Topband: Fading

[Don Kirk]

Hi Kris,

If you belong to the shared apex loop Yahoo Groups click on the file tab
and then look for my call sign.  You will see plots that I generated
looking at the front to back ratio versus elevation angle, and I think
these plots might help answer some of your questions.


Don (wd8dsb)

On Thu, Jan 14, 2016 at 4:33 PM, Kris Mraz <n5kilomike at gmail.com> wrote:

> I know that fading can be caused by phase rotation of the arriving signal.
> Can fading be caused by the signal changing arrival angle over time
> (1-3 seconds)?
> I ask this because of something I observed while attempting to tune my
> Shared Apex Loop (SAL)
> antenna the other night.
>
> In the forward direction I tuned in a strong, distant AM broadcast
> signal that was fairly steady
> strength-wise. It would vary less than an S unit as seen on my radio
> S-meter (FTdx5000). Then I
> switched to the reverse direction. From the SAL backside the signal
> experienced rapid fading
> from S0 to S8.
>
> Looking at the elevation pattern of the SAL (or just about any RX
> antenna design) it can be seen
> that the forward direction has a broad gain pattern around the 20
> degree arrival angle. In the reverse
> direction there is a deep steep null near that reverse angle. From
> this I assumed that the signal was
> changing arrival angle, moving into and out of that deep null. Is this
> the correct analysis?
>
>
> Kris N5KM
> _________________
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>