Wideband monopole MIMO antenna with pattern diversity and wide beamwidth coverage in elevation plane for C-band applications

A new four-element monopole MIMO antenna is proposed, featuring wide bandwidth, high isolation, high gain, and good pattern diversity with broad angular coverage across the entire C-band. By solely optimizing the offset-feeding position and patch width, three higher-order monopole resonances are effectively merged to achieve a 10-dB bandwidth covering 4–8 GHz. High isolation (> 23.3 dB) and low ECC (< 0.0017) are realized across the passband through the combination of rotationally symmetrical placement and shorting stubs. The stubs have minimal effect on the monopole resonances, and they can serve individually for isolation enhancement. The antenna also demonstrates good pattern diversity by producing four tilted omnidirectional radiation patterns, each with a broad HPBW (> 132°) and a passband gain of 6.5–9.4 dBi across the entire C-band.