Repeaters and Hubs
A repeater. Repeaters work only on layer 1 (Physical) of the OSI model.
hub
multiplexer is a device that add two or more signal in a single signal in networking
A 50 Ohm Terminator is used at each end of the network to prevent signal reflections.
The network device that regenerates data signals without segmenting the network is a repeater. Repeaters are used to prevent attenuation of signals.
a passive hub does not regenerate the signal received only let it pass
Hub
A Hub is the only network device for this type of job. Since a router stops broadcasts, it segments a network in a way. On the other hand, a switch does forward broadcasts but it creates segments because each switch port can be a network on their own.
Topology
If you are referring to radio transmissions as your form of communication then it's a device that improves or boosts an incoming signal so the receiver can hear what is being said or transmitted.
Transceiver
Signal strength diminishes over distance. A repeater boosts signal strength and passes it on.