High-security antenna system with dual polarization and frequency tunability for driverless vehicles

Antenna arrays featuring dual-polarization and beam-switching capabilities are highly suitable for autonomous vehicular communication systems, where reliable and adaptable wireless links are essential. In addition to these functionalities, frequency reconfigurability offers a significant advantage by enhancing communication security and mitigating interference. This paper presents, for the first time, a compact and cost-effective antenna array system that integrates all these features into a single-layer design.The proposed structure combines two independent Butler Matrices with a linear array of dual-polarized, frequency-tunable antennas. This configuration enables beam switching across two orthogonal polarizations, thereby improving pattern diversity and link reliability under dynamic vehicular conditions. The introduction of frequency tunability — ranging from 3.3 GHz to 3.7 GHz within the sub-6 GHz band — adds an additional layer of interference suppression, allowing the system to avoid congested or jammed frequencies in real time. The design achieves main beam directions at $\pm 30^{\circ }$ and $\pm 60^{\circ }$ with measured peak gains of 9.5 dBi and 9 dBi, respectively. The reflection coefficients are well below -10 dB and the isolation between the ports is more than 20 dB. These results validate the system’s efficiency in generating directional, dual-polarized beams with high gain over a reconfigurable frequency range. Overall, the proposed antenna system offers a promising solution for next-generation vehicular networks by combining low profile, low cost, and high-security communication capabilities in a single-layer platform.