Fully CAD-based design of mode transformer between NRD guide and vertical strip line and its application to junction circuits and MMIC integration at 60 GHz

Mode transformer between the NRD guide and vertical strip line was optimized, and was applied into right angle corner, T-junction, magic-T, and amplifier at 60GHz. An emphasis is placed on a fully CAD-based design procedure by using an electromagnetic field simulator. An agreement between the simulated and measured performances of the junction circuit is quite satisfactory, and thus the validity of the design procedure was confirmed. Well balanced transmission coefficient of each output port, found to be 4±0.5dB, was obtained in the bandwidth of 4 GHz around a center frequency of 60GHz. Moreover, an MMIC amplifier was mounted in the NRD guide using the transformer. A reasonable performance, measured to be 15dB in gain and -20dB in isolation was obtained at 59.5GHz.