UWB four ports MIMO antenna based on inscribed Fibonacci circles

In this paper, a novel ultrawideband (UWB) four ports multiple-input multiple-output (MIMO) antenna was developed. The MIMO antenna is based on four wideband circular monopoles with inscribed Fibonacci circles in order to reduce the size and stabilize the impedance over a wider bandwidth. The array shows a frequency bandwidth from 3.6 GHz to 13.8 GHz, obtaining inter-port coupling below −15 dB over the entire bandwidth. Convergent TARC curves over the entire bandwidth exhibit values less than −25 dB and high stability against phase changes in the incoming signals to the different radiators. Finally, the UWB MIMO antenna proposed generates a quasi-omnidirectional radiation pattern with orthogonal properties among radiators, demonstrated by a very small Envelope Correlation Coefficient (ECC) value, averaging 0.005.