LTE CAT-M Antenna Evaluation

I am looking for a suitable cellular antenna for the Digi XBee3 LTE-M/NB-IoT modem. My application will use the LTE CAT-M1 network only. I need to choose the proper antenna and mounting location for the antenna, however, I am not looking to design an antenna. Can someone please tell me how to evaluate an antenna? The only signal related information I can get from LTE-M modem is the RSSI reading. My instinct tells me looking at the RSSI wouldn’t be adequate (I am not a RF engineer). What electronic equipment will I need to evaluate LTE CAT-M1 antenna then? Thanks.

We give the following Guidnace:

The gain of the system antenna (i.e. the combined transmission line, connector, cable losses and radiating element gain) must not exceed the values below for mobile and fixed or mobile operating configurations:

3.67 dBi in 700 MHz, i.e. LTE FDD-12 band
4.10 dBi in 850 MHz, i.e. LTE FDD-5 band
6.74 dBi in 1700 MHz, i.e. LTE FDD-4 band
7.12 dBi in 1900 MHz, i.e. LTE FDD-2 band

Reference in user guide:|_____1

So to answer the question, any (not mono-pole) LTE antenna that has peak gain less than the above specifications for the bands used would be fine. Note, the XBee Cellular only has u.fl connectors.