Dispersion Analysis of Reltron Modulation Section and Simulation Study on the Effect of Coupling Depth on Device Performance

Abstract

The dispersion relation of the reltron modulation section has been derived using the lumped-element equivalent circuit model of a biperiodic side-coupled cavity resonator. Simultaneous equations involving voltage-current have been structured as eigenvalue problems and solved by the matrix method. The solutions, i.e., the eigenvalues and the corresponding eigenvectors, give the frequencies and electromagnetic (EM) field patterns of the three normal modes and, subsequently, the dispersion relation. The analysis shows that the frequency differences among the three modes are not equal, in general, because of the nonlinear dependence. A reltron modulation section has been designed in the S-band and modeled using MAGIC and CST Microwave Studio (MWS). The eigenvalues and the corresponding eigenvectors have been obtained at different coupling depths, and the corresponding coupling coefficients (k) are calculated. The effect of the coupling depth on the device efficiency has also been studied through the particle-in-cell (PIC) solver. © 1973-2012 IEEE.