{{tag>[hardware mikrotik rb751 wifi]}}

===== Mikrotik RB 751G-2HnD =====

====From documentation====
Wireless device RB751U includes a 2GHz 802.11b/g/n wireless device built in. It has PIF (Planar Inverted F-Shaped Antenna) type antennas (2.5dBi) built into the case, and one MMCX connector for an optional external antenna.

RB 751U has 3 built-in wireless antennas:

  * Chain0
    * one antenna for TX
    * one antenna for RX

  * Chain1
    * one antenna for TX/RX
    * MMCX connector for external antenna

To enable the external MMCX connector, set "antenna mode: antenna‐b" in RouterOS wireless settings, in the HT tab of Winbox. Note: enabling the external antenna disables the built-in Chain1 antenna.

====Default antenna setting====
  * Use both chains for TX and RX.
  * Chain0 tx and seperate antenna for rx.
  * Chain1 tx/rx antenna. <code>antenna-mode=ant-a
ht-txchains=0,1
ht-rxchains=0,1
</code>

====Antenna settings====
===All internal antenna's disabled===
  * Disables internal antenna chain1.
  * Disables tx/rx on chain0.<code>
antenna-mode=ant-b 
ht-txchains=1
ht-rxchains=1</code>

===Seperate tx & rx antenna's (chain0)===
  *Disables internal antenna chain1.
  *Enables tx/rx on chain0 (seperate antenna's).<code>antenna-mode=ant-b 
ht-txchains=0
ht-rxchains=0</code>

===Only one tx/rx antenna (chain1)===
  *Disables internal antenna's chain0.
  *Enables tx/rx on chain1.<code>antenna-mode=ant-a
ht-txchains=1
ht-rxchains=1</code>

====Transmit power settings====
Maximum radiated power in The Netherlands is 100mW / 20dBm (e.i.r.p.).

===Real vs Total tx power===
  * Real tx power = single chain power
  * Total tx power = dual chain power

Example:\\
14dBm + 14dBm = 17dBm (logarithmic)\\
25mW + 25mW = 50mW

===Configure tx power===
//Antenna gain in dBi, used to calculate maximum transmit power according to country regulations.//
  * Antenna gain: <code>antenna-gain=2</code>
  * Frequency mode: <code>frequency-mode=regulatory-domain</code>
  * Country: <code>country=netherlands</code>
  * TX power mode: <code>tx-power-mode=default</code>

===Current tx powers===
  * Show current TX powers: <code>/interface wireless> monitor wlan1 once 
                 status: running-ap
                   band: 2ghz-n
              frequency: 2472MHz
      wireless-protocol: 802.11
            noise-floor: -109dBm
         overall-tx-ccq: 40%
     registered-clients: 0
  authenticated-clients: 0
            wmm-enabled: yes
      current-tx-powers: 1Mbps:14(14/17),2Mbps:14(14/17),5.5Mbps:14(14/17),11Mbps:14(14/17),6Mbps:14(14/17),
                         9Mbps:14(14/17),12Mbps:14(14/17),18Mbps:14(14/17),24Mbps:14(14/17),36Mbps:14(14/17),
                         48Mbps:14(14/17),54Mbps:14(14/17),HT20-0:14(14/17),HT20-1:14(14/17),HT20-2:14(14/17),
                         HT20-3:14(14/17),HT20-4:14(14/17),HT20-5:14(14/17),HT20-6:14(14/17),HT20-7:14(14/17),
                         HT40-0:15(15/18),HT40-1:15(15/18),HT40-2:15(15/18),HT40-3:15(15/18),HT40-4:15(15/18),
                         HT40-5:15(15/18),HT40-6:15(15/18),HT40-7:15(15/18)
    notify-external-fdb: no</code>
====Frequency====
===Channels (Europe)===
^Channel^Frequency (MHz)^
|1|2412|
|2|2417|
|3|2422|
|4|2427|
|5|2432|
|6|2437|
|7|2442|
|8|2447|
|9|2452|
|10|2457|
|11|2462|
|12|2467|
|13|2472|

===Channel 13 / 40MHz===
  * Band: <code>band=2ghz-b/g/n</code>
  * Frequency: <code>frequency=2472</code>
  * Offset 0: <code>frequency-offset=0</code>
  * Possible widths: 10mhz, 20/40mhz-ht-above, 20/40mhz-ht-below, 20mhz, 40mhz-turbo, 5mhz<code>channel-width=20/40mhz-ht-below</code>
  * Dynamic Frequency Selection off: <code>dfs-mode=none</code>