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