Optimisation of MEMS-controlled reflectarray phase shifter cell

An optimised design of an MEMS-based phase-shifter cell (reflectarray unit cell) based on an equivalent circuit model is presented. The optimisation is performed by controlling five key design parameters of the unit cell which are: the number of MEMS switches, their state (ON/OFF), their appropriate location inside the slot, their ON/OFF capacitances and whether they should be used singly or in a pair. By controlling and regulating these parameters through the equivalent electrical circuit, the design of the phase-shifter cell can be optimised. This optimisation process results in phase-shifter configurations that permit a 360° phase range along with the required number of linearly distributed phase states. Minimisation of power losses within the unit cell is also an issue addressed by the optimisation process.