Low-RCS Monopolar Patch Antenna Based on a Dual-Ring Metamaterial Absorber

In this letter, a novel ring-type layout of metamaterial absorber (MA) is investigated for the first time. Three-layer MA unit cell is duplicated along the ring lattices to obtain the proposed dual-ring MA structure, which possesses desirable electromagnetic wave absorbing characteristics. A center-fed circular patch antenna (CPA) coupled with the dual-ring MA is presented to produce a monopole-like radiation pattern and reduce the in-band radar cross section (RCS). MA array acts as an absorber and a radiator simultaneously in this integrated antenna. Both the simulated and measured results demonstrate that compared with the CPA with an annular ring, the in-band RCS of the proposed antenna is dramatically reduced without degradation of antenna radiation performance.