After countless hours of modeling yagis with K6STI software my
conclusion was to go with Lawson's odd mult of a quarter wavelength for
a boom, yes...and if you are someone who only operates one end of the
band go with fewer elements (4) versus more (5 or 6) - very little
difference in gain but noticeable increase in bandwidth of low SWR with
the additional elements...hence, I have a lot of home brew 4 element
yagis! Also - unless you are a DXer, longer booms have narrower
patterns and as such are more critical about their aiming...sometimes
signals come in skewed paths and a 6 element yagi will not hear them
whereas the 4 element with its wider lobe will...this is all real life
observation - I am not an Engineer...for contesting 4 elements is gud.
OJ
Saul Abrams wrote:
> The answer is in W2PV's book--the number of elements is somewhat unimportant
> compared to boom length. In his book, Jim Lawson pointed out that a .75
> wavelength boom (54 feet on 20 meters) has almost the identical gain whether
> you use 4, 5 or 6 elements. It pretty much all in the boom length.
> Different number of elements gives you different levels of antenna coupling
> for stacking and also presents mechanical differences such as weight and
> balance and element position relative to the mast.
> ----- Original Message -----
> From: "Richard Karlquist" <richard@karlquist.com>
> To: "poster" <poster@gate.net>; <towertalk@contesting.com>
> Sent: Wednesday, August 14, 2002 12:23 AM
> Subject: RE: [Towertalk] What is the diffrence?
>
>
>
>>While we are on the subject:
>>
>>Why is it that M2 uses
>>5 elements on 20 meters
>>to get 8.1 dB gain but
>>uses only 4 elements on 10 meters
>>to get 8.0 dB gain? The
>>booms are almost the same
>>length, after you scale for
>>wavelength (44 ft and 24 ft
>>respectively). % bandwidth is
>>almost the same too.
>>
>>Rick Karlquist N6RK
>>richard@karlquist.com
>>www.n6rk.com
>>www.karlquist.com
>>
>>
>>>-----Original Message-----
>>>From: towertalk-admin@contesting.com
>>>[mailto:towertalk-admin@contesting.com]On Behalf Of poster
>>>Sent: Tuesday, August 13, 2002 6:44 PM
>>>To: towertalk@contesting.com
>>>Subject: [Towertalk] What is the diffrence?
>>>
>>>
>>>Between the 5El KLM 20mtr monobander and the KLM Big stick 6El?
>>>Is it just boom length and amout of elements?
>>>
>>>Jack
>>>
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>>_______________________________________________
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>>
> http://www.mscomputer.com
>
>>Call 888-333-9041 to place your order, mention you saw this ad and take an
>>
> additional 5 percent off
>
>>any weather station price.
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>>
>
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
> http://www.mscomputer.com
> Call 888-333-9041 to place your order, mention you saw this ad and take an
> additional 5 percent off
> any weather station price.
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