Beamforming radiation properties of absorbing/transparent zones-added horn antenna

In this study, we present beamforming of radiation patterns on a transmitter horn antenna by mounting an electromagnetic wave absorber, in which electromagnetic wave absorber is fabricated as concentric zones. The concentric zones consist of an absorbing material of manganese soft spinel ferrite blended with multi-walled carbon nanotubes with the thickness of 1 mm installed on the aperture of the antenna working in Ku-band. We have experimentally measured scattering parameter of transmission, S21, using a vector network analyser to perform radiation patterns in polar coordinates. As compared to the radiation properties of air horn antenna and absorbing/transparent zone-added horn antenna produces an appreciable effect to concentrate radiation beam in the main, side and back lobes with reducing side and back lobe levels for each frequency in H-plane. For the radiation pattern in E-plane, we have observed the suppressed side lobes at three frequencies of 15 GHz, 17 GHz and 18 GHz. The results indicate that the absorbing/transparent zone keeps an important role for further development of the applications of directional antennas so that the effective radiation is to be significantly concentrated.