Hi Rob,
Front to back ratio all depends on the arrival angle of the signal, and the
portable flag directional properties are just like full size flag
directional properties assuming you select the appropriate termination
resistor. On my portable flag website I show front to back ratio vs
elevation angle when using a 680 ohm termination resistor versus using a
820 ohm termination resistor and you will see that you can move where the
front to back ratio peaks to a higher elevation angle if using a 820 ohm
termination resistor compared with using a 680 ohm termination resistor. I
use a 680 ohm termination resistor because I wanted best performance for
ground wave based signals but if I wanted to reject skywave signals off the
back of the antenna versus local noise I would use a 820 ohm resistor as an
example. Here is a link to my website where you will see the plots I
mention: https://sites.google.com/site/portableflagantenna/
73,
Don (wd8dsb)
On Wed, Feb 24, 2021 at 6:31 AM Rob Atkinson <ranchorobbo@gmail.com> wrote:
> Bi-directional loops lose their directivity for the most part, when
> being applied to skywave signals. Is this mini-flag still
> unidirectional on skywave? I would think not, but must ask.
>
> 73
> Rob
> K5UJ
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