Gluing an Antenna-on-Chip (AoC) directly on a ground plane or heat sink in the lead-frame is a standard process for commercial applications. To reduce the effect of losses in the silicon substrate and improve the antenna’s radiation efficiency, the wafer thickness is often drastically reduced. However, the close proximity of the antenna and ground plane can cause an impedance mismatch. Metal tiles, which are embedded in silicon dioxide layers, are designed as an Artificial Magnetic Conductor (AMC) to increase the radiation efficiency and tune the antenna impedance. A double-layer AMC is applied instead of a single-layer AMC to reduce the silicon dielectric loss. Additionally, the double-layer AMC has more capacitance to tune the impedance when integrating with a monopole on-chip antenna. The resulting -10 dB impedance bandwidth is increased to 5.8 GHz around the 60 GHz band, the simulated realized gain increases by 3.3 dB, and the simulated antenna radiation efficiency is increased from 11% to 21%. The measured input impedance of the AoC shows good agreement with the simulation results after probe calibration.