###### Abstract  
In this article, we propose a light weight, low profile Multiple Input Multiple Output (MIMO) antenna system for compact 5 th Generation (5G) mmwave devices. Using a RO5880 substrate that is incredibly thin, the suggested antenna is made up of circular rings stacked vertically and horizontally on top of one another. The single element antenna board has dimensions of \(12\times 12\times 0.254\) mm\({}^{3}\) while the size of the radiating element is 6 \(\times\) 2 \(\times\) 0.254 mm\({}^{3}\) (0.56\(\lambda_{0}\times 0.19\lambda_{0}\times 0.02\lambda_{0}\)). The proposed antenna showed dual band characteristics. The first resonance showed a bandwidth of 10 GHz with a starting frequency of 23 GHz to an ending frequency point of 33 GHz followed by a second resonance bandwidth of 3.25 GHz ranging from 37.75 to 41 GHz, respectively. The proposed antenna is transformed into a four element Linear array system with size of 48 \(\times\) 12 \(\times\) 0.254 mm\({}^{3}\) (4.48\(\lambda_{0}\times 1.12\lambda_{0}\times 0.02\lambda_{0}\)). The isolation levels at both resonance bands were noted to be \(>\)20 dB which shows high levels of isolation among radiating elements. The MIMO parameters such as Envelope Correlation Co-efficient (ECC), Mean Effective Gain (MEG) and Diversity Gain (DG) were derived and were found to be in satisfactory limits. The proposed MIMO system model is fabricated and through validation and testing of the prototype, the results were found to be in good agreement with simulations. ol 2023 14, 776. 12.12.  
when it arrives at the receiver via multi-path in these circumstances, causing multi-path fading. The MIMO antenna, which is coupled with a combiner to increase the mean signal-to-noise (SNR) ratio and produce diversity gain, reduces the multi-path problem. There are four types of diversity combiners: switching, equal gain combining (EGC), maximum ratio combining, and selection combining (MRC). The branch with the highest SNR is chosen at any point in time in selection combining. The signal from the branch that meets the minimal threshold value is chosen by the switched combiner. The co-phased branch signals are added by EGC. Each branch in MRC has its phase weights applied so that the result is the sum of all of the SNR ratios. MIMO antennas when initially employed, boost spatial variety in order to combat channel fading. The information is being considered in a Rayleigh fading environment, where it is sent by antennas that take various routes to independently reach receiving antenna. The highest diversity increase in this scenario is referred to as Spatial Diversity. When separate information is delivered over antennas, the data rate is increased, which is known as Spatial Multiplexing. MIMO antennas have given wireless communication a new direction and are now particularly desirable for 5G applications. Higher data rate, low latency and with better system stability are the characteristics which make 5G a potential candidate for future wireless communication systems. Designing a MIMO antenna system is a complex task since modern communication devices are desired to be compact and slim. A wide scale placement of a 5G network requires the preparation of antenna infrastructure and the execution of new technical clarifications [5; 6]. The millimeter wave spectrum starting from 20 GHz to 300 GHz is well known for its multi gigabit/s transmission rate and larger bandwidth availability to meet the needs of 5G applications. The frequency bands centered at 28, 38, 60, and 73 GHz have been allocated for 5G mobile networks by the International Telecommunications Union (ITU). These frequency bands are currently unlicensed and are free to use. When using antennae for a communication system, the power is transmitted or received according to the spatial characteristics established for a network which results in determining the predefined users location. Several MIMO antenna systems have been proposed in the literature.