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I want to represent this value in a better way for my report. This value is 3.1x10^-4 the unit is dBi

Can I rather represent this value using this: 310 udBi

The u in udBi is micro dBi

JoeyB
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    Are you saying that the gain of your antenna is barely higher than the gain of an isotropic antenna ($3.1 \cdot 10^{-4}\mathrm{dBi}$ means a gain of 1.00071), or do you mean that your antenna gain is $3.1 \cdot 10^{-4}$ compared to an isotropic antenna (-35dBi). – TimWescott Jun 29 '19 at 19:26
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    I thought using the logarithmic scale of dB is supposed to do away with the need for scientific notation like that. – DKNguyen Jun 29 '19 at 19:32
  • It’s an XY problem, so I gave the Y answer (right?) – Tony Stewart EE75 Jun 29 '19 at 20:51
  • In most contexts it would be good enough to just say "0 dBi". – The Photon Jun 29 '19 at 20:54
  • @DKNguyen -- if you say "dB<something>" it means dB relative to that something. So -174dBm is 174dB down from 1mW (and, incidentally, the thermal power per Hz that you can extract from a resistor at room temperature) – TimWescott Jun 29 '19 at 20:57
  • I do apologize to everyone who took thier time to answer. But after investigation on the value from where I calculated it from I realised its not in dB/dBi but is unit less and needs to be converted to dB . Sorry for this careless mistake guys. – JoeyB Jun 29 '19 at 22:21
  • @TimWescott Not sure what your response has to do with my comment. dB anything is still always relative to something, it's still logarithmic, and you still use it so you don't have to go 10^x – DKNguyen Jun 30 '19 at 18:39

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I've never seen that notation but it's not good SI practice.

Leaving out the 'i' for the moment, the 'd' in dB is the deci (x 0.1) SI prefix. Your 3.1 × 10-4 dB is 3.1 × 10-5 B (bel) so I would think that the correct way would be 31 μB.

I can't find anything to back this up!

Transistor
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    The dB<something> means "decibels relative to ". dBV means dB relative to one V. dBW means dB relative to a Watt. Everyone uses dB. No one uses mB or $\mu$B. When in Rome... – TimWescott Jun 29 '19 at 20:53
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3.1x10^-4 the unit is dBi = -340 dBi which implies an antenna that doesn’t work (effectively null) relative to an isotopic antenna =0dBi.

In doing Friis Loss budget , one uses dBm for the Tx, Rx signals and dBi for the antennae like 3dBi and not the Rx level in dBi.

In any case -340 dB loss or even dBm means you need to reduce the distance as most Rx’s only have a dynamic range <<100 dB with a threshold that depends on BW , bit rate, matched filters, ambient noise, Rician Fading loss, Rayleigh Fading loss etc.

Tony Stewart EE75
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