Theoretical and Experimental Investigation of N-Bit Retrodirective Metasurface

The PIN diode -based N -bit reconfigurable retrodirective metasurface (N -bit RRDM) is a next -generation retro -reflector that offers the advantages of effective electronical control of the retro -reflection angle, low loss, and thin planar structure. However, since the unit cell of an N -bit RRDM is controlled by a quantized N -bit phase (360 degrees/2N), it encounters operational errors, such as beam gain reduction and spurious beams. This can be a fatal disadvantage in military radar or satellite communication, which requires accurate beam tracking. This paper theoretically analyzes the operation of the N -bit RRDM by utilizing generalized Snell's law and array factor theory. The analysis results present the design criteria for an N -bit RRDM that eliminates issues related to beam gain reduction and spurious beam errors. Furthermore, to verify the theoretical analysis results, High -Frequency Structure Simulator (HFSS) full -wave simulation and experimentation are conducted using the 1 -bit RRDM.