Radar and satellite systems still use traveling-wave tubes in the RF signal chain.  The reference to tubes could also be the radar displays, which were traditionally vector CRTs.  <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Traveling-wave_tube" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Traveling-wave_tube</a>