Tolerance Analysis of THz-Range Lens-Antenna and Balanced SIS Mixers

Effects caused by imperfection of extended hemispherical immersion lens-antenna are studied numerically at 865 GHz. Elliptical and aplanatic focusing regimes are tested in combination with double-slot and double-dipole feeds for their aperture efficiency in the presence of multiple misalignment factors, which include possible phase and amplitude asymmetry of complimentary SIS tuning circuit. A new balanced lens-antenna SIS mixer is analyzed for its aperture efficiency with respect to an IF bandwidth of 4-12 GHz. Experimental data on lens-antenna SIS mixers with epitaxial NbN-AlN-NbN tunnel junctions is presented.