Design Of Graident Index Metamaterial-Based Lens Antenna

Lens antenna is often used in various fields including satellite communications and local point to multipoint communication. Compared with conventional paraboloid antenna and phased array antenna,the lens antenna has the advantages of wide beam coverage, small beam difference, wide working frequency band, low loss, and simple feed network, easy setup and use, good wind resistance, etc., and thus is much favored by antenna designers in the practical engineering applications. But traditional lens antenna also has many inherent shortcomings, For example, the size and weight of the lens antenna is relatively large, when working at low frequencies. Moreover, with the increase of the number of dielectric layers of the lens antenna, there is the increasing air between two layers, thus affecting the performance of the antenna. Besides, the fabrication technology of the composite materials of the lens antenna is not mature for a long time, which to a great extent, restricts the development of the lens antenna technology. This paper is aimed at solving the difficulties of traditional lens antenna faced in the production process, and achieving the design of a plane lens antenna based on the electromagnetic metamaterials. The plane luneberg lens antenna and half a fisheye lens antenna are designed, respectively, with good directivity, high gain, and easier fabrication process. The author’s major contributions are outlined as follows:1. This paper first introduces the design principle of lens antenna. And then the working principle and the development status of representative Luneberg lens antenna and Maxwell fish eye lens antenna are discussed. In the following the gradient refractive index optical technique and theoretical aspects of electromagnetic matamaterials in the design process are introduced in details.2. In this paper, according to the varition of the refractive index and working principle of Luneberg lens antenna, we design a Luneberg lens composed of a kind of circular metamaterial units, which can transform incident spherical wave along arbitrary directions to a plane wave. The electromagnetic simulation software is used to simulate its electric field distribution to show good performance of our design.3. In addition, based on the varition of the refractive index and working principle of the Maxwell fish eye lens antenna, we designed a the wide-band Maxwell fish eye lens antenna composed of a slotted square ring unit cell in X-band. The refractive index ofthe slotted square ring unit cell can be obtained in two ways and the corresponding unit cells are arrayed to form the half Maxwell fish eye lens. Two types of fish eye lens antenna have good performance including good directivity of the main lobe, high gain. Furthermore, we design a modified lens antenna to improve matching problem between parallel plate waveguide and free space, and therefore the resultant directivity and the gain are further improved. Finally simulation and measured results of the lens antenna and the improved lens antenna are compared to demonstrate advantages of proposed lens antennas.