## 1 Introduction  
High-data technology and a low-cost wide bandwidth are suitable means of enhancing the data rate. The rate of transmission is the requirement of communication systems nowadays. In recent years, researchers have studied high data rates and increased channel capacity. The ultra-wideband (UWB) technology is capable to provide both of these properties when combined with MIMO systems. It is already used in short-range communication, radar, and position-tracking applications. The diversity technology performance of multiple-input-multiple-output (MIMO) systems enables high transmission and mitigates the multiple path fading to enhance the channel capacity. In 2002, the federal communication commission (FCC) introduced ultra-wideband technology and provided the frequency spectrum (3.1-10.6) GHz to it with limited power emission [1, 2]. The frequency band of ultra-wideband technology is used in commercial and a wide variety of mobile applications [3, 4, 5]. The allocated narrow band within the UWB, such as worldwide interoperability microwave access WiMax (3.1-3.9 GHz), C-band (4-4.3 GHz), WLAN (5.1-5.9 GHz), and X-band satellite communication (7.9-8.9 GHz) have high traffic in addition to interference with UWB. Different techniques have been stated in the past to perform band notching within the UWB technology in order to co-exist with the other band of communication. The UWB-MIMO antenna can achieve notching by placing slits and slots on either the main radiator or on the ground side. Decoupling structures can provide good isolation between the different elements of MIMO [6]. As a result, the antenna may achieve a wider bandwidth along with low mutual coupling. A slot is added to the main radiator which, along with parasitic elements, are used in quasi-self-complementary antennas to introduce multiple notches [7]. In [8], different band notches are introduced in the polygonal-shaped monopole antenna by inserting multiple L-shaped strips. Filters are also used to suppress certain bands. The bandpass filter (BPF) or band stop filters may be used to remove the interference as in [9; 10]. The UWB-MIMO antenna introduced F-shaped stubs in the ground plane to achieve low mutual coupling and better diversity parameters [11]. The antenna achieved better diversity performance and low mutual coupling between the antenna elements. In [12], a tapered-fed compact size, UWB-MIMO diversity antenna with dual notching characteristics is presented. The tapered fed microstrip slot antenna with a small size acts as a single element for radiation, and an inverted L-shape is used to introduce the notches at the WLAN and IEEE-INSAT C-band. In [13], the compact dual-band MIMO antenna has low mutual coupling between the elements which creates notches for WLAN and X-band satellites using orthogonal polarization. One slot is on the upper side of the patch, and two slots are etched at the bottom to reduce the interference between notching elements and further enhance the impedance matching. The two main things that are considered in designing an MIMO antenna system are an appropriate size and low mutual coupling between the antenna elements. The coupling between the elements of antenna is reduced with the incremental distance in array size. However, increasing the distance between antenna elements will create a larger antenna size. Different methods have been used for the miniaturization and reduction in mutual coupling of an antenna such as cross polarization, orthogonal elements, electromagnetic band gap (EBG) structure [14], meander line, in [15], defective ground structure (DGS) [16; 17; 18], parasitic element [19; 20], meta-material with neutralized line [21], and slits/slots or the use of carbon black film [22]. In [23], a quad port MIMO Filtenna with a compact dimension of 50 \(\times\) 50 mm\({}^{2}\) was presented. The MIMO antenna was designed based on the novel COVID-19 virus shape with a co-planar waveguide feeding structure.