Andy,

check out this site, it may you/someone else,

regards

http://www.ad5th.com/5-BTV.html



http://www.ad5th.com/5-BTV.html





I choose Polesoft Lockspam to fight spam, and you?
http://www.polesoft.com/refer.html

"Roger Adam" wrote in message
...
Andy,

Check out this site, it may you/someone else,

Regards

http://www.ad5th.com/5-BTV.html
AD5TH

Roger,

Since you selected the Hustler 75 meter Super Resonator to make your Hustler
4-BTV into a 5-BTV model, I would add guys (as recommended in the Hustler
installation manual) due to the weight at top and overall length of antenna.
3 or 4 guy wires should work well.

Greg
w9gb

Why do hams persist on using "tuned" radials on the ground? They cut them to
"resonance" which means nothing. A wire cut for resonance on 40 meters and
buried under 2 inches of soil is no where near resonant 7mhz. It would be
much more effective if they just made all the radials as long as possible
and forget this resonance stuff but no one listens.

--
Steve N4LQ
"Roger Adam" wrote in message
...
Andy,

check out this site, it may you/someone else,

regards

http://www.ad5th.com/5-BTV.html



http://www.ad5th.com/5-BTV.html





I choose Polesoft Lockspam to fight spam, and you?
http://www.polesoft.com/refer.html

What about the Hustler antenna instructions which provide the "correct
lengths" for cutting radials? Moreover they need not be "buried 2 inches" in
the ground but can safely remain on the ground once grass growth effectively
buries them. Also DX Engineering www.dxengineering.com has ground radials
for sale which are "pre-cut to length". I assume they know what they are
doing. Force 12 also recommends using "tuned radials" with their line of
vertical antennas. I assume they too know more about antennas then I do.

I researched this topic before installing my 5-BTV and tuned radials were
always recommended. If length means nothing I could have gone with 6 inch
radials if I followed your logic...eh? My 5-BTV installation with 72 "tuned"
radials at this page

1. http://www.ad5th.com/5-BTV.html

I am getting great reports so far but have only been on the air at this qth
for a couple weeks. A new AL-80B arrives in 3 days which should improve my
signal greatly. 73 / DX

--

Charlie
Ham Radio - AD5TH
www.ad5th.com
Live Blues Music
www.492acousticblues.com




"N4LQ" wrote in message ...
Why do hams persist on using "tuned" radials on the ground? They cut them
to "resonance" which means nothing. A wire cut for resonance on 40 meters
and buried under 2 inches of soil is no where near resonant 7mhz. It would
be much more effective if they just made all the radials as long as
possible and forget this resonance stuff but no one listens.

--
Steve N4LQ
"Roger Adam" wrote in message
...
Andy,

check out this site, it may you/someone else,

regards

http://www.ad5th.com/5-BTV.html



http://www.ad5th.com/5-BTV.html





I choose Polesoft Lockspam to fight spam, and you?
http://www.polesoft.com/refer.html

What about the Hustler antenna instructions which provide the "correct
lengths" for cutting radials? Moreover they need not be "buried 2 inches" in
the ground but can safely remain on the ground once grass growth effectively
buries them. Also DX Engineering www.dxengineering.com has ground radials
for sale which are "pre-cut to length". I assume they know what they are
doing. Force 12 also recommends using "tuned radials" with their line of
vertical antennas. I assume they too know more about antennas then I do.

Tuned radials are necessary and appropriate when the radials are
installed well above earth-ground level. When the antenna is mounted
up at a significant height, there's very little coupling between the
radials and ground, and the radials must be tuned in order to present
a low impedance on the frequencies of interest. Once tuned, each
radial presents a low-loss current path, and only a small number of
such radials are required.

When the radials are laid on the ground, buried, or placed a short
distance above the ground, matters are very different. There is a
great deal of capacitive coupling between the radials and the soil,
and the soil also presents a (resistive and rather lossy) path for the
current flow. As a result, two things are different:

- The coupling to the soil de-tunes the radials and greatly lowers
their Q. They no longer serve as a resonant system, and cutting
them to a tuned length is no longer essential.

- A much larger number of radials is necessary, in order to limit the
losses which occur when the return current flows through the soil.

So... in an elevated-antenna situation, as few as three or four
radials can give you low losses, but the radials must be tuned. For a
ground-mounted vertical, you need many more radials (dozens, and some
people prefer over 100), but they don't need to be tuned, and there's
not much performance difference to gain once the radials are at least
about an eighth of a wavelength.

I researched this topic before installing my 5-BTV and tuned radials were
always recommended.

For elevated antennas, that's true. For ground-mounted antennas,
tuning is simply unnecessary.

Take a look at http://www.cebik.com/gr.html which shows some antenna
modelling and graphs for vertical antennas with ground-mounted
radials. The chart of "Ground Radial Test 2" is an interesting one.
It shows that there's only a very modest difference in performance
(less than half of a dB!) between a 64-radial system using tuned
quarter-wavelength radials, and a 64-radial system using radials which
are only .15 wavelength long.

If length means nothing I could have gone with 6 inch
radials if I followed your logic...eh?

It is not true that "length means nothing". 6-inch radials are too
short to provide adequate coupling to the soil.

It *is* true that "length is not critical".

My 5-BTV installation with 72 "tuned"
radials at this page

1. http://www.ad5th.com/5-BTV.html

I am getting great reports so far but have only been on the air at this qth
for a couple weeks.

That's good news.

The bad news is that you could have used non-tuned radials, and saved
yourself some bother and perhaps some money (used somewhat shorter
lengths of wire), and gotten equally-good reports.

You didn't hurt yourself by tuning the radials. You just invested
some effort (and perhaps some money) unnecessarily.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

You're entitled to your opinion on this seemingly controversial topic.
73 / DX ..hope to catch you on the bands one day Dave

--

Charlie
Ham Radio - AD5TH
www.ad5th.com
Live Blues Music
www.492acousticblues.com




"Dave Platt" wrote in message
...
What about the Hustler antenna instructions which provide the "correct
lengths" for cutting radials? Moreover they need not be "buried 2 inches"
in
the ground but can safely remain on the ground once grass growth
effectively
buries them. Also DX Engineering www.dxengineering.com has ground radials
for sale which are "pre-cut to length". I assume they know what they are
doing. Force 12 also recommends using "tuned radials" with their line of
vertical antennas. I assume they too know more about antennas then I do.

Tuned radials are necessary and appropriate when the radials are
installed well above earth-ground level. When the antenna is mounted
up at a significant height, there's very little coupling between the
radials and ground, and the radials must be tuned in order to present
a low impedance on the frequencies of interest. Once tuned, each
radial presents a low-loss current path, and only a small number of
such radials are required.

When the radials are laid on the ground, buried, or placed a short
distance above the ground, matters are very different. There is a
great deal of capacitive coupling between the radials and the soil,
and the soil also presents a (resistive and rather lossy) path for the
current flow. As a result, two things are different:

- The coupling to the soil de-tunes the radials and greatly lowers
their Q. They no longer serve as a resonant system, and cutting
them to a tuned length is no longer essential.

- A much larger number of radials is necessary, in order to limit the
losses which occur when the return current flows through the soil.

So... in an elevated-antenna situation, as few as three or four
radials can give you low losses, but the radials must be tuned. For a
ground-mounted vertical, you need many more radials (dozens, and some
people prefer over 100), but they don't need to be tuned, and there's
not much performance difference to gain once the radials are at least
about an eighth of a wavelength.

I researched this topic before installing my 5-BTV and tuned radials were
always recommended.

For elevated antennas, that's true. For ground-mounted antennas,
tuning is simply unnecessary.

Take a look at http://www.cebik.com/gr.html which shows some antenna
modelling and graphs for vertical antennas with ground-mounted
radials. The chart of "Ground Radial Test 2" is an interesting one.
It shows that there's only a very modest difference in performance
(less than half of a dB!) between a 64-radial system using tuned
quarter-wavelength radials, and a 64-radial system using radials which
are only .15 wavelength long.

If length means nothing I could have gone with 6 inch
radials if I followed your logic...eh?

It is not true that "length means nothing". 6-inch radials are too
short to provide adequate coupling to the soil.

It *is* true that "length is not critical".

My 5-BTV installation with 72 "tuned"
radials at this page

1. http://www.ad5th.com/5-BTV.html

I am getting great reports so far but have only been on the air at this
qth
for a couple weeks.

That's good news.

The bad news is that you could have used non-tuned radials, and saved
yourself some bother and perhaps some money (used somewhat shorter
lengths of wire), and gotten equally-good reports.

You didn't hurt yourself by tuning the radials. You just invested
some effort (and perhaps some money) unnecessarily.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Fri, 7 Jan 2005 14:04:43 -0600, "Charlie"
wrote:

You're entitled to your opinion on this seemingly controversial topic.
73 / DX ..hope to catch you on the bands one day Dave

Possible the controversy is in your mind Charlie.

The velocity factor using wires buried under ground is a fraction of
the velocity factor in air or free space. Hence if you are hell bent
on having resonance in your buried radial system (which in this
application does nothing to improve system efficiency) they need be a
whole lot shorter than the length = 234/F that is used for elevated
radial systems.

Danny, K6MHE

TY for your candor. God Bless and 73

--

Charlie
Ham Radio - AD5TH
www.ad5th.com
Live Blues Music
www.492acousticblues.com




"Dan Richardson" wrote in message
...
On Fri, 7 Jan 2005 14:04:43 -0600, "Charlie"
wrote:

You're entitled to your opinion on this seemingly controversial topic.
73 / DX ..hope to catch you on the bands one day Dave

Possible the controversy is in your mind Charlie.

The velocity factor using wires buried under ground is a fraction of
the velocity factor in air or free space. Hence if you are hell bent
on having resonance in your buried radial system (which in this
application does nothing to improve system efficiency) they need be a
whole lot shorter than the length = 234/F that is used for elevated
radial systems.

Danny, K6MHE

You may find this article interesting.

http://www.bencher.com/pdfs/00361ZZV.pdf

73
Danny




On Fri, 7 Jan 2005 15:38:53 -0600, "Charlie"
wrote:

TY for your candor. God Bless and 73

For what it's worth, I'll add my voice to Dave's and Danny's. The change
in velocity factor Danny speaks of is on the order of a factor of 5 for
ordinary soil. That is, a quarter wavelength under the ground is about
1/5 the physical length of a quarter wavelength in free space or well
above the ground. So if you did need to "tune" buried radials for any
reason, you'd have to make them about 1/20 of a free space quarter
wavelength. And the "tuning" would be extremely broad because of the loss.

To amplify what Dave said, the current on an elevated or free space
radial has nearly the same distribution as on a dipole half -- it's
maximum at the feedpoint and drops to zero at the end, following a
nearly sine shaped curve. When buried in the lossy ground, it instead
decays in a more-or-less exponential fashion. In some cases there are
some remnants of the free-space distribution, but they're very muted. So
basically, the current just fades out as you get farther and farther
from the feedpoint. At the point where the current has dropped to a low
value, you can cut the radial with no significant effect. This is very
much different from the behavior above ground.

I'm not surprised to find technically inaccurate material coming from
antenna manufacturers. Although they might know how to build antennas,
and certainly how to sell them, they often don't have any great depth of
knowledge of fundamental principles. (In fact, a lack of knowledge of
fundamental principles is often an advantage in the selling area,
because it gives them an excuse for making claims of impossible
performance, and the invention of non-existent phenomena to explain it.)
I recall many years ago contacting a major manufacturer of coaxial cable
about a theoretical matter, and found that they knew nothing at all
about how transmission lines worked. They were experts at extruding
polyethylene and PVC and at weaving fine copper wire, and nothing else.

Roy Lewallen, W7EL

Dan Richardson wrote:
On Fri, 7 Jan 2005 14:04:43 -0600, "Charlie"
wrote:


You're entitled to your opinion on this seemingly controversial topic.
73 / DX ..hope to catch you on the bands one day Dave


Possible the controversy is in your mind Charlie.

The velocity factor using wires buried under ground is a fraction of
the velocity factor in air or free space. Hence if you are hell bent
on having resonance in your buried radial system (which in this
application does nothing to improve system efficiency) they need be a
whole lot shorter than the length = 234/F that is used for elevated
radial systems.

Danny, K6MHE