First high power results from the 57.12 GHz 5th harmonic frequency multiplier

Traditional linear interaction RF sources (klystrons and traveling wave tubes) provide limited amounts of power at the mm-wave and terahertz part of the spectrum because their critical dimensions have to be small compared to the wavelength they operate. Due to these small dimensions, the amount of current that can go through the beam apertures is limited. We designed, built and hot-tested a new gyrocon-like mm-wave source, with an output interaction circuit based on a spherical sector cavity. This spherical sector cavity provides a large beam aperture, allowing for a significant amount of current to go through. This source operates as a 5
^th
harmonic frequency multiplier, with an output frequency of 57.12 GHz. The measured peak output power was 54.26 W at the 5
^th
harmonic, while power at the other harmonics was at least 33.28 dB lower than the 5
^th
harmonic.