Compact ultrawideband MIMO slot antenna with high isolation

Abstract

SummaryAn ultrawideband multiple‐input‐multiple‐output (MIMO) slot antenna with a small size and high isolation is introduced. Two multi‐stepped microstrip lines are used to feed the MIMO antenna and the ground plane is designed in a defective structure for achieving good impedance matching in an ultrawide frequency range. A 3T‐shaped strip is utilized to diminish the coupling between the two microstrip feed lines for isolation improvement over the operating band. Two open‐end rectangular slots are attached in the ground plane of the MIMO antenna to generate anti‐phase current for further enhancing the isolation. By using this novel method, a compact ultrawideband MIMO slot antenna is designed and measured. It obtains an ultrawide bandwidth of 162.0%, ranging from 0.63 to 6 GHz, and excellent isolation of beyond 20 dB. Additionally, our MIMO antenna achieves a very low envelope correlation coefficient (ECC) of below 0.005, indicating its good diversity performance.