[Antennas] quagi vs yagi at vhf

Thu Nov 30 02:07:01 EST 2006

Glen
I agree with the comments by Bob W6NBI.
I have always favoured the quagi for its ease of construction, simple
matching and a lof of bang for your buck.
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ドル.20 to
> 0ドル.35 each. They are
> just shoulder washers, and I found some for 0ドル.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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