I would like to decrease TX Power. As I read “manual” or “card rates” isn’t supported. If I add a value in Antenna gain the “Current Tx Power” changes but I don’t think it works, or it should work? Should I use all rates fixed ? But seems to be a bad idea.
Don’t use “all rates fixed” unless you really know what you are doing and have equipment (spectrum analyzer) to see the resulting signal. Reason is that more complex modulations (ie. higher MCS levels) require more linear power amplifier and as a result, it can’t be driven as much as when using simple BPSK/QPSK on low speed levels. Card knows these safe values and will limit power accordingly to not distort the signal (and essentially turn AP into jammer), this is what “card rates” mean. In this mode, when power is too high, card will limit it to safe level.
So if you want to lower the power relative to max allowed one by the card, start by using “card rates” and set it to high value (say 40.. card will clamp it down). Then in Current TX power tab you can see actual values card supports and you can adjust them down as needed. Values are in dBm, change of -6 dBm means halving of the original power.
Normally you use
Frequency mode: regulatory domain
Country: your country or region
Installation: any
Antenna gain 2
2 is the minimum (and real physical) Antenna Gain for this entries to be accepted. The power used will depend on the Country set. E.G. for Europe this is 20dBm
Subtracting the entered antenna gain, the power will be 20-2=18dBm. As there are 2 antennas the power is divided by 2 (or -3dB), or TX power is 18-3=15dBm per antenna.
If 8 dBi is filled in in the antenna gain, then the used TX power will be (20-8=) 12 dBm, and 9 dBm per antenna. The physical emitted power in the best direction will be 12+2 (real antenna gain)= 14 dBm This works as set, but as smaller client devices such as tablets but even laptops also only have 14 dBm as TX power, this will not change the usefull range of this AP. for them. The interface rate may be reduced.
The result can be seen under advanced mode in Winbox tabs for WLAN1
TX power: leave on default
Current TX power: the current TX power used. E;G. for Europe/ETSI region this will be TX power 15 dBm, Total TX power 18 dBm if antenna gain set to 2
Status: The Channel information has also the total TX power of the radio : E.G. 2437/20/gn(18dBm)
Current TX power tab info is not available on all Mikrotik devices!
TX power used is negotiated. As an AP the device annouces it’s TX power every 100mSec in the beacon. The client will use that information to minimize its own TX power.
The received power at the AP and client, and the resulting interface rates can be seen in the tab “Registration” in “Wireless”.
(You may want to add more columns or use detail view, to see all information)
