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Understanding antenna patterns

Hi guys,

 

Just to clear up, I would like to know how to interpret the following elevation plane (from AP-315):

elev.png

What are the units of the vertical axis? dB? If so, for 180º is almost -10, does that mean that just below the AP the antenna has negative gain?

 

Regards,

Julián

Aruba

Re: Understanding antenna patterns

Antenna gain is typically expressied in dBi (gain relative to an isotropical radiator which emits energy equally in all directions in 3D).

-10dBi means that the EIRP level in that direction is 10dB lower than with an isotropical radiator, and probably about 15dB lower than the level in the direction of maximum/peak gain.

That implies that the range in that direction is reduced. 15dB signal reduction translates to roughly 6x range reduction using the (theoretical) open space pathloss model. Obviously that is typically not an issue when directly under the AP.

/Onno

Re: Understanding antenna patterns

Hi Onno,

So, the vertical axis is dBi.

-10dBi means that the EIRP level in that direction is 10dB lower than with an isotropical radiator

That's OK.

and probably about 15dB lower than the level in the direction of maximum/peak gain

Why do you say 15 dB lower than the maximum/peak gain? Why do you take the number of 15? In the specs I see this AP-315 has a maximum peak gain of 3.6 dBi in 2.4 GHz, so it would be 13.6 dB lower than the maximum/peak gain. Are you rounding the value?

Regards,
Julián
Highlighted
Aruba

Re: Understanding antenna patterns

Yes, I was rounding. Same for the -10dB

/Onno

Re: Understanding antenna patterns

Ah ok, it makes sense!

Regards,
Julián
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