DirectConnect Cellular Amplifier
Improving the cellular signal to a cellular data card can increase transmission speeds. If you just need a little help, attaching an external antenna to the data card’s RF port is usually enough. In areas where the signal is very weak, adding a directconnect or repeater type amplifier will usually do the job.
Amplifier Warning
Be aware that most data cards have amplifiers built into them (usually 1 or 2 watts). Many times adding another amplifier will not improve performance. In fact, if you’re in an area where the signal is not so bad, adding a directconnect or repeater amplifier may actually degrade the performance of data transmission. In these situations, using just an external antenna directly connected to the data card is best.
More Info on Mobile Internet Signal Improvement