Properties of Surface-Wave Resonators with the Transverse Radiation Output

We consider surface-wave resonators made as a planar corrugated structure with the operating π-mode and an additional double-period corrugation, which ensures radiation output in the form of a Gaussian beam in the direction transverse to the direction of the structure. The dependences of the intensity of the transverse energy output and the corresponding mode Q-factor on the parameters of the main and additional rectangular corrugations are studied. Analytical expressions are obtained in two limiting cases, specifically, one for a shallow corrugation with a period close to half the wavelength and a depth much smaller than the period, and the other, for a corrugation with a period much smaller than the wavelength and a depth close to quarter the wavelength. Such resonators can be used in relativistic surface-wave oscillators and non-relativistic clynotrons, respectively. The Q-factor of the surface-wave resonator with a rectangular corrugation having an arbitrary ratio of the period and the depth is calculated using direct numerical simulation. It is shown that the Q-factor related to the transverse radiation output decreases in inverse proportion to the squared depth of the additional corrugation and increases with decreasing corrugation depth for a fixed wavelength.