Mario Sorolla Ayza

Optimal horn antenna design to excite high-order Gaussian beam modes from TE/sub 0m/ smooth circular waveguide modes

The availability of medium-power gyrotron tubes (10-30 kW, CW) at millimeter-wave frequencies (30-100 GHz) allows applications such as advanced ceramic sintering, surface coating, radar, remote sensing, deep-space communications, etc. The concept of high-order Gaussian beam modes, which, under some conditions, can be assumed to be free-space modes, is applied to transport efficiently the power generated by a gyrotron for technological applications. A family of optimized nonlinear horn antennas is investigated in order to get the maximum coupling between the guided output mode of the gyrotron and the Gaussian beam modes. The numerical simulations show very favorable coupling with a conversion efficiency of about 99.8%.

Comparative analysis of mode reflection and transmission in presence of a cutoff cross section of nonuniform waveguide by using the cross section and the mode-matching and generalized scattering-matrix methods

By using the cross-section method, waveguide transitions containing parts where modes are in cutoff are analyzed. The problem of infinite value of coupling coefficients for modes in cutoff has been solved. Formulas for the calculation of reflection coefficients are presented. The results have been compared with the mode-matching and generalized scattering matrix methods.