Was hoping someone else recognized the equipment you linked so I delayed responding.
The engenius is a indoor access point not a antenna but it seems that you may actually have antenna attach to this since the terms you use related to direction antenna are correctly used.
If you have outdoor antenna attached to this you can pretty much use any AP that has the ability to have replicable antenna and has PoE (power over ethernet) Not 100% sure you need the PoE. The tricky part is there are 3 common types of connectors used on wireless antenna and a number of not so common ones. You can get converters. I will leave it to you to google this since you need to look at photos to learn the difference.
The key to making what you want work is to use outdoor directional antenna. This gets extremely complex since you get signal gain from the antenna but then signal loss from your cables. In many cases the cables that a normal person can afford will lose more signal that you gain with the antenna even at fairly short distances. The simplest solution to this is to buy AP rated for outdoor use and mount them directly to the antenna without any microwave cable. You would then connect them back using normal ethernet cable which does not have the signal loss issue.
Although this site sells mostly commercial grade stuff it is a good site to browse around on to see what is available. There are more consumer friendly models made by hawking technology but they have very limited options. http://www.wlanparts.com/
Greetings,

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