**Authors:** Min Liang, Xiaoju Yu, Rafael Sabory-García, Wei-Ren Ng, M. E. Gehm and Hao
Xin*

**Source:** FERMAT,Volume 19,Communication,Jan-Feb,2017

**Abstract:** Microwave direction of arrival (DOA) estimation is important in many sensor systems and has attracted a lot of attention due to its wide applications in the commercial and military areas, such as wireless communications and electronic warfare. Accurate and efficient direction finding will be very useful in next generation wireless communication system for location based services and applications.
Luneburg Lens is a gradient index which has a special property that every point on the surface of an ideal Luneburg Lens is the focal point of a plane wave incident from the opposite side. This property allows us to realize a precise DOA application based on the measured amplitude information from the detectors around the lens.
In this work, a Luneburg lens based DOA estimation system is studied. The lens is fabricated using a polymer jetting 3D printing technology and 36 detectors equally spaced with 10º separation on the equator of the spherical lens are used to receive the signal from all 360 degrees in the azimuth plane. A compressive sensing and a correlation algorithm is applied to estimate the DOA. Estimated direction result at different incident angles from all 360 degrees is shown in Figure 1. The averaged estimation error is about 0.14º, demonstrating that this Luneburg lens based direction finding system is a good candidate for low cost applications. This Luneburg lens based DOA estimation system has the advantage of broadband operation frequency and does not require any expensive phase shifter component in the system. Moreover, the high gain property of a Luneburg lens leads to small correlation between received power distributions for different incident angles, thus high accuracy for the incident angle estimation can be achieved.

**Index Terms:** DOA Estimation, Luneburg Lens Based DOA System, 3D Printed Luneburg Lens, Experiment Configuration.

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