Unit Cell Design for Passive Reflectarrays on Quartz Glass

Whereas the elements of conventional antenna arrays are fed by transmission lines, reflectarrays are excited in free space; for example, the array is illuminated by a horn antenna. Reflectarrays can bundle the incident beam or reflect it in a different direction that does not correspond to the principle “incident angle = reflection angle” known from optics. When considering passive structures (as in this work), the reflectarray is set to an arbitrary, but fixed, incident and reflection angle.

In the context of this work, reflectarrays with an operating frequency of 240 GHz will be considered. The phase distribution on the array, which is related to beam forming, is achieved by geometric variation of the unit cells. Each unit cell consists of a metallized structure on quartz glass substrate, comparable to a patch antenna excited from free space.

The aim of the work is to investigate and model the unit cells with respect to influencing factors such as geometry, coupling and angle-dependent behavior. Depending on the thematic focus of this work, a demonstrator shall be built and characterized by measurements.