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Re: [TowerTalk] 2 el yagi question

Subject: Re: [TowerTalk] 2 el yagi question
From: David Gilbert <>
Date: Fri, 18 May 2012 12:09:10 -0700
List-post: <">>
I'd add the Force 12 and Optibeam shorty-40's to that list ... probably 
others I'm forgetting at the moment.

The only modern driven/director 2-element yagi I can think of off the 
top of my head is the SteppIR 2-element, and it has the advantage of 
tunable elements.

Dave   AB7E

On 5/18/2012 11:22 AM, W2RU - Bud Hippisley wrote:
> Interestingly, virtually all of the 2-element commercial HF Yagis I've seen 
> successfully designed and marketed by manufacturers during my time as a ham 
> have been of the Reflector + DE variety.   On just 40 meters, for instance, 
> Mosley, Hy-Gain, Cushcraft, M2, and Wilson all come to mind.
> Q:  Why do you think that might be?
> A:  Dave has hit on most of the reasons below.  It's certainly not because 
> the manufacturers prefer to have their beams weigh more or cost more due to 
> the greater length of a typical reflector.
> Bud, W2RU
> On May 18, 2012, at 1:26 PM, David Gilbert wrote:
>>  From what I understand of the theory, a director is capable of slightly
>> (on the order of a tenth of a db) higher gain, but the tuning (spacing
>> and director length) is considerably more critical in order to achieve
>> that.  I'd have to check, but it might even be that case that in order
>> to get it optimized you'd need to adjust the driven element length as
>> well.  A reflector, on the other hand, gives its best gain at wider
>> spacing and generally has a broader SWR curve, and also results in a
>> higher feedpont impedance for the driven element.  I have no doubt that
>> the combination of those effects could make a reflector give higher gain
>> in practice.
>> Unless space (or boom length on a yagi) is absolutely critical, I'd vote
>> for the reflector.
>> 73,
>> Dave   AB7E
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