A 60GHz band 2×4 planar dipole phased array antenna using MMIC mixers is proposed for wide beamforming coverage area. 5 substrates are stacked vertically by using 3-D system-in-package (SiP) technology, and the element antenna is installed on the substrates. 8 passive double balanced MMIC diode mixers are used. By controlling the phase of each IF signal, proposed phased array antenna can operate as both transmitter and receiver. In this work, the beamforming coverage area where gain exceeds 10 dBi is measured by operating the fabricated array antenna as a receiver. The reflection at mixer's input port causes re-radiation and coupling to other element antennas. To reduce the fluctuation of phase and amplitude of received signal by the re-radiation and coupling, flip chip mounting are selected. Measured 3-D radiation patterns are in good agreement with simulated radiation patterns and show that the designed array antenna has a wide coverage area, covering 70° and 80° in the θ and φ directions, respectively, with gain exceeding 10 dBi. The proposed planar dipole array structure using 3-D SiP technology is feasible as a 60 GHz band 2-D beamforming antenna in small wireless terminals.