Research On Technology Of Direction Of Arrival Estimation Based On Gradient Index Lens

As the core of the passive detection, direction of arrival estimation technologyhas an extremely broad application areas. In order to obtain more accurate results,traditional DOA estimation technology usually set a number of antennas in front ofmany systems, which makes the system to be very complex and high costs, therebyconstraining the development of the DOA estimated technology. A Luneburg Lens isan attractive gradient index device for the ability to form multiple beams. It has asuperior performance compared with conventional uniform material lenses thatevery point on the surface of the lens is the focal point of a plane wave incidentfrom the opposite side. In this paper, GRIN Lens is employed for DOA estimationbecause of its unique electromagnetic property. It can reduces the number of therequired receiving antennas and the complexity of the algorithm. The main contentsof this paper can be divided into the following sections:Firstly, based on effective medium theory, this paper deduces the equivalentelectromagnetic parameters by using S-parameter extraction. A novelthree-dimensional cross-shaped structure is chosen as the unit of gradient indexmetamaterials. The relationship between the structure of its size and electromagneticparameters are obtained. On this basis, the designing of the three-dimensional GRINlens are finished. Simulation results show that this lens has a good focusing abilityduring the X-band.Secondly, this paper introduces electromagnetic resonators to designing ofGRIN lens. The permeability and permittivity of the resonatos can keepconstants when the operating band is far away from the resonantfrequency. Based on this designing a two-dimensional structure of a gradient indexlens. It also presents a gradient index lens based on high impedance surface, whichcontrolling the propagation path of the electromagnetic wave.Finally, the designing of DOA estimation algorithm. Since the GRIN lens havea good focusing ability, so the DOA estimation can be achieved by using maximumsignal method. While placing signal receivers around the lens, detecting the rotationof the lens receives the signal amplitude when the amplitude is maximum, and thereceiving device is pointing in the direction of the lens center is DOA. Thealgorithm is much simple. The results of simulation and measurement show its highaccuracy.