[TowerTalk] Yagi Antennas

[David J. Sourdis - HK1A]

My knowledge on this relies on W2PV's "Yagi Antenna Design" book:The elements may, or not, be electrically connected to the boom by, i.e., U "muffler clamps". If the metallic clamp system separates the element from the plate, there is practically no correction for the element length. If there is direct contact with the plates, I think there was a rule of thumb correction, to avoid converting the plate dimensions to an equivalent round conductor section, lengthening the element tips by some amount related to a small percentage of the sum of the plate dimensions.
This was before antenna simulation software was available for everyone and it might have changed. If so, let me (us) know. 

David  
HK1A
EC5KXA
AE5XQ


> Date: Sun, 18 Sep 2011 13:11:04 -0700
> From: jimlux at earthlink.net
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Yagi Antennas
> 
> On 9/18/11 12:41 PM, Pete Raymond wrote:
> >       I am wondering if anyone knows of any studies done with like Yagi
> > antennas, one with elements insulated from the boom, and one with elements
> > grounded to the boom, and how their respective performances compared.
> >
> >       73 Pete N4KW
> >
> 
> There's a huge amount of work on this in the VHF/UHF world
> 
>  From a theoretical standpoint (and borne out by practical experience), 
> there's no real difference, assuming the design accounted for whether 
> the boom was insulated or not.  It's really all about the currents phase 
> and magnitude in the elements and their spacing, and for the most part, 
> you can get the same kind of things either insulated or not.
> 
> That doesn't mean the design will be identical, or that there is some 
> simple automatic conversion (e.g. add 1" for insulated elements)
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