I suppose sticking with the hub word, the wheel analogy is as good as any so as the spokes radiate outwards from the hub, the switches could go on the end of as many spokes as you wish to extend the network further.
As to antennae, if you have one which can be disconnected (some are built-in) then it can be replaced by a higher gain alternative. Sometimes, though, it's more effective to add in an access point (AP), more effectively to extend the range.
The difference between a switch and a hub I learned was that a hub will send all traffic out of every port, a switch will send traffic down only the designated port based on layer-2 information (mac address). So you have a hub that sends information everywhere it can possibly send it, and a switch that sends it only down a specific port.