Re(2): [Antennas] quagi vs yagi at vhf

[DavidE Benedict]

But with a wood boom don't the antenna characteristics change when it
rains & soaks the wood?

David
W7DBH
Mobile in Oregon


>
>However, it is important to note that the original quagi design by Wayne
>Overbeck is for a wooden boom with the elements passing through the boom.
>Tests have shown that the performance and charactersitics of the quagi is
>affected a lot when the boom material is changed to metal.  The element
>lengths and spacing have to be recalculated to achive the same results as
>the wooden boom quagi and I have not seen a metal boom quagi which rivals
>the original wooden boom.
>
>Deon ZS1ZL
>
>----- Original Message ----- 
>From: "Bob Stein" <hamstuff at sbcglobal.net>
>To: "G B" <microsys at alltel.net>
>Cc: "Antennas" <antennas at mailman.qth.net>
>Sent: Thursday, November 30, 2006 12:42 AM
>Subject: Re: [Antennas] quagi vs yagi at vhf
>
>
>For a given boom length, there should be no appreciable difference in gain
>between a Yagi and quagi.  Gain is a function of boom length, and has
>nothing
>to do with the driven element if both designs are optimized.  There may be
>slight differences in the side lobes, but I can't really say.
>
>Bob, w6nbi
>
>
>G B wrote:
>> Hello,
>>
>> I have been searching the internet for a study on long boom vhf quagis
>> when
>> compared
>> to long boom yagis.  I could not find anything.
>>
>> One of the EU guys who is famous for vhf yagis told me he did not think
>> loops worked
>> very well.  That is contrary to my experience, but, mainly, I find
>quagis
>> easy to
>> construct and they are inexpensive.  I have compared the 8 element quagi
>> here to two
>> different colinear verticals which claim to have 6dbd and 8dbd
>> respectively,
>> which are
>> located well above the quagi.  The quagi is at least one, and many times
>> two
>> S units
>> better.
>>
>> Anyway, I am considering building a twenty foot boom yagi using a T
>match
>> and insulated
>> elements for sideband.
>>
>> I would sure like to see hard evidence on a test range.
>>
>> As a side query, I know I can find those stainless keepers for the 3/16"
>> elements on a couple
>> websites, but:  Where do they get them from?
>>
>> As an example, the 'insulators' they sell for the elements go for $0.20
>to
>> $0.35 each.  They are
>> just shoulder washers, and I found some for $0.01 each.  So, I figured
>> these
>> keepers have an
>> official industry name, but cannot find one.  I am expecting that
>several
>> of
>> our local club
>> members are going to build some of these antennas, and we will need some
>> quantity.
>>
>> Thanks for listening...
>> 73
>>
>> Glen K4KV
>>
>>
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>
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