Grounds and verticals - ??
CZG
Antenna people - I would appreciate some clarification on the vertical
antenna concept:
WIth a 1/4 wave or 5/8 wave vertical you need a ground plane to provide
the other "half" of the antenna, right?
Okay, so with a ground-mounted vertical you use radials on or under
ground, or ground rods.
Higher up, you use a "ground plane", consisting of three or four
additional quarter-wave sections oriented horizontally
around the driven vertical.
In the antenna books they say to get as good a ground as possible. But
-- what does that mean? For instance,
I have known of hams with typical 4 band trap verticals, mounted on pipes
driven into the ground, and that's it.
Signals from such verticals are often really lousy, too, even with
radials. Why?
The manufacturers, of course, suggest radials, and the more the better.
But how many is "enough"? If there is always going to be
some signal ground- loss, then wouldn't it be better to replace the
ground-system with "the other half" of the antenna, i.e., another 1/4 wave
of
wire or metal?
If you were to have one single radial, wouldn't it be the exact same thing
as a half-wave "v" dipole, with one side on/under the ground?
Finally, how does a ground plane antenna differ from a simple dipole, up
above ground & in an "L" shape? Do the additional 2 or 3 "legs" of the
radial system accomplish anything essential?
(How do broadcasters using verticals (e.g., typical low power AM
broadcaster) know when they have "enough" ground? Or would they be better
off providing several counterpoises of suitable length ABOVE the ground
surface, forming essentially a "dipole" with several equal 1/4 wave wires
on the "ground" side(?))
Any insightful comments would be appreciated. Is it generally accepted
that a vertical with ground coounterpoise will not perform as well as a
half wave center fed doublet? Thanks, all...
mike....@ziplog.com
In <jwg6-05019...@cu-dialup-1617.cit.cornell.edu>, jw...@cornell.edu (CZG) writes:
>Antenna people - I would appreciate some clarification on the vertical
>antenna concept:
> Any insightful comments would be appreciated. Is it generally accepted
>that a vertical with ground coounterpoise will not perform as well as a
>half wave center fed doublet? Thanks, all...
If we are talking about using verticals near to the ground where the earth
ground effects are present, such as those near it from, say 40 meters on down
to 80, then 160, then the broadcast band and so on, simply said, the ground
out a long way from the antenna also plays a part on how well the signal
gets out from the antenna.
Those people who wish to use verticals of most any kind in these operations
that are near to salt water are in operating heaven.. :)
Those poor blokes who have to do this over very poor RF ground are in
operating hell!
If you job is to cover a 100 mile circle of the Gobi desert from a sand dune
in the middle of it with a broadcast signal on 1150Khz from a vertical and
if you don't do a good job we'll cut off all your pleasures one by one for
every week you fail, well....
You can order tons of towers, hundreds of feet of radial wire, and even a
few hundred pounds of copper mat, a hundred KW rig and generators, and by
the end of the first six months, you, still, will be VERY short on pleasure and
won't even have a bottle in front of you with which to drown your misery!
:)
Most of us hams, relative to HF and verticals, that like low band work, live
kind of in some form of RF purgatory, somewhere between RF heaven and
RF hell. With a lot of work at radials and careful planning, we can get
the near field part of the vertical scenario down pretty well, if we use the
types of verticals that use them.
We can also get balanced vertically polarized radiators up that don't depend
on radials to return the current needed.
But even then, we still have to deal with all those wavelengths way out
beyond the near field that also enter into the whole picture. There is
no way to pave the whole countryside around us for hundreds and hundreds of
feet with copper plate! Thus, what turns out to be, perhaps, an easier
construction job to build them, is an empty return because the signal
takeoff angle is higher and there is still no good efficiency down at the very
low angles where we need it for long haul DX work.
Now don't get this all wrong. The ground also counts for horizontal arrays
that are close to it as well, but there, on the low bands, the take-off angles
from these arrays do not begin to come down to the lower values very well
until the heights rise above the half wave length mark. In fact, choosing a
QTH with downward sloping cround for miles away from your shack can really
help you a lot with horizontal arrays if the slope is right!
Few of us can really afford to put the stuff up above 132 feet on 80 meters,
or a paltry 264 feet on 160 meters, so we all get involved in scrambling
to figure out what to do to optimize our time, money, efforts, and our
location - turning, in the case of low bands, to verticals, as your interest
shows.
The bottom line, I think is simple.
Unless you have a VERY good natural ground in at least the 30+ micromho
conductivity range, vertially polarized HF arrays will not be much better as
balanced non-radial type arrays, than a decent 1/4 wave or so element with
a reasonable good radial system. That's a practical answer.
Oh sure, we can argue about a DB here or a DB there, but there is a
practical limit to all the foolishness of this. We buy, build and install
what we can afford that optimizes our site as best we can..
QED
That being said, it usually turns out to be more practical to use the lower,
shorter elements and spend time and money at ground level chunking in
radials, where they are at all possible.
The only real practical difference in station matters between elevated radials,
which may be fewer in number than at ground level for reasonable performance,
is that for lightning protection, an elevated ground plane can become one
of your worst nightmares during lightning strikes. A ten foot elevation that
you did not handle properly for lightning protection, at the moment a strike
hits it or near it, can bring tens of thousands of volts into your shack from
these elevated type HF arrays. That 9 feet up for 40 meters and 18 feet
up for optimizing such an array at 80 meters is LOTS of voltage at tens
of thousands of amperes pulse current, my friend.
By the time you do the radial and ground protection work for them at ground
level, you have spend just about as much time and money as if they were not
elevated. Therefore, all the arguements about cheaper costs found in the
elevated radial arrays are really, as I see it, moot, from a practical and a
safety standpoint. What good is it to save $500 if you get a $2000 ham
station destroyed two years later for your saving? At the 80 foot mark in
open country, your odds of taking a serious hit are about one in two years
or less out in open country, from published (and my practical experience) as
well.
The one possible chance to perhaps save a little work, if your ground is
reasonably good, may come from the folded unipole work now being done
at many MF sites as they scramble to fix failing aging ground systems.
As I see it, there may be some merit to an effective use of that technique,
which might help you save some money and time for a practical signal.
There is arguement still going on about the real effectiveness of that
technology, as far as I can see. I don't know enough at the moment to
champion or reject it; I'll admit my lack of research on it right up front.
:)
//-----------------------------
Mike - W5WQN
Mike....@ziplog.com
MIke....@f3000.n117.z1.fidonet.org
K1BQT
Hi--
Let me preface my comments by saying that I am not an expert on this
subject, and so my response will be simplistic and brief. Having said
that, I believe your perception about elevated radials is correct. In my
view, a ground-mounted monopole wants to have the best radial field
possible under it--not to couple to the earth--but to screen the antenna
FROM the lossy characteristics of the earth below it. At RF, the radial
field wants to look like a mirror. Otherwise, ground losses will be high
and the "image" antenna effect won't materialize in a useful way. Of
course, ground losses STILL may be high beyond the edge of the radial
field if soil conductivity is poor--but at least the signal will get a
reasonable launch at all but the lowest angles.
In my view, and despite some strong opinion to the contrary, I would agree
that antennas using so-called elevated radials are really disfunctional
dipoles--or balanced antennas thrown off balance and into a lossy
operating mode by their close proximity to that inherently-lossy medium
called dirt. Designing antennas of this type is probably an exercise in
compensation--and progressively more data is emerging that suggests a
6-7dB penalty may be paid for not installing a properly-designed radial
field (Smith, Rauche, and others), It IS a controversial topic--and your
thread will probably renew that debate!
Hope this helps.
Rick K1BQT
CZG
Thank you for the comments, guys. This stuff gets thick into the theory fast!
Okay. Well the first thing that's been bugging me for years is the
typical trap vertical setup, used by many hams, especially novices. I
have read articles in the ham rags about how alot of these guys are only
getting a few watts of RF out of the system, even though they are fully
loading their 180-watt transceivers. There is just so much loss in the
antenna system that they do a magnificently poor job on the air. I have
worked lots of those stations - with a dipole for my antenna, and similar
power output, and they by and large give me a much better report than I
can give them.
Several years ago the Cornell student radio club got together for a fun
experiment. It was the 160 meter cw contest, and we wanted to go for the
gusto. So we drove several miles up the lake, to a Cornell orchard plot
(this was on verrrry cold, gusty night). There we sent a weather balloon
aloft attached to a 5/8 wave 160 meter vertical!! On the ground we laid
dozens of radials, and had a matching network at the feed point. What an
antenna! As it turned out the winds were so strong the vertical was
tilted at about a 45 degree (or worse) angle, and the match was lousy, but
we won our section!
That was the first time I ever got frost-bite, in my fingers - ouch!-
while trying to hold down one of the guy lines in the wind! Anyway in the
freezing wind chill, out on a dark field, I remember looking up at the
stars and thinking, "WHY DO WE HAVE TO LAY SO MANY *#% RADIALS?!!!!"
The more the better. Well I am wondering, when do you finally reach the
point that you have "enough" so that you have reached performance equal to
a full size dipole, say 1/4 wave above ground? I realize the radiation is
vertical vs. horizontal polarization, but there must be some point where
you have sufficient ground, and can consider the radial system "adequate,"
so the field strength is equal to what you would have had with a complete
dipole.
What I would like to do is run a vertical, or more likely an end-fed Zepp
(half wave on 80 or 160) on multiple bands. The manuals state this is a
very unbalanced antenna and tricky to match. You need an EXCELLENT ground
on the matching network. (ARRL says several 8-foot pipes driven into the
ground are probably "adequate.") My question is, how can I know my ground
system is "good enough," or would a CENTER fed (with ladder line) half
wave be a much better idea?? After all, with the center fed design, you
don't need such an ideal ground connected to the system, so it is much
easier to construct.
Would the complete (center fed) dipole necessarily result in better
effective field strength (disregarding polarization) than a quarter wave
vertical with a less-than-perfect "ground"?
I realize there are many variables involved but I just don't ever recall
hearing a great signal from a 40 or 80 meter trap vertical. I greatly
appreciate any comments you could make to help clarify. Many thanks,
N1AEP
N1AEP -- Freeville, NY FN12
Bob Lewis
I believe the broadcasting standard is 120 radials! You can't really
compare verticals to dipoles. Dipoles are high angle radiators,
verticals (properly installed) are low angle radiators. Which one works
best depends how far away the other station is and how many hops you are
getting at that frequency.
My experience has been that the ground system becomes less lossy if you
can make the vertical feed impedance high. Quarter wave loaded (short)
verticals have a very low impedance which causes increased loss in the
ground. In general, I stick to balanced antennas (i.e. dipole) so I
don't have to worry about the ground system. It all depends what your
goal is (DX or Local), the frequency, and your physical constraints.
If you look at something like the Cuscraft R7 you'll see a 1/2 wave
vertical with high impedance (several hundred ohms) feed impedance, and
a broad-band matching system. Very little "ground" system required.
Probably a good "compromise" antenna for those who don't have room for
lots of radials or a beam.
w8j...@aol.com
In article <32D136...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
<sab...@crpl.cedar-rapids.lib.ia.us> writes:
>The elevated ground plane (10 feet or so) with a less than humongous
>radial system:
>
>1) Helps to get the antenna above some of the local RF "absorbers".
>
>2) Reduces dirt losses in the *near* field.
>
>It should be possible to get these advantages and still have good
>lightning protection, using the techniques for grounding the
>base of the antenna and the feed line, plus absorbers, that have been
>discussed on this forum.
>
>Bill W0IYH
I'd like to toss in my experience here.
In my actual FS measurements of a 1/4 wl veertical on 80 meters, the
advantage of elevating four radials eight feet was only a db or so over
four ground mounted radials. The four elevated radials were about 5 dB
down from a 60 radial test.
By the time 30 or so radials are used, it made no difference if they are
elevated or not.
The military (via N7CL) measured 5 to 7 dB loss with small elevated
systems compared to conventional full size systems, an engineeering firm
measured about the same loss (an average of 7 dB) at a AM broadcast
station, and Carl Smith's paper on elevated radials indicated the same
thing....about 7 dB down from theoretically perfectc in a elevated test
system he installed for Goodyear Aerospace.
So if you use a small elevated counterpoise not too high above earth,
expect to lose 5-7 dB minimum over what you could do with 60 1/4 wl
radials in the system.
I think trap losses would be minor, but most people use crummy grounds and
expect verticals to play well. Without a good radial ground ANY vertical
within 1/2 wl or so of earth, even one not "connected" to earth, will
suffer from lack of a proper counterpoise.
New-wave-theory has been presented that claims 1/8 wl radials are better
than 1/4 wl, and even one or two radials is more than enough for 100%
radiation efficiency. Of course those claims are technically true, since
HEAT can be considered a form of radiation. But if you want a good signal,
use many radials or put the antenna up 1/4 or 1/2 wl above earth.
73 Tom
William E. Sabin
This material, based on your experience, could be the basis for an
excellent article, Tom. Suggest you think about doing that. Let some of
the other experts review it.
Bill W0IYH
Richard W. Clark
Bob Lewis <rle...@staffnet.com> wrote:
>CZG wrote:
>>
>> Thank you for the comments, guys. This stuff gets thick into the theory fast!
>>
snip
>>, I remember looking up at the
>> stars and thinking, "WHY DO WE HAVE TO LAY SO MANY *#% RADIALS?!!!!"
>>
>> The more the better. Well I am wondering, when do you finally reach the
>> point that you have "enough" so that you have reached performance equal to
>> a full size dipole, say 1/4 wave above ground? I realize the radiation is
>> vertical vs. horizontal polarization, but there must be some point where
>> you have sufficient ground, and can consider the radial system "adequate,"
>> so the field strength is equal to what you would have had with a complete
>> dipole.
>>
I would recomend "The Amateur Radio Vertical Antenna Handbook" by
Capt. Paul Lee, N6PL. It has an excellant discussion of this matter
as well as the inherent RF quality of earth (soil, ground, whatever).
In a nutshell, field strength versus the number of radials is as
follows:
Theoretical Maximum 186 mV/meter at 1 mile from antenna
120 Radials 175 mV/meter
60 Radials 160 mV/meter
30 Radials 150 mV/meter
15 Radials 143 mV/meter
2 Radials 105 mV/meter
This is all based on commercial long wave antenna development but
generally extrapolatable to HF. As such the term for field strength
is expressed in volts per meter and is measured with a very short
dipole somehow arranged to be within the field without disturbing it
greatly. This field measurement is taken at a distance of 1 mile from
a quarter wave vertical antenna (this would easily preserve the rule
of being several long wavelengths away to reduce field disturbance).
>My experience has been that the ground system becomes less lossy if you
>can make the vertical feed impedance high. Quarter wave loaded (short)
>verticals have a very low impedance which causes increased loss in the
>ground. In general, I stick to balanced antennas (i.e. dipole) so I
>don't have to worry about the ground system. It all depends what your
>goal is (DX or Local), the frequency, and your physical constraints.
The ground system loss does not change with the antenna design. What
you are describing is that ground system losses become proportionately
larger as the physical size of the antenna is shortened (and the
frequency held constant). For example consider there is 2 ohms of
loss contributed by the physical soil absorbing the signal
(literally). This fixed loss in the ground presents:
1/2 wave 1000 Ohms, base resistance 0.2% ground loss
3/8 wave 300 Ohms, base resistance 0.67% ground loss
1/4 wave 35 Ohms, base resistance 5.4% ground loss
1/8 wave 1.5 Ohms, base resistance 57% ground loss
1/10 wave 1 Ohm, base resistance 67% ground loss
The antennas described above in terms of actual physical height at
operating wavelength. The guesstimate of 2 Ohms loss in the soil is
extremely optimistic. By using radials we'd be lucky to be able to
draw down the losses to this value.
>If you look at something like the Cuscraft R7 you'll see a 1/2 wave
>vertical with high impedance (several hundred ohms) feed impedance, and
>a broad-band matching system. Very little "ground" system required.
>Probably a good "compromise" antenna for those who don't have room for
>lots of radials or a beam.
It may appear that the data above supports this thesis, but Capt. Lee
has discussion to this point that may shave some of the apparent gain
(he does allow that a taller antenna is more efficient).
Richard Clark, KB7QHC
Cecil Moore
Richard W. Clark wrote:
> I would recomend "The Amateur Radio Vertical Antenna Handbook" by
> Capt. Paul Lee, N6PL.
Hi Richard, someone previously reported that Paul Lee sez
a vertical has more gain than a dipole. Did he really say
that?
73, Cecil, W6RCA, OOTC
George McCrary
Any comments on the length of radials?
I've seen some who say that there is no advantage to making the
radials any longer than the vertical is tall. For example : an
inverted L for 80M with 35 ft vertical, the radials need only be 35
feet long.
In the ARRL Antenna book it says the following in relation to the
length and number of radials:
Number 16 24 36 60 90 120
Wavelength .1 .125 .15 .2 .25 .4
Any comments on this?
BTW page 3-3 for the above.
73 DE KQ4QM (George)
My DXCC Pages are at http://www.ipass.net/~geo
Richard W. Clark
Cecil Moore <Cecil_...@ccm.ch.intel.com> wrote:
>73, Cecil, W6RCA, OOTC
Hi Cecil,
No.
73's
Richard, KB7QHC
William E. Sabin
William E. Sabin wrote:
>
>
> The ARRL numbers are for a 1/4 wave vertical. As I understand it, the
> purpose of the radials is to provide a return path for the *near field*
> E and H electromagnetic fields. For a physically short radiator, it makes
> sense that the radials need not be as long as for a 1/4 wave radiator,
> because the area of ground covered by the near field would be smaller.
>
> Your formula is probably about as good as any. This whole subject is far
> removed from "exact science". If we use a number of radials equal to the
> number of feet of height of the antenna, each radial 1/8 wave long, I'll
> bet the near field ground losses will be fairly (acceptably) small. A
> greatly expanded radial system might be worth a dB or so.
>
> Also, for the inverted L, only some fraction of the total radiation
> involves the vertical segment. This makes the radial system even less
> critical.
>
P.S. Extend a few of the radials along the length of the flat top part of
the inverted L. Also, at higher frequencies, 14 MHz and higher, the
radials can easily be 1/4 wave, rather than 1/8 wave, for a modest
improvement.
Bill W0IYH
William E. Sabin
George McCrary wrote:
>
>
> I've seen some who say that there is no advantage to making the
> radials any longer than the vertical is tall. For example : an
> inverted L for 80M with 35 ft vertical, the radials need only be 35
> feet long.
>
> In the ARRL Antenna book it says the following in relation to the
> length and number of radials:
>
> Number 16 24 36 60 90 120
> Wavelength .1 .125 .15 .2 .25 .4
>
The ARRL numbers are for a 1/4 wave vertical. As I understand it, the
purpose of the radials is to provide a return path for the *near field*
E and H electromagnetic fields. For a physically short radiator, it makes
sense that the radials need not be as long as for a 1/4 wave radiator,
because the area of ground covered by the near field would be smaller.
Your formula is probably about as good as any. This whole subject is far
removed from "exact science". If we use a number of radials equal to the
number of feet of height of the antenna, each radial 1/8 wave long, I'll
bet the near field ground losses will be fairly (acceptably) small. A
greatly expanded radial system might be worth a dB or so.
Also, for the inverted L, only some fraction of the total radiation
involves the vertical segment. This makes the radial system even less
critical.
Bill W0IYH
John Kaufmann
The definitive study of ground radials and vertical antenna performance
is the classic paper "Ground Systems as a Factor in Antenna Efficiency", by
G.H. Brown, R.F. Lewis, and J. Epstein, Proceedings of the Institute of Radio
Engineers, Vol. 25, No. 6, June 1937, pp. 753-787. I summarized their
findings on the Top Band Reflector a few months back, and that info is
now posted on KE1FO's Web page at:
http://www.tiac.net/users/ke6ber/radials.html
73, John W1FV
John Kaufmann
kauf...@ll.mit.edu
Ian White, G3SEK
George McCrary wrote:
>Any comments on the length of radials?
>
antenna efficiency as a function of length of vertical, and length and
number of radials. He made a series of systematic experiments on all of
these factors, to produce one big set of data that all correlate
together and make sense.
>I've seen some who say that there is no advantage to making the
>radials any longer than the vertical is tall. For example : an
>inverted L for 80M with 35 ft vertical, the radials need only be 35
>feet long.
>
It depends what you mean by "need". According to Sevick's data there are
improvements in efficiency with radials that are longer than the height
of the vertical, but the first priority should be to increase the NUMBER
of radials rather than the length (unless of course you already have a
large number). That brings us to the second statement...
>In the ARRL Antenna book it says the following in relation to the
>length and number of radials:
>
>Number 16 24 36 60 90 120
>Wavelength .1 .125 .15 .2 .25 .4
>
>Any comments on this?
The correct interpretation is based on the idea that the radials should
'shield' the near field of the antenna from the lossy ground. The
effectiveness of the shielding will depend on the spacing between the
radials, especially at the outer ends where the wires are farthest
apart.
The table is sying that if you only have enough real estate for 0.1wl
radials, there is no point in using more than 16 because that's enough
radials to adequately cover a circle of 0.1wl radius. Efficiency will be
poor, but adding more radials of the same length will not make it
better.
As the radials get longer, they also spread farther apart, so you need
more wires to cover the ground. The table shows that roughly speaking,
whatever the length of the radials, you need enough of them to make sure
that the spacing at the ends is no more than about 0.02wl.
>
>BTW page 3-3 for the above.
>
Your reference seems to be to an older edition. In the current 17th
edition it's all explained quite clearly on pages 3-13 and 3-14.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
Professionally:
IFW Technical Services Clear technical English - world-wide.
w8j...@aol.com
In article <32d31ab9...@news.ipass.net>, g...@ipass.net (George
McCrary) writes:
>
>Number 16 24 36 60 90 120
>Wavelength .1 .125 .15 .2 .25 .4
>
>Any comments on this?
>
>BTW page 3-3 for the above.
>
>
Diminishing benefits of adding radials occur when the ends of the
(straight) radials are about .03 wl apart. The longer the radials, the
more radials you can use.
You'll see the ARRL book agrees for the most part with the RCA study I
partially posted.
73 Tom
w8j...@aol.com
Compare Lewis Brown and Epsteins work for RCA at 3 MHz....(there is some
missing data from the Capt Lee text quoted.) Missing is how tall is the
radiator and how long are the radials?
For comparison, I'll quote the RCA report by B,L and E.
In article <5aueeu$e...@q.seanet.com>, rwc...@rwclark.seanet.com (Richard
W. Clark) writes:
>I would recomend "The Amateur Radio Vertical Antenna Handbook" by
>Capt. Paul Lee, N6PL. It has an excellant discussion of this matter
>as well as the inherent RF quality of earth (soil, ground, whatever).
>In a nutshell, field strength versus the number of radials is as
>follows:
>Theoretical Maximum 186 mV/meter at 1 mile from antenna
Theoretical maximum 1 kW 80 degree tall vert is about 196 Mv/m at one
mile
>120 Radials 175 mV/meter (-.53 dB)
113 Radials .437 wl long...192 mV/m (-.18 dB from ideal)
113 radials .274 wl long..182 mV/m
>60 Radials 160 mV/meter (-1.3 dB)
60 Radials .437 wl long...178 mV/m (-.84 dB)
60 radials ,274 wl long.....175 mV/m
>30 Radials 150 mV/meter (-1.9 dB)
30 radials .437 wl .....171 mV/m (-1.2 dB)
30 radials .,274 wl.....161 mV/m (-1.7 dB)
>15 Radials 143 mV/mete r
15 radials .274 wl.....152 mV/m
15 radials .137 wl ....148 mV/m
>2 Radials 105 mV/meter (-5.0 dB)
2 radials .274 wl long ....117 mV/m
2 radials .137 wl long...115 mV/m (-4.6 dB)
>This is all based on commercial long wave antenna development but
>generally extrapolatable to HF.
My measurements at 3.8 MHz agreed very closely with the RCA study.
This all illustrates the fact that if you use two or four radials, expect
your signal to be about 5 dB down, That's even what I measured. If the
antenna is SHORTER than 1/4 wl signal loss will be even greater with less
radials.
Even 1/2 wl verticals need radials. That's important to remember.
Ground independent HF verticals sold by amateur manufacturers will be
about four to ten dB down from a monoband 1/4 vertical with 60 1/4 wl
radials. Part of the loss is ground loss, and part is the loading and
matching methods used.
73 Tom
w8j...@aol.com
In article <32D3A0...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
<sab...@crpl.cedar-rapids.lib.ia.us> writes:
>
>The ARRL numbers are for a 1/4 wave vertical. As I understand it, the
>purpose of the radials is to provide a return path for the *near field*
>E and H electromagnetic fields. For a physically short radiator, it makes
>sense that the radials need not be as long as for a 1/4 wave radiator,
>because the area of ground covered by the near field would be smaller.
>
>
Hi Bill,
Actually the ground needs to be LARGER with a short vertical, not smaller.
Unless of course you used a nichrome loading coil and the loss resistance
of the vertical increased greatly. Then the ground loss would become less
important (of course the efficiency of such a system would stink).
We have the EQUIVALENT of three major resistances in series, the base
radiation resistance of the entire system sticking up in the air, the loss
resistance of that system sticking up in the air, and the resistance of
the ground. Loss is a function of the ratios of these resistances. We want
the radiation resistance normalized to one point in the system as high as
possible, and the other resistances normalized to the same point in the
system as low as possible
The ground system represents a resistance. When the base radiation
resistance of the antenna is decreased by shortening, the ground
resistance and loading loss resistances become more important. Ground
resistance is proportional to the length and number of radials, it has
NOTHING to do with antenna height.
The whole concept of "return currents" will get us into trouble VERY fast
when picturing what happens in an antenna. It is the source of much Voo
doo and folklore. The ground provides two things in a marconi antenna of
any type (this includes inverted L's). It allows people to "invent"
magical antennas that break the laws of physics.
1.) Something for the feedpoint to push against. The current flowing into
the ground system must equal the toatal current flowing up into the
radiator. The ground system MUST distribute these currents as uniformly as
possible over a large area in order to minimize I^2 R losses in the
ground..
2.) Something that shields or isolates the lossy earth from induction and
radiation fields. The only way to stop these effects is to provide a low
loss path for charges moved by the effects of having the antenna nearby.
Only by moving the correct number of opposing charges will a "shield" or
reflector work.
Even with an inverted L, be absolutely sure to distribute the radials as
evenly as possible around the antenna. Loss is I^2 R. Distributing I
around as uniformly as possible over as wide an area as possible is the
real goal, not concentrating it in one spot.
73 Tom
Teddy Bear
On Tue, 7 Jan 1997, Cecil Moore wrote:
>
> Hi Richard, someone previously reported that Paul Lee sez
> a vertical has more gain than a dipole. Did he really say
> that?
>
> 73, Cecil, W6RCA, OOTC
Except for a 1/4 wave they DO!
A 1/2 wave has about 2.1 dB gain, a 3/4 wave about 2.6 dB gain and a 5/8
wave vertical has about 3 dB gain while the horizontal dipole and the 1/4
wave vertical are both considered to be about equal at 0 gain,(since they
are THE reference point for the relative gain of the others).
When we talk about a vertical's "gain" we are really saying "gain over a
1/4 wave ground plane", but we just abbreviate it as the term "gain".
Likewise, when we talk about horizontal "gain" we are really saying "gain
over a dipole", but we just abbreviate it as the term "gain".
Remember, a 1/4 wave groundplane is really just a 1/2 wave dipole with a 90
degree bend in the middle. :-)
Is that an over-simplified statement? Yes, but it's basicly true.
William E. Sabin
w8j...@aol.com wrote:
>
> In article <32D3A0...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
> <sab...@crpl.cedar-rapids.lib.ia.us> writes:
>
> >
> >The ARRL numbers are for a 1/4 wave vertical. As I understand it, the
> >purpose of the radials is to provide a return path for the *near field*
> >E and H electromagnetic fields. For a physically short radiator, it makes
>
> >sense that the radials need not be as long as for a 1/4 wave radiator,
> >because the area of ground covered by the near field would be smaller.
> >
> >
>
> Hi Bill,
>
> Actually the ground needs to be LARGER with a short vertical, not
> smaller.
What I'm thinking is this:
If the vertical radiator is short, the *near-field* E and H fields that
return to earth from the radiator cover a smaller area at the base than
would be the case for a 1/4 wave radiator. If this is true, and it seems
reasonable to me, then extending the radials to much larger distances
would not improve this capture area of near-field voltages and currents
very much. In other words, making the radials *much* longer would not
improve the "system" performance much because the other losses that you
mentioned would dominate. And of course, the radials don't affect the
Brewster angle and the far field.
Bill W0IYH
Cecil Moore
Teddy Bear wrote:
>... the horizontal dipole and the 1/4 wave vertical are both considered
> to be about equal at 0 gain ...
Hi Teddy, I probably wasn't clear. The previous hawker of the Paul Lee
book said that Mr. Lee claimed that a 5/8 WL vertical has more gain than
a 1/2 WL horizontal dipole. If he says a horizontal (1/2 WL) dipole has
a maximum gain equal to a 1/4 WL vertical, he is just downright incorrect.
The unfocused omni-direction pattern of a 1/4 WL vertical ensures that it
will never have as high a gain as the focused bi-directional pattern of
a 1/2 WL dipole, assuming reasonable installations for both. It's pretty
easy to get 6 dBi gain out of a dipole over real ground. Let us know if
that ever happens with a single element 1/4 WL vertical. (Hint: EZNEC sez
5.15 dBi gain for a 1/4 WL vertical over *perfect* ground).
73, Cecil, W6RCA, OOTC
Teddy Bear
On Thu, 9 Jan 1997, Cecil Moore wrote:
>
> Teddy Bear wrote:
> >... the horizontal dipole and the 1/4 wave vertical are both considered
> > to be about equal at 0 gain ...
>
> Hi Teddy, I probably wasn't clear. The previous hawker of the Paul Lee
> book said that Mr. Lee claimed that a 5/8 WL vertical has more gain than
> a 1/2 WL horizontal dipole. If he says a horizontal (1/2 WL) dipole has
> a maximum gain equal to a 1/4 WL vertical, he is just downright incorrect.
I never said that he said it. I said they are equal, and I am not wrong.
Read on...
> The unfocused omni-direction pattern of a 1/4 WL vertical ensures that it
> will never have as high a gain as the focused bi-directional pattern of
> a 1/2 WL dipole, assuming reasonable installations for both. It's pretty
There is your mistake. A dipole is not more focused than a 1/4 ground
plane. It's just that one side of it,(the bottom side), has no place to
radiate to except the Earth.
The dipole is acually less efficient in that it has 2 radiation pattern
nulls in USABLE directions and radiates much of it's signal in an unusable
direction,(straight up, only to bounce right back at itself off of the
ionisphere or to continue into space, depending of frequency &
conditions). The dipole tends to have a more 3 dimensional signal, toward
both the horizion as well as perpendicular to the Earth. This is fine,(if
you are trying to talk to a 747 flying over your shack).
The 1/4 Ground Plane is just the opposite. It's only radiation pattern null
is the conical one straight up above it where a signal would be wasted
anyway, and the radials & capacitence hat, if present, magneticly lower
the angle of radiation thus providing a more 2 dimensional focus toward
the horizon than the dipole can do.
> easy to get 6 dBi gain out of a dipole over real ground. Let us know if
> that ever happens with a single element 1/4 WL vertical. (Hint: EZNEC sez
> 5.15 dBi gain for a 1/4 WL vertical over *perfect* ground).
Then EZNEC is wrong. Both the dipole and the 1/4 ground plane are
considered to have ZERO gain and THAT is why these two are the standard by
which all other horizontal and vertical antennas' gain are compared to.
In fact, not only is this a long standing part of antenna design theory,
it is also in one or levels of the VEC question pools for the ham theory
test as I remember it.
Roy Lewallen
In article <32D2CF...@ccm.ch.intel.com>,
>> Capt. Paul Lee, N6PL.
>
>a vertical has more gain than a dipole. Did he really say
>that?
In looking at the first two chapters (of his 2nd edition), in which he
discusses various types of antennas and their gain, I don't see any claim
that a vertical has more gain than a dipole. He does say that "The gain of
a colinear vertical can approach that of a three-element horizontal Yagi.
It is actually greater at the low angles of interest."
In the section on gain, he emphasizes the importance of comparing gain at
the particular angles of interest, which I heartily endorse. Yet I can't
find where he actually does so in his discussion of verticals and dipoles.
(He probably lacked the tools we have today.) He compares free-space gains,
and observes that the angle of maximum radiation from a vertical is lower
than that from a moderately high dipole, then extends this to imply that
the vertical will have more gain at lower angles than a dipole. But he
misses the fact that in many cases, the dipole, even a low one, still can
have more gain at the lower angles because of its initial higher gain and
the effects of ground absorption of reflected low-angle vertically-
polarized energy. His graphs show quite well the effect of this absorption,
but he implies that it can be reduced or eliminated by constructing an
adequate ground system. (It can be reduced, but usually only slightly
unless the ground system is several wavelengths in diameter.)
Roy Lewallen, W7EL
Hiller
Ian White, G3SEK wrote:
>
>
>
> >In the ARRL Antenna book it says the following in relation to the
> >length and number of radials:
> >
> >Number 16 24 36 60 90 120
> >Wavelength .1 .125 .15 .2 .25 .4
> >
> >Any comments on this?
> 'shield' the near field of the antenna from the lossy ground. The
> effectiveness of the shielding will depend on the spacing between the
> radials, especially at the outer ends where the wires are farthest
> apart.
>
> The table is sying that if you only have enough real estate for 0.1wl
> radials, there is no point in using more than 16 because that's enough
> radials to adequately cover a circle of 0.1wl radius. Efficiency will be
> poor, but adding more radials of the same length will not make it
> better.
>
> As the radials get longer, they also spread farther apart, so you need
> more wires to cover the ground. The table shows that roughly speaking,
> whatever the length of the radials, you need enough of them to make sure
> that the spacing at the ends is no more than about 0.02wl.
>
Comment on the above: a major lessening of the associated ground losses
can occur by adding a 'solid' ground plane area directly around the base
of the antenna(ie. a chicken wire mesh for a 10 by 10 or 15 by 15 foot
area right at the base). This would decrease the radial requirement or
improve the performance of the existing radial system depending on
which way you want to take advantage of the benefit.
W5RH
>
Roy Lewallen
In article <Pine.BSF.3.91.97010...@prog1.caprica.com>,
Teddy Bear <ted...@prog1.caprica.com> wrote:
>On Tue, 7 Jan 1997, Cecil Moore wrote:
>>
>> Hi Richard, someone previously reported that Paul Lee sez
>> a vertical has more gain than a dipole. Did he really say
>> that?
>>
>
>Except for a 1/4 wave they DO!
>
>A 1/2 wave has about 2.1 dB gain, a 3/4 wave about 2.6 dB gain and a 5/8
>wave vertical has about 3 dB gain while the horizontal dipole and the 1/4
>wave vertical are both considered to be about equal at 0 gain,(since they
>are THE reference point for the relative gain of the others).
>
>When we talk about a vertical's "gain" we are really saying "gain over a
>1/4 wave ground plane", but we just abbreviate it as the term "gain".
>Likewise, when we talk about horizontal "gain" we are really saying "gain
>over a dipole", but we just abbreviate it as the term "gain".
Please don't include me in "we" for either of these!
>Remember, a 1/4 wave groundplane is really just a 1/2 wave dipole with a
90
>degree bend in the middle. :-)
>
>Is that an over-simplified statement? Yes, but it's basicly true.
I'm afraid it's over-simplified to the point that it isn't true.
The gain of a 1/4-wave vertical antenna mounted on a perfect ground plane
is 3 dB relative to a 1/2-wave dipole in free space, your chosen reference.
This is simply because the energy from the vertical is concentrated in a
hemisphere rather than the free-space sphere of the dipole.
A 1/2 wave dipole over a perfect ground plane has a gain typically about 3
dB greater than a 1/4 wave vertical over a perfect ground plane (depending
on dipole height). This is because the dipole has horizontal directivity
while the vertical does not.
Of course, these comparisons are pretty meaningless because our antennas
aren't in free space or over perfect ground planes. So we're left with
comparing dipoles over ground with verticals mounted on or above the
ground. This makes the problem a lot different and much more interesting,
with too many variables to quote a single meaningful number. In fact, it's
hard to even make a reasonable generalization. One fact is, however, that a
vertical above real ground, even with an elaborate ground system, has a
much lower gain at low elevation angles than it does over perfect ground.
And in many cases, a moderately high, or even quite low, dipole will have
more gain even at quite low angles.
Roy Lewallen, W7EL
Cecil Moore
Teddy Bear wrote:
> Then EZNEC is wrong. Both the dipole and the 1/4 ground plane are
> considered to have ZERO gain and THAT is why these two are the standard by
> which all other horizontal and vertical antennas' gain are compared to.
Hi Teddy, I think if you double check you will find that horizontal
antennas are compared to the horizontal 1/2 WL dipole and vertical
antennas may be compared to the vertical 1/4 WL monopole but the maximum
gains of the dipole and monopole are *not* the same, not in free space,
not over perfect ground, not over real ground. Picture a 1/2 WL
dipole 1/2 WL in the air and a 1/4 WL vertical mounted on a metal boat
on the ocean. The dipole will have a maximum gain of about 8 dBi at
a TOA of 29 deg. The vertical will have a maximum gain of about 5 dBi
at a very low TOA. The 3 dB difference in maximum gain obviously comes
from the dipole radiating in two horizontal directions and the vertical
radiating in all horizontal directions.
W7EL may want to respond to your "EZNEC is wrong" comment. Roy, I'm
familar with a dBd. Is there such a thing as a dBv? No, no, not Bvd.
73, Cecil, W6RCA, OOTC
Desmond Power
Teddy Bear <ted...@prog1.caprica.com> wrote:
>Then EZNEC is wrong. Both the dipole and the 1/4 ground plane are
>considered to have ZERO gain and THAT is why these two are the standard by
>which all other horizontal and vertical antennas' gain are compared to.
Really!
I believe that EZNEC and NEC express their gain values in dBi, i.e. dB
relative to an isotropic radiator in free space. Most texts that I
have seen use this standard, and not the dB relative to a dipole. I
also know a few experienced antenna people who use the 'dB relative to
dipole' terminology.
Try and get your facts straight please before shooting someone down!
w8j...@aol.com
Don't you just love radial discussions!
In article <32D5D8...@flash.net>, Hiller <Nex...@flash.net> writes:
>
>Comment on the above: a major lessening of the associated ground losses
>can occur by adding a 'solid' ground plane area directly around the base
>of the antenna(ie. a chicken wire mesh for a 10 by 10 or 15 by 15 foot
>area right at the base). This would decrease the radial requirement or
>improve the performance of the existing radial system depending on
>which way you want to take advantage of the benefit.
From RCA's famous "Ground Systems as a Factor In Antenna Efficiency"
study, it concludes in the summary....
"Experimental data has shown that an eighth wave vertical antenna is
practically as efficient as a quarter wave antenna It has also been found
that 120 buried radial wires, each one half wavelength long, is desirable.
Tests of ground screens show them to be of no importance when adequate
ground systems are used."
73 Tom
w8j...@aol.com
In article <5b4t1v$lo8$1...@nadine.teleport.com>, w7...@teleport.com (Roy
Lewallen) writes:
>One fact is, however, that a
>vertical above real ground, even with an elaborate ground system, has a
>much lower gain at low elevation angles than it does over perfect ground.
>And in many cases, a moderately high, or even quite low, dipole will have
>more gain even at quite low angles.
>
>Roy Lewallen, W7EL
>
>
Hi Roy,
I hate to open this can of worms, but I'll bet if you did a user survey
you'd find many more people get better results with a 1/4 wave vertical on
160 and 80 for DX than a dipole 1/4 wl high!
With DX'ers on 160, 1/8 wl to 1/4 wl verticals are much more popular than
1/8 wl to 1/4 wl high dipoles for just that reason.
My 1/8 wl 80 meter vertical consistantly ties a dipole broadside to Europe
at 135 feet into Europe. In dozens of A-B tests night after night, the
vertical seems to have just the slightest edge.
I wonder why that is, and why almost every serious DXer on 160 quickly
changes from a 100 ft or more high dipole to a vertical? Do you think the
wave angle is lower than we expect?
73 Tom
Richard Karlquist
In article <19970110171...@ladder01.news.aol.com>,
What are you supposed to do in a phased array of verticals?
It seems like you need to have a wire mesh filling the area
enclosed by the verticals. Outside of that area, I guess you
can have radials that go out away from the centroid of the array.
There seems to be little info about this in the literature.
Rick Karlquist N6RK
rka...@scd.hp.com
Roy Lewallen
>I hate to open this can of worms, but I'll bet if you did a user survey
>you'd find many more people get better results with a 1/4 wave vertical on
>160 and 80 for DX than a dipole 1/4 wl high!
>
>With DX'ers on 160, 1/8 wl to 1/4 wl verticals are much more popular than
>1/8 wl to 1/4 wl high dipoles for just that reason.
>
>My 1/8 wl 80 meter vertical consistantly ties a dipole broadside to Europe
>at 135 feet into Europe. In dozens of A-B tests night after night, the
>vertical seems to have just the slightest edge.
>
>I wonder why that is, and why almost every serious DXer on 160 quickly
>changes from a 100 ft or more high dipole to a vertical? Do you think the
>wave angle is lower than we expect?
>
>73 Tom
I shouldn't have said it's nearly impossible to make a generalization, then
make one. Among the variables involved are:
Ground conductivity (better ground favors the vertical)
Ground system (a better one favors the vertical)
Frequency (lower frequency favors the vertical because ground reflection
improves)
Dipole height (higher favors the dipole)
I imagine most serious 160-meter DXers have a pretty good ground system.
With this and the other factors, I'm not surprised that the vertical has
"the slightest edge", or greater. I do believe that the antenna analysis
programs do a pretty good job of comparing dipoles with verticals, provided
that you include a realistic value for ground system loss, and are located
on fairly flat ground. TA is probably good at evaluating the effect of
non-flat ground.
By all means, please don't take my hedged generalization of the
low-dipole-vs-vertical to be a statement that it's always true. You should
look at your individual case. But don't discount the low dipole out of
hand, without evaluation, either.
Roy Lewallen, W7EL
CHARLES J. MICHAELS
George reported -
In the ARRL Antenna book it says the following in relation to the
length and number of radials:
Number 16 24 36 60 90 120
Wavelength .1 .125 .15 .2 .25 .4
This data seems fairly true but what it is saying is
that with the number of radials of each length you have reached
approximately the point of diminishing returns.
Incidently this is probably taken from Browns famous
1936 paper and the onl y reason it goes to .4 wavelengths is
that at that point he (with Epstein, and Lewis) ran out of wire
for the field test at 3 MHz.
Charlie. W7XC
--
Richard W. Clark
w8j...@aol.com wrote:
>Compare Lewis Brown and Epsteins work for RCA at 3 MHz....(there is some
>missing data from the Capt Lee text quoted.) Missing is how tall is the
>radiator and how long are the radials?
>For comparison, I'll quote the RCA report by B,L and E.
>In article <5aueeu$e...@q.seanet.com>, rwc...@rwclark.seanet.com (Richard
>W. Clark) writes:
>>I would recomend "The Amateur Radio Vertical Antenna Handbook" by
>73 Tom
Hi Tom,
Captain Lee cites Brown, et al. "Ground Systems As A Factor In Antenna
Efficiency," Proc. of I.R.E., June 1957, p. 735. This is, I believe,
the RCA study you mention. The difference between my numbers and
yours were a function of my projecting the knee of the curve back onto
the Y axis of a graphical rather than tabular display of this data.
The numbers you cite all fall on the Quarter Wave antenna (as all
might expect) interception point rather than the Y axis I projected
back to.
73's
Richard, KB7QHC
w8j...@aol.com
Hi Bill
In article <32D539...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
<sab...@crpl.cedar-rapids.lib.ia.us> writes:
Studies have proven that untrue. The data is available in Ground Systems
As A Factor In Antenna Efficiency, proceedings of the IRE Volume 25,
number 6 June 1937. I can fax you a copy of the appropriate pages.
Page 780 shows the measured ground current at different distances from
different height radiators. Let me give you two examples from this series
of measurements.
For 1000 watts of power and:
radiator height of 22 degrees>>> (wl distance from base)amperes
(.05)20 (.1)12.5 (.2) 7 (.4)6
radiator height of 99 degrees
(.05)4.9 (.1)5 (.2)5 (.4)5
You can see ground current is higher at all distances near the antenna
(out to .4 wl anyway) with the shorter antenna. A shorter vertical
absolutely needs a larger ground system if efficiency is to be maintained.
Of course if the system uses lossy loading, ground loss will be reduced.
But only because dissipated power moves into the loading system. Less
power remains for the ground loss to dissipate.
Visualizing current gets in the earth by displacement currents, and
returns to the antenna via the ground, really gives us a very poor mental
picture of what is going on.
73 Tom
William E. Sabin
w8j...@aol.com wrote:
>
>
> radiator height of 22 degrees>>> (wl distance from base)amperes
> (.05)20 (.1)12.5 (.2) 7 (.4)6
44% 27% 15% 13%
>
> radiator height of 99 degrees
> (.05)4.9 (.1)5 (.2)5 (.4)5
25% 25% 25% 25%
For the shorter antenna a larger percentage of the return current is
close to the base. Doesn't this give some credence to my intuition?
Bill W0IYH
mike....@ziplog.com
William E. Sabin
It also gives some support to those who favor a ground screen at the base
of a short vertical.
Bill W0IYH
mike....@ziplog.com
In <5b6rir$g67$1...@nadine.teleport.com>, w7...@teleport.com (Roy Lewallen) writes:
>In article <19970110171...@ladder01.news.aol.com>,
> w8j...@aol.com wrote:
I appologize for pushing the wrong key to post a stupid re-post just above.
What I meant to do was the below.
>By all means, please don't take my hedged generalization of the
>low-dipole-vs-vertical to be a statement that it's always true. You should
>look at your individual case. But don't discount the low dipole out of
>hand, without evaluation, either.
>
>Roy Lewallen, W7EL
Looking at the individual case is *ALWAYS* important because, there *ARE*
times where, given a little height from which to work, a reasonably high
dipole *MAY* be a better DX choice than a vetical for a particular location
or path.
The simple downward slope away from a horionzontal dipole up at the top of
a hillside in the favored direction can often mean a far better choice than a
vertical for the required path. Not all of us can put a dipole up at 90 feet
on 40 meters, but those that can will find much to entice us to do it, rather
than use a vertical at the same site over poor ground, if the desired path is
broadside to the dipole.
The same thing holds true, as I see it, for 80, and on down to 160, in a
relative sense. An 80 meter dipole up at 180 feet is not the same comparison
in real-world effectiveness as one at 40 feet up, when compared to a ground
mounted vertical at that same site, for most practical ground levels of
conductivity.
As I see it, the furor continues over all this mostly because the height really
needed to make horizontal arrays work well on low bands for DX, is simply
beyond the financial reach of many folk here.
Right?
Richard W. Clark
>Bill W0IYH
Bill, Tom,
You are both right. Bill's logic is compelling and Tom's data is
intriguing.
Richard, KB7QHC
w8j...@aol.com
In article <32D79F...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
<sab...@crpl.cedar-rapids.lib.ia.us> writes:
>For the shorter antenna a larger percentage of the return current is
>close to the base. Doesn't this give some credence to my intuition?
>
>Bill W0IYH
Hi Bill,
Maybe we aren't disagreeing about anything, just looking at the situation
differently.
Resistance of earth, in a given location, is independent of radiator
height. Power loss is I^2 R at every point around the antenna, and all of
this power loss must come from the source of power, the transmitter.
Even at .4 wl distance, ground current is larger with a short vertical
than a tall vertical. Power loss must also be higher. It is an absolute
fact that a reduction in the number of radials at .4 wl will result in a
larger power loss expressed in dB, percentage of transmitter power, or
absolute power lost. Unless we have found a situation where the Ohm's Law
becomes Ohm's Suggestion.
While it is absolutely true that ground system integrity near the vertical
becomes even MORE critical with a short vertical, the ground distance from
the vertical also becomes even more important. This is true until the
currents become equal, which I recall occuring at a distance of a
wavelength or so from even a 1/10 wl vertical.
Any increase in ground resistance within that one wavelength radius causes
more loss with a short vertical than with a taller vertical. The ground
beyond that distance has a nearly equal effect in both, for radiators <1/2
wl height.
If you and I agree that 10% of transmitter power loss, 1 dB of transmitter
power loss, or 10 watts of total power loss is the limit we can
tolerate... the short vertical needs more ground system even at .4 wl
distant.
If we use a crummy vertical with lots of loss, and the additional loss is
expressed as a field ratio, then the distant ground system of a short
vertical is not as important. But only because the whole system has so
much loss. The same effect would be true if we added a resistor in series
with a tall vertical to lower it's efficiency, except the additional loss
reduction by removing ground system .4 wl out would STILL be less as
expressed any way we like.
I feel stating a small vertical is less dependent on more distant ground
system losses is misleading. I think it is much better to say a lossy
vertical is less dependent on a good ground system when compared to the
maximum field possible from that crummy system. The only reason it is less
critical is because we have swamped out power changes by adding fixed loss
in or very near the radiator.
Experimenters often "assume" lower resistance at the base indicates lower
loss, when it may be indicating concentrated current and increased
dissipation in the surrounding soil. Base resistance has little to do with
actual ground losses when current distribution assumes a different shape
in the ground system. This is why valid conclusions of efficiency changes
can only be reached with actual FS measurements as opposed to base
measurements.
Both W8XO and myself, observing changes in FS in small elevated radial
systems, have witnessed more base current producing less FS as the system
was altered. This is the opposite of the effect expected in common
perception. The idea of return current gets us in trouble with the real
results.
73 Tom
Cecil Moore
mike....@ziplog.com wrote:
> As I see it, the furor continues over all this mostly because the height really
> needed to make horizontal arrays work well on low bands for DX, is simply
> beyond the financial reach of many folk here. Right?
But Mike, what are dollars compared to the necessities of ham-life? :-)
But you're right, even those of us with the necessary financial reach
have a hard time justifying the resulting dent in the savings account.
73, Cecil, W6RCA, OOTC
w8j...@aol.com
Hi Bill,
In article <32D7BD...@crpl.cedar-rapids.lib.ia.us>, "William E. Sabin"
<sab...@crpl.cedar-rapids.lib.ia.us> writes:
>
>It also gives some support to those who favor a ground screen at the base
>of a short vertical.
>
>Bill W0IYH
That it does. But only if the builder does not plan on installing a good
radial system.
The RCA study concluded if an adequate ground system is used a screen
makes no difference. To directly quote the study in a test of a 22 degree
tall radiator:
"In the first test, the ground system consisted of 113 radials, each 135
feet long. The ground screen consisted of a square copper screen nine feet
on a side. Absolutely no difference in field strength or antenna
resistance coule be detected when the ground screen was
removed..........".
When only 15 radials were used, FS improvement due to addition of the
ground screen was about 3 dB. FS with the screen was 2 dB down from 113
radial FS. Someplace between those extremes with a short vertical, the
ground screen becomes useful.
Ironically, people putting a lot of effort in ground systems often add a
screen when their systems do not need one, while people with small yards
and marginal radial systems who could benefit most with a screen don't
bother installing one.
73 Tom
William E. Sabin
w8j...@aol.com wrote:
>
> people with small yards
> and marginal radial systems who could benefit most with a screen don't
> bother installing one.
>
That's me, old chum. Too lazy, etc.
Bill
mike....@ziplog.com
>Ironically, people putting a lot of effort in ground systems often add a
>screen when their systems do not need one, while people with small yards
>and marginal radial systems who could benefit most with a screen don't
>bother installing one.
>
>
>73 Tom
Exactly. Plus, a further clue to what might be happening is that when it
rains real good and wets down land that is ordinarily sort to dry, there
is less changing in the SWR when the screens are there for systems which
do not have lots of radials..
:)
w8j...@aol.com
In article <5b6l2f$k...@hpscit.sc.hp.com>, rka...@scd.hp.com (Richard
Karlquist) writes:
>What are you supposed to do in a phased array of verticals?
>It seems like you need to have a wire mesh filling the area
>enclosed by the verticals. Outside of that area, I guess you
>can have radials that go out away from the centroid of the array.
>There seems to be little info about this in the literature.
>
>Rick Karlquist N6RK
I've never seen measurements of that Rick, but that would be the sort
where a screen would be most effective. Currents are very high in this
area, and I have measured that in direct measurements.
What I do on 160 is overlay both radial systems. Where the radials cross,
I solder them together. Where they are almost parallel, I eliminate one of
the radials.
73 Tom
Steve
mike....@ziplog.com wrote:
>
> In <5b6rir$g67$1...@nadine.teleport.com>, w7...@teleport.com (Roy Lewallen) writes:
> >In article <19970110171...@ladder01.news.aol.com>,
> > w8j...@aol.com wrote:
> >
> >>you'd find many more people get better results with a 1/4 wave vertical on
> >>160 and 80 for DX than a dipole 1/4 wl high!
> >>
> >>With DX'ers on 160, 1/8 wl to 1/4 wl verticals are much more popular than
> >>1/8 wl to 1/4 wl high dipoles for just that reason.
> >>
> >>My 1/8 wl 80 meter vertical consistantly ties a dipole broadside to Europe
> >>at 135 feet into Europe. In dozens of A-B tests night after night, the
> >>vertical seems to have just the slightest edge.
Good for you, but the guys with the biggest signals into Europe from the
East coast are using high, >130 feet, horizontal arrays.
> >>
> >>I wonder why that is, and why almost every serious DXer on 160 quickly
> >>changes from a 100 ft or more high dipole to a vertical? Do you think the
> >>wave angle is lower than we expect?
> >>
> >>73 Tom
> >
> >I shouldn't have said it's nearly impossible to make a generalization, then
> >make one. Among the variables involved are:
> >
> > Ground conductivity (better ground favors the vertical)
> > Ground system (a better one favors the vertical)
> > Frequency (lower frequency favors the vertical because ground reflection
> > improves)
> > Dipole height (higher favors the dipole)
> >
> >I imagine most serious 160-meter DXers have a pretty good ground system.
> >With this and the other factors, I'm not surprised that the vertical has
> >"the slightest edge", or greater. I do believe that the antenna analysis
> >programs do a pretty good job of comparing dipoles with verticals, provided
> >that you include a realistic value for ground system loss, and are located
> >on fairly flat ground. TA is probably good at evaluating the effect of
> >non-flat ground.
> >
> >By all means, please don't take my hedged generalization of the
> >low-dipole-vs-vertical to be a statement that it's always true. You should
> >look at your individual case. But don't discount the low dipole out of
> >hand, without evaluation, either.
> >
> >Roy Lewallen, W7EL
>
Roy Lewallen
>. . .
:There is your mistake. A dipole is not more focused than a 1/4 ground
:plane. It's just that one side of it,(the bottom side), has no place to
:radiate to except the Earth.
:The dipole is acually less efficient in that it has 2 radiation pattern
:nulls in USABLE directions and radiates much of it's signal in an unusable
:direction,(straight up, only to bounce right back at itself off of the
:ionisphere or to continue into space, depending of frequency &
:conditions). The dipole tends to have a more 3 dimensional signal, toward
:both the horizion as well as perpendicular to the Earth. This is fine,(if
:you are trying to talk to a 747 flying over your shack).
:The 1/4 Ground Plane is just the opposite. It's only radiation pattern
:null
:is the conical one straight up above it where a signal would be wasted
:anyway, and the radials & capacitence hat, if present, magneticly lower
:the angle of radiation thus providing a more 2 dimensional focus toward
:the horizon than the dipole can do.
>: easy to get 6 dBi gain out of a dipole over real ground. Let us know if
>: that ever happens with a single element 1/4 WL vertical. (Hint: EZNEC
sez
>: 5.15 dBi gain for a 1/4 WL vertical over *perfect* ground).
:Then EZNEC is wrong. Both the dipole and the 1/4 ground plane are
:considered to have ZERO gain and THAT is why these two are the standard by
:which all other horizontal and vertical antennas' gain are compared to.
:In fact, not only is this a long standing part of antenna design theory,
:it is also in one or levels of the VEC question pools for the ham theory
:test as I remember it.
This contains so many fundamental misconceptions that it's not worthwhile
to try and correct them one at a time. Instead, I encourage readers to
consult any antenna text, such as the ARRL Antenna Book, to get a
understanding of how antennas work and how verticals and dipoles compare.
Roy Lewallen, W7EL
w8j...@aol.com
In article <32D9B3...@erols.com>, Steve <theb...@erols.com> writes:
>
>Good for you,
??? If you say so.
>but the guys with the biggest signals into Europe from the
>East coast are using high, >130 feet, horizontal arrays.
How do 70 -130ft high dipoles (NOT ARRAYS ) compare to 70 ft high
verticals with good (ie, not the crummy four radial wonders) from the east
coast to Europe on 80?
73 Tom
Peter Markham
> Date: Sun, 12 Jan 97 15:11:23 PST
> From: Ham-Ant Mailing List and Newsgroup <ham...@UCSD.EDU>
> Reply-to: Ham...@UCSD.EDU
> Subject: Ham-Ant Digest V97 #36
> To: Ham...@ucsd.edu
> hard to even make a reasonable generalization. One fact is, however, that a
> vertical above real ground, even with an elaborate ground system, has a
> much lower gain at low elevation angles than it does over perfect ground.
> And in many cases, a moderately high, or even quite low, dipole will have
> more gain even at quite low angles.
>
> Roy Lewallen, W7EL
>
From the central north shore of Lake Michigan
As the snow fell, and temperatures plummeted, I finished
decoupling the feedlines and rotator lines from my newly erected 43'
Rohn 25G plus 7' mast tower. At the 44' level resides a pair of
phased 16 element 430 mhz yagis between a phased pair of 20 element
145 mhz yagis, all RHCP. I laid out 43, 67' radials of insulated
#14 wire in a bow tie pattern on my 50' x 100' lot, snaked around my
26' x 30' "cracker box", woodpile, 3 small sailboats and an old
van/shed.
I built the base for the tower so that I could end feed the
tower against the radials or shunt feed it, with little effort to
change the feed method. I played with 2 matching
options:
1. MFJ 949B to 8' RG-213, to tv deflection
yoke ferrite? choke balun, to #6 copper
shunt feed, to grounded tower.
2. MFJ 949B, to 8' RG-213, to tv deflection yoke ferrite?
choke balun, to base of insulated tower.
The dipole to which I compared it is 134' of #14 copper, 32'
above ground, centerfed with approximately 57' of typical #16 450
ohm "ladder line" going to an "FMI" 4:1 balun, from Amidon, on the
output of an MFJ989C "tuner". The antenna runs from 300 to 120
degrees, diagonally across the radial field and the house and the
feeder gets to the tuner within 15 degrees of perpendicular to the
antenna, mostly within 5 degrees.
My shack desk, is stacked 3 levels high with computer and radio
stuff in an organized mess, as close as 30" to as far as 90" from
the base of the tower. An FT-890 running 100 watts out was switched
between the 2 tuners feeding their respective antennas.
After A-B ing the 2 antennas for approximately 1 month, at all
hours of the day and night and modelling and comparing them with
AO, and NEC Wires, I will vouch for Roy's statement. A low dipole
aint too shabby if its set up right. (apologies to Cecil for my balun
arrangement with the balanced feeders...;-). I played mostly in the
receive mode on 14, 10, 7, 3, and 1.8 mhz.
As a general rule the dipole was better by far on 14 and 10 mhz,
at all elevation angles. The major exceptions I attribute to the
nulls in the dipole's pattern. On 7 mhz the tower started to come
alive showing varying degrees of gain over the dipole at lower
angles, most evident during the night to dx and perimeter US
states. It was noticed that even at higher angles the vertical
often provided >1 S unit of gain over the dipole off the lobes.
Generaly, toe to toe in the favored directions of those 2 half waves
in phase on 7 mhz, the dipole provides equal or stronger signals.
.
On 3 mhz, the general impression is the dipole has it all over
the vertical unless the angles are under ~15 degrees where the tower
starts to show noticeable gain over the dipole.
Never having owned or operated a vertical of similar stature or
modelled and compared, in a serious analytical manner, the 2 antennas
prior to getting the tower and radials installed, I had no
preconceived ideas other than, to paraphase the general consensus,
"vertical antennas kick butt on the long haul". The higher noise
levels from the tower, on many occaisions, killed whatever advantage
existed. I live in an old residential neighbourhood, with very close
old wood frame houses, many still with 2 wire outlets and wiring.
These buildings are a source of everything from dimmer and microwave
oven emi to scanner and tv rfi. The noisy power poles that are
scattered about the neighbourhood are real killers at times, but that
is another story. I will admit that I am somewhat dissappointed that
I do not have +40 from New Zealand :-)
The most interesting gain from all the work, sweat, near
frostbite and loss of sleep was the gains on 1.8 mhz. All out of
state qso's on ssb indicate a minimum of 2 S units gain over the
80m dipole in any and all directions. It was consistent on transmit
but showed little reciprocity on receive. Assuming no "lies", screwup
or equipment failure, here, it does not sound reasonable to me. Am I
missing something?
In closing I will emphasize my awareness that this is a real
world comparison, with much scientific method missing. The base of
the tower is now under nearly 3' of ice and snow after freezing
rain and lotsa snow. I intend to gain access to the feed points and
radial juncture to play a little more, within a week. I would like to
set up some scheds for a week from now to play some more on 1.8 to
7mhz to get a more objective grip on the differences between the
performance of the 2 antennas. At this time, if I had no interest in
low band dx, I would say my low dipole, in most cases, is what "kicks
butt", from 3 to 29 mhz.
Note: for all those that may wonder about rf in the shack; what
there is doesn't bite me, on any band, at the 100 watt output level,
on both antennas. All my stuff, works all the time, while I am
transmitting and, yes, I get into my tv and phone on some bands and
the into a neighbour's phone. I also realize that I may cook what
brains I have left, but chances are I will expire for other reasons,
and will be condemned to wonder, until then, about trains. C'est
la vie?
All enlightened criticism will be appreciated.
Pete/wa4hei
The meek will not inherit the Earth.
Steve
Varies. A "good" (as you described it) vertical will be in the same
ballpark as dioples on the lower end of your height range. The higher
dipoles will generally win. I've seen a high (180 ft) extended double
zepp, beat (by 5-7 db) a "good" 4-square array into Europe. Both
stations were within 100 miles of each other (I know this can make a big
difference, sometimes).
Few guys have both antennas so the variations are probably as much to do
with location and propagation differences as they are w/antennas.
I'd be interested in what you've seen or measured (vert vs dipole) on
paths longer than E. Coast (USA) to Europe.
S
Teddy Bear
On 13 Jan 1997 w8j...@aol.com wrote:
> How do 70 -130ft high dipoles (NOT ARRAYS ) compare to 70 ft high
> verticals with good (ie, not the crummy four radial wonders) from the east
> coast to Europe on 80?
>
> 73 Tom
Excellent point and well stated too. Arrays are not a fair test case.
When comparing a single element vertical,(a monopole with a proper ground
plane), to a single element horizontal,(ie: a full physical length
dipole), the verticals take it hands down, especially on receive! I say
this from personal experience by experimentation with both. I even found
that a 10M vertical gets much better reception than a properly made 75M
dipole mounted at the same height.
Of course, the polarity of your antenna need not be the same as that used
by the transmitter in the case of a skipped signal, because of the
tumbling effect that occurs to a skipped signal's polarity, after it has
bounced off of the ionosphere, you could say that by the time it gets to
you the skipped signal has become an "omni-polorized" to coin a phrase.
Understanding skip is a little easier if one thinks of the process as
being something like playing pool in the dark on a pool-table that has VERY
warped bumpers made of felt-covered Jello!
I've also done some interesting experimets with very narrow HF beams
equipped with an elevation rotator to "change the angle of the shot" so
that when everyone else in Southern New York could receive stations no
closer than say Utah, for example, I could hear almost any state, coast to
coast, depending on where I set my beam's X & Y positions. Much like
deciding between whether to bank it into the side or corner pockets.
Of course the beam was an electrically shortened, vertically polorized "LPQ"
as I call it, which stands for "Log-Periodic Quad" for the 10 to 80 Meter
bands. Maybe I'll post the details someday.
w8j...@aol.com
Hi Peter,
Let's all put this in proper scientific perspective. We are starting to
compare apples and oranges. First of all, I was speaking of a simple
dipole VS a vertical, not an array. I was also speaking of a vertical
using a fairly good ground, not a truncated ground, or a pathetic system
of four or eight elevated radials. I was also speaking of 160 and 80, an
A-B comparison at one location, and DX or longer distance comparisons
only.
A dipole will outperform a vertical on 160 within 200 miles or so, and on
80 within perhaps twice that distance in many cases.
.
In article <9701130759.AA28523@btc1>, pmar...@up.NET (Peter Markham)
writes:
> The most interesting gain from all the work, sweat, near
>frostbite and loss of sleep was the gains on 1.8 mhz. All out of
>state qso's on ssb indicate a minimum of 2 S units gain over the
>80m dipole in any and all directions. It was consistent on transmit
>but showed little reciprocity on receive. Assuming no "lies", screwup
>or equipment failure, here, it does not sound reasonable to me. Am I
>missing something?
Receiving to transmitting reciprocity does NOT relate to S/N ratio. It
only relates to pattern and gain. A very poor transmitting antenna can be
a great receiving antenna, and vice versa. As long as you have any noise
beyond thermal noise in the antenna system, receiving S/N ratio tests only
determine which antenna is a better receiving antenna. Transmitting
results may be far different.
It has been the experience of many hundreds of 160 meter stations any
moderately good vertical over 20 or 30 feet tall will beat any dipole
below perhaps 100 feet height, at distances over a few hundred miles.
That's why you find almost NO horizontal antennas in use on 160 unless the
guy likes to yak within a few hundred miles.
>performance of the 2 antennas. At this time, if I had no interest in
>low band dx, I would say my low dipole, in most cases, is what "kicks
> butt", from 3 to 29 mhz.
Anyone with any antenna experience on 80 would generally agree with that
statement, even though very few 160 operators would. 80 meters seems to be
the "crossover band". Below 80, any moderately well constructed vertical
outperforms any dipole at height<150 feet nearly every time. This even
happens with crummy ground systems.
Years ago, my single 1/8 wl vertical on 160 consistantly beat a 70 ft high
full size dipole SEVERAL S units into DX. The dipole was only louder
within perhaps 100 - 200 miles. Dozens and dozens of others I've talked to
have had the same results.
On 80, the crossover distance is larger and not as clearly defined. Here
the line is less defined.
Remember nearly any test between two separate stations is invalid, because
of power level changes and propagation. I can give a specific example of
the sneaky stuff that goes on at times. For example, a station in the
Youngstown Ohio area used a short vertical and "kicked butt". He even
wrote articles describing how short verticals with big hats eliminate E
field losses, and he got quite a following in the late 70's and early
80's. What everyone else didn't know is he "owned" a 4CX5000 PA. That's
only one reason why we have to be careful making general assumptions by
listening to one or two stations, or concluding from the glow of our S
meters, the real reason why "W1AW" is louder than "W2NSD".
73 Tom
MERVW2OE
I've just run a few quick models with NEC4WIN* to compare a "good"
vertical with an "average" dipole and a "good" dipole all on 80 meters.
"Good" Vertical: 61.5 Feet Tall; Average Ground; 36 radials each 20
meters in length.
"Average Dipole: 123 Feet Long; 20 meters high.
"Good" Dipole: 123 Feet Long; 40 meters high.
At a 15 degree angle of elevation the Vertical is 3 dB better than the
"Average" Dipole. The "Good" Dipole is 2 dB better than the Vertical.
At a 25 degree angle of elevation the Vertical and the "Average" Dipole
are roughly equivalent.
At a 30 degree angle of elevation the "Average" Dipole is 1.5 dB better
than the Vertical.
The "Good" Dipole out performs the Vertical at all angles - 2 dB at 15
degrees; and 4 to 5 dB between 25 and 30 degrees.
* NEC4WIN is the product of VE2GMI, Madjid who offered evaluation copies
in this news group a month or so ago. Madjid, as well as Roy (W7EL) has
warned against placing too much stock in mininec models for antennas which
are close to the ground. Nevertheless, this does seem to confirm my
experience in chasing DX on 80 meters. In summary, on the long haul a
good vertical will beat most dipoles. I say most dipoles, because most of
us can't get a dipole up more than 20 meters. At higher angles even the
low dipole will outperform the vertical; and if you can put your dipole
1/2 wave length or higher forget the vertical.
Regards, Merv, W2OE
Steve
w8j...@aol.com wrote:
>
> In article <32DA89...@erols.com>, Steve <theb...@erols.com> writes:
>
> >Varies. A "good" (as you described it) vertical will be in the same
> >ballpark as dioples on the lower end of your height range. The higher
> >dipoles will generally win. I've seen a high (180 ft) extended double
> >zepp, beat (by 5-7 db) a "good" 4-square array into Europe. Both
> >stations were within 100 miles of each other (I know this can make a big
> >difference, sometimes).
>
> provided on the air "proof" by beating many ststions into Europe with his
> short vertical, hi. He even wrote articles describing the advantages of
> his "E-field terminated radiator" (as he called it). His E-field was
> indeed terminated, in a 4CX5000.
Nice termination!
>
> 5-7 dB on S meters is usually about 3-4 dB in real life, and a simple
> collinear is much less dependent on design and construction than a four
> square (an antenna that many people feed incorrectly, and use crummy
> radial systems with).
>
No doubt. This particular 4 sq was feed properly.
> The only meaningful test is a series of many A-B tests made over a period
> of time with proper consideration to antenna installation and simple
> structures. I can't speak for others, but from my location in Georgia and
> from my old locations in Ohio, at distances over 3000 miles a 35 foot tall
> top loaded vertical with a good ground system has the slightest reported
> edge over a 135 foot high dipole (when checked broadside to the dipole).
> Night after night after night.
Not the only meaningful test. Better still - have two colocated (far
enough apart to avoid coupling) antennas, one horizontal, one vertical.
Feed both with equal power on frequencies separated by a few kHz (or
whatever would be required to avoid interference). A receiving site
(other end of the link to be measured). would receive both signals and
measure the signal strength over a long period of time (Pref 24 hours a
day for days or weeks). Then data analysis could be performed and things
like ave sig of vert vs. ave sig of horiz could be compared, std dev,
etc. Then you could get the complete picture of which antenna gave the
best signal most of the time. Who knows, you might find that one is
better than the other at certain times of the day. If you really wanted
to get crazy, do the test for an entire solar cycle to see if the sunspot
number favors on e antenna over the other.
Or you could just forget it and put up the antenna that best fits your
space and monetary budgets. HI!
>
> On 160 the difference favoring a vertical with a lower dipole was always
> many S units, although a dipole at 300 feet on a BC tower wiped out my 130
> ft vertical at any distance tested. When I had the 160 dipole at 200 ft,
> the vertical generally won into DX.
For sure. A friend of mine recently had a 160 meter dipole up around 350
feet. Needless to say, he had a killer signal w/only 100 watts. Too bad
he had to take it down :(
>
> >I'd be interested in what you've seen or measured (vert vs dipole) on
> >paths longer than E. Coast (USA) to Europe.
>
> Once compared past 1000-2000 miles, it seemed to make no difference how
> far away any test was.
>
> 73 Tom
S
w8j...@aol.com
>Varies. A "good" (as you described it) vertical will be in the same
>ballpark as dioples on the lower end of your height range. The higher
>dipoles will generally win. I've seen a high (180 ft) extended double
>zepp, beat (by 5-7 db) a "good" 4-square array into Europe. Both
>stations were within 100 miles of each other (I know this can make a big
>difference, sometimes).
So can power, see my true story about the Youngstown area station who
provided on the air "proof" by beating many ststions into Europe with his
short vertical, hi. He even wrote articles describing the advantages of
his "E-field terminated radiator" (as he called it). His E-field was
indeed terminated, in a 4CX5000.
5-7 dB on S meters is usually about 3-4 dB in real life, and a simple
collinear is much less dependent on design and construction than a four
square (an antenna that many people feed incorrectly, and use crummy
radial systems with).
The only meaningful test is a series of many A-B tests made over a period
of time with proper consideration to antenna installation and simple
structures. I can't speak for others, but from my location in Georgia and
from my old locations in Ohio, at distances over 3000 miles a 35 foot tall
top loaded vertical with a good ground system has the slightest reported
edge over a 135 foot high dipole (when checked broadside to the dipole).
Night after night after night.
On 160 the difference favoring a vertical with a lower dipole was always
many S units, although a dipole at 300 feet on a BC tower wiped out my 130
ft vertical at any distance tested. When I had the 160 dipole at 200 ft,
the vertical generally won into DX.
>I'd be interested in what you've seen or measured (vert vs dipole) on
J. Fred Riley
On 14 Jan 1997 18:10:36 GMT, w8j...@aol.com wrote:
>a 4CX5000.
Also known, ala Japanese Jack Giehl, as an
Eimac Antenna Tuner.
Fred, W8OY
JFR...@AIRMAIL.NET
FREDW...@AOL.COM
Larry Deering
Teddy Bear wrote:
> <lots snipped!>
> I've also done some interesting experimets with very narrow HF beams
> equipped with an elevation rotator to "change the angle of the shot" so
> that when everyone else in Southern New York could receive stations no
> closer than say Utah, for example, I could hear almost any state, coast to
> coast, depending on where I set my beam's X & Y positions. Much like
> deciding between whether to bank it into the side or corner pockets.
>
> Of course the beam was an electrically shortened, vertically polorized "LPQ"
> as I call it, which stands for "Log-Periodic Quad" for the 10 to 80 Meter
> bands. Maybe I'll post the details someday.
I wonder which of these groups he'll post on:
3 alt.binaries.pictures.teen-starlets
3 rec.radio.amateur.equipment
2 alt.binaries.nude.celebrities
2 alt.fan.mr-kfi
2 rec.radio.amateur.homebrew
1 alt.binaries.pictures.erotica.child.female
1 alt.binaries.pictures.erotica.pre-teen
1 alt.fan.teen.starlets
1 alt.irc.dalnet
1 alt.sex.pedophilia.girls
1 rec.radio.amateur.space
Good Luck, and Be Gone Mr. Ted T. Barry!