There is provided an electronic amplification apparatus (40) comprising a travelling wave tube amplifier (20) and a limiter (10), wherein the configuration of the amplifier (20) is optimised whilst maintaining signal linearity for operation with improved DC power efficiency at an operating point below saturation, and the limiter (10) is arranged to prevent the output power of the amplifier from going beyond a predetermined limit. This can prevent possible damage. There is also provided a multiport amplifier system (50) containing the electronic amplification apparatus (40), and a multi-feed, multi-amplifier phased array type antenna system (130) containing the electronic amplification apparatus (40), and a satellite communications system comprising the electronic amplification apparatus (40) or the multiport amplifier system (50) or the multi-feed, multi-amplifier phased array type antenna system (130).