A tri-stub loaded tree shaped 4-element multi-band MIMO antenna for 5G and advanced wireless systems

A four-element tri-stub loaded tree shaped multi-band MIMO antenna is elaborated in this article for the forthcoming 5G and advanced wireless communication systems. This structure of antenna encompasses four proportioned elements produced in alignment with each other on an FR4 substrate of size 73 × 77 mm2. The basic antenna comprises a tree shaped patch with 3 arms on the side, and the ground is flower shaped with concentric spiral slots at each side to improve port isolation characteristics. The antenna operating bands are 2.5 GHz Wi-Fi/LTE 38/40 (1.87–2.72 GHz), 3.6 GHz for LTE 77/78 (3.01–4.13 GHz), 5.5 GHz for WLAN/Wi-Fi (5–5.87 GHz), and the ITU band (7.7–7.9 GHz), having an isolation of more than 15 dB over the full range of operating frequencies. Average radiation efficiency is above 80%, and the peak value of realized gain is found to be equal to 4 dBi. The Envelope Correlation Co-efficient (ECC) value stated is less than 0.006, and the value of diversity gain is around 10 dB. Channel capacity loss noted is <0.5 bit/s/Hz, and TARC is below −10 dB within operating frequency ranges. A lumped element equivalent circuit model of the proposed single element antenna presents a good match with the EM simulation. The fabricated prototype is tested, and the measured results are found in the acceptable range.