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Re: BBQ Dish Gain Data



At 09:48 AM 2/7/03 -0600, Gene Marcus wrote:
>Central States VHF Society antenna gain results for this antenna is 
>located at:
>
>http://www.csvhfs.org/CSANT01.HTML
>
>73,
>
>Gene Marcus W3PM GM4YRE
>Huntsville, AL

Thanks, Gene:

Central States and other VHF/UHF groups do a good job of making the
"reality" measurements to compare with our theoretical assumptions.  To
summarize, it looks like the larger BBQ dish (labeled 38x26-inch and
submitted by K5GNA) measured at 20.8 dBi, while the smaller BBQ 17x22-inch
dish came in at best gain of 18.3 dBi.

These two data points kind of establish the upper limit of performance that
one should expect...I would use these gains in the AO40v2.0 spreadsheet for
estimating purposes.

Interesting to note that a 0.9m dish submitted by K5VH measured at 22.2
dBi...I am using an 85cm-offset feed dish which is approx the same size (he
uses a loop feed vs my helix).  This is approx. -3dB of my est. gain.

Also interesting to see the effects that choice of feeds make. 

Ed - AL7EB
*Looking real close it appears that the measurements were in comparison to
a linear-polarity reference, so take that into consideration (AO40v2.0 does
this)
 Note that the measurements were made at 2304 MHz, not 2401.

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