Accurate method for synthesis of shaped-beam non-uniform reflectarray antenna

This study presents an accurate method to synthesise a shaped-beam flat reflectarray (RA) antenna based on the phase synthesis of its equivalent aperture. For this purpose particle swarm optimisation is used to determine the optimal phase distribution on the reflective surface of the antenna. Furthermore, by dividing the equivalent aperture of the antenna into small parts and by appropriate approximation of the induced current in each part, the radiation fields have been evaluated via the sum of the simple integrals. In this approach the relation of the amplitude and phase of the reflection co-efficient of the RA elements with the radiation fields of the antenna can be obtained. Therefore the effect of the RA elements can directly be considered in the optimisation process. Also, in the proposed method the effects of the feed antenna including the angle, polarisation, amplitude and phase of the radiated fields from the feed are fully considered in the synthesis procedure. To verify the synthesis method a RA with flat reflective surface has been designed and manufactured that shows a good agreement with the simulation results obtained from commercial full-wave electromagnetic software, CST Microwave Studio.