Computer Tool for Design of Reflectarrays and Conformed Reflectors


题目:Computer Tool for Design of Reflectarrays and Conformed Reflectors


A new computer aided technique to automatically design reflectarrays and conformed reflectors will be presented. The reported technique is able to generate the geometrical model of both antennas taking into account some input parameters such as the unit cell type, the operating frequency, the focal length, the desired main beam radiating direction, etc. The characteristics of the reflecting elements are selected considering the spatial phase delay at each unit cell to achieve a progressive phase shift. The tool also computes and provides the phase curve of the unit cell. To validate the proposed method, an offset-fed reflectarray,a center-fed subreflectarray and conformed reflector and subreflectors have been designed. Good results have been achieved.

One of the goal of the proposed approach is the automatic design of reflectarray and subreflectarray antennas by varying the parameters of the unit cells. The variation may include the resonant size of the cells, their position, orientation, stub’s length, periodicity, number of layers, dielectric materials, etc., so that the phase shift given by every element is compensated according to its reflected phase.

The first step is to create a database to store the values of the modified parameters and its correspondent reflection coefficient phase at a given frequency and for a certain periodicity. Each entry in the database that associates pairs of parameter values and reflection phases is obtained by analyzing the behavior of a quasi-infinite array of identical elements by applying a full wave method based on the MoM, so truncation effects due to the finite size of real reflectarrays/subreflectarrays are also considered. Despite the big computational effort required to obtain the whole database, it is affordable in time because the MoM code is parallelized. A normal incident plane wave is considered to compute the reflection coefficient phases.

Then, the phase delay caused by the path difference from the feed point is calculated taking into account the position of each unit cell. Once all phase delays are obtained, the system searches in the database the proper dimensions to compensate the required phase at every element. Hence, each cell can properly adjust their phase delay, introducing no errors and obtaining the maximum directivity. The next step consists in creating the geometrical model of the reflectarray/subreflectarray, according to the values provided by the database. The user is also able to define its shape, which can be rectangular, square, or circular.

报告人:阿尔卡拉大学, Cátedra Pérez Manuel Felipe 教授