Integrated Low-Loss mmWave On-Chip Arrays

A 60 GHz coplanar folded slot antenna with an off-chip ground and a deep air cavity is proposed, featuring both a single element and a 1x8 linear array with corporate feed. The single-element on-chip antenna (OCA) operating at 60 GHz achieves a -10 dB measured fractional bandwidth of 6.9%. The measured peak gain is 5.6 dBi with a directivity of 6.4 dBi, and the antenna's efficiency is simulated to be 83%. The 1x8 array exhibits a 9.8 dBi realized gain with a radiation efficiency of 71%. We introduced a phase shifter using microfabricated vanadium dioxide (VO2)-based switches. The resulting phase shifter demonstrated input impedance matching, indicating a fractional bandwidth of 182%. Integration of OCA with VO2-based phase shifters will be instrumental in exhibiting beam steering capabilities up to 45 degrees.