OT - SteppIR Vertical and Elecraft Products

[dave.wilburn]

Recent discussion regarding verticals, internal antenna tuners and
remote antenna tuners was very interesting.  Based on that discussion,
it seemed the "optimized" solution was a vertical, with good radials,
and a remote tuner at the base (generalization).  Based on a quick
check of remote tuner cost, new they seemed to start around $400 and
go up from there.  I have not looked at used cost.  I have been burned
too many times on eBay.

Some have used cheaper tuners and put them in a waterproof bin.  A
worth while option to consider.

I would like to try a vertical here, and possibly a setup for when I
travel.  Being on the east coast, it is not hard to get near salt
water for major contests.  I only have basic wire antennas, no beams,
no quads, and no tower.

In the near term I want to try out (experiment with) a 33' vertical.
At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
going to tape a wire to this that is 34' long, twist the mast to wrap
the slack up, much like a widely spaced helical.

When setup at home, it would (eventually) have a good ground field
(would start out with 16 radials and work my way up to 60'ish). The
coax run when used at the house would be less than 40'.

When setup for portable operation (connected to mount I have for my
trailer hitch, to use when parked) it would have 4 radials of a length
not yet determined and the coax run would be less than 20'.

In both cases I would be using the tuner for the K2 (portable) or K3
(at home).

In the long term, I am thinking about the SteppIR vertical (haven't
decided which one).  Same deal with the radials.  It would inherit
what I had down, or start at 16 and work up.
http://www.steppir.com/files/vertical%20brochure.pdf

Current plans are for ground mounting.  I understand that as radials
go, more is better. The radials would be black insulated wire on, or
within 1" of the surface of the ground. They would not be cut to 33'
or less if the space was not available.

I am curious on the experience of the group with a similar vertical,
tuner at the rig, and short coax run.

I am also curious of the experience of the group with the SteppIR
verticals.  There is similar up front cost as the vertical / remote
tuner solution (assuming a new weather proof tuner).

Thanks for the always enlightening discussions.  73

Dave Wilburn
NM4M
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[Craig Smith]

I think you have arrived at a good understanding of the benefits/limitations of both the StepIR and the remote tuner approaches.  I use the remote tuner approach, but would think that the StepIR should give similar results.  And, as you point out, the total costs of the two approaches are somewhat similar.  Most of the manual labor is involved with the radial field, which is a constant for any approach.

There are a couple of less expensive alternatives if you are mostly interested in a couple/few bands rather than the complete 80 thru 10 range.  All of these vertical element heights can be attained with a light weight fiberglas mast of at most 40 ft.  This is easy to put up and take down.  I can do mine in less than 2 minutes.  So the least expensive approach would be to use different element lengths for your bands of interest and making them resonant so that no tuner is required.

Another option would be to use the 43 ft height and customized relay selected matching networks in an enclosure at the base for your bands of interest - say 40, 30 and 20.  This is fairly easy to accomplish at the 100W level.  If the number of networks is reasonable (3 in this example), this customized tuner can be constructed for significantly less expense than purchasing a new autotuner.  In this example you could reduce expenses further by making the vertical resonant on 30 and using only two matching networks for 40 and 20.

     73    Craig  AC0DS

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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Kok Chen]

On May 16, 2009, at 11:26 AM, Craig Smith wrote:
> I think you have arrived at a good understanding of the benefits/
> limitations of both the StepIR and the remote tuner approaches.  I  
> use the remote tuner approach, but would think that the StepIR  
> should give similar results.

Bear in mind too that resonating a fixed length vertical with a remote  
tuner will give you a different radiation pattern than resonating the  
antenna system by physically adjusting the height of a vertical.  
Sometimes with good advantage.

73
Chen, W7AY

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[WILLIS COOKE]

David, whether a vertical is the best antenna or not depends on where you are and what you are trying to achieve.  Some things to consider are:
1. Verticals are generally more subject to man made noise than horizontal antennas.
2  When putting down radials the first radial is most important.  How many you need depends on your local conditions.  You will probably get about 50% as much good from your second radial as the first.  You will not get much after about 16, but you will get a little.  Think about parallel resistors because you are coupling to the ground.  The subject is very complicated and if you interview 100 vertical owners you will find that either what they have is the very minimum or that they need more, whether they have one or two hundred radials.  Putting the antenna in the middle of the ocean is the best, but few can manage that.
3.  The angle of radiation above the horizon depends mostly on the conductivity of the surface well beyond the radial area, not the number of radials.  You can't do much about the conductivity of the soil beyond your property, but it is important.
4.  If you want to contact stations that are farther than 10 miles away and less than 1,000 statute miles away you are better off with an inverted V at about 40 ft or so.  If you want stations beyond 2,000 miles away the vertical is usually best.
5.  The shorter the vertical, the lower the radiation resistance and the lower the efficiency, up to about 0.33 wavelength.
6.  Don't use a half wavelength at your desired frequency because it is very difficult to match an antenna with nearly infinite reactivity.  You can put a coil in series to make it about 0.75 wavelength so you can match it, but it will not be easy.
7.  The SteppIR BIG IR vertical has a tape that runs up a fiberglass tube so the vertical can be any length.  Usually 0.25 wavelength at your frequency of operation.  They work well, but they are not inexpensive and they require a control cable as well as a coax.  The same radial rules apply as for any other vertical.
8.  An antenna tuner at the base of a vertical is a good thing.  Weather proof antenna tuners are not common and usually only accommodate low power, 100 to 200 watts.  If you coax is fairly short and your SWR is not really high you usually can use the tuner in your transceiver in the house.

Selecting an antenna is great fun, but not easy.  Good Luck.

Willis 'Cookie' Cooke
K5EWJ


--- On Sat, 5/16/09, David Wilburn <[hidden email]> wrote:

> From: David Wilburn <[hidden email]>
> Subject: [Elecraft] OT - SteppIR Vertical and Elecraft Products
> To: "Elecraft Discussion List" <[hidden email]>
> Date: Saturday, May 16, 2009, 10:52 AM
> Recent discussion regarding verticals, internal antenna
> tuners and
> remote antenna tuners was very interesting.  Based on that
> discussion,
> it seemed the "optimized" solution was a
> vertical, with good radials,
> and a remote tuner at the base (generalization).  Based on
> a quick
> check of remote tuner cost, new they seemed to start around
> $400 and
> go up from there.  I have not looked at used cost.  I have
> been burned
> too many times on eBay.
>
> Some have used cheaper tuners and put them in a waterproof
> bin.  A
> worth while option to consider.
>
> I would like to try a vertical here, and possibly a setup
> for when I
> travel.  Being on the east coast, it is not hard to get
> near salt
> water for major contests.  I only have basic wire antennas,
> no beams,
> no quads, and no tower.
>
> In the near term I want to try out (experiment with) a
> 33' vertical.
> At Frostfest this year I picked up 32' or so of
> fiberglass mast.  I am
> going to tape a wire to this that is 34' long, twist
> the mast to wrap
> the slack up, much like a widely spaced helical.
>
> When setup at home, it would (eventually) have a good
> ground field
> (would start out with 16 radials and work my way up to
> 60'ish). The
> coax run when used at the house would be less than 40'.
>
> When setup for portable operation (connected to mount I
> have for my
> trailer hitch, to use when parked) it would have 4 radials
> of a length
> not yet determined and the coax run would be less than
> 20'.
>
> In both cases I would be using the tuner for the K2
> (portable) or K3
> (at home).
>
> In the long term, I am thinking about the SteppIR vertical
> (haven't
> decided which one).  Same deal with the radials.  It would
> inherit
> what I had down, or start at 16 and work up.
> http://www.steppir.com/files/vertical%20brochure.pdf
>
> Current plans are for ground mounting.  I understand that
> as radials
> go, more is better. The radials would be black insulated
> wire on, or
> within 1" of the surface of the ground. They would not
> be cut to 33'
> or less if the space was not available.
>
> I am curious on the experience of the group with a similar
> vertical,
> tuner at the rig, and short coax run.
>
> I am also curious of the experience of the group with the
> SteppIR
> verticals.  There is similar up front cost as the vertical
> / remote
> tuner solution (assuming a new weather proof tuner).
>
> Thanks for the always enlightening discussions.  73
>
> Dave Wilburn
> NM4M
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list:
> http://www.qsl.net/donate.html

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[Dave, G4AON]

Dave, you could do a whole lot worse than read about radial lengths at:

http://www.antennasbyn6lf.com/

Look about halfway down the page at the various pdf documents describing his experiments and measurements.

73 Dave, G4AON
K3/100 and fishing pole vertical against 16 radials on 40m
---------------------------
Recent discussion regarding verticals, internal antenna tuners and
remote antenna tuners was very interesting.

<Big snip>

Thanks for the always enlightening discussions.  73

Dave Wilburn
NM4M


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[K7TV]

David,

W.r.t. radials you may want to study the findings of Rudy Severns, N6LF at
www.antennasbyn6lf.com. His findings have also been published in QEX (spread
over several recent issues). Some of his findings in simplified bullet form:
"A number of 1/8 wave radials will be better than half that number of 1/4
wave radials. At least until you have 32 or more radials." "Four is just not
enough." The latter quote applies to radials on the ground. In contrast he
confirms that four elevated radials work great. You really need to read it
all, and you should certainly not assume that 1/4 wave radials on the ground
are a good choice.

Personally I can testify that elevated radials can be very very much better
than a poor ground level "ground". Years ago I had put up inverted L's for
80 and 160. I first tried feeding them against my existing safety ground
system which consists of a number of ground rods; one  the feed point,
another at the electrical meter, a couple at my tower (an important tie-in
to my station ground still to be completed). These are tied together with 4"
wide buried copper ribbon, branches of which also extend to some far-away
parts of the lot. Although I achieved a good impedance match, the received
signal strength was incredibly poor. I then added two elevated 1/4 wave
radials for each band, suspended under the eaves of the 1-story house,
trees, and short poles attached to the fence. The impedance match was still
very good, and the antennas worked very well indeed. I believe I would have
had the same results with verticals. I also recall trying just a few 1/4
wave buried radials for a vertical way back in my youth, with poor results.
I am now a big fan of elevated radials. If you decide to go with ground
level radials, I suggest you perform a sanity check after you install them:
Temporarily string up one or two 1/4 wave radials at a height of 10 ft or
so, sloping one end down to the feed point. Compare the results from the
temporary radial(s) with results from your radials on the ground. If the
elevated radials work best, consider either making them permanent, or
improving your other radial system by adding more radials, and possibly
making them shorter.

73,
Erik K7TV

> In the near term I want to try out (experiment with) a 33' vertical.
> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
> going to tape a wire to this that is 34' long, twist the mast to wrap
> the slack up, much like a widely spaced helical.
>
> When setup at home, it would (eventually) have a good ground field
> (would start out with 16 radials and work my way up to 60'ish). The
> coax run when used at the house would be less than 40'.
>
> When setup for portable operation (connected to mount I have for my
> trailer hitch, to use when parked) it would have 4 radials of a length
> not yet determined and the coax run would be less than 20'.
>

.......


> Current plans are for ground mounting.  I understand that as radials
> go, more is better. The radials would be black insulated wire on, or
> within 1" of the surface of the ground. They would not be cut to 33'
> or less if the space was not available.
>
> I am curious on the experience of the group with a similar vertical,
> tuner at the rig, and short coax run.


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[dave.wilburn]

Good stuff as always Ron, thanks.  The multiple wires on the
fiberglass is a VERY interesting idea.

Plus if I add sections, 43'ish is 5/8 on 20m, the main ban I operate
on.  I am mainly interested in 40' and up.  I'll get 80 and 160 with
other wires.

Thanks for taking the time to reply Ron.  I seldom walk away from one
of your enjoyable posts without learning something.

73

Dave Wilburn
NM4M

Ron D'Eau Claire wrote:

> If you are talking about multi-band operation, you can expect the SWR to
> range up to above 60:1 on some bands, particularly where the radiator is
> near 1/2 wavelength. That's why ATU's designed for operation at the antenna
> are used for such applications. And, yes, they tend to be expensive.
>
> The Stepper antenna adjusts its length to 1/4 wave on the band in use,
> AFAIK. That way it presents a decent match to coax on any band in its range.
>
> However, matching to a longer antenna up to 5/8 wave provides substantial
> low-angle gain over a 1/4 wave radiator. That's easily done with a matching
> network at the base.
>
> One way to accomplish that at a lower price than a commercial ATU at the
> antenna is to put in a matching network for each band, relay switched, at
> the base. On some bands only an inductor will be needed, with taps for each
> band selected by relays if you are adverse to going out to the antenna. On
> others capacitors may be involved (such as when the antenna is near 1/2 wave
> long and presents a very high impedance at the base). IN that case you might
> have a separate network that is switched in.
>
> It's not as "hammer simple" as buying an ATU and plugging it in, but it can
> be even more efficient and at a lot lower cost. For many of us, that's what
> makes Ham radio fun: doing for $1 what anyone with a fat wallet can do for
> $100.
>
> You can probably get away with one matching network setup per band, at least
> on 40 and up, and keep as low an SWR to the actual rig as you want using the
> rig's built in ATU. (That's what it is really for ;-) Just be sure the SWR
> on the coax isn't so high you have unacceptable losses.
>
> With an insulated pole like you have, another way to economically arrange a
> vertical covering several bands is to tape several radiators to it,
> insulated from each other, each 1/4 wave long for the band of interest. You
> can feed them in parallel with one run of coax, especially when dealing with
> harmonically-related bands (e.g. 40/20/10 meters) but it can be made to work
> on other combinations with a little pruning so that the SWR is low enough to
> avoid excessive coax losses. Then you let your rig's ATU do the final
> tweaking to keep your finals happy.  
>
> You might do a little research on radials. The relationship of the number of
> radials to antenna efficiency is not linear. The more radials you have, the
> less adding more improves the efficiency. Also, the higher the feed point
> impedance, the less important near-field ground losses become. For example,
> a half wave radiator with a feed point impedance typically several thousand
> ohms is very efficient with no ground connection at all.  OTOH a 1/8 or 1/16
> wave radiator with a feedpoint impedance of less than an ohm requires the
> best possible ground for any reasonable efficiency.
>
>
> Ron AC7AC
>
>
> -----Original Message-----
> Recent discussion regarding verticals, internal antenna tuners and
> remote antenna tuners was very interesting.  Based on that discussion,
> it seemed the "optimized" solution was a vertical, with good radials,
> and a remote tuner at the base (generalization).  
>
> In the near term I want to try out (experiment with) a 33' vertical.
> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
> going to tape a wire to this that is 34' long, twist the mast to wrap
> the slack up, much like a widely spaced helical.
>
> When setup at home, it would (eventually) have a good ground field
> (would start out with 16 radials and work my way up to 60'ish). The
> coax run when used at the house would be less than 40'.
>
> When setup for portable operation (connected to mount I have for my
> trailer hitch, to use when parked) it would have 4 radials of a length
> not yet determined and the coax run would be less than 20'.
>
> In both cases I would be using the tuner for the K2 (portable) or K3
> (at home).
>
> In the long term, I am thinking about the SteppIR vertical (haven't
> decided which one).  Same deal with the radials.  It would inherit
> what I had down, or start at 16 and work up.
> http://www.steppir.com/files/vertical%20brochure.pdf
>
> Current plans are for ground mounting.  I understand that as radials
> go, more is better. The radials would be black insulated wire on, or
> within 1" of the surface of the ground. They would not be cut to 33'
> or less if the space was not available.
>
> I am curious on the experience of the group with a similar vertical,
> tuner at the rig, and short coax run.
>
> I am also curious of the experience of the group with the SteppIR
> verticals.  There is similar up front cost as the vertical / remote
> tuner solution (assuming a new weather proof tuner).
>
> Thanks for the always enlightening discussions.  73
>
> Dave Wilburn
> NM4M
>
>

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[Phil Salas]

"One way to accomplish that at a lower price than a commercial ATU at the
antenna is to put in a matching network for each band, relay switched, at
the base."

I use a 43-foot vertical for 160-20 meters.  The higher radiation resistance
(compared to other verticals) helps with antenna efficiency over other than
a perfect ground system (I do have a lot of radials, but I know my ground
system still isn't perfect).  The 1:4 unun at the base gives a relatively
low compromise SWR on 40-10 meters, resulting in negligeable SWR-related
coax losses if you use good low-loss cable.  My worst-case SWR is on 20
meters where it is about 5:1, resulting in only a fraction of a dB loss
through my 60 feet of 1/2" heliax.  The problem is on 160- and 80-meters
where the SWR is very high so coax and unun losses can be high - and
matching from the shack is very difficult or impossible due to the high SWR.
So I built a relay-switched matching unit that lets me select 160, 80, and
60-10 meters.  Actually, I couldn't stop myself until I'd built three
different matching units.  Details are in the "Articles" section at
http://w6rvb.com/ad5x/.

Phil - AD5X

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[dave.wilburn]

Oh yea, been there.  Thats some good stuff.  I have been going back
and forth between that, some really good info that SteppIR provides on
radials, ON4UN's book, and the ARRL antenna book.  The two books laid
the foundation, but N6LF's page, and the info from SteppIR really tied
the pieces together nicely.  Thanks.

Dave Wilburn
NM4M

Dave G4AON wrote:

> Dave, you could do a whole lot worse than read about radial lengths at:
>
> http://www.antennasbyn6lf.com/
>
> Look about halfway down the page at the various pdf documents describing his experiments and measurements.
>
> 73 Dave, G4AON
> K3/100 and fishing pole vertical against 16 radials on 40m
> ---------------------------
> Recent discussion regarding verticals, internal antenna tuners and
> remote antenna tuners was very interesting.
>
> <Big snip>
>
> Thanks for the always enlightening discussions.  73
>
> Dave Wilburn
> NM4M
>
>
>

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[David Gilbert]

That's a really bad comparison.  A good safety ground has no
relationship whatsoever to a good radial field.  They perform different
functions, and while a good radial field might also provide some safety
benefits as a distributed path for lightning protection, the reverse is
rarely true.  There is also no assured correlation between a
ground/radial system that gives a decent impedance match and one that
gives decent signal performance.  A little web searching will bring up
several references on both points.

It is true, though, that a buried radial system requires more than just
"a few" radials to give decent results.  I don't want to get into the
elevated versus buried radial argument since both have their place and
(properly implemented) both will work well, but if space permits the
installation of enough sufficiently long buried radials they have some
definite advantages.

73,
Dave   AB7E


Erik N Basilier wrote:

> Personally I can testify that elevated radials can be very very much better
> than a poor ground level "ground". Years ago I had put up inverted L's for
> 80 and 160. I first tried feeding them against my existing safety ground
> system which consists of a number of ground rods; one  the feed point,
> another at the electrical meter, a couple at my tower (an important tie-in
> to my station ground still to be completed). These are tied together with 4"
> wide buried copper ribbon, branches of which also extend to some far-away
> parts of the lot. Although I achieved a good impedance match, the received
> signal strength was incredibly poor. I then added two elevated 1/4 wave
> radials for each band, suspended under the eaves of the 1-story house,
> trees, and short poles attached to the fence. The impedance match was still
> very good, and the antennas worked very well indeed. I believe I would have
> had the same results with verticals. I also recall trying just a few 1/4
> wave buried radials for a vertical way back in my youth, with poor results.
> I am now a big fan of elevated radials. If you decide to go with ground
> level radials, I suggest you perform a sanity check after you install them:
> Temporarily string up one or two 1/4 wave radials at a height of 10 ft or
> so, sloping one end down to the feed point. Compare the results from the
> temporary radial(s) with results from your radials on the ground. If the
> elevated radials work best, consider either making them permanent, or
> improving your other radial system by adding more radials, and possibly
> making them shorter.
>
> 73,
> Erik K7TV
>
>  
>> In the near term I want to try out (experiment with) a 33' vertical.
>> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
>> going to tape a wire to this that is 34' long, twist the mast to wrap
>> the slack up, much like a widely spaced helical.
>>
>> When setup at home, it would (eventually) have a good ground field
>> (would start out with 16 radials and work my way up to 60'ish). The
>> coax run when used at the house would be less than 40'.
>>
>> When setup for portable operation (connected to mount I have for my
>> trailer hitch, to use when parked) it would have 4 radials of a length
>> not yet determined and the coax run would be less than 20'.
>>
>>    
>
> .......
>
>
>  
>> Current plans are for ground mounting.  I understand that as radials
>> go, more is better. The radials would be black insulated wire on, or
>> within 1" of the surface of the ground. They would not be cut to 33'
>> or less if the space was not available.
>>
>> I am curious on the experience of the group with a similar vertical,
>> tuner at the rig, and short coax run.
>>    
>
>
> ______________________________________________________________
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>
>  

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[dave.wilburn]

Yes that is a good page.  I had considered elevating the vertical, but
with the fiberglass mast I would need to get several more sections,
and then wasn't that crazy about the elevated wires over the back
yard.  If I recall, he wanted a pair of resonant wires for each band
for the elevated setup.

Dave Wilburn
NM4M

Erik N Basilier wrote:

> David,
>
> W.r.t. radials you may want to study the findings of Rudy Severns, N6LF
> at www.antennasbyn6lf.com. His findings have also been published in QEX
> (spread over several recent issues). Some of his findings in simplified
> bullet form: "A number of 1/8 wave radials will be better than half that
> number of 1/4 wave radials. At least until you have 32 or more radials."
> "Four is just not enough." The latter quote applies to radials on the
> ground. In contrast he confirms that four elevated radials work great.
> You really need to read it all, and you should certainly not assume that
> 1/4 wave radials on the ground are a good choice.
>
> Personally I can testify that elevated radials can be very very much
> better than a poor ground level "ground". Years ago I had put up
> inverted L's for 80 and 160. I first tried feeding them against my
> existing safety ground system which consists of a number of ground rods;
> one  the feed point, another at the electrical meter, a couple at my
> tower (an important tie-in to my station ground still to be completed).
> These are tied together with 4" wide buried copper ribbon, branches of
> which also extend to some far-away parts of the lot. Although I achieved
> a good impedance match, the received signal strength was incredibly
> poor. I then added two elevated 1/4 wave radials for each band,
> suspended under the eaves of the 1-story house, trees, and short poles
> attached to the fence. The impedance match was still very good, and the
> antennas worked very well indeed. I believe I would have had the same
> results with verticals. I also recall trying just a few 1/4 wave buried
> radials for a vertical way back in my youth, with poor results. I am now
> a big fan of elevated radials. If you decide to go with ground level
> radials, I suggest you perform a sanity check after you install them:
> Temporarily string up one or two 1/4 wave radials at a height of 10 ft
> or so, sloping one end down to the feed point. Compare the results from
> the temporary radial(s) with results from your radials on the ground. If
> the elevated radials work best, consider either making them permanent,
> or improving your other radial system by adding more radials, and
> possibly making them shorter.
>
> 73,
> Erik K7TV
>
>> In the near term I want to try out (experiment with) a 33' vertical.
>> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
>> going to tape a wire to this that is 34' long, twist the mast to wrap
>> the slack up, much like a widely spaced helical.
>>
>> When setup at home, it would (eventually) have a good ground field
>> (would start out with 16 radials and work my way up to 60'ish). The
>> coax run when used at the house would be less than 40'.
>>
>> When setup for portable operation (connected to mount I have for my
>> trailer hitch, to use when parked) it would have 4 radials of a length
>> not yet determined and the coax run would be less than 20'.
>>
>
> .......
>
>
>> Current plans are for ground mounting.  I understand that as radials
>> go, more is better. The radials would be black insulated wire on, or
>> within 1" of the surface of the ground. They would not be cut to 33'
>> or less if the space was not available.
>>
>> I am curious on the experience of the group with a similar vertical,
>> tuner at the rig, and short coax run.
>
>
>

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[K7TV]

Dave, I agree. The reason I tried the safety ground was that it was there.
The reason I mentioned it here was as an example of what not to do. BTW I
later ran the inverted L with just one of the elevated radials with
excellent results. There is definitely a point at which a ground radial
system crosses from being poorer than one elevated radial (= half dipole) to
being better, as radials are added. I suggest it is a good idea to know
which side of that point one is at.

73,
Erik K7TV

----- Original Message -----
From: "David Gilbert" <[hidden email]>
To: "Erik N Basilier" <[hidden email]>
Cc: "David Wilburn" <[hidden email]>; "Elecraft Discussion List"
<[hidden email]>
Sent: Saturday, May 16, 2009 1:23 PM
Subject: Re: [Elecraft] OT - SteppIR Vertical and Elecraft Products

>
> That's a really bad comparison.  A good safety ground has no relationship
> whatsoever to a good radial field.  They perform different functions, and
> while a good radial field might also provide some safety benefits as a
> distributed path for lightning protection, the reverse is rarely true.
> There is also no assured correlation between a ground/radial system that
> gives a decent impedance match and one that gives decent signal
> performance.  A little web searching will bring up several references on
> both points.
>
> It is true, though, that a buried radial system requires more than just "a
> few" radials to give decent results.  I don't want to get into the
> elevated versus buried radial argument since both have their place and
> (properly implemented) both will work well, but if space permits the
> installation of enough sufficiently long buried radials they have some
> definite advantages.
>
> 73,
> Dave   AB7E
>
>
> Erik N Basilier wrote:
>> Personally I can testify that elevated radials can be very very much
>> better than a poor ground level "ground". Years ago I had put up inverted
>> L's for 80 and 160. I first tried feeding them against my existing safety
>> ground system which consists of a number of ground rods; one  the feed
>> point, another at the electrical meter, a couple at my tower (an
>> important tie-in to my station ground still to be completed). These are
>> tied together with 4" wide buried copper ribbon, branches of which also
>> extend to some far-away parts of the lot. Although I achieved a good
>> impedance match, the received signal strength was incredibly poor. I then
>> added two elevated 1/4 wave radials for each band, suspended under the
>> eaves of the 1-story house, trees, and short poles attached to the fence.
>> The impedance match was still very good, and the antennas worked very
>> well indeed. I believe I would have had the same results with verticals.
>> I also recall trying just a few 1/4 wave buried radials for a vertical
>> way back in my youth, with poor results. I am now a big fan of elevated
>> radials. If you decide to go with ground level radials, I suggest you
>> perform a sanity check after you install them: Temporarily string up one
>> or two 1/4 wave radials at a height of 10 ft or so, sloping one end down
>> to the feed point. Compare the results from the temporary radial(s) with
>> results from your radials on the ground. If the elevated radials work
>> best, consider either making them permanent, or improving your other
>> radial system by adding more radials, and possibly making them shorter.
>>
>> 73,
>> Erik K7TV
>>
>>
>>> In the near term I want to try out (experiment with) a 33' vertical.
>>> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am
>>> going to tape a wire to this that is 34' long, twist the mast to wrap
>>> the slack up, much like a widely spaced helical.
>>>
>>> When setup at home, it would (eventually) have a good ground field
>>> (would start out with 16 radials and work my way up to 60'ish). The
>>> coax run when used at the house would be less than 40'.
>>>
>>> When setup for portable operation (connected to mount I have for my
>>> trailer hitch, to use when parked) it would have 4 radials of a length
>>> not yet determined and the coax run would be less than 20'.
>>>
>>>
>>
>> .......
>>
>>
>>
>>> Current plans are for ground mounting.  I understand that as radials
>>> go, more is better. The radials would be black insulated wire on, or
>>> within 1" of the surface of the ground. They would not be cut to 33'
>>> or less if the space was not available.
>>>
>>> I am curious on the experience of the group with a similar vertical,
>>> tuner at the rig, and short coax run.
>>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>

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[K7TV]

I recall that either Rudy or someone else has shown that a "gullwing"
arrangement where the elevated radial has a sloping section that goes down
to a ground-level feedpoint works well, so you wouldn't have add to the mast
in order to use it. AFAIK the main drawback with a single elevated radial is
that it will be noticeably directive, maybe not a drawback in every
situation. When I used two elevated radials, one formed a half circle around
the house, under the eaves, and one followed one side of the house and from
there went close to the property line to a pole on the back fence. That way
neither wire got in the way at all, but every lot is different. Anyway, I am
not advising against a good buried radial system, but I do suggest that when
you have put it in to an extent you are comfortable with, just string up an
elevated radial in a temporary manner to compare it to. The performance of
an elevated radial is less subject to all kinds of design considerations, so
it is a rather good standard against which to compare. (I am assuming you
trim the length to have a resonant system. If you use more than one, and
want full benefits thereof, you need some way to compare currents in them,
as any difference in geometry tends to produce very unequal currents in
equal wire lengths.)

73,
Erik K7TV

----- Original Message -----
From: "David Wilburn" <[hidden email]>
To: "Elecraft Discussion List" <[hidden email]>
Sent: Saturday, May 16, 2009 1:30 PM
Subject: Re: [Elecraft] OT - SteppIR Vertical and Elecraft Products


> Yes that is a good page.  I had considered elevating the vertical, but
> with the fiberglass mast I would need to get several more sections,
> and then wasn't that crazy about the elevated wires over the back
> yard.  If I recall, he wanted a pair of resonant wires for each band
> for the elevated setup.
>
> Dave Wilburn
> NM4M


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[AC7AC]

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[WILLIS COOKE]

You are absolutely right Ron.  It is possible to end feed a half wavelength antenna.  All it takes is very big coils and very high voltage capacitors and a lot of knowledge and usually a lot of money.  Not quite so bad if you stay with QRP power levels.  And when you are through you have an Antron 99 for whatever band you build for.  I certainly don't recommend it to beginners.  But for those of you who want to try it, lots of luck.  When you are done you will have the equivalent of a center fed half wave antenna.

Willis 'Cookie' Cooke
K5EWJ


--- On Sat, 5/16/09, Ron D'Eau Claire <[hidden email]> wrote:

> From: Ron D'Eau Claire <[hidden email]>
> Subject: Re: [Elecraft] OT - SteppIR Vertical and Elecraft Products
> To: "'Elecraft Discussion List'" <[hidden email]>, "'David Wilburn'" <[hidden email]>
> Date: Saturday, May 16, 2009, 2:09 PM
> -----Original Message-----
> 6.  Don't use a half wavelength at your desired
> frequency because it is very
> difficult to match an antenna with nearly infinite
> reactivity.  You can put
> a coil in series to make it about 0.75 wavelength so you
> can match it, but
> it will not be easy.
>
> -----------------------------
>
> Not at all. I do it all the time. The reactance of a 1/2
> wave wire is zero
> (A 1/2 wave is, by definition, resonant. Resonant means it
> has zero
> reactance).
>
> The impedance in a "real world" 1/2 wave antenna
> is something in the range
> of 4000 or 5000 ohms, tops, and often much less. It's
> affected by the
> length/diameter ratio. That's only the resistive value
> since the reactance
> is zero.
>
> Such an antenna is often referred to as a "Fuchs"
> antenna, since he
> popularized it in the 1930's.
>
> What I *have* noticed is that most commercial matching
> networks (ATUs) today
> won't handle an impedance of several thousand ohms.
> Either they simply don't
> have the range of adjustment needed or they'll arc over
> inside. That's
> because of the very high RF voltages that are present when
> the impedance is
> in the thousands of ohms. That's why you see *big* air
> variables or even
> vacuum capacitors were commonly used in the ATUs from the
> 1930's and 40's
> just as they were in the high-impedance "tank"
> circuit at the output of a
> vacuum tube power amplifier.
>
> Overall, it's wonderfully efficient antenna, as is any
> end fed, vertical,
> inverted L or otherwise, that has a very high feed point
> impedance compared
> to the impedance of the ground connection. Remember that
> the RF current is
> divided between the antenna (almost all of it becoming
> electromagnetic
> waves) and the ground connector according to Ohm's law.
> The two impedances
> are in series, so the idea is to reduce the ground
> impedance as far as
> possible while *raising* the radiator's impedance to a
> value as high as
> possible.
>
> Since we're often constrained by a given radiator
> impedance, we're usually
> struggling to reduce the ground impedance to improve the
> ratio and so the
> efficiency.
>
> Ron AC7AC
>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list:
> http://www.qsl.net/donate.html

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[Stephen W. Kercel]

Willis and others:

There is a much cheaper trick than big coils and capacitors that ought
to work, and could easily handle high power.

Although I have never tried end feeding a half wave antenna, I have had
great success in center feeding full wave antennas. The trick is to use
an open wire feedline as a quarter wave transformer. I used the old
fashioned "ladder line" with plastic spreaders and bare copper wire
rated at 450 Ohms. Since the velocity factor is practically 1, I cut the
length to the theoretical free space quarter wavelength. One end feeds
the center of the antenna, and the other end goes to a 1:1 balun. It
presents a very low SWR to 50 Ohm coax. I have done this on various
bands with great success.

I have not tried the "end fed Zepp" configuration implied by an end
feeding scheme, but for the sake of this discussion, I have run a quick
simulation.

Here's what the math says:


I ran the "Backyard Dipole" File that Roy provides with  with EZNEC. I
Moved the feedpoint to one end, changed the ground conditions to
"Real-Medium" and included the copper losses in the wire.

The computed end point impedance at 14 MHz (where it is a half
wavelength) 1282-J1791.

If you use 450 Ohm window ladder line in the TLW program and use a 14
foot length of line in the traditional single ended Zepp fed
configuration, the impedance at the input of the transmission line is
43.15-J18.06. Connecting RG-8 to that works out to an SWR of about 1.5
on the coax.

In the simulation the transformer length did not turn out to be exactly
a quarter wavelength. I had to tweak it a bit to find a workable
transformation. In practice, the ground losses will not be exactly the
same as the simulation, and one might have to play a bit  with the
transformer length when you try it for real.

However, my experience with the "double Zepp" scheme above is that it is
not that hard to find the right line length and the antenna is quite
forgiving in practice. I see no reason why a single ended Zepp scheme
should be significantly more difficult to do in practice.

Some posters may object that the antenna's behavior is impractical to
predict because  the end point impedance can vary over a wide range.
That is true, but by using a quarter wave transformer with relatively
high characteristic impedance, that wide range at the high-Z end is
transformed to a narrow range at the low-Z end.  Thus, in practice, with
perhaps a bit of tweaking, using this scheme will give you acceptable
SWR in the coax, even if your actual impedance numbers are not the same
as my numbers.

73,

Steve Kercel
AA4AK



WILLIS COOKE wrote:

> You are absolutely right Ron.  It is possible to end feed a half wavelength antenna.  All it takes is very big coils and very high voltage capacitors and a lot of knowledge and usually a lot of money.  Not quite so bad if you stay with QRP power levels.  And when you are through you have an Antron 99 for whatever band you build for.  I certainly don't recommend it to beginners.  But for those of you who want to try it, lots of luck.  When you are done you will have the equivalent of a center fed half wave antenna.
>
> Willis 'Cookie' Cooke
> K5EWJ
>
>
> --- On Sat, 5/16/09, Ron D'Eau Claire <[hidden email]> wrote:
>
>  
>> From: Ron D'Eau Claire <[hidden email]>
>> Subject: Re: [Elecraft] OT - SteppIR Vertical and Elecraft Products
>> To: "'Elecraft Discussion List'" <[hidden email]>, "'David Wilburn'" <[hidden email]>
>> Date: Saturday, May 16, 2009, 2:09 PM
>> -----Original Message------
>> 6.  Don't use a half wavelength at your desired
>> frequency because it is very
>> difficult to match an antenna with nearly infinite
>> reactivity.  You can put
>> a coil in series to make it about 0.75 wavelength so you
>> can match it, but
>> it will not be easy.
>>
>> -----------------------------
>>
>> Not at all. I do it all the time. The reactance of a 1/2
>> wave wire is zero
>> (A 1/2 wave is, by definition, resonant. Resonant means it
>> has zero
>> reactance).
>>
>> The impedance in a "real world" 1/2 wave antenna
>> is something in the range
>> of 4000 or 5000 ohms, tops, and often much less. It's
>> affected by the
>> length/diameter ratio. That's only the resistive value
>> since the reactance
>> is zero.
>>
>> Such an antenna is often referred to as a "Fuchs"
>> antenna, since he
>> popularized it in the 1930's.
>>
>> What I *have* noticed is that most commercial matching
>> networks (ATUs) today
>> won't handle an impedance of several thousand ohms.
>> Either they simply don't
>> have the range of adjustment needed or they'll arc over
>> inside. That's
>> because of the very high RF voltages that are present when
>> the impedance is
>> in the thousands of ohms. That's why you see *big* air
>> variables or even
>> vacuum capacitors were commonly used in the ATUs from the
>> 1930's and 40's
>> just as they were in the high-impedance "tank"
>> circuit at the output of a
>> vacuum tube power amplifier.
>>
>> Overall, it's wonderfully efficient antenna, as is any
>> end fed, vertical,
>> inverted L or otherwise, that has a very high feed point
>> impedance compared
>> to the impedance of the ground connection. Remember that
>> the RF current is
>> divided between the antenna (almost all of it becoming
>> electromagnetic
>> waves) and the ground connector according to Ohm's law.
>> The two impedances
>> are in series, so the idea is to reduce the ground
>> impedance as far as
>> possible while *raising* the radiator's impedance to a
>> value as high as
>> possible.
>>
>> Since we're often constrained by a given radiator
>> impedance, we're usually
>> struggling to reduce the ground impedance to improve the
>> ratio and so the
>> efficiency.
>>
>> Ron AC7AC
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list:
>> http://www.qsl.net/donate.html
>>    
> ______________________________________________________________
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>
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>
>  

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[Don Wilhelm-4]

Steve,

Since your simulation showed that the feedpoint had a reactive (-J)
component, it was not resonant half wave dipole.  You should adjust the
antenna length to bring the +/- j component of the impedance to zero.  
That is the condition of resonance for antennas.

You other points were quite valid based on the feedpoint impedance that
you used (with the reactive component).

73,
Don W3FPR

Stephen W. Kercel wrote:
> The computed end point impedance at 14 MHz (where it is a half
> wavelength) 1282-J1791.
>  
>
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