Dick Rollema wrote:

To All from PA0SE

Walter Blanchard quoted the RACAL expert who has in the past  designed the
Decca antennas as follows:

>(...)  If the small one has an assymetric horizontal component (flat-top)
> this will complicate matters considerably since it will radiate both
> vertical and
> horizontally-polarised and there will be interaction between them that
> will affect the radiation pattern. So it would be unlikely to have a
circular
> polar pattern and this might account for some of the observed variations.

This is not confirmed by computer simulation.

Shouldn't you say "Computer simulations do not model this". Decca did a lot of
measurements when they developed Navigator, and the physics always has the last
word. The question should therefore be "what is wrong with the computer model?"

Stewart G3YSX