2
$\begingroup$

Aaronia released this ultra-wide-range antenna, that can measure up to 35GHz. This was really impressive for only 3000 Euros, so I was considering purchasing it, when I figured I would look at the spec sheet to compare it with their previous model. And that's when I realized that, above ~23GHz, the antenna's gain is all negative!
PrintScreen of spec sheet

Does this mean that when I point the antenna toward the source of the signal, then the reading would actually decrease?

Improve this question
$\endgroup$
1
  • 1
    $\begingroup$ yes, I'd guess so – at higher frequency, the main lobe is probably just pointing somewhere else. $\endgroup$
    – Marcus Müller
    Mar 16 '19 at 10:22
4
$\begingroup$

The vertical axis is in dB, which indicates a ratio. The literature probably mentions that it's the ratio of the antenna's gain to that of an isotropic antenna, or a dipole for the frequency in question (i.e. which is 2.15dB more). So a negative dB means the gain is less than that of a dipole or isotropic antenna. As far as directionality goes, I'd say this is the gain at the boresight. Again, the literature should make this clear.

EDIT: corrected gain of dipole to 2.15dB

Improve this answer
$\endgroup$
1
  • 1
    $\begingroup$ And, more specifically, the vertical axis is the logarithm of a ratio. If the ratio is less than unity, the logarithm is less than zero, producing the negative gain in dB. $\endgroup$
    – Brian K1LI
    Mar 17 '19 at 23:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.