60 GHz band 2×4 dipole array antenna using multi stacked organic substrates structure

Wireless systems using license-free 60 GHz band have been focused as Gbps ultra-high speed data rate short range communication. Beamforming techniques based on array antennas have been employed to obtain high directional antenna gain [1]. In order to realize an array antenna in millimeter-wave frequency range, the accuracy of positioning of the antenna elements becomes considerably important. Conventional 60 GHz band beamforming antennas have used a patch array antenna configuration [1], [2]. Since the patch antenna is patterned on a substrate, high accuracy of the positioning is obtained. These patch array antennas realize a main beam in the vertical direction of the substrate. In order to realize a main beam in the horizontal direction of the substrate, 1×4 dipole array antenna was developed and beam scanning in the azimuth plane was possible [3]. For 2-dimensional (azimuth/elevation) beam scanning, 3×2 vivaldi array antenna using multi-layered substrate was reported [4]. It showed the 2-dimensional beam scanning function, but a high antenna gain could not be obtained. Since the antenna elements were fabricated in a multi-layered substrate, the antenna elements were placed very close (nearly 1/25 λ₀) in elevation direction and it caused relatively low antenna gain.