In article , Richard Clark
writes:

On 10 Apr 2004 18:25:04 GMT, PAMNO (N2EY) wrote:
All of this supports both your experiences and those of others. If the exact
characteristics of tubular Twin Lead are important to the design, it's no
wonder that the reported results cannot be obtained.

One more point. The SWR graphs shown for the 5 band version show quite
narrow
SWR bandwidths. If anyone is interested I can report them in a future post.

Hi Jim,

I stand corrected on the tubular twin lead (must've died in the
mid-60s then).

No biggie. I did not expect to find it in the 1953 catalog, but there it was,
and not a new item either.

Probably unobtanium now.

It offers nothing substantially different to the physics of design
however, just a different velocity factor which is scalable to suit
any implementation.

Lattin seemed to think it was important. Do you have the 1960 QST article?

However, my data to this point confounds the "theory" of it all by
exhibiting stubs that do NOT resonate at their computed length
(complete with correction for ANY velocity factor commonly observed).

More data is always appreciated.


Well, here's the info from the 1960 QST article.

Dipole dimensions:

Innermost section (not a stub; shorted at both ends): 8'
Next section (stub; open at inner end): 6' 11" [resonant at 10 meters?]
Next section (stub, open at inner end): 13' 10" [resonant at 20 meters?]
Outermost section (stub, open at inner end): 27' 5" [resonant at 40 meters?]

Entire antenna 57' 2" per side (plus connections)

SWR, 50 ohm coax, coax length not given (all numbers guesstimated from graph):

80 meters:
Minimum SWR: 3725 kHz - 1.1:1
2:1 SWR points: 3625 & 3800 kHz (175 kHz)
SWR at 3500: 5:1
SWR at 4000: 4.5:1

40 meters:
Minimum SWR: 7225 kHz - 1.6:1
2:1 SWR points: 7150 & 7275 kHz (125 kHz)
SWR at 7000: Off end of scale (5:1 at 7075 kHz)
SWR at 7300: 3:1

20 meters:
Minimum SWR: 14250 kHz - 1.3:1
2:1 SWR points: 14100 & 14375 kHz (275 kHz)
SWR at 14000: 3.5:1
SWR at 14350: 1.8:1

10 meters:
Minimum SWR: 28600 - 1.6:1
2:1 SWR points: 28500 & 28750 kHz (250 kHz)
SWR at 28900: 3:1

Chart for 10 meters covers 28500 to 28900 only. No chart for 15 meters but text
says it will work there on 3/2 wavelength resonance of 40 meter section and SWR
of not less than 3:1.

Note how tight the 2:1 SWR points are, even on the higher bands.

--

Also described is an 80/40 dipole. Inner section is 28' and shorted both ends,
outer stub section is 27' 5". Interesting feature of this one is that in order
to achieve 40 meter resonance there are pieces of wire 2' 6" long hung from the
junction of the two sections. The text and diagram say the outer section
resonates on 40 but the inner section has to be kept at 28 feet or the 80 meter
resonance will be too low.

--

Seems to me that the classic W3DZZ trap dipole would be a lot less aggravation
to model and get working, plus more flexible in choice of minimum SWR points.
Particularly if additional "resonance wires" were added if needed. Certainly
easier to make mechanically strong traps than stubs, and adjusting single wire
lengths with Burndys is a lot easier than fooling with tubular Twin-Lead.

73 de Jim, N2EY

N2EY wrote:
Innermost section (not a stub; shorted at both ends): 8'

No wonder it didn't work on EZNEC. The web page I referenced
had that as a stub.
--
73, Cecil, W5DXP



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On 11 Apr 2004 00:59:23 GMT, PAMNO (N2EY) wrote:

Lattin seemed to think it was important. Do you have the 1960 QST article?

Hi Jim,

No, but hopefully Irv will rectify that.

Well, here's the info from the 1960 QST article.

I will keep those numbers close by, thanx.

73's
Richard Clark, KB7QHC

N2EY wrote:
Dipole dimensions:
Innermost section (not a stub; shorted at both ends): 8'
Next section (stub; open at inner end): 6' 11" [resonant at 10 meters?]
Next section (stub, open at inner end): 13' 10" [resonant at 20 meters?]
Outermost section (stub, open at inner end): 27' 5" [resonant at 40 meters?]

Is this just an attempt at a trapped antenna using stubs for traps?
It doesn't seem to model out to be very functional. The outermost
stub on 40m needs to have a very high impedance, i.e. 1/4WL shorted.
That works well to resonate the vertical on 40m, but 1/8WL on 80m
makes the antenna resonant at 3 MHz according to EZNEC.
--
73, Cecil, W5DXP



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Cecil Moore wrote in message ...
N2EY wrote:
Dipole dimensions:
Innermost section (not a stub; shorted at both ends): 8'
Next section (stub; open at inner end): 6' 11" [resonant at 10 meters?]
Next section (stub, open at inner end): 13' 10" [resonant at 20 meters?]
Outermost section (stub, open at inner end): 27' 5" [resonant at 40 meters?]

Is this just an attempt at a trapped antenna using stubs for traps?

That's exactly what it looks like to me, Cecil. That's also how its
operation is explained in the article. Why a stub that is excited
along its length should behave as a trap is not explained, nor how the
shortened sections act as loading coils (the entire antenna is only
112' 4" long, plus connections).

Note that the antenna works as follows:

10 meters: 6'11" sections act as open circuits so that 8' sections
function as dipole.

20 meters: 13'10" sections act as open circuits so that 8' plus 6'11"
sections function as dipole.

40 meters: 27'5" sections act as open circuits so that 8' plus 6'11"
plus 13'10" sections function as dipole.

80 meters: Entire antenna functions as dipole.

15 meters: 27'5" sections act as open circuits so that 8' plus 6'11"
plus 13'10" sections function as dipole on 3/2 wavelength resonance.

It doesn't seem to model out to be very functional.

Modeling the thing looks like a real challenge for a whole bunch of
reasons. The gaps between sections may be important, for example.

The outermost
stub on 40m needs to have a very high impedance, i.e. 1/4WL shorted.
That works well to resonate the vertical on 40m, but 1/8WL on 80m
makes the antenna resonant at 3 MHz according to EZNEC.

Lattin's results prove that it is *possible*, so your model obviously
needs work to agree with physical reality. But whether the Lattin
antenna is worth all the effort and mechanical troubles is another
story.

The antenna described is a dipole rather than a vertical, but the same
principles apply.

I suspect that a key element to the antenna's operation is the use of
the tubular Twin-Lead, with its 0.8 velocity factor. This stuff is
probably close to being unobtanium these days. Another point is the
extreme narrowness of resonance on most bands.

The W5GI antenna seems to be a variation on the Lattin theme.

For all that trouble, it seems to me that a better choice (if you want
direct coax feed on the non-WARC HF bands) is the classic W3DZZ trap
dipole. With only two traps and mechanically robust construction it is
possible to achieve direct coax feed and low SWR on 80/40/20/15/10,
and the cut-and-try is much easier.

73 de Jim, N2EY

N2EY wrote:
The W5GI antenna seems to be a variation on the Lattin theme.

He says nobody has been able to model or explain why the
antenna works. KA8NCR over on qrz.com says it's lossy
on receive compared to a resonant dipole and about the
same as a trap dipole. I think this is the thread:

http://www.qrz.com/cgi-bin/ikonboard...=6015 8;st=10

Looking at the W5GI antenna, it would seem that reflections
from the ends of the antenna would flow towards the feedpoint
on the coax braid due to skin effect and encounter an open
circuit. If one sent a TDR pulse toward the end of the antenna
from the feedpoint, what do you suppose one would see coming
back?
--
73, Cecil http://www.qsl.net/w5dxp

On 19 Apr 2004 05:14:44 -0700, (N2EY) wrote:

Why a stub that is excited
along its length should behave as a trap is not explained, nor how the
shortened sections act as loading coils (the entire antenna is only
112' 4" long, plus connections).

Hi Jim,

Simply because the so-called explanations are more wish than reality.
I've not slackened my study of this design. I've done thirty or forty
measurements that have interest in their own right, but show the
"theory" is sheer fantasy. These notions of tuned stubs as traps are
so far off the mark in practice that no one notices they don't make
sense electrically either.


Modeling the thing looks like a real challenge for a whole bunch of
reasons. The gaps between sections may be important, for example.

....

I suspect that a key element to the antenna's operation is the use of
the tubular Twin-Lead, with its 0.8 velocity factor. This stuff is
probably close to being unobtanium these days. Another point is the
extreme narrowness of resonance on most bands.

These apologies ring false. The issue of gaps is desperate and the
selection of tubular has no basis in special characteristics. All
such considerations MUST yield to simple scaling. For instance, if
you need 0.8 and have 0.9, there is no magic formula beyond
proportions necessary to achieve "what should be."

The difficulty lies in the supposed explanations.

The W5GI antenna seems to be a variation on the Lattin theme.

And it is even more gauche. It approaches antenna design as an allied
art of Palmistry.

73's
Richard Clark, KB7QHC

Richard Clark wrote in message . ..
On 19 Apr 2004 05:14:44 -0700, (N2EY) wrote:

Why a stub that is excited
along its length should behave as a trap is not explained, nor how the
shortened sections act as loading coils (the entire antenna is only
112' 4" long, plus connections).

Hi Jim,

Simply because the so-called explanations are more wish than reality.
I've not slackened my study of this design. I've done thirty or forty
measurements that have interest in their own right, but show the
"theory" is sheer fantasy. These notions of tuned stubs as traps are
so far off the mark in practice that no one notices they don't make
sense electrically either.
Modeling the thing looks like a real challenge for a whole bunch of
reasons. The gaps between sections may be important, for example.

...

I suspect that a key element to the antenna's operation is the use of
the tubular Twin-Lead, with its 0.8 velocity factor. This stuff is
probably close to being unobtanium these days. Another point is the
extreme narrowness of resonance on most bands.

These apologies ring false. The issue of gaps is desperate and the
selection of tubular has no basis in special characteristics. All
such considerations MUST yield to simple scaling. For instance, if
you need 0.8 and have 0.9, there is no magic formula beyond
proportions necessary to achieve "what should be."

I disagree! In the QST article, Lattin describes an 80/40 dipole using
his method. It has wires dangling from the stub junctions to get 40
meter resonance.

The difficulty lies in the supposed explanations.

Agreed. They are oversimplified at best and just plain wrong at worst.
However, I take it as a given that W4JRW got the results he claimed
from the antennas he built.

The fact that people report so much trouble duplicating and modeling
the W4JRW antennas indicates to me that there is more to it than meets
the eye - and maybe more than met W4JRW's eye, as well.

Most important to me is that the antenna offers no real advantages
over, say, a conventional trap dipole. Yet it offers many
disadvantages, such as mechanical frailty and difficulty of
duplication.


The W5GI antenna seems to be a variation on the Lattin theme.

And it is even more gauche. It approaches antenna design as an allied
art of Palmistry.

HAW!

And again - what advantages does it have over, say, a W3DZZ trap
dipole?

73 de Jim, N2EY

On 20 Apr 2004 09:06:35 -0700, (N2EY) wrote:
These apologies ring false. The issue of gaps is desperate and the
selection of tubular has no basis in special characteristics. All
such considerations MUST yield to simple scaling. For instance, if
you need 0.8 and have 0.9, there is no magic formula beyond
proportions necessary to achieve "what should be."

I disagree! In the QST article, Lattin describes an 80/40 dipole using
his method. It has wires dangling from the stub junctions to get 40
meter resonance.

Hi Jim,

OK, you disagree, but with what? Scaling will ALWAYS answer
everything but the mystical apologies.


Most important to me is that the antenna offers no real advantages
over, say, a conventional trap dipole. Yet it offers many
disadvantages, such as mechanical frailty and difficulty of
duplication.

This is more pilot error than design error (which has its own
problems, of course).

And again - what advantages does it have over, say, a W3DZZ trap
dipole?

I see no such issues if the theory were hammered out. It is plainly
these readings of tea leaves that frustrate construction, because when
a design is described, it is most clear and concise - it just doesn't
work is all.

Like I said, I've done some measures and added a dozen more since.
The results are interesting. I can come up with a four band antenna
without too much trouble; however, getting those bands into Ham
regions (all of them) is another matter. I can do this with a simple
run of twin lead, and one strategically placed short between them.

This antenna (usefully resonant or otherwise) is no worse than any
wire strung between poles - just two wires instead of one, hardly what
I would call fragile. If it has an advantage over your W3DZZ trap
dipole, I leave that strictly in the eye of the beholder as I have
full faith it won't be any worse.

Any way, such work offers a step towards an antenna with MORE gain
(and more wire, a third one) by constructing a Franklin Array style of
antenna. True, not a multi bander, but I am not particularly nailed
to the floor over that.

73's
Richard Clark, KB7QHC

Richard Clark wrote in message . ..
On 20 Apr 2004 09:06:35 -0700, (N2EY) wrote:
These apologies ring false. The issue of gaps is desperate and the
selection of tubular has no basis in special characteristics. All
such considerations MUST yield to simple scaling. For instance, if
you need 0.8 and have 0.9, there is no magic formula beyond
proportions necessary to achieve "what should be."

I disagree! In the QST article, Lattin describes an 80/40 dipole using
his method. It has wires dangling from the stub junctions to get 40
meter resonance.

Hi Jim,

OK, you disagree, but with what?

With the idea that scaling answers all questions.

Scaling will ALWAYS answer
everything but the mystical apologies.

The two-band 80/40 dipole in the QST article has extra wires at the
junctions of the 80 and 40 sections because (according to the author)
the velocity factor of the tubular Twin Lead makes it necessary. Those
wires might or might not be required with a unity velocity factor.

Most important to me is that the antenna offers no real advantages
over, say, a conventional trap dipole. Yet it offers many
disadvantages, such as mechanical frailty and difficulty of
duplication.

This is more pilot error than design error (which has its own
problems, of course).

In a perfect world, maybe. But in the real world of ham radio, most
hams have limited materials, test equipment, time and space. An
antenna made out of unobtainable materials, which requires
unobtainable tools and test equipment to build and adjust is only of
academic interest to a ham.

And again - what advantages does it have over, say, a W3DZZ trap
dipole?

I see no such issues if the theory were hammered out. It is plainly
these readings of tea leaves that frustrate construction, because when
a design is described, it is most clear and concise - it just doesn't
work is all.

Exactly! If it cannot be easily duplicated by a ham with typical
resources, what good is it?


Like I said, I've done some measures and added a dozen more since.
The results are interesting. I can come up with a four band antenna
without too much trouble; however, getting those bands into Ham
regions (all of them) is another matter. I can do this with a simple
run of twin lead, and one strategically placed short between them.

Which is not what Lattin did at all. Your design sounds far superior.
Is it on the web anywhere?

This antenna (usefully resonant or otherwise) is no worse than any
wire strung between poles - just two wires instead of one, hardly what
I would call fragile. If it has an advantage over your W3DZZ trap
dipole, I leave that strictly in the eye of the beholder as I have
full faith it won't be any worse.

All depends on the wires. I use recycled #12 house wire, which stands
up under ice loading and high winds here in EPA. Yet it is hardly
noticed by the neighbors.

Any way, such work offers a step towards an antenna with MORE gain
(and more wire, a third one) by constructing a Franklin Array style of
antenna. True, not a multi bander, but I am not particularly nailed
to the floor over that.

The main attraction of the Lattin is its claim to multiband operation.
Otherwise one might as well go with a plain dipole.

73 de Jim, N2EY