Design and Performance Analysis of Double T-Shaped Reflectarray Unit Cells with Circular Double Rings

This paper presents a compact T-shaped design with slotted circular double rings for a reflectarray unit cell operating at 7 GHz resonant frequency, featuring a grid size of 0.5λ × 0.5λ. It maintains symmetry and integrates slotted circular double-ring patches to achieve effective resonance at the target frequency. Using CST simulations for optimization, an extensive parametric analysis was done to assess the impact of substrate and foam/air thickness on performance. Air with a thickness of 4 mm and FR-4 material with a thickness of 1.57 mm were used to create the prototype. According to simulation findings, the unit cell exhibits a substantial return loss (S11) and resonates at the correct frequencies. Additionally, with a bandwidth of about 1 GHz, the concept achieves a remarkable reflection phase dynamic range of 510 degrees. Moreover, regardless of the polarization mode, it exhibits steady reflection phase behavior even at an incidence angle of 20 degrees. In summary, this compact and high-performance reflectarray unit cell holds significant promise for reflectarray applications, making it well-suited for contemporary communication systems.