Does 10BaseT cable need terminators

Every transmission line requires termination, either in the form of the ultimate load, such as an antenna, or in the form of some kind of resistor. 10BaseT is no different.

However, that termination is usually built in to the device in which the cable is plugged. This is different from older systems, such as ArcNet, where the coax cable requires termination on each of the far ends. This is because the 10BaseT system is a star system rather than a partial ring system, so the termination is not a function of the chosen topology.

The reason termination is required in a transmission line is that every step change in characteristic impedance encountered by the wave front as it propagates through the line results in some kind of reflection back towards the source. These reflections result in distortion, loss of power, even damage to the transmitter or circuit.

To reinforce this understanding, consider the 75 Ohm coax cable typically used in a television distribution system. In the simplest case, you connect a cable from the service entrance to the TV set, and you are properly terminated. If, however, you use a splitter, such as for a TV set and a VCR, you now have three transmission lines, one to the splitter and two from the splitter. Is the RF output of the VCR connected to something? It should be, either to a TV set or to a terminator, otherwise there will be problems due to ringing, interference, ghosting, etc.