Crescent shaped novel 4 x 4 port MIMO design with defected ground structure for multiband sub 6 GHz applications

A Quad port MIMO antenna resonating at sub-6 GHz 5G band is designed by utilising FR4 epoxy material having a dielectric constant of 4.4 and thickness of 1.6 mm. Four identical crescent shaped radiating elements fed by utilising a microstrip feed line are designed by utilising the finite element method based high frequency structure simulator. The antenna parameters are characterised by utilising sets of real measurements to validate the antenna design and modelling. Chemical etching has been utilised for fabricating the quad port antenna on a FR4 substrate. Vector network analyser has been used for measuring the scattering and transmission coefficients. As well as, an anechoic chamber has been used for measuring the far field radiations and the gain of the antenna under test. The basic antenna is a part of the quad-port structure consists of a crescent shaped circular patch with a defected ground structure and are fed individually. MIMO ability is obtained by arranging 4 identical antenna elements in a successive rotational means for obtaining good polarization diversity. The connected ground between the antenna elements is obtained by subtracting 4 circular slots from the ground plane by maintaining a common ground plane. None of the slots touches each other thus ensuring the common reference while maintaining the inter isolation better than 15 dB. The antenna demonstrated maximum gain and efficiency of 4.59dBi and 90%, respectively besides attaining a 10-dB impedance bandwidth of 2-6.2 GHz and ECC < 0.01. Finally, the quad-port compact MIMO antenna is designed, simulated, fabricated and tested, it shows that the antenna is useful for n1, n40, n41, n77, n78 and n79 5G bands. This bandwidth makes the antenna useful for Sub-6 GHz 5G wireless applications.