Want guidance for choose best UART or USART RF module for Arduino

[Hamid Zajkani]

hello every body , I want to create a Star or Mesh network with arduino like image below :
the distance node between master is about 2 km.
I want to create full duplex communication , send sensor information from nodes to master node , that master node reply to each one.
witch kind of RF module is best for my solution ?
my RF module must be UART or USART , Cause of I cant use SPI Protocol , because I use SD card that use SPI Protocol.

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[Arouse1973]

You first need to tell us the ISM bands in your country. In know 2.4 GHz is a global band but I think you will struggle to get 2 Km with the currently available modules out there, I might be wrong though.
Adam

 

[Hamid Zajkani]

You first need to tell us the ISM bands in your country. In know 2.4 GHz is a global band but I think you will struggle to get 2 Km with the currently available modules out there, I might be wrong though.
Adam

like global ISM