Dual-Beam Leaky-Wave Antenna Based on Dual-Mode Spoof Surface Plasmon Polaritons

In this letter, a dual-beam leaky-wave antenna (LWA) based on dual-mode longitudinal asymmetry (LA) spoof surface plasmon polaritons (SSPP) is presented. The dispersion curves of the LA SSPP unit cell are extracted and analyzed. On the basis of obtained dispersion curves, it is found that two different modes can be simultaneously excited using the LA SSPP unit cell and each mode can be independently manipulated by groove depth at two sides. By exciting the LA SSPP unit cell, two radiation beams can be generated with proper modulation. Different from the traditional dual-beam LWA, whose two radiation beams relies on both -1st and -2nd space harmonics, the proposed design method can independently control two radiation beams by using only -1st space harmonic, avoiding the radiation beam, which is difficult to control generated by -2nd space harmonic. In details, the radiation angles of the two beams can be easily controlled by introducing different modulation period in the forward and backward regions respectively, which increases the flexibility of dual-beam applications. The detailed design process is presented in this letter and a prototype of the proposed dual-beam antenna is simulated and measured. The measured results are in good agreement with the simulated results, strongly indicating validity of proposed method.