When choosing a mobile phone antenna, you should consider the following factors:
There are many different kinds of antennas such as directional and omni directional antennas. Directional antennas are best for long-range communication while omni directional antennas are best for short-range communication.
Antennas are rated in dBi; the higher the rating the higher the signal strength the antenna will achieve.
An antenna needs to be connected to the device to receive the increased signal and it can be connected to devices in different ways depending on the device used.