This paper presents the design and analysis of the Triple band Circular Quarter Mode Substrate Integrated Waveguide (QMSIW) 1 × 2 MIMO antenna for sub-6 GHz 5 G wireless applications. The antenna operates at three distinct frequencies those are 3.57GHz, 4.41GHz and 5.43 GHz respectively. The 3.57 GHz used to operate for WiMAX, 5 G, and Fixed Wireless Access, the 4.41 GHz, is often used for specific satellite uplink/downlink operations, Radar Systems and the third one 5.43 GHz is used for Wi-Fi, DSRC, and WLAN systems. The proposed architectural design underwent simulation utilizing electromagnetic (EM) tools to the extract results, followed by antenna fabrication and measured results, it was observed that there is a close match between the simulation, measured results and validated results. The measured, simulation gain values are 5.092dBi,4.98dBi at 3.57 GHz, 4.51dBi,4.6dBi at 4.41 GHz and 3.075dBi,3.06dBi at 5.43 GHz frequency, while also demonstrating satisfactory isolation between the ports, quantified as being less than −15 dB. The characteristic parameters of the MIMO antenna, including a diversity-gain (DG) surpassing 9.95 dB (>9.95 dB), alongside an envelope-correlation-coefficient (ECC) of less than 0.0001, Mean effective gain (MEG) lies between − 3 dB to − 4 dB, among any two radiating elements at every operational frequency, indicate that the antenna has been meticulously designed.