Re: [amsat-bb] BBQ Dish Gain

[Scott Townley <nx7u@xxxxxxxx>]

I'll believe the "MODEL" comment if you can substantiate your guess.  There 
is nothing particularly "stressful" about this model vis-a-vis NEC 
modelling rules.
Why is this not unusual?  FWIW, I ran the average gain calculation and it 
indicated a 0.1dB potential error.
Now, one thing I will say is that I have one of these dishes...and of 
course the model is a perfect doubly-curved parabola...and I know mine isn't.


At 14:06 2003-03-09, Frederick M. Spinner wrote:
>I can believe it, that's why it's called a MODEL.  My guess that the 
>efficiency is overestimated in NEC-2.  This isn't unusual for NEC-2 with 
>"reflector screen" antennas.
>
>All I can say is that I've seen range testing on BBQ's more than once and 
>usually the "24 dBi" antennas test in between 18 and 20 dBiL.  Never 
>better than that.  +/-2 dB or so is about the accuracy of the ranges that 
>hams use in parking lots at VHF/Microwave Conferences.
>
>Fred W0FMS
>
>
><rom: Scott Townley <nx7u@arrl.net>
>>To: amsat-bb@AMSAT.Org
>>Subject: Re: [amsat-bb] BBQ Dish Gain
>>Date: Sun, 09 Mar 2003 06:41:08 -0700
>>
>>I have a NEC-2 model of K5GNA's 38"x26" BBQ dish, including the 
>>integrated AIDC3733 dipole/reflector plate feed.  Interestingly enough it 
>>comes out to 25.5dBi maximum forward gain.  This gain calculation would 
>>include spillover and aperture illumination efficiencies.  That's a 
>>nearly 70% reflector efficiency...hmmm...
>>Of course, in circular terms that's 22.5dBic.
>
>
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Scott Townley NX7U
Gilbert, AZ  DM43di

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