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A novel high-resolution electromagnetic-wave-source visualization system is presented. The system can determine the incidence angle and visualize the wave source by combining a Lüneburg lens with an electromagnetic band gap (EBG) absorber. The Lüneburg lens is used to physically separate the incident waves coming from different directions and to focus them onto the different focal points on the lens surface. Every element of the EBG absorber coincides with a different focal point on the lens surface, so that the intensity and angle information of the incident wave can be obtained based on the absorbed power and position of the corresponding sensor element. The estimated angular resolution is 2.56 degrees and the system sensitivity is-65.6 dBm/m 2 at 2.45 GHz. The results were confirmed by prototype evaluation.

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.

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