On the dispersion relation of radiation from charged particles in periodic structures

This work was supported by the Ministry of Science and Higher Education of the Russian Federation in the framework of Federal Targeted Program “Research and Development in the Priority Directions of Development of the Scientific and Technological Complex of Russia for 2014–2020” (agreement on November 24, 2017, N 14.616.21.0088, ID RFMEFI61617X0088).