On the reflection phase characteristics of rectangular and circular patch reflectarray elements

In reflectarray design, computation of the reflection phase of unit cells is of prime importance. In this paper, a theoretical method to calculate the reflection phase of circular patches is reported. This is done by adapting an already published work for rectangular patch elements. The estimated reflection phases for circular patches in X band are compared with simulated values for substrates of varying thickness and dielectric constant. The comparison leads to the understanding that the method works satisfactorily for thin substrates with any dielectric constant and for moderately thick substrates with high dielectric constant. This observation is, of course, consistent with that made for the rectangular patch.