Impedance Matching for Planar Quasi- Yagi Antenna with Zero-Index Metamaterial

An optimized zero-index metamaterial (ZIM) structure is proposed to enhance the gain of a planar Quasi-Yagi antenna in the X-band, addressing the impedance mismatch issues commonly encountered in conventional designs. By strategically adjusting the dimensions and placement of ZIM unit cells, significant improvements in impedance matching are achieved, resulting in reduced reflection losses. The zero-permittivity point of the ZIM structure is approximately 8.5 GHz, and the ZIM cells are integrated into the antenna’s aperture for optimal performance. Comparative simulations and experimental results of two antenna designs—one with ZIM cells and one conventional—demonstrate a gain enhancement ranging from 0.5 to 4 dB across the frequency range of 8.5–11.5 GHz, compared to a gain range of 0.5 to 2 dB in the conventional design. The reflection coefficient in the conventional design is -10 dB, while the proposed method achieves a reflection coefficient of -2 dB, highlighting the effectiveness of ZIM cells in improving impedance matching and minimizing performance degradation due to mismatching. The design and optimization were carried out using Ansys Electronics Desktop, demonstrating the potential of ZIM structures for next-generation antenna systems.