Elecraft

What Vertical Antenna Do I Need?

Classic

List

Threaded

17 messages Options

Fred (FL)

What Vertical Antenna Do I Need?

I'm another limited space, restricted community
ham (for now). I've been considering different
types of verticals which might be best. I THINK,
I'm looking for an antenna which:

- vertical ?
- no radials
- no counterpoises
- no guy-wires
- 40 thru 10
- maybe 4 shorter buried radials (if I must)
- not a lot of "visual" space, for neighbors

We have a MOBILE Home (mostly plastic, and
wood) - which sits on a slab of concrete,
surrounded by 8x8 wood timers, 2 feet high on
front side of mobile. Can easily get UNDER
mobile, thru removable siding.

Park owner, OK'd a "marine antenna" - whatever that
means to him. We live on shore of St. Lawrence
River - Canada in the distance.

What commercial or home-made antenna could suit
my bill?

Fred
N3CSY

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Ron D'Eau Claire-2

RE: What Vertical Antenna Do I Need?

Fred N3CSY asked:

I'm another limited space, restricted community
ham (for now). I've been considering different
types of verticals which might be best. I THINK,
I'm looking for an antenna which:

- vertical ?
- no radials
- no counterpoises
- no guy-wires
- 40 thru 10
- maybe 4 shorter buried radials (if I must)
- not a lot of "visual" space, for neighbors

We have a MOBILE Home (mostly plastic, and
wood) - which sits on a slab of concrete,
surrounded by 8x8 wood timers, 2 feet high on
front side of mobile. Can easily get UNDER
mobile, thru removable siding.

Park owner, OK'd a "marine antenna" - whatever that
means to him. We live on shore of St. Lawrence
River - Canada in the distance.

What commercial or home-made antenna could suit
my bill?

------------------------------------

To most people familiar with ships a "marine" antenna is a 20 foot whip,
usually a robust self-supporting fiberglass pole that is mounted with side
brackets on the side of the house on smaller boats or on the side of one of
the stack on large ships or, on large ships, is mounted at the base with a
ring about 1-foot in diameter that is bolted to the steel deck. They work FB
as Marconi antennas (1/4 wave or shorter worked against ground) because the
"ground" on a ship is the best you'll find on the earth: miles and miles of
salt water.

With such a ground those antennas are astonishingly effective. A big part of
the efficiency comes not from the immediate ground connection, but from the
fact that out in the Fresnel zone some wavelengths from the antenna where
the electromagnetic waves interact with the earth, the "earth" there is very
good conducting salt water.

Your requirements include "no radials". In that case you might go with one
of the so-called "ground independent" verticals such as the Cushcraft R6000.
They are electrically 1/2 wavelength long, so they don't require radials but
they are *not* as efficient as a true half-wave antenna. Still, a 40-10 or
40-6 meter antenna like the Cushcraft is only a bit over 20 feet tall, which
should meet the demands of the park owner, and will deliver good performance
in the smallest space. The only issue will be that instead of the clean,
simple fiberglass pole that one usually sees on boats, these antennas have
several vertical sections all interconnected.

On land you'll need radials with a typical marine whip. The closer to the
ground, the more radials you'll need for a given efficiency. The idea of the
radials is to intercept the RF currents and have them flow in good
conducting copper instead of through the lossy earth. If they have to be on
the ground, the "rule of thumb" the FCC and broadcast engineers have used
for over half a century is to have 120 radials 0.2 wavelengths long
radiating from the base of the antenna. If you can raise the radials even
only five or six feed above the earth, half a dozen are just as effective as
the 120 on (or in) the ground. Fewer will work, but not work as well.

Such an antenna with, say, four elevated 1/4 wave radials, will work quite
well on 15 and 20 meters, work fair on 40 meters and even provide some
contacts on 80, although there it'll be a very inefficient antenna.

Ron AC7AC

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

k0wa@swbell.net

Re: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

Fred,

I would look at one of the Force 12 verticles. They are very good radiators....

Lee - K0WA

In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some and use it. If you can't find any common sense, ask for help from somebody who has some common sense.
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Art - W6KY

Re: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

I have a Gap Challenger. Ground mounted. 3 25 ft
radials laying on the ground (no pattern). 302
countries confirmed. QRP 200 plus confirmed.
5BDXCC. WAZ. WAS. WAC. etc..
Painted light grey and sky blue. Neighbors think its a
sculpture. WORKS GREAT! What more can I say....
Good luck, 73 Art W6KY K1-4

--- "Fred (FL)" <[hidden email]> wrote:

> I'm another limited space, restricted community
> ham (for now). I've been considering different
> types of verticals which might be best. I THINK,
> I'm looking for an antenna which:
>
> - vertical ?
> - no radials
> - no counterpoises
> - no guy-wires
> - 40 thru 10
> - maybe 4 shorter buried radials (if I must)
> - not a lot of "visual" space, for neighbors
>
> We have a MOBILE Home (mostly plastic, and
> wood) - which sits on a slab of concrete,
> surrounded by 8x8 wood timers, 2 feet high on
> front side of mobile. Can easily get UNDER
> mobile, thru removable siding.
>
> Park owner, OK'd a "marine antenna" - whatever that
> means to him. We live on shore of St. Lawrence
> River - Canada in the distance.
>
> What commercial or home-made antenna could suit
> my bill?
>
> Fred
> N3CSY
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam
> protection around
> http://mail.yahoo.com
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Arnie Grubbs

Re: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

Darwin, Keith

RE: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

Hey Fred,

Verticals - it's all I run. I've played with them and researched them
off and on for several years. I'm no expert but here is a quick summary
of what I've learned.

Vertical efficiency depends on ground conduction in two fields. Near
field (which can be enhanced by radials) and far field (out of your
control). Radiation patterns are greatly affected by ground conduction
in the far field so don't expect yagi-crushing performance from a
vertical unless you're surrounded by salt water. The near field you
have some control over. The better job you do of screening the ground
at the base of the antenna, the higher the efficiency and the more of
your signal gets radiated. A minimum ground system is something like 16
radials, .15 wave long. Better performance can be achieved with 104
radials, 0.5 wave long.

But that's all theory, what about practice?

If you have a way to support a horizontal antenna 1/2 wave in the air,
it's a better way to go. I don't so I'm "vertical bound".

Cushcraft R6000 and HyGain AV640 have received good reviews from folks.
Cushcraft MA5V is not a good antenna due to very narrow bandwidth (I had
one - never again). I've heard good and bad reviews of the GAP
antennas. Some love them, others say it performs poorly on all bands.
Force 12 look interesting but IIRC have a requirement of keeping the
feedline at a right angle for some distance. I may be wrong on this so
check it out.

I have yet to see a good head-to-head of various verticals. My theory
is that most of the commercial antennas perform about the same provided
you give an adequate radial field to those that need it.

Butternut is a tried & true antenna. Hustler 4BTV or 5BTV is very
inexpensive and works just fine, thank you. Both of these require
radials & neither covers all the WARC bands.

If you want to use only a few radials, elevate them. Eight raised
radials can equal 60 or more buried radials.

If I were in your shoes (I'm close), I'd go with R6000 or AV640 and
would try to mount them as high as possible.

The best thing you can do to your antenna is to put RF into it. You'll
make lots more contacts on a middle-of-the-road antenna that regularly
sees RF than on a top-notch radiator that sits idle. And yes, you can
make lots of contacts and have lots of fun on a mediocre antenna. I
certainly have.

- Keith KD1E -
- K2 5411 -

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Fred (FL)
Sent: Monday, June 12, 2006 9:38 PM
To: [hidden email]
Subject: [Elecraft] What Vertical Antenna Do I Need?

I'm another limited space, restricted community ham (for now). I've
been considering different types of verticals which might be best. I
THINK, I'm looking for an antenna which:

- vertical ?
- no radials
- no counterpoises
- no guy-wires
- 40 thru 10
- maybe 4 shorter buried radials (if I must)
- not a lot of "visual" space, for neighbors

We have a MOBILE Home (mostly plastic, and
wood) - which sits on a slab of concrete, surrounded by 8x8 wood timers,
2 feet high on front side of mobile. Can easily get UNDER mobile, thru
removable siding.

Park owner, OK'd a "marine antenna" - whatever that means to him. We
live on shore of St. Lawrence River - Canada in the distance.

What commercial or home-made antenna could suit my bill?

Fred
N3CSY

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com _______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Richard Thorne-2

RE: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

I'm vertical bound at my home qth also as well as in a restricted neighborhood.

I installed a 29' home brew self supporting vertical on one of my fence posts. I then ran two elevated radials along the fence at 90 degrees, one to the north and one to the east. Both are about 30' long.

I use an SGC-239 auto tuner 200 watt model (installed in a water proof fiberglass box) at the base of the antenna and it works just great. I use it mainly for the WARC bands. The only bands I have trouble with are 10 and 80 meters. I think the antenna is a little long on 10 meters and on 80 I get rf in the shack. I'm guessing that the coax is probably acting as part of the antenna. I will probably install a feed line current choke near the antenna.

In my situation I think a vertical works well because of my ground conductivity here in Amarillo. According to the FCC chart my ground conductivity is 30 millimhos per meter which is the best you can do other than salt water. See http://www.fcc.gov/mb/audio/m3/

When things are tough or I'm trying to work a new country I connect to my remote hf system that has full size wires and a tribander.

So if a vertical is the only way to go, put up a piece of aluminum and attach at least one radial/counter poise and get after it. Mine as well keep it simple.

Rich - N5ZC

---- "Darwin wrote:

> Hey Fred,
>
> Verticals - it's all I run. I've played with them and researched them
> off and on for several years. I'm no expert but here is a quick summary
> of what I've learned.
>
> Vertical efficiency depends on ground conduction in two fields. Near
> field (which can be enhanced by radials) and far field (out of your
> control). Radiation patterns are greatly affected by ground conduction
> in the far field so don't expect yagi-crushing performance from a
> vertical unless you're surrounded by salt water. The near field you
> have some control over. The better job you do of screening the ground
> at the base of the antenna, the higher the efficiency and the more of
> your signal gets radiated. A minimum ground system is something like 16
> radials, .15 wave long. Better performance can be achieved with 104
> radials, 0.5 wave long.
>
> But that's all theory, what about practice?
>
> If you have a way to support a horizontal antenna 1/2 wave in the air,
> it's a better way to go. I don't so I'm "vertical bound".
>
> Cushcraft R6000 and HyGain AV640 have received good reviews from folks.
> Cushcraft MA5V is not a good antenna due to very narrow bandwidth (I had
> one - never again). I've heard good and bad reviews of the GAP
> antennas. Some love them, others say it performs poorly on all bands.
> Force 12 look interesting but IIRC have a requirement of keeping the
> feedline at a right angle for some distance. I may be wrong on this so
> check it out.
>
> I have yet to see a good head-to-head of various verticals. My theory
> is that most of the commercial antennas perform about the same provided
> you give an adequate radial field to those that need it.
>
> Butternut is a tried & true antenna. Hustler 4BTV or 5BTV is very
> inexpensive and works just fine, thank you. Both of these require
> radials & neither covers all the WARC bands.
>
> If you want to use only a few radials, elevate them. Eight raised
> radials can equal 60 or more buried radials.
>
> If I were in your shoes (I'm close), I'd go with R6000 or AV640 and
> would try to mount them as high as possible.
>
> The best thing you can do to your antenna is to put RF into it. You'll
> make lots more contacts on a middle-of-the-road antenna that regularly
> sees RF than on a top-notch radiator that sits idle. And yes, you can
> make lots of contacts and have lots of fun on a mediocre antenna. I
> certainly have.
>
> - Keith KD1E -
> - K2 5411 -
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Fred (FL)
> Sent: Monday, June 12, 2006 9:38 PM
> To: [hidden email]
> Subject: [Elecraft] What Vertical Antenna Do I Need?
>
> I'm another limited space, restricted community ham (for now). I've
> been considering different types of verticals which might be best. I
> THINK, I'm looking for an antenna which:
>
> - vertical ?
> - no radials
> - no counterpoises
> - no guy-wires
> - 40 thru 10
> - maybe 4 shorter buried radials (if I must)
> - not a lot of "visual" space, for neighbors
>
> We have a MOBILE Home (mostly plastic, and
> wood) - which sits on a slab of concrete, surrounded by 8x8 wood timers,
> 2 feet high on front side of mobile. Can easily get UNDER mobile, thru
> removable siding.
>
> Park owner, OK'd a "marine antenna" - whatever that means to him. We
> live on shore of St. Lawrence River - Canada in the distance.
>
> What commercial or home-made antenna could suit my bill?
>
> Fred
> N3CSY
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Darwin, Keith

RE: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

Actually, my antenna is similar. 28 Foot tall alum. radiator over a
field of sixteen 20 foot radials. Thirty feet of RG-213 connect the
antenna to the manual ATU in the garage. From there I run RG8x into the
shack. Changing bands requires that I go to the garage with my antenna
analyzer and adjust the ATU to get a match on the band I wish to use.
Some bands tune easier than others (80 is very tough, 20/17 are touchy).
The antenna works well on 40 & 30, adequate on 20, 17, 15 and quite
poorly on 80.

Lately I've come across info that suggests that verticals taller than
3/8 wave perform poorer than 1/4 wave unless the ground conductivity in
the Fresnel zone is very good. With that, I've been playing with
changing the height of the antenna to see how it compares to my
reference inverted vee. So far, raising the antenna from 1/4 wave to
3/8 wave resulted in signals being either the same or slightly weaker.

That suggests a WARC vertical should be 18 feet tall.

Or one could cover 10-80 with 2 verticals with base mounted tuners; one
12 feet tall (20-10) and the other 32 feet tall (30-80).

- Keith -

-----Original Message-----
From: Rich

I installed a 29' home brew self supporting vertical on one of my fence
posts. I then ran two elevated radials along the fence at 90 degrees,
one to the north and one to the east. Both are about 30' long.

I use an SGC-239 auto tuner ... at the base of the antenna ... mainly
for the WARC bands.
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Joseph Reed-2

Re: What Vertical Antenna Do I Need?

In reply to this post by Darwin, Keith

Keith,

Actually, the Butternut does cover all the WARC bands. On 17 meters tuning it is a bit touchy, but on 10 MHz and 24 MHz it is very well behaved and gets out great. Using a tuner I even get a match on 5 MHz.

I have confirmed around 309 countries on my Butternut. And I live on a tiny city lot.

For the serious student of vertical antennas I would highly recommend "The Vertical Antenna Handbook" by Capt. Paul H. Lee, N6PL (SK). Published by CQ, my copy doesn't have an ISBN number, but the Library of Congress card number is 74-83411.

Regards,

Joe N9JR

----- Original Message ----
From: "Darwin, Keith" <[hidden email]>
To: [hidden email]
Sent: Tuesday, June 13, 2006 7:56:08 AM
Subject: RE: [Elecraft] What Vertical Antenna Do I Need?

Hey Fred,
[SNIP}

Butternut is a tried & true antenna. Hustler 4BTV or 5BTV is very
inexpensive and works just fine, thank you. Both of these require
radials & neither covers all the WARC bands.
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Joseph Reed-2

Re: What Vertical Antenna Do I Need?

In reply to this post by Richard Thorne-2

Rich,

I envy your ground conductivity. Also I appreciate your conclusion that when facing challenges a simple vertical is better than no signal at all.

I'm curious as to how well you feel your vertical works, mounted on a fence post the feed point must be fairly close to the ground, and you are using two non tuned radials close to ground in the near field. (But then again you are in Texas, and fence posts could be *big*.)

Back in the early 70's my elmer erected 80 and 40 meter verticals mounted on telephone poles with 4 elevated tuned radials each. It was amazing what he could work. And as a ham I thought it was a beautiful sight to behold - two phone poles with verticals mounted at the top and the Telex mounted on a windmill tower. (And at the time he owned Don Miller's (yes that Don Miller, he had just moved to California.) S-Line.)

Regards,

Joe N9JR

----- Original Message ----
From: [hidden email]
To: [hidden email]
Sent: Tuesday, June 13, 2006 8:51:47 AM
Subject: RE: [Elecraft] What Vertical Antenna Do I Need?

I'm vertical bound at my home qth also as well as in a restricted neighborhood.

I installed a 29' home brew self supporting vertical on one of my fence posts. I then ran two elevated radials along the fence at 90 degrees, one to the north and one to the east. Both are about 30' long.

I use an SGC-239 auto tuner 200 watt model (installed in a water proof fiberglass box) at the base of the antenna and it works just great. I use it mainly for the WARC bands. The only bands I have trouble with are 10 and 80 meters. I think the antenna is a little long on 10 meters and on 80 I get rf in the shack. I'm guessing that the coax is probably acting as part of the antenna. I will probably install a feed line current choke near the antenna.

In my situation I think a vertical works well because of my ground conductivity here in Amarillo. According to the FCC chart my ground conductivity is 30 millimhos per meter which is the best you can do other than salt water. See http://www.fcc.gov/mb/audio/m3/

When things are tough or I'm trying to work a new country I connect to my remote hf system that has full size wires and a tribander.

So if a vertical is the only way to go, put up a piece of aluminum and attach at least one radial/counter poise and get after it. Mine as well keep it simple.

Rich - N5ZC

---- "Darwin wrote:

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Chris Kantarjiev K6DBG

Re: What Vertical Antenna Do I Need?

In reply to this post by Fred (FL)

I don't know anything about it other than what I read on the web
page, but the photos of HB9ABX's homebrew mobil antenna sure are intriguing:

http://www.datacomm.ch/hb9abx/antmob-e.htm

He has designs for a number of mag loop antennas as well, which
might fit your restrictions.

73 de chris K6DBG
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Stuart Rohre

Re: What Vertical Antenna Do I Need?

In reply to this post by Darwin, Keith

Keith, on the Force 12 verticals, which are true half wave (loaded)
verticals:

They provide a feedline support for about 18 inches or so out from the
center. After that, the coax can simply go to earth to the rig, or be
supported for a greater distance. Does not make that much difference in my
experiments at 100 watts to 200 watts. Ideally, yes, a feeder should come
off at right angles to either a horizontal dipole or a vertical dipole, but
in practice few horizontal dipoles have a perfect right angle feeder
arrangement for the entire distance where it might have an effect.
Likewise, what you can do in practice with the Force 12 verticals is
whatever works in your installation. Don't be dissuaded just by such a
concern. They are efficient and easy to use antennas. Put it up in 5 to 10
minutes and you are on the air. You could even take it down after every
operating session it is so easy. Especially good for vacations and covenant
restricted hams.

-Stuart
K5KVH

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Stuart Rohre

Re: What Vertical Antenna Do I Need?

In reply to this post by Arnie Grubbs

For Fred's antenna need:

I would investigate the Force 12 vertical antennas. I have used several of
the Sigma 5 model, (20 to 10) on science projects and they are durable, easy
to set up and take down, and work with high efficiency, equal or better to,
a dipole of full size. They are bar loaded, with center matching coils and
remote switching for the high bands in model Sigma 5. There are also 40
meter capable models. They are true vertical loaded dipoles, thus requiring
NO auxiliary ground wires, radials, or counterpoises. They are coax
fed,with bead chokes on the coax so that bringing off the coax from the
center is not a problem.

See the Force 12 web site for the DX contest performance of Sigma verticals.
They were also written up in the ham magazines with favorable results.

-Stuart
K5KVH

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Vic K2VCO

Re: What Vertical Antenna Do I Need?

Stuart Rohre wrote:
> They are coax
> fed,with bead chokes on the coax so that bringing off the coax from the
> center is not a problem.

This isn't true. The bead balun solves the problem of current flow on
the outside of the coax which occurs when the feedline length is such
that the outside of the coax has a low impedance compared to the
impedance of the line (that is, the common mode impedance is not much
higher than the differential mode impedance). It does *not* prevent
imbalance caused by capacitive coupling between the outside of the line
and one of the legs of the vertical dipole.

It's still a good idea to try to reduce such coupling. Having said
that, it probably doesn't matter much in practice unless you run the
coax parallel to the antenna for some distance.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Greg - AB7R

Re: What Vertical Antenna Do I Need?

If I remember correctly, the manual for the Sigma V says
to run the coax away from the antenna at ~90degrees as
much as possible to prevent coupling.

I had one of these in the past and was always amazed at
how well it performed for such a small antenna.

Greg-AB7R

On Tue, 13 Jun 2006 11:14:40 -0700
Vic K2VCO <[hidden email]> wrote:

> Stuart Rohre wrote:
>> They are coax
>> fed,with bead chokes on the coax so that bringing off
>>the coax from the
>> center is not a problem.
>
> This isn't true. The bead balun solves the problem of
>current flow on the outside of the coax which occurs when
>the feedline length is such that the outside of the coax
>has a low impedance compared to the impedance of the line
>(that is, the common mode impedance is not much higher
>than the differential mode impedance). It does *not*
>prevent imbalance caused by capacitive coupling between
>the outside of the line and one of the legs of the
>vertical dipole.
>
> It's still a good idea to try to reduce such coupling.
> Having said that, it probably doesn't matter much in
>practice unless you run the coax parallel to the antenna
>for some distance.
> --
> 73,
> Vic, K2VCO
>Fresno CA
> http://www.qsl.net/k2vco
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Stuart Rohre

Re: What Vertical Antenna Do I Need?

Yes, in theory any vertical half wave that is center fed should have the
feeder run at exactly a right angle, but in practice, Force 12 provides a
support arm for the coax, and that is sufficient to bring the coax off a
couple of feet where it then can hang either parallel or at an angle to the
vertical and we noticed no interaction at all.

Stuart
K5KVH

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Stuart Rohre

Re: What Vertical Antenna Do I Need?

In reply to this post by Vic K2VCO

Well Vic, details, details, I meant that the beads do help in the near
center area, as they are quite long, as good bead chokes are.

Yes, outside the bead area, you should bring the line off as orthogonal as
you can; but in practice, the angular droop of the coax has not caused one
bit of feedback into our station.

Stuart
K5KVH

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com