A High-Gain Periodic Leaky-Wave Conformal Endfire Antenna Array Based on HISL Technology for X-Band Applications

This letter presents an X-band high-gain periodic leaky-wave conformal endfire antenna array based on hybrid integrated suspended line (HISL) technology, offering advantages such as high gain, stable endfire radiation, and ease of integration and assembly. To address the challenge of conformal design for installation on large metal planes, the double-sided slot element structure with an appropriate element radiation pattern is proposed. To achieve stable endfire radiation, the fundamental mode of the rectangular waveguide within the cavity needs to be suppressed, allowing the transmission line to operate in TEM mode to feed the proposed elements. In this design, we introduce HISL technology for the first time and implement the periodic leaky-wave antenna array based on this technology. Compared with existing air-substrate periodic leaky-wave antennas, the proposed HISL technology overcomes assembly challenges, meeting the manufacturing precision requirements of higher frequency bands. The technology enables array formation and integration with the feeding network, thereby enhancing the endfire gain. We also analyze the aperture distribution and phase constant characteristics of the antenna. The dual-path coupling approach ensures a uniform aperture distribution, while the antenna achieves high gain endfire radiation close to the Hansen–Woodyard condition. Finally, the antenna array is fabricated and measured. The proposed antenna array achieves a maximum gain of 16.32 dBi in X band, demonstrating potential applications in high-speed mobile radar detection systems.