Metamaterial-Based AMC Antenna With Reduced RCS and Increased Bandwidth for Wireless X-Band Applications

This paper presents a method to enhance antenna bandwidth, reduce radar cross section (RCS), and increase antenna gain by using a metamaterial-based artificial magnetic conductor (AMC) structure for the applications of X-band. In the suggested antenna, we provide a coaxial probe-fed with 50$\Omega$ impedance matching circuit. Furthermore, in the presented work, two AMC unit cells are designed to achieve a 180° reflection phase difference across a wide frequency range, and these unit cells are employed to construct a chessboard-like metamaterial surface (CLMS) for low RCS. The AMC structures provide an adequate bandwidth in the desired frequency by adjusting the phase. A 3 $\times$ 3 periodic AMC structure with a defected ground structure (DGS) configuration is proposed and experimentally demonstrated to enhance antenna bandwidth and gain. The antenna's overall size is significantly reduced to (1.35${\lambda }_0$ $\times$ 1.35${\lambda }_0$) with a thickness of (0.025${\lambda }_0$); here, ${\lambda }_0$ is free space wavelength at 9.8 GHz operating frequency, with an AMC structure. The proposed antenna with the DGS ground structure has been constructed and tested. The results of the simulations and measurements demonstrate an excellent gain performance and improved bandwidth.