Multiple antennae can be used, but it comes down to what system you are pairing them with. A system that has 4 female SMA ports for antennas will work with two of these directional Poynting units. The signal strength is not increased, but a cellular modem that can utilize multiple inputs will see benefits to performance. These units usually leverage multiple frequency bands simultaneously. For example a cat 18 or 20 modem can use two of these units whereas a cat 4 modem can only use one.