Generally, the recommended solution for extending the coverage range is to add more Ruckus access points. If it's not practical to run Ethernet out that far, you can consider using "SmartMesh" to wirelessly extend and repeat your network.
I would strongly recommend using one of the above solutions instead of looking at the various solutions on the market for wifi extenders / repeaters.
However, be aware that extending a wifi network via wifi (e.g. SmartMesh or third party wifi extenders) trades off total capacity in favor of range, which may or may not suffice for your purposes. SmartMesh supports the notion of a hybrid "eMAP" (ethernet connected mesh AP) where two Ruckus AP's may be connected back-to-back via ethernet, such that one acts as the mesh uplink while the other can serve clients on a new channel (hence with new bandwidth). With that said, I've found the use of Ruckus SmartMesh to be superior in performance/range/reliability compared to any previous wifi extending / repeating solution I've tried. So I highly recommend sticking with Ruckus if you elect to go the wireless route.
So, is adding another AP via ethernet feasible, or do you need a wireless extending solution? What are your bandwidth / capacity requirements? Can your network cope with losing approximately half of its maximum speed due to mesh uplink overhead?