The sometimes excellent 4G mobile internet coverage in the Algarve may leave a number of people satisfied with their internet speed and may find the additional expense of a 3G or 4G antenna unnecessary.
We'll try and keep this in plain English!
Channel-Dependent Scheduling (AKA Whoever has the best signal gets the most data)
So the first concept is all mobile internet devices (including smartphones, mobile internet routers and USB dongle) in a certain area continuously connect to the cell base station to tell it how good the signal is between them. Using this information from all devices in the area the base station decides how much internet data each device gets - the devices with the best connections get the MOST data. In a situation where there are a large number of devices (think Algarve summer time with all those iPhones!), a normally fast 3G or 4G internet link will easily suffer unless you are at the "top of the tree" in the connected device list. Here a mobile internet 4G antenna will improve your signal strength and reliability considerably which will benefit your internet speed during the busiest times of the year.
Fig 1.1 Keep your 4G internet as fast as possible in the urban Algarve or in the busy summer tourist season.
Beamforming (AKA Directing more signal to YOU meaning faster, more reliable 4G internet)
The mobile cell base station, rather than sending signal out in any and all directions, is able to "lock onto" devices and focuses power in the direction of devices - this improves operating range and allows multiple 4G devices to use the network. Again, with an antenna you'll have more capacity to receive more data, therefore the cell base station will be able to send more data in your direction giving you faster internet vs other devices in your area.
Fig 1.2 With a 3G or 4G antenna in the Algarve you will be able to get faster internet than users without an antenna in a similar location, especially important in more developed areas with lots of mobile internet users.