[TowerTalk] Cage dipole revisited.

[Roger (K8RI)]

Dan Zimmerman N3OX wrote:
> About a month ago (4 March), I posted about a newly hatched business plan of
> mine and referred to a cage dipole that sold for $350 and had 5dBd claimed
> gain.  There was possibly an implication in my post that **any such claim**
> was a **lie**, and that I had some specific knowledge that a factual
> mis-statement must be taking place if such a statement is made.
>
> I have since been contacted by an individual whose company sells an antenna
> meeting that description, and that individual assures me that the gain claim
> for his company's antenna is truthful,  based on an engineering analysis,
> and he is concerned that my implication could be harmful to his business,
> given the truthful nature of his gain claims for his company's antenna.
>
> So I feel I should apologize for any implication that those who sell cage
> dipoles with with gain over dipoles are lying. I did not intend to
> misrepresent the truth or falsehood of the claims of others.
>   
If it is truly a cage dipole then it has no gain over a regular dipole 
or 2.2 db gain over an isotropic source.
I've not seen the literature the other company has so they may not have 
a true "cage dipole". However the name "Cage Dipole" is a "common use" 
name with an established reference that goes back many years. It is 
generic to a family of dipoles made of wire, or tubing that effectively 
increases the diameter of the dipole thus lowering the Q and widening 
the bandwidth.  It has been widely shown with widely available data to 
have no gain over a regular dipole, but a wider bandwidth based on 
diameter to length ratio. 

I've also seen a Yagi design using the cage dipole principle for the 
driven element, but that is a Yagi not a cage dipole antenna.

Claims that a cage dipole has higher gain that those accepted are a bit 
more than optimistic.
As it is a well established principle/design it should not be 
patentable, but strange things do happen..


73

Roger (K8RI)
> Based on long established, daily tested antenna physics, any such antenna is
> impossible, since it would have to be around 300 percent efficient.  I
> cannot know and do not know, however, if those who claim such things are
> truthful.   I can only factually maintain that the antenna is impossible.
>
> However, do not take this retraction to mean that have given up on my
> business plan of 4 March, as I think there's still a market, and in fact, I
> am assured that I have fewer competitors than I thought.
>   

> 73
> Dan
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