The potential of this SWS is that it provides higher interaction impedance and has low phase velocity thus, higher output power can be expected at a lower beam voltage. As the next step, we are going to study S-parameters of microfabricated D-band microstrip meander-line slow wave structure samples experimentally by using vector network analyzer with D-band frequency converters.Ī novel slow wave structure (SWS), called the chevron-shaped double-staggered grating waveguide structure, is proposed for traveling wave tube (TWT) amplifier for the terahertz (THz) region. It was shown that each considered CNC precision laser machine allows fabricating D-band microstrip meander-line slow wave structure with required dimensions, but picosecond laser ablation has such advantages as the absence of ablation products (droplets, and etc.) on the slow wave structure surface. Samples of slow wave structures were fabricated and characterized by scanning electron microscopy and profilometry methods. We have verified our original approach for planar slow wave structures microfabrication by using different CNC precision laser machines operating with different values of laser pulse duration (100 ns, 8 ns, 4 ns and 10 ps). An application of nanosecond and picosecond laser ablation for microfabrication of D-band (110-170 GHz) planar microstrip meander-line slow wave structure was considered. An original approach based on magnetron sputtering and laser ablation methods was utilized for microstrip meander-line slow wave structure microfabrication. All analyses reveal that the four-port hole-grating system could be a feasible high-frequency system of a subterahertz backward-wave radiation source.ĭesign and preliminary numerical simulations of D-band planar microstrip meander-line slow wave structure for low-voltage tubes with sheet electron beam were carried out. The proof-of-principle experiment shows an excellent transmission performance of the system, which agrees well with the theoretical results. It indicates that the four-port high-frequency system can help to reduce the requirement of the dual-beam electron gun and increase the feasibility of the dual-beam hole-grating BWO. Particle-in-cell simulations show that this high-frequency system could produce stable output signals as long as the current density of one electron beam is higher than the minimum starting current density. S-parameter results indicate the four-port system has good transmission characteristics, which could demonstrate the coupling effect of the hole array and the symmetrical properties of the electric fields at two output/input ports. The hole-grating slow-wave structure consists of two back-to-back gratings and a diaphragm with a two-hole array, which ensures the electric fields in two electron beam tunnels symmetrical. The future work will be aimed to expansion of the proposed technology to manufacturing of higher-frequency E-band (110–170 GHz) planar slow wave structures.Ī four-port high-frequency system for a 0.14-THz dual-sheet-beam hole-grating backward-wave oscillator (BWO) is presented in this paper. The proposed technology has significant advantages in cost, speed and flexibility over lithography processes commonly utilized for such applications. The experimental results are in good agreement with the numerical ones. Cold-test measurement are also carried out for microfabricated meander-line slow wave structures. Electromagnetic parameters of the developed slow wave structures are studied by numerical simulation. V-band (50–70 GHz) and W-band (75–110 GHz) meander-line slow wave structures are fabricated and characterized by scanning electron and optical microscopy. Then laser ablation is utilized to cut a slow wave structure from the copper layer. The magnetron sputtering method is used to deposit a thin layer of metal (copper) on a dielectric substrate. The technology is based on magnetron sputtering and laser ablation methods. A novel technology for microfabrication of millimeter-band planar microstrip slow-wave structures is considered.
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