2-D Multibeam Leaky-Wave Antenna Based on Modified Luneburg Lens

In this letter, a multibeam leaky-wave antenna (LWA) based on a modified Luneburg lens (LL) beamforming network is proposed. The antenna performs a simple structure and low profile with 2-D beam scanning. First, the modified LL serves as a beamforming network since its variation range ratio of refractive index can be determined by the relative permittivity of the substrate. This can be simply achieved using a printed circuit board technique rather than the square root of two of conventional LL. Then, the relationship between the input port angle and the multibeam angle is analyzed using the geometric-optical method. Finally, a high-scanning-rate LWA array based on spoof surface plasmon polaritons is designed, and its open-stopband is effectively suppressed. A prototype is simulated and fabricated. The measured results show that the proposed antenna has a multibeam range of -42 degrees to 40 degrees in the E-plane and a beam scanning range of -53 degrees to 44 degrees in the H-plane within 8-10.5 GHz, which agrees well with the calculation and simulation.