An Aperture-Sharing Array for 3.5/28 GHz Terminals with Steerable Beam in Millimeter Wave Band

The integration of the sub-6 GHz and millimeter-wave (mmWave) antennas has become an important issue for the next-generation wireless communication. For the mmWave band, adaptive beam steering is required to solve the path loss and coverage range problems. In this communication, an aperture-sharing technique is developed, so that a four-unit linear 28 GHz array and a 3.5 GHz dipole antenna can be integrated and the same aperture can be shared. The SIW is utilized to enable the integration and maintain the radiation of both antennas, without mutual interference. By adopting a separate feeding network, each mmWave array unit is independently excited, so that a beam steerable in the E-plane can be synthesized in the mmWave band. A prototype is fabricated with a compact size owing to the shared aperture. The measured results show good radiation characteristics and broad 10 dB impedance bandwidth exceeding 20% in both bands. Furthermore, the mmWave beam steering is obtained with a stable gain level. The proposed dual-frequency antenna is suitable for some terminal applications in the next-generation wireless networks.