Experimental Characterization of a Metal-Only Circularly-Polarized Reflectarray Unit-Cell in Rectangular Waveguide at X-band

The paper introduces the numerical and experimental characterization of reflectarray unit-cell in circular polarization with waveguide simulator at X-band. The rectangular waveguide (WR-90) is used to measure the performance of the unit-cell in reflection mode. The proposed reflectarray unit-cell exhibits wideband operation in circular polarization with sub-wavelength periodicity (particularly 0.385 of a wavelength at 10.5 GHz). The reflected phase is varied by rotation technique to achieve 360° phase range. The characterization of circularly-polarized unit-cell in waveguide is challenging due to the unmatched polarization at various rotation angles. Therefore, a technique, namely approximate waveguide simulator, is proceeded to set up the experiment in numerical analysis, simulation, and measurement. The simulated 3-dB bandwidth expands from 10 GHz to 12.2 GHz, corresponding to 20% at 11 GHz. The successful characterization validates the proposed concept of the unit-cell and the experimental setup. The success of this study confirms the procedure to characterize circularly-polarized unit-cell in various frequency bands with appropriate rectangular waveguide.