Ladder line with end fed wire
 

Just wondering: If you had a 33 foot horizontal wire, fed at one end with a
ladder line, which was connected to an atu, it would work on 20 metres, but
would it work on 40, 80 and 160metres? TIA.

On Wed, 8 Sep 2004 15:25:35 +0100, "Richard"
wrote:

Just wondering: If you had a 33 foot horizontal wire, fed at one end with a
ladder line, which was connected to an atu, it would work on 20 metres, but
would it work on 40, 80 and 160metres? TIA.

Hi Rich,

It might, but your atu might not. ATUs are not a one-size-fits-all
solution. In fact they fit very few problems that are not already
pretty close (and what you describe above and in other posts is
definitely not close). Maybe two bands will pull in, the others will
not (unless the loss of the ATU adds to the appearance of being
"tuned").

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Wed, 8 Sep 2004 15:25:35 +0100, "Richard"
wrote:

Just wondering: If you had a 33 foot horizontal wire, fed at one end
with a
ladder line, which was connected to an atu, it would work on 20 metres,
but
would it work on 40, 80 and 160metres? TIA.

Hi Rich,

It might, but your atu might not. ATUs are not a one-size-fits-all
solution. In fact they fit very few problems that are not already
pretty close (and what you describe above and in other posts is
definitely not close). Maybe two bands will pull in, the others will
not (unless the loss of the ATU adds to the appearance of being
"tuned").

73's
Richard Clark, KB7QHC

Hi.

I know the zeppalin antenna I described works when the top wire is a half
wavelength or greater. I was just wondering if the set up (ie 10 metre
length of top) might at least be a good as a 20 metre long inverted L (well,
L on it's side) on 40, 80 & 160, using a not very good ground arrangement.

Thing with the zepp is that there is no ground losses. Thing is, ground
losses with inverted L are probably replaced by greater atu losses? And of
course the inverted L would radiate also from the vertical section which
migh be useful. I do wonder of the two arrangements, which would be better.
I wonder also whther I might not get a true balance on the open line when
the top is less than half a wavelength.

On Wed, 8 Sep 2004 20:21:46 +0100, "Richard"
wrote:

I know the zeppalin antenna I described works when the top wire is a half
wavelength or greater.

Hi Rich,

You also need to consider the length of the transmission line (what
makes the Zeppelin work with your rig).

I was just wondering if the set up (ie 10 metre
length of top) might at least be a good as a 20 metre long inverted L (well,
L on it's side) on 40, 80 & 160, using a not very good ground arrangement.

For 160 it is quite short, for 80 somewhat short; but being short is
not a sin in and of itself. What is a sin is what the tuner has to
put up with. Most ATU's only cope with up to 3:1 SWR. A short
antenna may well exceed that. Obtain a copy of EZNEC (using the free
version) and give yourself an education on what to expect.

Thing with the zepp is that there is no ground losses. Thing is, ground
losses with inverted L are probably replaced by greater atu losses? And of
course the inverted L would radiate also from the vertical section which
migh be useful. I do wonder of the two arrangements, which would be better.
I wonder also whther I might not get a true balance on the open line when
the top is less than half a wavelength.

You won't have a true balance unless you are feeding a true balanced
antenna (which a Zepp is not, nor an inverted L).

73's
Richard Clark, KB7QHC

Read up on the topic of linear loading. You can bend that wire back on
itself and increase the total length of wire. There are discussions of this
in ON4UNs Low Band Dxing book. One commercial example is the Cobra
Ultralite at http://www.k1jek.com/.

I use a top center fed L. One side is horizontal and the other side is
vertical. Fed at the top center with ladder line. Cebik has several
articles on his site about center fed Ls. No ground plane, horizontal and
vertical polarization, fewer nulls in the pattern. Very nice

I think the center feds make a lot more sense for multiband operation.

--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64
"Richard" wrote in message
...
Just wondering: If you had a 33 foot horizontal wire, fed at one end with
a
ladder line, which was connected to an atu, it would work on 20 metres,
but
would it work on 40, 80 and 160metres? TIA.

"Craig Buck" wrote

I use a top center fed L. One side is horizontal and the other side is
vertical. Fed at the top center with ladder line. Cebik has several
articles on his site about center fed Ls. No ground plane, horizontal and
vertical polarization, fewer nulls in the pattern. Very nice

I think the center feds make a lot more sense for multiband operation.

--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64

Hi Craig, is that fed with ladder line right out of the tuner? I'm hoping
there is a best-fit arangement from my tuner to an inverted-L with either a
top-fed through a 4:1 balun or end-fed without a balun. In either case the
intention is to cover 2182khz with a 107' 1/4~ L. Any suggestions on the
best arrangement for that work?

Thanks,

Jack
Virginia Beach VA

You can go with ladder line right out of the tuner or to a short piece of
coax to a balun, then to ladder line. I have about ten feet of coax to a
1:1 balun outside. The coax is easier to get out of the house and away from
things that might unbalance the ladder line. Loss on such a short piece of
coax is negligible even at high SWRs on HF.

Whether you use a 4:1 or 1:1 depends on the antenna and feedline. I use a
1:1. Your antenna will be the "right" length so the impedance at the
transmitter end won't be too far off from 70 ohms. A 4:1 balun would be a
mistake as it would lower the impedance making it harder to match the
transmitter.

I have to ask, "Why are you using ladder line?" Usually it is only used
when the antenna has a high SWR and we want to avoid losses in the coax.
You won't have much of a mismatch, if any. I would think you would go with
coax, you might not even need a tuner.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64


"Jack Painter" wrote in message
news:UuM%c.173651$Lj.145677@fed1read03...

"Craig Buck" wrote

I use a top center fed L. One side is horizontal and the other side is
vertical. Fed at the top center with ladder line. Cebik has several
articles on his site about center fed Ls. No ground plane, horizontal
and
vertical polarization, fewer nulls in the pattern. Very nice

I think the center feds make a lot more sense for multiband operation.

--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64

Hi Craig, is that fed with ladder line right out of the tuner? I'm hoping
there is a best-fit arangement from my tuner to an inverted-L with either
a
top-fed through a 4:1 balun or end-fed without a balun. In either case the
intention is to cover 2182khz with a 107' 1/4~ L. Any suggestions on the
best arrangement for that work?

Thanks,

Jack
Virginia Beach VA

Thanks Craig - and if you could, please elaborate on these design
considerations:

The antenna is not erected yet - still planning. I would choose a 1:1 balun
if I used one at all with an end-fed inverted-L configuration. But if I
configure the antenna as a sloper (same L-shape) and top-feed at the angle
point, then I thought a 4:1 balun could help make 2182khz tunable on an
antenna with dipole properties that is really too short (would have to be
107' each leg not 107' total, which is about all I can get at that
location). Of those two choices, I had not intended to use ladderline for
either, but would consider it if some benefit was possible. Ideally, the
antenna would be desireable to cover 2-20mhz. No compromse on the 2182 end
is worth the upper bandwidth though, with 5.7 & 8.9 mhz the other
requirements that should not unduly strain a tuner under high tx power. The
antenna would be primarily for 2182 - 4125 khz.. Thanks for any help.

Jack

"Craig Buck" wrote in message
news:Y6O%c.7112$OZ6.5222@okepread06...
You can go with ladder line right out of the tuner or to a short piece of
coax to a balun, then to ladder line. I have about ten feet of coax to a
1:1 balun outside. The coax is easier to get out of the house and away
from
things that might unbalance the ladder line. Loss on such a short piece
of
coax is negligible even at high SWRs on HF.

Whether you use a 4:1 or 1:1 depends on the antenna and feedline. I use a
1:1. Your antenna will be the "right" length so the impedance at the
transmitter end won't be too far off from 70 ohms. A 4:1 balun would be a
mistake as it would lower the impedance making it harder to match the
transmitter.

I have to ask, "Why are you using ladder line?" Usually it is only used
when the antenna has a high SWR and we want to avoid losses in the coax.
You won't have much of a mismatch, if any. I would think you would go
with
coax, you might not even need a tuner.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64


"Jack Painter" wrote in message
news:UuM%c.173651$Lj.145677@fed1read03...

"Craig Buck" wrote

I use a top center fed L. One side is horizontal and the other side
is
vertical. Fed at the top center with ladder line. Cebik has several
articles on his site about center fed Ls. No ground plane, horizontal
and
vertical polarization, fewer nulls in the pattern. Very nice

I think the center feds make a lot more sense for multiband operation.

--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64

Hi Craig, is that fed with ladder line right out of the tuner? I'm
hoping
there is a best-fit arangement from my tuner to an inverted-L with
either
a
top-fed through a 4:1 balun or end-fed without a balun. In either case
the
intention is to cover 2182khz with a 107' 1/4~ L. Any suggestions on
the
best arrangement for that work?

Thanks,

Jack
Virginia Beach VA

Craig Buck wrote:
Read up on the topic of linear loading. You can bend that wire back on
itself and increase the total length of wire. There are discussions of
this in ON4UNs Low Band Dxing book. One commercial example is the
Cobra Ultralite at http://www.k1jek.com/.

I use a top center fed L. One side is horizontal and the other side is
vertical. Fed at the top center with ladder line. Cebik has several
articles on his site about center fed Ls. No ground plane, horizontal
and vertical polarization, fewer nulls in the pattern. Very nice

I think the center feds make a lot more sense for multiband operation.

You're absolutely right, Craig... in principle.

But Richard's situation reflects the reality for many British hams whose
house is at one end of a short and narrow rear lot. With neighbors very
close on all sides, we're lucky to have even one mast, so center-fed
antennas are often not very practical for us - they either sag in the
middle or wind up in a very sharp inverted-V configuration.

As a result, we're very much forced towards considering end-fed or
base-fed solutions.

However, I wouldn't go near an end-fed long wire or zepp configuration,
because of the very high risk of feeding the RF return currents into the
mains. Been there, done that, had the doorbell ring!

Living in that situation myself, my best solution has been a 30-33ft
vertical at the far end of the garden, fed against the best ground
system I can manage. This can be fed directly on 7MHz; with an ATU at
the base it is good for 10, 14 and 18MHz, and is usable on the higher
bands too.

Over the years, this system has acquired an auto-ATU at the base, and
has evolved into a guyed tilt-over mast with various quick-change
"accessories" that can be attached at the top. A lightweight 12ft
fishing pole makes a taller vertical, which has slowly crept up to 45ft;
or a selection of horizontal loading wires running back towards the
house at the 33ft level make inverted-L configurations for the lower
bands.

With the auto-ATU, any configuration can easily be loaded on any band.
It won't be optimum on more than one HF band, but it will get you on the
air on *every* band - and that's what counts for most.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

"Ian White, G3SEK" wrote in message
...

But Richard's situation reflects the reality for many British hams whose
house is at one end of a short and narrow rear lot. With neighbors very
close on all sides, we're lucky to have even one mast, so center-fed
antennas are often not very practical for us - they either sag in the
middle or wind up in a very sharp inverted-V configuration.

As a result, we're very much forced towards considering end-fed or
base-fed solutions.


Although center-fed is not totally impossible or out of the question, you
are right, a lot of UK hams have small back lots/gardens and so many of us
do tend to seek verticals or end-fed arrangements with the feed point away
from the house. In my particular case, the problem with a vertical is that
it would practically be surrounded on all sides by either trees or the
house, so I'm not sure if going for a vertical alone would be a good idea,
and that's why I'm considering either an inverted-L or zepp or something
better.


However, I wouldn't go near an end-fed long wire or zepp configuration,
because of the very high risk of feeding the RF return currents into the
mains. Been there, done that, had the doorbell ring!

Noted.

Living in that situation myself, my best solution has been a 30-33ft
vertical at the far end of the garden, fed against the best ground
system I can manage. This can be fed directly on 7MHz; with an ATU at
the base it is good for 10, 14 and 18MHz, and is usable on the higher
bands too.

Yes. Any vertical at my QTH would be about 10 metres away from the house to
the south, and about 2 metres away from tallish conifers to the north. A
vertical would seem to be hemmed in to me. No clear take of in any direction
actually.

The problem with using a center-fed arrangement, is that the most I could
put up in backgarden would be ap 40 metre doublet as per:


x-------------------
| \
| \
| \
| \
| \feedline

back garden

But the feed would be at the top of a 10 metre mast. I would have to have
the feedline go in at an angle.

So one thinks perhaps I need to end-feed as per:

-------------------
|
|
|
|
|
x

back garden

BUT, I could be daring and do this:


/ | \
/ | \
/ house \

back garden front garden

Erect a 40 dipole, feeding at point of small mast on chimney stack of house.
That means half of the antenna ends up in front garden.

Or even put up cobra:
http://www.k1jek.com/index.html
Junior does not do 160 though.

"Richard" wrote in message
...

So one thinks perhaps I need to end-feed as per:

-------------------
|
|
|
|
|
x

back garden


Latest thoughts:

If I could get a decent ground (and that's unknown) I bet I could do a lot
worse than an inverted -L, to use for 40, 80 and 160.

Best I could do:

10m 10m
------------------------------------------------
| |
| pole on house
| 10m
|
|
x feed

back garden front garden

Yep, might be worth a try if I can get a decent ground.

In article ml50d.17720$aW5.7105@fed1read07,
"Craig Buck" wrote:

With linear loading, you can get up a lot of wire in a small space. Take a
look at
http://hamgate.sunyerie.edu/~larc/su...inverted_v.htm for
an example of a 160 meter inverted vee in a 40 foot yard!

If you want multi band operation, put up as much wire as you can and feed it
with ladder line to a 1:1 balun to a short piece of coax to a tuner.

Feed it at the top so the maximum current is up high.

If an inverted L works for your lot, try feeding it at the top middle
instead of the bottom end and using the linear loading technique to make
each leg longer. According to Cebik if you can get 3/8s wavelength, you are
very close to the full performance of a half wave. Feeding at the top
middle does not require a radial field to work.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64
[snip]

Some nice suggestions, there, especially the point about keeping the
maximum current area of the antenna as high as possible.

The antenna can be end-fed (high impedance), off-center fed (moderate
impedance) and center-fed (low impedance). With a good antenna tuner, I
don't s'pose it much matters about impedance, as long as the varying
amounts fall within the tuner's range.

It was a revelation to me to realize that a half-wave length of wire
doesn't really care where it is fed: end, off-center, or mid-point. The
high-current portion will be in the middle and the high-voltage points
will be at the ends, regardless of where the feed point is located, as
long as the wire is resonant at the operating frequency.

Linear loading is effective, but as more wire is tightly folded back
from the ends, the more narrow the 'bandwidth' becomes, limiting the
tuneable range. This would also pretty much kill the multi-band utility
of the antenna.

I use a 130-foot ladderline fed dipole, center-fed. In a location like
yours, I'd keep as much of the center portion of the antenna as high and
level as possible, and then at each far end I'd fold them down and to
the side, and then back along the fence toward to the center as far as
needed, clipping the wire to stand-off insulators and keeping them up
out of reach of curious fingers. The radiation from the end portions is
less, and is a practical compromise for 80 meters and up.

For 160 meter operation, I use "clip on" extensions that run along my
perimeter fence on both sides, and they make a sort of "Z" in respect to
the main antenna. This works very well, letting the center part of the
dipole radiate up high, while providing enough physical wavelength to
allow tuning.

All of this is a compromise, of course, but it's practical and effective.

I suspect that the performance of the "all band" antenna is somewhat
less effective on 20 meters up .. but this is a much more approachable
situation. I've acquired an end-fed trapped half-wave vertical for 20
thru 10 meters that is only 17 feet in length. I plan to mount it on a
mast alongside the house. I suspect that the radiation pattern on 20
meters and up from this "vertical halfwave" will be much more evenly
distributed and predictable than the multi-node variations of the
tuneable dipole. Between the two antennas, one should be pretty well
covered, given the space restrictions.

Gray K7VGW

--
Reply to: allen/at/graybyrd/dot/com

"Those who figure that freedom is maintained by putting a .50 caliber slug
through anyone and everyone who disagrees with their flag-waving, chest-beating
histrionic rants of patriotism will probably live to see the end of their own
freedoms while hiding behind their locked and shuttered doors, sucking the
barrel of their own shotgun." --me

"Graybyrd" wrote
"Craig Buck" wrote:

With linear loading, you can get up a lot of wire in a small space.
Take a
look at
http://hamgate.sunyerie.edu/~larc/su...inverted_v.htm
for
an example of a 160 meter inverted vee in a 40 foot yard!

If you want multi band operation, put up as much wire as you can and
feed it
with ladder line to a 1:1 balun to a short piece of coax to a tuner.

Feed it at the top so the maximum current is up high.

If an inverted L works for your lot, try feeding it at the top middle
instead of the bottom end and using the linear loading technique to make
each leg longer. According to Cebik if you can get 3/8s wavelength, you
are
very close to the full performance of a half wave. Feeding at the top
middle does not require a radial field to work.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64
[snip]

Some nice suggestions, there, especially the point about keeping the
maximum current area of the antenna as high as possible.

The antenna can be end-fed (high impedance), off-center fed (moderate
impedance) and center-fed (low impedance). With a good antenna tuner, I
don't s'pose it much matters about impedance, as long as the varying
amounts fall within the tuner's range.

It was a revelation to me to realize that a half-wave length of wire
doesn't really care where it is fed: end, off-center, or mid-point. The
high-current portion will be in the middle and the high-voltage points
will be at the ends, regardless of where the feed point is located, as
long as the wire is resonant at the operating frequency.

Linear loading is effective, but as more wire is tightly folded back
from the ends, the more narrow the 'bandwidth' becomes, limiting the
tuneable range. This would also pretty much kill the multi-band utility
of the antenna.

I use a 130-foot ladderline fed dipole, center-fed. In a location like
yours, I'd keep as much of the center portion of the antenna as high and
level as possible, and then at each far end I'd fold them down and to
the side, and then back along the fence toward to the center as far as
needed, clipping the wire to stand-off insulators and keeping them up
out of reach of curious fingers. The radiation from the end portions is
less, and is a practical compromise for 80 meters and up.

For 160 meter operation, I use "clip on" extensions that run along my
perimeter fence on both sides, and they make a sort of "Z" in respect to
the main antenna. This works very well, letting the center part of the
dipole radiate up high, while providing enough physical wavelength to
allow tuning.

All of this is a compromise, of course, but it's practical and effective.

I suspect that the performance of the "all band" antenna is somewhat
less effective on 20 meters up .. but this is a much more approachable
situation. I've acquired an end-fed trapped half-wave vertical for 20
thru 10 meters that is only 17 feet in length. I plan to mount it on a
mast alongside the house. I suspect that the radiation pattern on 20
meters and up from this "vertical halfwave" will be much more evenly
distributed and predictable than the multi-node variations of the
tuneable dipole. Between the two antennas, one should be pretty well
covered, given the space restrictions.

Gray K7VGW


Many thanks. I do not have the space for this 4th HF antenna to get 1/2
wavelength of 2.182 mhz (214'). I can manage 1/4~ in the fashion of an inv-L
antenna. A big compromise to begin with, but how would that utilize it's
desired 1/4~ electrical length if I fed it anyplace but from the end? I can
add radials and will have to do so if the end-fed inv-L turns out to be the
best by consensus. Earth is sandy with a little clay - not very good. An
MFJ-962D manual or MFJ-994 ATU, whichever performs better, and a 1:1 current
balun at the feedpoint (if helpful) will be used. Estimated height of the
vertical radiator from shield-grounded feedpoint to the "L" would be 37' and
the remaining 70' of radiator would be horizontal. Comments on the expected
efficiency of this arrangement for best performance on 2182-4125 khz are
greatly appreciated. Anyone who is capable of modeling this design, that
would be seriously helpful too ;-)

73,

Jack Painter
Virginia Beach VA

Jack Painter wrote:
... then I thought a 4:1 balun could help make 2182khz tunable on an
antenna with dipole properties that is really too short (would have to be
107' each leg not 107' total, which is about all I can get at that
location).

A "too short" dipole has a feedpoint resistance lower than 50 ohms.
Why would one use a 4:1 balun to attempt to divide that already too
low resistance by 4?
--
73, Cecil http://www.qsl.net/w5dxp


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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Two big advantages of the center top feed as opposed to bottom end feed is
center top requires no radials. Bottom L will need a minimum of 8 100 foot
radials in your application and some would argue you need many more than 8.
Have fun burying 800+ feet of wire. Second, top feed gets the high current
radiating part of the antenna up higher. Check out
http://www.cebik.com/ltv.html and his discussion of ladder line at
http://www.cebik.com/gup/gup32.html. He concludes a 1:1 balun is best.

If you have 37 feet of height you can feed at the top and run the wire
straight down, back up and then down again for a total of 3x37= 111 feet of
wire on the vertical side. On the horizontal just bend back at the end or
let the end drop down vertically. Sure it will have narrower bandwidth than
a straight dipole but you have a tuner and you can't have a straight dipole.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64


"Jack Painter" wrote in message
news:n890d.31528$Ka6.3203@okepread03...

"Graybyrd" wrote
"Craig Buck" wrote:

With linear loading, you can get up a lot of wire in a small space.
Take a
look at
http://hamgate.sunyerie.edu/~larc/su...inverted_v.htm
for
an example of a 160 meter inverted vee in a 40 foot yard!

If you want multi band operation, put up as much wire as you can and
feed it
with ladder line to a 1:1 balun to a short piece of coax to a tuner.

Feed it at the top so the maximum current is up high.

If an inverted L works for your lot, try feeding it at the top middle
instead of the bottom end and using the linear loading technique to
make
each leg longer. According to Cebik if you can get 3/8s wavelength,
you
are
very close to the full performance of a half wave. Feeding at the top
middle does not require a radial field to work.
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64
[snip]

Some nice suggestions, there, especially the point about keeping the
maximum current area of the antenna as high as possible.

The antenna can be end-fed (high impedance), off-center fed (moderate
impedance) and center-fed (low impedance). With a good antenna tuner, I
don't s'pose it much matters about impedance, as long as the varying
amounts fall within the tuner's range.

It was a revelation to me to realize that a half-wave length of wire
doesn't really care where it is fed: end, off-center, or mid-point. The
high-current portion will be in the middle and the high-voltage points
will be at the ends, regardless of where the feed point is located, as
long as the wire is resonant at the operating frequency.

Linear loading is effective, but as more wire is tightly folded back
from the ends, the more narrow the 'bandwidth' becomes, limiting the
tuneable range. This would also pretty much kill the multi-band utility
of the antenna.

I use a 130-foot ladderline fed dipole, center-fed. In a location like
yours, I'd keep as much of the center portion of the antenna as high and
level as possible, and then at each far end I'd fold them down and to
the side, and then back along the fence toward to the center as far as
needed, clipping the wire to stand-off insulators and keeping them up
out of reach of curious fingers. The radiation from the end portions is
less, and is a practical compromise for 80 meters and up.

For 160 meter operation, I use "clip on" extensions that run along my
perimeter fence on both sides, and they make a sort of "Z" in respect to
the main antenna. This works very well, letting the center part of the
dipole radiate up high, while providing enough physical wavelength to
allow tuning.

All of this is a compromise, of course, but it's practical and effective.

I suspect that the performance of the "all band" antenna is somewhat
less effective on 20 meters up .. but this is a much more approachable
situation. I've acquired an end-fed trapped half-wave vertical for 20
thru 10 meters that is only 17 feet in length. I plan to mount it on a
mast alongside the house. I suspect that the radiation pattern on 20
meters and up from this "vertical halfwave" will be much more evenly
distributed and predictable than the multi-node variations of the
tuneable dipole. Between the two antennas, one should be pretty well
covered, given the space restrictions.

Gray K7VGW


Many thanks. I do not have the space for this 4th HF antenna to get 1/2
wavelength of 2.182 mhz (214'). I can manage 1/4~ in the fashion of an
inv-L
antenna. A big compromise to begin with, but how would that utilize it's
desired 1/4~ electrical length if I fed it anyplace but from the end? I
can
add radials and will have to do so if the end-fed inv-L turns out to be
the
best by consensus. Earth is sandy with a little clay - not very good. An
MFJ-962D manual or MFJ-994 ATU, whichever performs better, and a 1:1
current
balun at the feedpoint (if helpful) will be used. Estimated height of the
vertical radiator from shield-grounded feedpoint to the "L" would be 37'
and
the remaining 70' of radiator would be horizontal. Comments on the
expected
efficiency of this arrangement for best performance on 2182-4125 khz are
greatly appreciated. Anyone who is capable of modeling this design, that
would be seriously helpful too ;-)

73,

Jack Painter
Virginia Beach VA

Richard wrote:
Just wondering: If you had a 33 foot horizontal wire, fed at one end with a
ladder line, which was connected to an atu, it would work on 20 metres, but
would it work on 40, 80 and 160metres? TIA.

On 40m, 80m, and 160m, it would act more like an inverted-L
with lots of feedline radiation. On those bands, you might
as well put up an inverted-L.

On 20m, it would have a very high feedpoint impedance in the
neighborhood of thousands of ohms. The feedpoint current is
pretty low so the current unbalance has a limit. For 100w, the
feedpoint current would be about 0.15a. Of course, the feedpoint
current in the other wire is zero since it is floating at the
antenna feedpoint.

On 40m, it would have a very low feedpoint impedance in the
neighborhood of 40 ohms. For 100w, the feedpoint current
would be about 1.5a, a magnitude more current unbalance
than the 20m case.
--
73, Cecil http://www.qsl.net/w5dxp


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"Craig Buck" wrote

Two big advantages of the center top feed as opposed to bottom end feed is
center top requires no radials. Bottom L will need a minimum of 8 100
foot
radials in your application and some would argue you need many more than
8.
Have fun burying 800+ feet of wire. Second, top feed gets the high
current
radiating part of the antenna up higher. Check out
http://www.cebik.com/ltv.html and his discussion of ladder line at
http://www.cebik.com/gup/gup32.html. He concludes a 1:1 balun is best.

If you have 37 feet of height you can feed at the top and run the wire
straight down, back up and then down again for a total of 3x37= 111 feet
of
wire on the vertical side. On the horizontal just bend back at the end or
let the end drop down vertically. Sure it will have narrower bandwidth
than
a straight dipole but you have a tuner and you can't have a straight
dipole.
--

Hi Craig, Mr. Cebik says nothing about wrapping radiators back and forth
near each other as the earlier referenced url:
http://hamgate.sunyerie.edu/~larc/su...inverted_v.htm

Cebik does comment:
"Bending the horizontal arm far end down: If horizontal space is limited, a
common practice is to bend (or dangle) the outer ends of a dipole downward.
since the region is the high voltage and low current portion of the antenna,
the radiation pattern is least affected by modifying the geometry." -and-

"Like many wire antennas, the inverted-L will tolerate moderate alterations
of geometry to fit the space available and still yield good, if not peak,
performance."

each leg longer. According to Cebik if you can get 3/8s wavelength,
you
are
very close to the full performance of a half wave. Feeding at the
top
middle does not require a radial field to work.

It doesn't appear that Cebik intended to imply that 3/8~ off-center feed
would ever approach true1/2~ dipole performance, just that it would still
operate. These off-center-fed variations (of Carolina Windhams?) are
confusing, no matter how much wire they use. Remember I don't need an
all-band compromising performer like the T2FD or Windham, but a specific
performer on 2182 Khz, and hopefully at least through 4125 Khz. Doing this
with 70' of horizontal span and two vertical attachment points about 37'
high is the challenge I am asking for help with. I cannot run anything like
KGØZP does, which creates (in his location) a near-field coupling nightmare,
in my opinion. Your suggestion (doubling the verticals), which varies from
both the KGØZP design and Cebik's "moderate geomtery alterations", would at
least add electrical length, but it remains off-center-fed and therefore
never creates a 1/2~ dipole, correct?

If I stuck with a 1/4~ end-fed L, and only used 8 radials of 20-40', could
this still outperform an off-center-fed antenna off any length on 2182 Khz?

Thanks again for the comments and ideas,

Jack painter
Virginia Beach VA

On Fri, 10 Sep 2004 13:39:05 -0400, "Jack Painter"
wrote:

But I need to improve transmit capability to a reliable 200 miles
minimum. And yes, we do get grazed often and ocassionally hit by hurricanes
here. ;-)

Hi Jack,

What options are available to you? Got any towers?

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Fri, 10 Sep 2004 13:39:05 -0400, "Jack Painter"
wrote:

But I need to improve transmit capability to a reliable 200 miles
minimum. And yes, we do get grazed often and ocassionally hit by
hurricanes
here. ;-)

Hi Jack,

What options are available to you? Got any towers?

73's
Richard Clark, KB7QHC

Richard, towers are courtesy of Virginia Loblolly Pine! They run all the way
into the heavens, attract lightning like nobody's business, and pretty much
ruin homes when they come down in hurricanes or Nor'Easter's. But they are
also god-given antenna towers offering large limbs starting at about 50' on
up. I try to use the lower parts of the trees (50') so as to reduce sway.
From a 3' dia tree there is none, the more slender sky-cranes move a lot.

| |
-0- ------------------------------------0-
| |


-- --
| |
^ |----- / /------|
| | |
50' | |
| |
| |
------------ 70' ----------------

Basically, I have similar arrangements for 5 & 8mhz dipole, longwire, random
wire, etc.

Jack

Hi Jack,

I usually lurk here quietly, but thought
I'd stick my neck out.

I just did a quick analysis on EZNEC.
Imagine a wire that is 50 feet up, 70
feet across the top, hanging down 40
feet on each end for a total of 150 feet.
Feed it in the center of the top with
75 feet of 450 ohm line.

The impedance seen at the end of 75
feet of 450 ohm feedline looked pretty
workable on both 2182 and 4125 kHz.
(Yes, you need an antenna tuner, but
it could be very simple for just two
frequencies.) An NVIS antenna like
this is great for short range (a few
hundred miles).

Download the demo version of EZNEC
from www.eznec.com . It'll take you a
couple of hours to get familiar with it,
but then you can play "what if" with
a lot of simple antennas like this.

73, John - K6QQ

Thank you very much John. I admit not giving two hours of learning time to
my EZNEC demo, but I wrote it off as too complicated to assimilate in the
time I could spend on it. That's an interesting finding on a "short" dipole
tuning up on 2182. I had not considered what ladderline to a dipole might
allow...

Jack

"John Moriarity" wrote

Hi Jack,

I usually lurk here quietly, but thought
I'd stick my neck out.

I just did a quick analysis on EZNEC.
Imagine a wire that is 50 feet up, 70
feet across the top, hanging down 40
feet on each end for a total of 150 feet.
Feed it in the center of the top with
75 feet of 450 ohm line.

The impedance seen at the end of 75
feet of 450 ohm feedline looked pretty
workable on both 2182 and 4125 kHz.
(Yes, you need an antenna tuner, but
it could be very simple for just two
frequencies.) An NVIS antenna like
this is great for short range (a few
hundred miles).

Download the demo version of EZNEC
from www.eznec.com . It'll take you a
couple of hours to get familiar with it,
but then you can play "what if" with
a lot of simple antennas like this.

73, John - K6QQ

Most of the info I got on linear loading comes from ON4UN's book Low Band
Dxing. It is a great source.

The top fed L I am describing is center fed. There is an equal amount of
wire on each side of the center insulator.

I just find this solution a whole lot easier than burying 800 feet of wire
to make a bottom fed inverted L.

--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64
"Jack Painter" wrote in message
news:cfj0d.178414$Lj.153426@fed1read03...

"Craig Buck" wrote

Two big advantages of the center top feed as opposed to bottom end feed
is
center top requires no radials. Bottom L will need a minimum of 8 100
foot
radials in your application and some would argue you need many more than
8.
Have fun burying 800+ feet of wire. Second, top feed gets the high
current
radiating part of the antenna up higher. Check out
http://www.cebik.com/ltv.html and his discussion of ladder line at
http://www.cebik.com/gup/gup32.html. He concludes a 1:1 balun is best.

If you have 37 feet of height you can feed at the top and run the wire
straight down, back up and then down again for a total of 3x37= 111 feet
of
wire on the vertical side. On the horizontal just bend back at the end
or
let the end drop down vertically. Sure it will have narrower bandwidth
than
a straight dipole but you have a tuner and you can't have a straight
dipole.
--

Hi Craig, Mr. Cebik says nothing about wrapping radiators back and forth
near each other as the earlier referenced url:
http://hamgate.sunyerie.edu/~larc/su...inverted_v.htm

Cebik does comment:
"Bending the horizontal arm far end down: If horizontal space is limited,
a
common practice is to bend (or dangle) the outer ends of a dipole
downward.
since the region is the high voltage and low current portion of the
antenna,
the radiation pattern is least affected by modifying the geometry." -and-

"Like many wire antennas, the inverted-L will tolerate moderate
alterations
of geometry to fit the space available and still yield good, if not peak,
performance."

each leg longer. According to Cebik if you can get 3/8s wavelength,
you
are
very close to the full performance of a half wave. Feeding at the
top
middle does not require a radial field to work.

It doesn't appear that Cebik intended to imply that 3/8~ off-center feed
would ever approach true1/2~ dipole performance, just that it would still
operate. These off-center-fed variations (of Carolina Windhams?) are
confusing, no matter how much wire they use. Remember I don't need an
all-band compromising performer like the T2FD or Windham, but a specific
performer on 2182 Khz, and hopefully at least through 4125 Khz. Doing this
with 70' of horizontal span and two vertical attachment points about 37'
high is the challenge I am asking for help with. I cannot run anything
like
KGØZP does, which creates (in his location) a near-field coupling
nightmare,
in my opinion. Your suggestion (doubling the verticals), which varies from
both the KGØZP design and Cebik's "moderate geomtery alterations", would
at
least add electrical length, but it remains off-center-fed and therefore
never creates a 1/2~ dipole, correct?

If I stuck with a 1/4~ end-fed L, and only used 8 radials of 20-40', could
this still outperform an off-center-fed antenna off any length on 2182
Khz?

Thanks again for the comments and ideas,

Jack painter
Virginia Beach VA

"Richard" wrote in message
...

Best I could do:

10m 10m
------------------------------------------------
| |
| pole on house
| 10m
|
|
x feed

back garden front garden


or even better perhaps:

10m 10m
------------------------x------------------------
| | feed |
| pole on house |
| 6m | 6m
| |
| |

back garden front garden

Getting G5RV-ish now. Not that great for 160 though.