My understanding is that the value of the axis (like -10 / 0 dB) refers to the maximum antenna gain (e.g. 12dbi).

So, if a point on the figure is -5dB, then antenna gain of that point is

12 - 5 = 7 dBi.

Is this correct?

The axes in the figure are in degrees and dB.



1 Answer 1


In your example, the outer ring in the polar plot would be 12 dBi. So you are correct in thinking that any point -5 dB from the outer ring would represent a gain of 7 dBi.

It works the same for referencing dB, dBi (isotropic), and dBd (dipole).

  • $\begingroup$ More detailed information about pattern plots can be found here. $\endgroup$ Jul 22, 2019 at 19:45
  • $\begingroup$ Also, since Mike mentions dBi and dBd, remember that 0dBd = 2.15dBi. So if you see one, and need to convert to the other, that's all you need to note. $\endgroup$
    – Scott Earle
    Jul 23, 2019 at 6:59
  • $\begingroup$ Thank you so much !! haha !! first time I did not notice the db in the figure $\endgroup$
    – vvv
    Jul 26, 2019 at 5:21

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