Active reconfigurable reflectarray based on voltage-controlled oscillators

A reconfigurable reflectarray based on the use of voltage controlled oscillators is presented. Each of the cells in the reflectarray is formed by an active oscillator antenna consisting of a radiating element aperture coupled to a voltage-controlled oscillator (VCO). The various cells due to radiation coupling form a coupled oscillator array. Beam-steering as well as beam forming can be achieved by appropriately tuning the free-running frequency of the individual oscillators. After the desired beam pattern is synthesized, modulation is introduced to the array by synchronizing each individual cell to the feeding horn signal in a star topology. The proposed system allows a continuous and electronic control of the reflected wave phase. Harmonic balance continuation methods combined with EM simulation are used to design the array. A 2×4 prototype at 6.1 GHz has been designed, implemented and tested.