X-Band Reconfigurable Reflectarray Element using Frequency Selective Surface

An X-Band reconfigurable reflectarray (RA) element is designed using a frequency selective surface (FSS). The design consists of two layers. The radiating geometry at the top layer comprises of multiple smaller sized patches which are closely spaced to create strong coupling while a circular slotted patch is used as an FSS at the bottom layer. The element is a square of length 10mm (0.38λ at 11.5 GHz). A surface mount varactor diode is attached at the top layer geometry. To isolate the RF signal from DC, the biasing line is also considered. The proposed FSS-based electronically tunable element results in a phase tuning range of 250° with amplitude loss below 2 dB.