For example: Agilent E4440A or Anritsu 68369

Attenuators

Electronic Step and fixed Attenuator for RF Equipment

Manufacturers: Keysight / Agilent, Narda, Aeroflex - Weinschel, Bird Electronics, Rohde and Schwarz, Trilithic, Texscan - Trilithic, Weinschel TEGAM, Aeroflex IFR, Tektronix