[PSDR] Reference antenna problems

Bart Kus me at bartk.us
Tue Dec 11 02:42:17 PST 2012


Well, it seems the situation is a LOT better with the parabolic 21dBi 
antennas:





Since these are identical models and the variances seen in the top trace 
represent twice their error, these are indeed quite nice even leveled 
antennas, at least at this 2ft distance apart.  Gotta do more testing @ 
various other locations and separation distances to verify everything is 
cool.

--Bart

On 12/11/2012 2:23 AM, Bart Kus wrote:
> Hello,
>
> So I tried to measure the reference antennas (simple dipoles). It's 
> kind of a disaster.  With the antennas only 2ft apart:
>
>
>
> The received signal is pretty weak:
>
>
> The marker is down 20dB from the previous measurement:
>
> I guess that pair of sectors I was using were really helping things 
> out.  I'm also concerned about the uneven response, but that could be 
> multipath given the really low signal levels.  Does anyone have any 
> experience with antenna measurement like this? I'm thinking my next 
> step is using the 21dBi parabolic dishes as the reference antennas 
> instead.  Having thought about it, the high directional gain, although 
> it would need precise alignment to make accurate measurements, would 
> help with ignoring/overcoming multipath, no?  Some of those peaks and 
> valleys might disappear. A 20dB range over the spectrum is pretty 
> ridiculous.
>
> --Bart
>

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