Dual-Functional Quasi-Uniform Beam-Scanning Antenna Array with Endfire Radiation Capability for Integrated Sensing and Communication Applications

This paper proposes a novel dual-functional quasi-uniform beam-scanning antenna array (BSAA) with endfire radiation capability for integrated sensing and communication (ISAC) applications. A controllable quasi-uniform leaky-wave structure is developed by introducing subwavelength slots on both sides of the substrate integrated waveguide (SIW) and integrating tunable varactor diodes. This structure enables a dynamic fast-wave radiation mode within the targeted frequency range, allowing flexible dispersion control. By leveraging the fast-wave nature of the excited mode and tuning the varactor capacitance, the proposed BSAA realizes both frequency-scanning (FS) and fixed-frequency electronic-scanning (ES) functionalities, both supporting endfire radiation. The BSAA is designed by integrating two pairs of mirror-symmetric leaky-wave antenna elements, with metallic vias incorporated to enhance impedance matching. Experimental results demonstrate that, with a capacitance setting of 0.8 pF, the array achieves continuous beam-scanning exceeding 50° per steerable beam as the frequency increases from 5.6 to 6.3 GHz. Furthermore, at a fixed frequency of 5.9 GHz, the array achieves a beam-scanning range exceeding 65° per steerable beam by adjusting the varactor bias voltage from 1.1 to 7.5 V. This fixed-frequency ES functionality remains effective across multiple frequencies within the 5.6-6.3 GHz range, covering the dedicated short-range communication (DSRC) band for vehicle-to-infrastructure (V2I) applications. Moreover, the proposed BSAA achieves high gain performance in both FS and ES functions. These features position the proposed BSAA as a highly promising solution for various ISAC applications in intelligent transportation systems.