To understand what is happening in WiFi you first need to know that WiFi antennas and receivers have the same basic concepts as the AM/FM radio in your car. Inside your laptop there is a WiFi “radio” which is tuned to the 2.4GHz frequency in which WiFi works on. Much like how you can tune your car stereo to a certain frequency, except that it stays on one frequency the whole time.
The WiFi radio in your computer is a weak one. Only receiving with a power of about 40mW (milliwatts) ~ 100mW and since the power of the internal radio is so low, the range will be limited. In order to increase the range of your WiFi reception you need to purchase an external WiFi radio, most commonly called a USB adapter since it plugs into your USB port on the computer. These operate on more power ranging from 160mW to 2000mW or 2 watt. More power = more reception coverage.
Now that you have setup your USB adapter and you’re able to receive signals, antennas can be used to increase your coverage with the ability to focus the power coming from the radio. All WiFi antennas have a dBi (decibel isotropic) rating and the higher the rating the further your WiFi signal will travel. Important to know is that there are two kinds of antennas, each category named after the radiation pattern (reception cone) which it uses.
Omni directional Antenna- Which takes the power coming from the radio and makes a reception cone of 360 degrees. Looking in all directions for WiFi signals.
|Able to find signals in all directions||Distance covered is low|
|High area coverage||Wasted receiving power when known signal is located|
|Easier to find signals, no pointing needed.|
Directional Antenna - Focus the radio’s coverage power in one direction with cones in varying degrees of width.
|Distance covered is high||Narrow reception core|
|Once signal is found, better signal strength||Harder to find signals|
When choosing which antenna is best for you think of how far your signal is and what application is best for you. Each type of antenna has its own pros and cons.