and in
reality, again go back and re-read what N6LF discovered
and posted in his text and graphs. Where is this 12 to
18 dB GAIN you are claiming? It is simply not there.
What is the gain of a perfect vertical on a perfect ground
with no losses?
What is the gain of a perfect dipole on a perfect ground
with no losses?
2.1 dBi is an accepted value, the "i" = "isotropic"
So in a perfect backyard world ...
Allowing 2.1 for gain over isotropic, and 6 - 8 dB for the
ground reflection, that puts the net at 8.1 to 10.1 dBi
in favor of the dipole, not + 12-18 dBi for the vertical.
C. If you want to consider another idea for a ground system
with possibly less loss, then see an excellent recent work
by K2AV as published in the most recent NCJ for details and
note the actual measured losses of most vertical systems.
D. Which leads to another point, when the typical ham uses
a "trap" or less than full sized vertical, which is common,
then you have even MORE losses, both in the antenna and
for the same stated ground system, again the 12-18 dB gain
statement drifts more and more into fiction and a dream.
We, with diligence can overcome some of this additional
LOSS, but once again, first we have accurately understand
what/where/why the LOSS occurs.
Sadly, that's not what happens is it? A post is made on
a forum, and Joe or Jane, the new ham reads it, and they
go and invest limited resources and try and build up a
new antenna, and then the expected performance is NOT there.
Pop quiz? How many can complete this statement: Ready?
"Verticals radiate equally ........ in all directions.
OK, quick show of hands if you used the word "poorly"
as the missing word in the above sentence? I thought so.
Not an accurate statement, without qualification is it?
Yet, "ham lore" continues to repeat it year after year.
Why? Because we don't hit the PAUSE button and take a
moment or two, and ask "is that really true?"
Here's what I suggest you replace that above sentence
with and repeat it over and over in the right context.
"Verticals, like any antenna, with the proper design
and attention to details such as loss, work well!"
I did not say 12 - 18 dB stronger.
I did not say 1st one to break the pileup.
I did not say always is the very best antenna.
"Verticals, like any antenna, with the proper design
and attention to details such as loss, work well!"
Now, I understand the point you were trying to make as to
the lower wave angle of a vertical verses the higher wave
angle of the lower horizontal, but you can't claim what is
theory as an advantage and then ignore the real world of
where the respective lobe peaks and nulls occur.
Example? Let's say at 10 degrees wave angle, the vertical's
main lobe is 12 dB stronger on 160m than the main lobe of
the 40' high 160m dipole, which would be at 90 degrees or
directly up. Sounds great right?
WRONG as Jim, K9YC would say, why? Because your 4 elevated
radials and a short vertical, as most of us are not going to
be able to install a 130' tall vertical, may really have a
real world LOSS of 12 - 18 dB ... NOT an improvement!
We have losses due to the short vertical
We have losses due to less than perfect grounding
We have losses due to less than perfect feedpoint matching.
BTW, read and re-read Jim's work in this area as to
the proper use of baluns for feedpoints.
So then what's the net net overall gain or loss here now?
Aha, well, we don't know unless we accurately measure it!
It might be a break even, or the dipole might be better
due to the total losses of the 4 elevated radials and
a base loaded 45' vertical. That's the world we live in
and it's not one with an extra 12-18 dB of improvement
just because someone says so on an Internet forum.
In the real world, when you consider the total losses
for each piece of the system, 12-18 dB loss may really
be closer to an accurate figure once it is measured.
That's what several, including K2AV have found as truth.
Real world, despite years of effort with my low band
arrays, for say 80m, a simple dipole at 130' is going to
be stronger for a given situation, say from TN to your
Germany QTH there, than my 4x even if I was able to reduce
my total ground losses to NIL.
Why? The best gain of the 4x array will be 4.5-5.5 dBI
while the 130' high 80m dipole, due to ground reflection,
at say 30 degree wave angle is going to be roughly 2 to
3 dBi stronger than the much more complex array.
If I am trying to work someone in the NULL of the 4
main lobes, say 90 degrees to Africa, then that same
high dipole is going to 'appear' even stronger?
Now when that same dipole, positioned to be strongest
into Germany is used to try and work the JT1 on 80m
CW, which is in-line with my NW pattern, and in a null
on the 130' dipole. The dipole may never hear the JT1
because the dipole has a NULL on the JT1's heading.
Such is the life of antennas and sometimes being simple
is still the 'best' route to take. Sometimes it is not.
Again, I repeat, there is NO FREE lunch with the total
system performance. Losses have to properly addressed
otherwise we are all writing fictional stories. hihi.
That's why N6LF has continued to experiment and provide
additional information as to what one has to do in order
to achieve the level of performance some say is so easy.
So do we agree, each of us needs to decide what is "best"
for our individual situations. Total agreement here.
However, to make postings claiming 12-18 db GAIN or that
elevated radials are "best" is a distortion of technical
truths and may cause others to incorrectly understand how
our antenna SYSTEMS really work with each QSO we make.
Here's to ALL of us being open to learning new facts about
how our antennas really work, what impact that, and things
maybe can be made better by taking the time to read and
understand what goes on out of sight in the backyard or up
on the rooftops at our homes.
One of my favorite quotes about this mysterious thing
called radio and how it works is this:
""Albert Einstein, when asked to describe radio, replied:
"You see, wire telegraph is a kind of a very, very long
cat. You pull his tail in New York and his head is meowing
in Los Angeles. Do you understand this? And radio operates
exactly the same way: you send signals here, they receive
them there. The only difference is that there is no cat.""
Have a great weekend!
73 de Billy, AA4NU ... who is still learning too ...
>From: Rick - DJ0IP / NJ0IP
>Sent: May 19, 2012 8:48 AM
>To: 'Discussion of Ten-Tec Equipment'
>Subject: Re: [TenTec] Radial Research
>REALITY: We all should strive to make our antennas as efficient as possible
>and Rudi's work is an excellent guide, but even if you can't build anything
>remotely close to what he describes, EVERYONE with just a little bit of
>real-estate can build themselves a great vertical antenna with a lot less
>effort than Rudi described.
>I would remind you of the THREE reasons for using a vertical antenna in the
>1. Because you have to; no space for a low band horizontal dipole
>2. Because you want to improve your ability to work low band DX
>3. NEW: Your sea container with all of your equipment and antennas got
>lost in transit on its way to some distant island (see T32C DXpedition to
>Christmas Island - www.tt2c.com ), so you organize a bunch of telescoping
>fiberglass poles and some wire and build your vertical antennas on-site.
>Let's focus on #2 because this would be the case where we have time and
>space to apply what we've learned from Rudi.
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