Dual-Beam High-Scanning Rate Leaky-Wave Antenna Based on a Tree-Shaped Strong Dispersion Spoof Surface Plasmon Polariton

This letter presents a high-scanning-rate leaky-wave antenna (LWA) based on spoof surface plasmon polaritons (SSPPs). The innovation of this design lies in the integration of oval-shaped patches and a tree-shaped SSPP transmission line (TL) that features a significant gradient of dispersion, enabling a high beam scanning rate. Most previous SSPP LWAs achieve high scanning rates by adjusting the periodicity of patches. However, they often overlook the importance of the dispersion relationship of the SSPP unit cell and utilize SSPP TLs with a relatively small gradient of dispersion. To further enhance the scanning rate, we developed an SSPP TL based on a tree-shaped unit cell exhibiting a substantial gradient of dispersion and a smooth-slope dispersion curve. The proposed LWA operates on the −1st space harmonic, allowing for a wide scanning angle ranging from backfire (–90°) to forward (18°) within the operating frequency range of 5.45–6 GHz and a high beam scanning rate of 11.24°/% has been achieved. Additionally, simulation results indicate that the average realized gain and total efficiency are 10.2 dBi and 78%, respectively. The scanning rate surpasses that of most previously reported SSPP LWAs, while the overall performance remains less unaffected.