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Re: Mobile antenna question



>>> Andrew Glasbrenner <glasbrenner@mindspring.com> 1/26/05 11:38:39 AM
>>>
>The chart says it includes "range gain". Is this basically 
>a plot of the average signal strengths or have you adjusted 
>the chart to compensate for the distance from the signal source?

Yes, adjusted it for distance...

>Also it looks to me like the 1/4 and 3/4 wave plots cross at 
>about 35 degrees, not 25 degrees. Am I misreading this?

My web page is down so I cannot look at it.  But my 
speaking of where they cross had to do with the
elevation plot of the two GPS live tests on the black background
which are real data.  I guess I havent looked at the
EXCEL plots I did to see what they say... maybe you
are talking about them?  

Yes, seems I remember that they gave a higher angle..
but they were based on EZNEC antennas over 
infinite grounds.  The live GPS (scaled to 435 MHz)
data was with a scaled car roof ground plane only.

>Quite a novel idea on how to model antenna gain BTW....

Thanks.  I thought it was cute at the time.
Especially how the GPS constellation and an omni
atnenna scaled to 1575 gives everyone a perfect
anechoic test "chamber"....

Bob

73, Drew KO4MA
 
>
>Yes, it gives worse gain below 20 deg, about equal at 25 and is
>3 dB better above 30 on up to 80 deg.  See plot about 80% down
>my page:
>
>http://www.ew.usna.edu/~bruninga/astars.html 
>
>So if you drive back east and are always in trees except for
>everything around you above 25 deg, then use the same 2m
>19.5" whip as a 1/4 on 2m and as a 3/4 on 70 cm for better
>performance.  BUT of all the times that a satellite is in view, it 
>is only above 25 deg less than 30% of the time..
>
>But when it is, you'll be 3 dB better off.
>
>But previous mode J birds had such low pwoer that
>the 1/4 couldnt hear it reliably at the horizon anyway
>(its 6dB further away) so having better 1/4 performance
>down below 20 deg where you can't hear the bird anyway
>is a moot point.
----
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