Direction-of-arrival estimation with Lüneburg lens and metamaterial absorber

In this article, we introduce a direction-of-arrival (DOA) estimation by combining a Lüneburg lens and a frequency tunable metamaterial absorber. The Lüneburg lens is used to physically separate the multiple incident waves with different DOAs and focus them into the different focal points near the lens surface. The metamaterial absorber is set on the focal plane as a sensor array. Therefore, the DOA information of an incident wave can be obtained based on the position of the sensor element having detected it. The resonance (absorption) frequency of the metamaterial absorber can be changed from 2 to 3 GHz using variable capacitors on the absorber. The error in estimated DOAs obtained by using a correlation algorithm is less than 2 degrees at 2 to 3 GHz, which is confirmed by prototype evaluations.