MAGICTRAC, a novel method for conversion of whispering-gallery modes into a free-space Gaussian-like beam

摘要

A novel device, MAGICTRAC, is described for efficient conversion at millimeter wavelengths of the TEm,nwhispering-gallery mode into a linearly polarized, free-space Gaussian-like beam. MAGICTRAC uses a mode-converting waveguide taper and three mirror optics, one of which incorporates a twist reflector to linearly polarize the output beam. An example design is presented for the TE15,2mode at 140 GHz with a calculated efficiency of 96. Related possible applications include (1) installation of the MAGICTRAC within the vacuum envelope of a gyrotron to separarate the spent e-beam from the generated rf, (2) generation of a whispering-gallery mode by injection of a Gaussian-like beam into the output end, and (3) conversion of TEm,nmodes into TE0nmodes for low-loss transmission in smooth-wall waveguide.