A full-angle scanning SSPP leaky-wave antenna: Suppression of open stopband effect and m = −2 space harmonic

This study introduces a high-efficiency full-angle scanning leaky-wave antenna (LWA) based on a large dispersion spoof surface plasmon polariton (SSPP) transmission line (TL) featuring groove units. To convert the tightly bound SSPP waveguide mode into a radiation mode in free space, elliptical metal patches are strategically placed equidistantly within the central region between the two inward-grooved SSPP TLs. The rotation of the elliptical patch unit at a specific angle not only alleviates the open stopband effect but also suppresses sidelobes generated by the m = −2 space harmonic, significantly expanding the scanning range of the main beam. We elucidate the operational principles of the LWA through a synthesis of array antenna theory and Floquet theory. The occurrence of the bandgap phenomenon is illustrated by the band structure of a one-dimensional photonic crystal. The experimental results closely align with the simulation outcomes. The proposed LWA covers all angles from backward to forward in 6.3–10.6 GHz with a scanning rate of 3.54°/%. It features a low-profile design, a notable gain of 12 dBi, and an impressive efficiency of 95%. This achievement underscores its significant potential for deployment in microwave radar and wireless communication systems.