[dogma1138]

RF is a bit more complicated than that, you have also a specific gain on an antenna. https://en.wikipedia.org/wiki/Antenna_gain

The gain on the antenna doesn't create "energy" but it tells you how efficient an antenna is and what its RF characteristics would be, in general a high gain antenna is a directional one it would send a more focused transmission and would attenuate better to a receiving transmission from a certain direction only, a low gain antenna would have a more uniform RF profile (doughnut/spherical).

High gain antennas are usually used for point to point applications so MW transmitters, P2P Wifi Links, TV/Satellite etc. while low gain antennas are used in devices where the transmission can come from any direction like for example GPS receivers, cell phones and handheld radios.

For Wifi for most applications you would want a low gain antenna on your routers/AP's as they would give you uniform coverage, people often buy high gain antennas without understanding what it means, it's great if you want to line of sight 2 AP's across long distances but unless you also want to line of sight your XBOX it wouldn't have any positive impact on your wifi reception at home.