Millimeter-Wave Active Beam-Tilted Phased Array Modules and Seamless Integration Design With Ultrawideband Sub-6 GHz Antenna for Future V2X Applications

In this article, an antenna system that seamlessly integrates millimeter-wave (mmWave) active phased array modules and an ultrawideband Sub-6 GHz antenna is proposed for future vehicle-to-everything (V2X) communications. Two kinds of different polarized mmWave 45° beam-tilted antennas are first developed using novel approaches, respectively, without the introduction of additional structures. Then, two arrays of the proposed 45° beam-tilted antennas are embedded in an ultrawideband Sub-6 GHz half-mode Vivaldi (HM-Vivaldi) antenna, forming large frequency ratio antenna system. Then, to validate the ability to maintain high isolation between disparate frequency bands while allowing for the seamless incorporation with mmWave active circuits, mmWave front-end active circuits are mounted on the surface of the Vivaldi antenna and further integrated with the corresponding mmWave antennas. Experimental results indicate that the entire antenna system can achieve a measured $\vert S_{11} \vert \lt -10$ dB impedance bandwidth fully covering 0.6–6 GHz and 24.5–29.5 GHz, respectively. The maximum gain fluctuations of the mmWave antennas in the 45° direction for corresponding polarizations are only 1.88 and 1.64 dB, respectively. It has been confirmed that the existence of active circuits in this design has less impact on the antenna performance and the 3 dB beam scanning ranges exceed 80° for both polarizations at 27 GHz. The merits of the proposed antenna system such as wideband, stable mmWave dual-polarized tilted beams, high isolation, and ease of integrating mmWave active circuits, make it a promising solution for the future vehicle-to-everything (V2X) communications.