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Application of higher harmonics generation mode in a compact low-voltage vircator-type vacuum electronic device utilizing nonlaminar electron beams operating in millimeter band is considered and preliminary experimental results are reported. Higher harmonics generation was achieved by formation of translaminar electron layer through the choice of the optimal voltages for the control electrode and electron beam inhibition by the electrostatic field of the collector. This approach allowed for dense electron grouping in nonlaminar electron beams that provided the growth of the amplitude of the higher harmonics in the output power spectrum. In this system, the increase of the fundamental operating frequency by application of external magnetic field was experimentally demonstrated. If combined with higher harmonics generation mode, this can lead to significant increase of resulting operating frequency of the compact low-voltage system to millimeter wavelength band.

The results of fabrication and cold-test study of the slow-wave interaction structure for the V-band backward-wave oscillator with a pseudospark-sourced sheet electron beam are presented. The proposed interaction structure is comprised of a truncated sine waveguide with wideband-matched output couplers. The slow-wave structure is designed, simulated, and fabricated by CNC-micro milling. The results of characterization of the microfabricated SWS sample by the scanning electron microscopy and stylus profilometry technique are presented. Preliminary results of experimental studies of electromagnetic parameters and their comparison with the numerical simulation are presented. The electron gun providing a high-current-density pseudospark sheet electron beam is also developed.

Results of experimental study of the reflection and transmission losses in the V-band of µm-thick Si-Al films on the dielectric substrates are considered. Two sources magnetron co-sputtering deposition of Si-Al alloys was utilized to prepare a series of coatings of varied chemical composition and thus different properties. Control over films composition was provided by variation of Al magnetron power source with constant Si magnetron power source. Segregation of Si and Al atoms in Al-Si films was observed at a specific power of Al magnetron source during the deposition: Si atoms were mainly concentrated at the lower levels of the film adjacent to the substrate, while Al atoms tended to concentrate near the upper surface of the coating. Distinct electromagnetic properties of Al-Si films fabricated at the transient phase of segregation mode were observed: one side of the film demonstrated low reflection in the millimeter-band while almost full reflection was observed from the other side. Such properties of µm-thick Si-Al films upon dielectric substrates can be useful for development of millimeter-wave antenna modules technology.