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 ( 132°) and a passband gain of 6.5–9.4 dBi across the entire C-band.
Tan et al. (Sun,) studied this question.