[TowerTalk] Re:

[art unwin]

At 09:11 AM 2/3/01 -0600, you wrote:
>> The saying still goes, trust but verify(the facts Mam,just the facts)
>> and it is not really that hard to do !
>>
>> Regards
>> Art Unwin KB9MZ
>
>
>** Interesting points Art, let me cite the Cushcraft spec sheets, these are
>2 meter beams on 15 foot booms.:
>
>15 element 3 reflectors: fwd= 15.5 dBd, f/b 24 dB
>
>13 element 1 reflector : fwd: 15.8 dBd, f/b 26 dB.
>
>Allowing that CC has a better antenna range than I do, I've always wondered
>why this is so. First blush, one would expect more reflectors= more f/b.
>As you know, we EMEers are always looking for a smidgen more gain and a
>cleaner pattern.


Geo,
I suppose one has to know what the target is !
One could assume that NF is the primary factor in EME. 
The fact that they even offer multi reflectors would suggest
that such designs DO have a place, but why they would offer it
with lower specs does raise questions as to what the real target is ?
(You also state dbd and not dbi tho' they are using > 1 WL booms !)

My present antenna needs a lot to break the rear rejection
but obviously there are different 'needs' in EME and other
higher frequency uses than the 'more populated' H.F.bands

 One thing that does come to mind in  EME designs is the supposed
desirablity of clean pattern design and yet present designs
show 'wasteful' minor side lobes in the FORWARD direction ,
the extra reflectors would certainly address that question

But as I stated earlier, one must beware  not to extrapolate targets
and data beyond the  known and verifiable boundaries 

Thank you for the interesting observations and your time 
considering your extensive published expertise in
multi element beam designs

Art  KB9MZ


>
>Happy Homebrewing, Geo>KØFF
>http://homepages.dstream.net/K0FF
>
>
>
>


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