@TeslaFan
Hey
The EAP225 Outdoors uses the standard 5db omni directional antenna, therefore anything with a RP SMA connector should work for a replacement.
In terms of "better coverage", this is a compromise and a larger antenna wont always help.. if you are going for a bigger antenna look for a 5db or 7db omni directional antenna (similar to what you have, just bigger), the antenna supplied with the AP are 3db omni
Bear in mind however that more gain on the antenna will reduce the height of the coverage, this can in fact reduce the signal strength at close range! Personally, 5 to 7db is the sweet spot imho
For example below.. if you are in the yellow spot, you will get a greatly reduced signal with a 9db antenna vs a 3 or 5db
