When adding an AP, you can set the antenna properties for it or import the antenna information from a file.

If you don’t already have an antenna file, you can download it from an AP vendor’s official website. For example, Ubiquiti antenna patterns are available on their website. If you cannot find an antenna file on a vendor’s website, try contacting their support.
There are also general databases with antenna pattern files that you can use, like this one or this one.
File types can have various extensions. NetSpot supports .json, .ant, .ana, .msi, .adf, and .prn.

There are resources that allow you to create your own antenna patterns; however, we do not recommend doing this due to the complexity and depth of radio engineering data involved.