Nonradiative dielectric (NRD) waveguide diplexer for millimeter-wave applications

In this paper, a T junction and a right angle elbow in Nonradiative dielectric (NRD) guide technology are carefully analyzed. This analysis is based on our mode-matching program combined with a cascading procedure that allows formulating generalized admittance and then generalized scattering matrices. These structures are optimized to reach the maximum power transfer from LSM to LSE mode. Putting these together, a splitter from LSM to LSM mode is created. Two LSM bandpass filters are then designed and added to the previous structure to obtain a diplexer. This diplexer presents two kinds of isolation. The first one can be easily minimized by increasing the order of filters. The second one is defined as a coupling isolation. A new physical topology is then presented to minimize this isolation. Our simulations are compared with HFSS software simulations and results are in very good agreement.