Highly Integrated mmWave Antenna-on-Chip Arrays Using Substrate-Integrated Air Cavities

We present the design, simulation, fabrication, and measurement results for a novel highly integrated and efficient silicon-based V-band 1×8 coplanar folded slot antenna (CFSA) array with 1-D beam steering up to 45°. Radiation efficiency and realized gain are enhanced by integrating a substrate-integrated air cavity (SIC) and a backside conductor into the CFSA. We further propose introducing stepped SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> bridges and rounded bends to the 1:8 corporate feed, ensuring uniform amplitude across output ports. Radiation patterns were measured using a robotic arm. The CFSA demonstrated a -10 dB bandwidth of 55.4-60.3 GHz for a single element, with a peak measured efficiency of 93%. The broadside array covered a bandwidth of 52-60.2 GHz, achieving a gain of 9.8 dBi. This study showcases a silicon-based CFSA phased array, achieving a 7.9 dBi gain at 45°.