I agree, Steve. My read of the advertising is that it is conveying the
notion that when the cage is substituted for a single-wire dipole at
some reasonable height the cage will increase signal strength by 5dB.
This notion is in contradiction with bedrock antenna theory.
I also agree that the cage antenna has merit even if it doesn't have the
advertised gain over a dipole. The company in question should be able
to sell plenty of these antennas even if they drop the claims about the
extraordinary gain over a dipole.
73, Mike W4EF......................
Steve Hunt wrote:
>Dan,
>
>More eloquently put than I could have - I agree entirely!
>
>The 5dBd figure can't be passed off by saying they might be referencing
>a dipole in free space. Take a look at the advertising. The 5dBd figure
>refers to "actual testing", and operators getting reports "all the time
>of 2 "s" units difference". What can that mean if it's not side-by-side
>comparisons?
>
>Like Dan I was contacted by PM by this company. I was admonished for not
>understanding what "radiation resistance" is. The advertising claims: "
>The cage antenna has 1/6th of the radiation resistance of a standard
>dipole antenna". Interesting that it should be one sixth - corresponding
>to the number of wires in the cage!! I'll leave you to judge who really
>understands "radiation resistance" and who doesn't.
>
>I'm generous enough to think that the ludicrous claims are down to
>misunderstandings rather than a deliberate attempt to mislead. It's a
>shame - a cage dipole has merit, and shouldn't need advertising "hype".
>
>Steve G3TXQ
>
>
>Dan Zimmerman N3OX wrote:
>
>
>>> Really?
>>>
>>>Do you know of a product that would allow me to mount my comparison dipole
>>>in free space for tests?
>>>
>>>To use dBd to refer specifically to a dipole in free space is misleading
>>>marketing BS.
>>>
>>>If antenna makers were interested in clear reporting of their products
>>>specifications, dBi would be the only gain number specified with respect to
>>>an ideal theoretical source. I know that it is not always used this way,
>>>but when dBd gain is published, it should express the gain over a dipole
>>>mounted at the same height over the same earth conditions.
>>>
>>>It's no fair trying to claim that dBd means "gain over a dipole in free
>>>space" The clear, misdirection free use of dBd is "gain over a dipole in
>>>the same location." That has meaning and is a useful gain measurement,
>>>because it automatically subtracts out any ground gain advantage.
>>>
>>>A dipole has zero dBd gain no matter where you install it. I know some
>>>disagree with that, but it doesn't make one bit of sense to use it at ALL
>>>otherwise.
>>>
>>>You want to refer to the gain including ground gain of some installation,
>>>use dBi.
>>>
>>>73
>>>Dan
>>>_______________________________________________
>>>
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>>>
>>>
>>>
>>>
>
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