Isolation Improvement of Cylindrical Millimeter-Wave Repeaters Using a Reactive Impedance Surface

The design and implementation of reactive impedance surfaces (RIS`s) for cylindrical millimeter wave (mmW) repeaters are discussed in this paper. A specific consideration is for the enhancement of transmit-to-receive isolation between wideband dual-polarized antennas. Using Floquet analysis, a hexagonal mushroom unit cell is designed to have a capacitive reactance in 16-40GHz range for the TM mode, and an array of unit cells (RIS) is fabricated and mounted on a metallic cylinder. The RIS is seen to improve isolation by an average of 15 dB across a wide bandwidth in KiKa-bands.