Electronic controllable reflectarray elements in X band

This paper shows the design and measurements of two types of reflectarray (RA) elements with electronic control for pattern reconfigurability in X band (10.5 GHz). The radiating element consists of a patch which is coupled to a microstrip line through a slot. This structure can produce a wide range of phase shift in the re-radiated signal with a very linear response. By adding a proper electronic controllable phase-shifter to the line section it is possible to control the reflected signal allowing the pattern reconfigurability through a proper design. Two different phase-shifters have been studied: one is based on PIN diodes and allows a phase change by discrete steps. The second uses a varactor diode which allows a continuous phase-shift in the range of 120 degrees, which would be valid for some cases of reconfigurable antennas. These elements have been validated using a Waveguide Simulator.