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Q on dBi, dBd & dB(nothing) vendor data?

Nov 20th 2014, 20:31


Joined: Jul 7th 2012, 16:27
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Total Posts: 0
When vendors (or even authors of some technical papers) report Antenna Gain with no relative reference to "i"-isotropic (dBi) or "d"-dipole (dBd), and therefore report the gain as simply a certain amount of dB, e.g., 3dB, should one assume that it means the same as dBi? I know that Antenna Gain is always a number that is relative to "something," and yet, as I have said, I see Antenna Gain from time to time reported with no reference to "i" or "d." Many thanks - Fred K4XXK.
Nov 21st 2014, 14:55


Super Moderator

Joined: Apr 4th 1998, 00:00
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Total Posts: 0

You should not assume anything with regard to antenna gain figures. It is extremely easy to produce misleading gain figures, which is why they aren't allowed in QST unless backed up by computer modeling.

In January, 1998, the ARRL Board of Directors changed the ARRL advertisement-acceptance policy to permit the advertising of antenna gain figures for antennas whose performance can be accurately modeled using either NEC-4 or Yagi Optimizer modeling programs. To do this, advertisers submit their antenna models for verification by the ARRL Laboratory staff. If the Lab is able to verify that the model accurately represents the design of the antenna, the advertiser may then advertise the antenna gain figures in ARRL publications.

Zack Lau W1VT
ARRL Senior Lab Engineer

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