Direction-of-Arrival Estimation with Planar Luneburg Lens and Waveguide Metasurface Absorber

Direction of arrival (DOA) estimation using array antennas is known to have high resolution. However, these algorithms require high computational resources. This paper proposes a unique DOA estimation system without a sophisticated algorithm, using a planar Luneburg lens and a waveguide metasurface absorber. The planar Luneburg lens consists of a convex lens and a waveguide that separates incoming electromagnetic waves from different directions and focuses them at different points on the sides of the convex lens. The metasurface absorber consists of a mushroom-shaped structure that, when placed at the focal point of the lens, behaves like a compact 2D sensor array. Information regarding the intensity and angle of the incident electromagnetic wave can be obtained from the power and position of the sensor element. The resolution of the system is 2.2-2.4 degrees (depending on the sensor position), and the maximum estimation error is within 2.4 degrees in the 5.65 GHz frequency band.