LAUSR

In sub-THz communication systems, compact, high-power, tunable radiation sources are required. Backward wave oscillators (BWO) have been practical devices for THz communication, but the maximum output power can be several times more than the minimum in the operation frequency range. To obtain the low peak-to-average ratio (LPAR) of the maximum power to the average power, the local maximum output power in the operation frequency range is first found theoretically and verified by particle-in-cell simulation. The LPAR 850 GHz BWO is then proposed. It applies a corrugated rectangular waveguide slow-wave structure, whose geometrical parameters are optimized using a multi-constrained optimization method. The optimized BWO operating in the frequency range from 790  to 882 GHz is simulated by the CST Particle Studio. The device can deliver at least 0.58 W with a LPAR of 1.08 when the conductivity of the slow-wave structure is 5.96 × 107 S/m. For a smaller conductivity of 3 × 107 S/m, the BWO can deliver at least 0.4 W with a LPAR of 1.13.