The Double Extended Zepp or Extended Double Zepp (DEZ or EDZ, as you
prefer) goes back at least to the 1930s and has been used successfully by
innumerable hams.
Current levels on the wire depend on the band. As N4PC cut it for 40,
where it is about 1.25 wl, the current on 40 shows a peak at the center,
but the highest peaks are 1/4 wl in from each end. On 80, where it is
about 5.8 wl, current is highest at center. Also on 160, where the
antenna is about 3/8 wl, the shortest recommended length for a center-fed
wire, since the feed Z goes very high as you shorten further. (This is
the length of a standard 102' G5RV on 80 meters--3/8 wl.) On bands above
40, the antenna is a center-fed long wire, with multiple lobes and nulls,
according to how many wl long it is.
Since the antenna generally present a good bit of reactance and requires
sharp tuning by any ATU, the bandwidth is fairly narrow without retuning,
and this generally means less noise. (Miniloops are remarkably quiet, but
exceptionally shrply tuned.)
As with almost all single wire antennas, fold, spindle, and mutilate as
necessary to get a yard fit. No, do not coil, but zig-zags, end droops,
mild fold-backs, etc., all affect performance only mildly and should not
be feared as the ruination of the antenna. Parallel feedline for
multi-band use, with a good atu is best. A good atu is one that has
settings that give the minimum loss in addition to giving a 1:1 SWR on the
rig side. Lots of 1:1 settings possible for any atu design, but only 1
(sometimes 2) will give lowest loss--and poor atu designs often switch by
these. However, in a pinch, any atu that gives 1:1 can be used with
success.
If you have the space, cut one for 80 (320-350') and get it even higher at
the center--and the ends, if you can. It will make 160 sing even louder,
although somewhat more directionally. 160 - 80 broadside; 20-10 near the
ends.
With either version, put 3 in a triangle (or 3-way crossing) and cover the
world. I recall a W7 with tall firs doing this with great success in
contests. (Senility makes the rest of the call and the switch box a bit
memory faded.)
DEZ or EDZ: still a very good wire. Contracts with antenna enthusiasts
require that the antenna be revived every two-three years, and Paul had
the duty this time. My turn was back in '95 in Com Quart.
-73-
LB, W4RNL
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