Topband: FW: The WD8DSB mini-flag antenna (LONG!)

[Jim Brown]

On 2/26/2021 7:31 AM, John Kaufmann via Topband wrote:
 >
When dealing with narrowband
 > coherent signals, this can really make very weak signals become
 > visible on the display

That's exactly what I said in my first post.

 > when they are virtually invisible in a larger measurement
 > bandwidth.

The effect of the bandwidth of bins is to increase the frequency 
resolution (and decrease the time resolution) of a measurement. It is a 
fundamental property of spectral measurements that we can not know both 
frequency and and time with infinite accuracy from the same measurement, 
because they are the inverse of each other.

On 2/26/2021 8:46 AM, Richard (Rick) Karlquist wrote:
> Averaging is a nice technique that mitigates the poor sensitivity
> of the mini-flag, but only for "bright lines" due to power
> supplies, etc.  

And for signals from ham transmitters.

I would be surprised if it would do anything
> to improve DF'ing power line noise, which is clearly a major
> application domain.

Of course not -- that noise is not coherent. Averaging is useful for 
chasing noise from electronic sources, not the noise generated by arcing 
in power systemsn or by lightning, which is impulse noise. Impulse noise 
will be displayed by horizontal lines on a waterfall if the time scale 
is fast enough.

73, Jim K9YC