KC1XX ran stacked 80M deltas but dont know if they have been replaced after
the ice storm a few years ago.
Carl
KM1H
----- Original Message -----
From: "Grant Saviers" <grants2@pacbell.net>
To: <topband@contesting.com>
Sent: Monday, September 09, 2013 12:55 AM
Subject: Topband: Bruce arrays
Wondering what experience there is for 3L Bruce arrays and if a reflector
has been tried? It looks like a good "bang for the buck" way to get some
low angle gain. My interest is to 80m to improve low angle (5-20deg)
versus a 86' rotatable dipole (Tornado tuned redesigned/rebuilt EF180C) at
100'. The goal is a better signal to EU from Seattle, a tough path vs
the W1's. I have some free antenna supports in the form of 100' hemlocks
and cedars with the right orientation and the highest support rope can be
about 90' agl.
I've run a bunch of EZNEC sims which show 18deg gain improves by 1.1db and
at 10deg by 3.6db for the 3L Bruce with its top at 80'. Helpful, but not
dramatic. Very wet winter earth here is a bit better than average, I use
0.01ms for ground conductivity.
I think it is mechanically feasible to add a close spaced passive
reflector, 25' separation. Then the sim'd gain improvement vs dipole is
4.1db at 18deg and 6.9db at 10 deg and 10.1db at 5deg (my QTH has a good
EU HFTA) over the dipole. That is really getting interesting, but I am
wondering how much to trust EZNEC with such close spacing ~0.1wl.
I have no place to put radials for a 80m 4 sq transmit antenna, and the
cost would be a LOT more if I did. I've modeled phased delta loops hung
from a 90' tower, but the reported tuning difficulties and sim'd tower
interactions are a big concern plus poorer low angle gain.
Inputs and better alternatives appreciated.
Grant KZ1W
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