WIFI ANTENNA BASICS
If you landed here first without reading theGET STARTED FAQ, go back and do that. You will get confused unless you understand the core principles regarding WiFi systems.
The right antenna for the job depends on what function you need it to perform. Not all antennas are made equal. Aside from difference in performance from different manufacturers, antennas are divided into 2 different parameters. Omnidirectional and Directional.
Simple. An omnidirectional antenna acts just like a lightbulb. While a directional antenna acts in the same way a flashlight does. Omni sends signal in all directions while directional antennas send signal where you point.
The dBi rating tells you a lot about how far that signal will travel. The higher the dBi, the further distance the signal will travel. The antenna manipulates (not increase) the signal to act a certain way. Which way depends on the antenna.
The WiFi signal coming from the antenna is only changed based on the design. More power is done by increasing the radio strength. For example, when a directional antenna dBi rating gets higher its focusing the signal beam into a more narrow path. By narrowing the path in which signal it let out, it allows for more range to be achieved. The trade off is less area is covered by that signal.
Omnidirectional antennas send/receive signals in a 360 degree disk around the antenna. Directional antennas send/receive signal from the area in which you point the antenna. For more distance or when working with a known signal location, use a directional antenna. To send/receive from all directions use omnidirectional antenna. A typical use for this would be when creating a hotspot.
Both. While a WiFi signal consist of both information being sent and received by both parties, it's important to know that the antenna acts to IMPROVE the chances of success of the radio its connected. Whether it be a router (sending out signal) or USB adapter (receiving signal) it will only improve the transmitting or receiving chances of the radio.
The answer depends on how directional you need the antenna to be. Some may think to be as directional as possible but its important to remember that you may have a tougher time finding the signal as well as lose it easier after installation. This is due to how narrow the beam is on antenna's like the Grid.
Out of a 360 degree pie, the Grid is at 7 degree, the Yagi is 36 degrees and the Panel is 34 degrees.