vacuum electronic devices, namely, backward wave oscillators and traveling wave tubes; componentes of vacuum electronic devices, namely, cathodes, electron guns, slow wave structures, electron collectors, magnets, magnetic circuits, and vacuum envelopes; millimeter wave electronic systems, consisting primarily of signal sources, amplifiers, detectors, modulators, demodulators, power supplies, phase shifters, and attenuators for wireless communications; and terahertz electronic systems, consis...