A compact octagonal fractal UWB MIMO antenna with WLAN band-rejection

In this article, a compact octagonal-shaped fractal ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna is presented and its characteristics are investigated. The application of Koch fractal geometry at the edges of octagonal monopole provides desired miniaturization and wideband phenomena due to its self-similar and space filling properties. The two octagonal fractal antennas are placed orthogonal to each other and used to construct UWB MIMO antenna. An L-shaped stub is used in the ground plane of the geometry to provide an improvement in the isolation. The band rejection in wireless local area network band is achieved by etching a C-shaped slot from the monopole of the individual antenna. The compact dimension 40 × 25 mm2 of the antenna exhibits nearly omnidirectional radiation pattern, a low envelope correlation coefficient (<0.01), with good S-parameters over the entire UWB frequency range. The measured results show good agreement with the simulated one.