Design and implementation of a four‐port ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO)/diversity antenna with dual band‐notched characteristics are presented. The proposed diversity antenna is composed of four identical rhombic‐shaped monopole radiators arranged orthogonally to achieve better interelement isolation and polarization diversity. At each port, the MIMO antenna shows an impedance bandwidth (S11 ≤ –10 dB) of 10.5 GHz (2.8‐13.3 GHz) and an interelement isolation larger than 18 dB. Furthermore, in order to eliminate 3.5 GHz (Wi‐MAX) and 5.5 GHz (WLAN) bands from the UWB range, the antenna radiators are loaded with elliptical complementary split ring resonator structures. The MIMO performance metrics such as isolation, envelope correlation coefficient, and apparent diversity gain are calculated and presented. The MIMO/diversity antenna prototype is fabricated, and experimental results are verified with simulated results.
