New Phase Realization Approach for Implementation of Braodband Reflectarrays

We present a new phase realization approach applied to design the broadband single-layer reflectarray antennas. Such an optimization technique minimizes the adverse effects of frequency dispersion which limit the bandwidth of reflectarray antenna designed by traditional methods. Using this new approach leads to obtaining a wideband reflectarray by finding the optimum element arrangement on the antenna aperture. The excellence of such an approach in comparison with its counterparts is to decrease the dependency of wideband reflectarray design to the element phase behavior. For really assessment this phase synthesis approach, a single-layer reflectarray compromising of square patches loaded with split rings is designed with the help of this optimization technique. It is analytically and numerically shown that the simulated reflectarray can be a broadband antenna in which Side Lobe Level (SLL) value is reduced. To validate the obtained numerical results, a designed 29×29cm2 reflectarray is fabricated and measured. Measurements demonstrate 1.5dB gain bandwidth of about 28% covering 12-16GHz frequency band. Its |SLL| is also less than -17dB (<-13.5dB for uniform excitation arrays). Such a design technique is applicable for approximately all reflectarray elements and relieves the designer from complex elements and multilayer structures.