[Elecraft] OT - anyone have experience with effects of metal roofs on antenna performace?

[Jan Erik Holm]

On 2013-07-05 22:22, Brian Alsop wrote:
> 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
>
You forgot the Gain. Forexample you can loose  2 - 3 dB gain on an 
antenna due to interaction with another antenna or "object" and see
no nothing on the SWR you measure down in the shack. Then you think
everything is fine a perfect, well maybe it´s good since what you don´t 
know you don´t worry about.
/SM2EKM