SWR is a pretty coarse indication of interaction. Interactions can
change directional antenna F/B and F/S ratio by 6-10 db easily (assuming
you have it in the first place) and hardly affect SWR.
At least, this is my experience from antenna modeling.
However, we have to live with the hands we're dealt. Without any field
strength measurements or calculations, one probably won't detect much.
Ignorance is bliss.
73 de Brian/K3KO
On 7/5/2013 20:13, Ignacy wrote:
I had verticals on concrete, roof shingle and metal roofs. Always radials
lying on top. The metal roof was the best by far.
One way to find out how much the roof is affecting the performance of a beam
is to look at SWR changes as the antenna is rotating.
Ignacy, NO9E
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