Huawei E3131 USB Surf Stick

We have not the technical idea in the things, but I can say something about it.
We had a supposedly no bad stick of favorable provider (supplier D1), but had no socket for an additional antenna and in the spa clinic on the outskirts of the transmission tower, where all had poor reception (on the North). After much back and forth I decided this Huawei E3131 (the there was quite cheap) to buy and even bought an antenna equal to.

So the Surfstick surpasses the provider by a mile, have the same antenna without fairly good reception with fast Internet connection, but this and the connected antenna is qualitatively very deteriorated.
Thus, the part is in my eyes a Prima Stick, who made a very good impression without additional antenna, but how and for what is the antenna connector (antenna) then needed I do not know.
I hope I could help you something ;-))

Greeting

Kurt