For the best possible cellular network connectivity, a dedicated antenna will deliver the best performance from whatever the signal quality is in your area. People are used to using their phones or a dedicated hotspot device but either one is less than optimum. The size of an antenna in your phone or hotspot device are about the size of a dime, or even smaller!
In the old days of broadcast television, people were accustomed to having an antenna on their roof or chimney. Our cellular antennas are smaller than those but work off the same idea. A bigger receiver area, put up high, and ideally pointing at the signal source worked for broadcast television and it works for cellular signal reception as well, only the antenna type has changed.
Same thing for your mobile internet reception. I roof mounted antenna will increase you signal strength and quality. In a vehicle deployment, they closely resemble a sharkfin style FM antenna that most cars currently have from the factory, only cellular ones are wider since they have 5 on more antennas inside.
Why 5 antennas? To fully exploit the speed of 4G LTE, they MUST support 2 x 2 MIMO. This means 2 each for Media In, Media Out. MIMO, get it? The fifth one is for GPS. Having a dedicated GPS antenna on the roof, looking for satellites without the metal frame of the car to interfere will improve GPS performance as well!
Our marine antennas provide 2 x 2 MIMO and enhanced GPS, but are housed in a more robust weatherized housing to better resist the harsh conditions of a marine environment.