Topband: Center support on K9AY Loop

[Michael Tope]

Tom and Tom:

FWIW, I have been modeling a set of K9AY loops with EZNEC.
My modeling results (real high-accuracy ground - average conductivity)
indicate that their is only a slight difference (about 2dB F/B) at 1.8 MHz
between a grounded metal support, and floating metal support, and
no support (or non-conductive support). The loops I modeled follow
K9AY's suggested dimensions (85' total loop circumference). Modeling
results at 3.8 MHz are similar (minor changes due to mast configuration).

The modeled array was installed locally last weekend using a 30ft
push-up mast that was grounded at the base. Measured performance
seems to be consistent with the modeling on 80 meters (couple of S-units
F/B and improved SNR). The 1.8 MHz measured results don't look
so hot (moderate F/B, but no apparent SNR improvement over the TX
antenna) , but this probably has more to do with the mutual coupling to
the nearby 60' Rohn 45 tower with TH7DX/402CD on top than the
configuration of the array support pole.

73 de Mike, W4EF...............................