Compact 2-port fractal monopole MIMO antenna with polarization diversity and high isolation

A compact 2-port multiple input multiple output (MIMO) antenna system with fractal shaped antenna elements of total size 17×40 mm2 is proposed for WiMax/WLAN applications. The physical separation between the antenna elements of the proposed system is 0.15λ (λ being the free-space wavelength at 5.4 GHz). The two antenna elements are orthogonally placed and the MEMO system exhibits pattern diversity with high isolation, without additional structures for isolation improvement. The performance of the antenna is studied in terms of S-parameter, radiation pattern and envelope correlation coefficient. The measured results show that the relative bandwidth of the proposed antenna is 1.2 GHz (4.8 - 6 GHz) with S11 ≤ -10dB, S11 ≤ -20dB and envelope correlation coefficient (ECC) <; 0.01. The proposed MEMO system is believed to be a good candidate for high density packaged MIMO system.