Televes DAT aerial - a hoax?
Matti Kaki
look a little bit odd to me. I can't find out how this aerial really
works with three booms. Or are they just for looks? All the tiny
passive elements of these booms look equal length and they have
equal spaces. So if I took those three booms off, is the aerial
still the same? How can these equal length passive elements do
any good for antenna? Are these two aerials equal?
http://www.mattikaki.fi/antennit/DAT.jpg
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Matti Kaki at iki dot fi http://www.sci.fi/~oh2bio
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Dave Farrance
>I noticed that handsome and popular aerial Televes DAT-45 and DAT-75
>look a little bit odd to me. I can't find out how this aerial really
>works with three booms. Or are they just for looks? All the tiny
>passive elements of these booms look equal length and they have
>equal spaces. So if I took those three booms off, is the aerial
>still the same? How can these equal length passive elements do
>any good for antenna? Are these two aerials equal?
>
> http://www.mattikaki.fi/antennit/DAT.jpg
No, it's not a hoax, and the tri-boom directors work reasonably well, but
I think not well enough to justify the overall size and weight. Have a
look at these graphs in which the smaller of the tri-boom aerials is
compared with the more common straight-element and X-element yagis.
According to the text there, the DAT-75 is about the same as the DAT-45
at the lowest frequency, and is about 2dB better at highest frequency:
http://www.aerialsandtv.com/atvstockaerialtests.html#Widebands
The plots show that it's outperformed by this modest aerial:
http://www.aerialsandtv.com/atvschoiceofaerials.html#pic_287
And well outperformed (except at the very lowest frequencies) by the gain
of this large aerial, which is still less impacting on the landscape.
http://www.aerialsandtv.com/atvschoiceofaerials.html#XB16
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Dave Farrance