Design and fabrication of 77 GHz HEMT mixer modules for automotive applications using experimentally optimized antipodal finline transitions

77 GHz PHEMT gate mixer module and resistive mixer module were fabricated for automotive applications using the LG-CIT low noise PHEMT process and WR12-to-microstrip antipodal finline transitions. The finline transitions were experimentally optimised for wideband operation and low insertion loss by adjusting the geometrical design parameters. The average insertion loss was measured to be 0.74 dB per transition in the 75-90 GHz range. The fabricated gate mixer module and the resistive mixer module showed very good conversion loss of 2 dB and of 10.3 dB, respectively, including finline transition loss and IF cable loss, which were very competitive performances.