The objective of this proposed research is to develop a highly efficient silicon-based on-chip antenna array operating in the mmWave band. In the first part of this paper, I present a V-band 1×8 on-chip miniaturized cavity coplanar folded slot antenna (CFSA) array with high efficiency and reduced mutual coupling. Substrate-integrated air cavities (SICs) are used to enhance efficiency and gain, diminish element-to-element coupling, and counter parasitic parallel-plate modes to improve CFSA efficiency. I developed CPW corporate feeds using SiO2 bridges and rounded bends to demonstrate beamsteering. The measured CFSA single element −10 dB bandwidth is 55.4–60.3 GH (8.5%) with an efficiency of 93%. The measured broadside array's bandwidth spans 52–60.2 GHz (14.6%), with a total efficiency of 67% and 11.0 dBi gain. This study marks the first demonstration of beamsteering using on-chip antennas with SICs, steering up to 45°, and corresponding gains of 8.1, 8.9, and 9.2 dBi. In the second part, I present V-band dual-polarized on-chip antennas where the radiating patch is patterned on the silicon wafer instead of the back end of line (BEOL) region, eliminating the need for lossy TSVs or wirebonds for interconnection. The −10 dB impedance bandwidth for port 1 (P1) is 59.2–60.35 GHz, and for port 2 (P2) it is 59.4–61.0 GHz. The realized gain of the patch antenna at P1 is 3.86 dBi with a directivity of 5.94 dBi, while P2 has a realized gain of 4.15 dBi and a directivity of 5.82 dBi at 60 GHz, indicating efficiencies of 62% and 68%, respectively. The proposed on-chip antennas and arrays offer the potential for monolithic integration with radio frequency (RF) circuitry for V-band system-on-chip (SoC) applications that demand high data throughput..