In this paper, we present a dual-band (28/39GHz) 2 by 2 antenna array design on a 10(4+2+4) multi-layer organic substrate bringing broad bandwidth and higher isolation onto a compact AiP module. The antenna structure is a stacking patch antenna with multi-parasitic elements to improve bandwidth. This proposed H-type slot antenna structure can improve interference and isolation between 28 and 39GHz bands. The dimension of dual band AiP is about 13 by 13 mm 2 . Our AiP design has better than 10 dB return loss in 24.6-29.65 GHz range, with ~5 GHz bandwidth and provides a high-gain (above ~11.5 dBi) radiation pattern for 28GHz applications. For 39GHz band, the antenna has 6 GHz bandwidth and provides a 10 dBi gain between 38–44 GHz. The isolation is greater than 15 dB between low and high band. Finally, the 3D beam steering of 2 by 2 antenna array is simulated with multi-states at 27GHz, with a maximum realized gain of 11.1dBi achieved in the beam direction (θ=28°, Φ=312°) of quadrant IV. It shows that beamforming can be generated at a specific beam direction by controlling the phase of the signal in each antenna element. The compact size antenna structure provides a broadband benefit to approach 28GHz mmWave bands of 3GPP standard for n257, n258, and n261.