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 3D-printed convex lens with a waveguide, which separates incoming electromagnetic waves from different directions and focuses them at different points on the sides of the convex lens. The metasurface absorber has a mushroom-shaped structure designed as a compact 2D sensor array, which is placed at the focal point of the lens. Information regarding the intensity and angle of the incident electromagnetic wave can be obtained from the power and position of the sensor element. This compact and simple system measures the DOA of an incoming wave in seconds without complicated calculations. The angular 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.