Hello @Hootan_Rastkar,
We look at the shipped antennas as being there primarily for initial testing of the router and normally replace them with purpose antennas that are fitted to the clients installation as necessary.
In Australia we’d source most of our antennas from Telco Antennas in Queensland. A suitable antennas that has everything built in for the MAX range (based on just one LTE modem) is the MA450.K.LBICG.003
You can read more on the antennas specifications via this URL:
They ship internationally, and your own local suppliers should be able to help you source these also.
Happy to Help,
Marcus 