Bi-functional Fresnel Zone Plate From Transformation Optics

In the modern electronic information communication, traditional lens and reflector antenna are widely used when it comes to improve the gain of antenna.But because of they are non-planner devices, which is not convenient in practical use and processing, the Fresnel lens and reflector, with the characteristics of small size,low consumption,planner design and convenience in processing, have gradually replaced the traditional devices. Influenced by the optical transformation, observers have start to use the gradient refractive index material to design the flat lens. Based on the study of the traditional Fresnel lens and optical transformation, a bi-function device combines the lens and reflector is proposed in this paper, which can achieve the two functions by using a PEC on the back, and it has the same performance in bandwidth with the Fresnel devices.In this paper, the bi-function Fresnel zone plate is mainly discussed are studied, and the main contents are as following. 1. On the basis of traditional optical devices and the principle of the traditional Fresnel devices, the flat Fresnel lens and the reflector are designed. This paper compares the devices we proposed with the traditional optical devices. 2. This paper proposes the flat lens and reflector using the principle of electromagnetic transformation and compared the focal length, the permittivity, direction, bandwidth and the beam control capability of them with the traditional devices and flat Fresnel devices. 3. The bi-function Fresnel zone plate, which can be used as lens and reflector, is proposed in this paper. We make the comparisons of this device, planar optical devices and the traditional optical devices in the aspects of the focal length, relative permittivity, radiation performance and the bandwidth, which demonstrates the good performance of the bi-function device. Our design approach to obtain the equal electric path length by flattening the primary spherical wave front in the air space, instead of reshaping the standard parabolic reflector or the hyperbolic lens, paves the way for proposing novel planar architectures of the compact reflector system with reduced focal length, and the easy fabrication lens with small-value range dielectric compositions.