Design of Arbitrarily Controlled Multi-Beam Antennas via Optical Transformation
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Design of Arbitrarily Controlled Multi-Beam Antennas via Optical Transformation Yan Yang · Xiangmo Zhao · Tianjiao Wang
Received: 11 December 2008 / Accepted: 5 January 2009 / Published online: 16 January 2009 © Springer Science + Business Media, LLC 2009
Abstract The design of arbitrarily controlled multi-beam antennas is investigated by using the technique of optical transformation. Based on the optical transformation, cylindrical waves emitted from a line source can be converted to plane waves through a metamaterial layer which has a circular shape in the inner outline and a polygon shape in the outer outline. Hence the line source together with the metamaterial layer constructs a high-performance multi-beam antenna. The number of sidelines and the shape of polygon are used to control the number and directions of beams. Analytical formulas of the permittivity and permeability tensors are presented for the metamaterial layer in the antenna. The designed multi-beam antennas are validated by full-wave simulations using the finite-element method. The proposed multi-beam antennas will be very useful in the intelligent traffic system. Keywords Electromagnetic theory · Optical transformation · Anisotropic and inhomogeneous metamaterials · Multi-beam antennas PACS 41.20.Jb · 42.25.Gy · 42.79.Dj
1 Introduction Driving safety has become an important issue for car designs and car manufacturers. The most efficient approach is to anticipate the safety problem while driving. Anticipating a delicate situation requires the knowledge of the surrounding context.
Y. Yang (B) · X. Zhao School of Information Engineering, Chang’an University, Xi’an 710096, P. R. China e-mail: [email protected] Y. Yang · T. Wang Transportation Research Group, School of Civil Engineering and the Environment, University of Southampton, Southampton, U.K.
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J Infrared Milli Terahz Waves (2009) 30:337–348
Hence the anti-collision radar becomes essential, which uses electromagnetic waves to detect the surrounding obstacles. In an embedded anti-collision radar system, the antenna emits electromagnetic waves. When the emitted waves hit an obstacle, such as other vehicles, animals, etc., the waves will be reflected. By comparing the emitted and reflected waves and computing their time difference, the radar system can determine the distance between the car and the obstacle. By periodically computing this distance, the system can also estimate the relative speed of the car and the obstacle. Hence a high-performance radar antenna which can emit and detect electromagnetic waves in all directions efficiently is the key of the radar system. Recently, in the field of electromagnetics, the transformation optics has attracted much attention due to its unprecedented flexibility in designing various electromagnetic devices. The optical transformation provides many possibilities and approaches to control the electromagnetic waves through metamaterials [1–16]. The first use of optical transformation is the invisible cloak [1–12]. Following the theory of coordina
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