A:Answer ok so... The symbol is an abbreviation for "decibels relative to isotropic." Think about it like this, the higher the dbi gain the farther the antenna is set to reach and maintain best possible signal strength. But here's the thing... when operating at a higher dbi for said longer reach, you're actually going to get weaker signal strength and slower speeds from what's closer to you. And now this I'm not 100% sure on but pretty certain , the reason things closer will see poorer signal strength and speed is because the antenna is essentially set to dedicate its, "resources" so to say, to a target at a distance and therefor not focused on the things under or even within the negative side of the set range. Not sure on exact calculation, but as a reference if 18 dbi was to equal 100 ft. anything even within the 50 ft range lets say would experience poorer quality.
Now disclaimer** this is only my understanding... Not to say that someone may have a better explanation or be able to tell me why this logic is flawed or incorrect.
So It would be adjustable just for the sake of situational adjustment Id call it.
