LB2120 Modem external antennas.

[Barreller]

• Connector for an external antenna. One switched RF connector for an optional external antenna (the external antenna requires two inputs)

Does anybody know what this means in the user manual?

[JasBro]

The unit uses a MIMO antenna array. You can query the Internet to learn a lot more about this. Basically there are two radio waves being used for communications back and forth between your LB2120 and the LTE Tower. They are broadcast at 90° angles to each other (think tilted 45° to the right for one and 45° to the left for the other). External antennas are needed for both the channels to reach optimum connection speeds. Hope that hleps. 

[Barreller]

Thanks JasBro,  That does help.  It doesn't really explain the wording in the manual regarding switching, but I note that a MiMo antenna is really needed.  I have one and will try it sometime.