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MikroTik App
 
ludekhabarta
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tx power under 0dBm

Wed May 18, 2016 1:35 pm

Hello,

I would like to use "mANT30", but in my country (Czech Republic) the maximum EIRP in 5500-5700 MHz is about 27dBm.
According to manual there is an option to set negative power in dBm (-30 .. 30), which will effectively solve the problem (transmit power between 1um and 1W).

But, it silently does not work on a model I tried (RB922UAGS-5HPacD).
Every value under 0dBm works the same as 0dBm.
That actually prevents me from using this product or even more gain antenna with RouterBOARD.

Is there a RouterBOARD hardware with such real capability?
Where can I find a list ?
It would be nice to have such info in product description.


Regards

Ludek
 
haik01
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Re: tx power under 0dBm

Sat May 28, 2016 10:50 pm

In the wireless propertie sof the WiFi card, you can set "Antenna gain". Fill in 30 here, then Mikrotik will automatically adjust the output power to overcome the antenna gain, and so you can be compliant.
 
ludekhabarta
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Re: tx power under 0dBm

Mon Jun 13, 2016 12:19 am

That is incorrect.

Country regulations has the same limits as manual TX power.
So there is NO way to go under 0dBm except of LHG 5. According to MikroTik tech support this is the only model which is capable of reducing power under 0dBm.
 
Bomber67
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Re: tx power under 0dBm

Tue Jun 21, 2016 12:19 pm

That said, lowering TX power too much may introduce unwanted effects.
In order to stay legal on a short link with 24dBi dishes, I went for 0dB TXPwr, but the wireless performance was poor, although I were in the low 50s.
Uldis then told me that the chipsets are optimized to perform in the high end of the power scale, not at 0 or negative dBm values.
 
jarda
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Re: tx power under 0dBm

Tue Jun 21, 2016 10:11 pm

You should use low gain antenna for close distances or you can try to tilt it slightly up out of the axis to lower the gain.
 
jebz
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Re: tx power under 0dBm

Sun Jun 26, 2016 12:47 am

Hello,

I would like to use "mANT30", but in my country (Czech Republic) the maximum EIRP in 5500-5700 MHz is about 27dBm.
According to manual there is an option to set negative power in dBm (-30 .. 30), which will effectively solve the problem (transmit power between 1um and 1W).
Depending on the reason for choosing the mANT30 you could use a 6-10dB attenuation in the RF cable from the aerial to the AP. The attenuation will also reduce the receive signal but the noise will also be reduced. The very tight beam width of the mANT30 also helps with noise reduction. Do the figures, if the RX level is still > -60dBm the link should still be very good.
http://www.mikrotik.com/test_link.php
With the attenuators just reduce the antenna gain figure in the website link calculator above to get the figures.
 
ludekhabarta
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Re: tx power under 0dBm

Tue Oct 11, 2016 9:37 pm

Hello jebz,

with an attenuation unit You will loose precious dB. This is NOT acceptable option. Other radios can do that. Atheros chipset (Qualcom now) support it.
What stops Mikrotik from implementation ?


Regards

Ludek

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