Nanoparticle-coated Vivaldi antenna array for gain enhancement

A novel technique is described to significantly enhance the gain of a Vivaldi antenna (CVA) array by a factor of four (6 dB) without compromising its size and radiation characteristics. This is achieved by loading the antenna with Complementary Split-Ring Resonators (CSRR) and periodic array of open-loop meander-line unit cells. The unit cells are designed to exhibit properties of anisotropic zero-index metamaterial (AZIM) over a frequency range of the antenna. The inclusion of CSRR and AZIM in the antenna design is shown to effectively expand its aperture size with the advantage of not impacting on the overall size of the antenna. Moreover, the antenna is excited with a novel feedline consisting of hair-comb radial stubs (HCRS) that matches the impedance the 50-Ω feedline with the radiating elements of the antenna to thereby maximize power transfer. The proposed antenna array was fabricated to validate its performance. The peak measured gain of the array is 7.49 dBi at 177 degrees in the E-plane and its sidelobes are 10 dB below the peak gain. The 3-dB beamwidth of the array is 32.8 degrees. Furthermore, it is shown for the first time that by depositing a thin film of Graphene/copper nanoparticles onto the CSRR, the array’s gain is increased to 10 dBi at 180 degrees with sidelobe reduction of better than 15 dB.