Hello,
I'm looking for an antenna like mAnt30PA to use all 3 chains of the Net Metal 5 MikroTik Routerboard NetMETAL 5 (RB921UAGS-5HPacT-NM)

Are there any antennas from Mikrotik?

Has anybody experience which speed is possible with best conditions?

Thanks for your help.

I cannot find any antenna with 3 connectors.
Or is it the same like Ubiquiti, where you use the 3rd connector for the gps antenna?

No, the antenna needs 3 connectors. It's not very popular (yet)

http://itelite.net/antennas/206/

I had to buy some adapters off of eBay to adapt the cable to the NM.

I'll try to dig up some photos when I get a chance.

Hello,

This Antennas has 3 slots fot this devices.

https://www.ispsupplies.com/RF-Elements-SEC-CC-5-16-HHV

What´s main difference between this model and the dual chain? it´s for GPS, for more througput? whats the purpose?

It's for more throughput ... effectively it's got 3 antennae built in, one vertical and two horizontal. AP device with 3 TX/RX chains is needed to take full advantage. It's not completely necessary that the other end is triple-chain as well, the link can benefit by employing Tx and Rx diversity on one end only.

GPS utilizes 1.57GHz (and 1.2GHz), GLONASS utilizes 1.6GHz, Gallileo 1.6GHz (and 1.2GHz), BeiDou as well ... None can be effectively received using antenna for WiFi (either 2.4GHz or 5GHz).