Topband: Bruce arrays

[Carl]

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 at pacbell.net>
To: <topband at 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
>
>
> _________________
> Topband Reflector
>
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