# Triple-Band Notched Ultra-Wideband Microstrip MIMO Antenna with Bluetooth Band
## 1 Introduction  
The communication link depending on ultra-wideband technology is a promising solution for numerous wireless networks, such as wireless body area networks (WBANs), Internet of Things (IoT) network systems, personal area networks (PAN), and remote sensing networks. The ultra-wideband communication network was selected because it uses a very high bandwidth radiator, which enables high-speed data transmission with low power consumption (i.e., \(-\)44.2 dBm) [1]. The UWB technologies utilize a very small pulse width (i.e., very large frequency range) through the transmission process over a short range distance (i.e., few meters) in smart homes, hospitals, etc. Therefore, the UWB radiator is an essential component of ultra-wideband network systems. In 2002, the US Federal Communications Commission (US-FCC) issued an unlicensed spectrum of bands ranging from 3.1 to 10.6 GHz with an operating bandwidth of 7.5 GHz for commercial applications. The profile of the ultra-wideband antenna design can be classified into a 3D-UWB antenna and a 2D-UWB antenna according to the requirements of the communicationsystem [1; 2]. The 3D-UWB antenna includes the biconical antenna, the discone antenna, and the log periodic dipole antenna. The 2D-UWB antenna includes planar antennas, printed/microstrip antennas, and dielectric resonator (DRA) antennas. The UWB microstrip radiators have numerous benefits, such as a small circuit size, low cost of fabrication, and the ability to connect with a different circuit. In [2], a printed ultra-wideband antenna fed by the coplanar waveguide (CPW) technique was reported. The reported antenna was designed and fabricated on FR-4 substrate material with relative permittivity of 4.4 and a substrate height of 1.6 mm. Both the radiating element with its feeding line and the ground plane were placed on the top layer of the substrate material. The radiating patch antenna was embedded within the rectangular slot of the ground plane and connected to the CPW input feed line. Since the FCC-UWB spectrum signal is utilized within a small distance (i.e., office, home, or hospital), it faces the main problem of interfering with other narrow unlicensed band signals such as WiMAX 3.5 GHz (3.3-3.8 GHz), WLAN 5.8 GHz (5.15-5.85 GHz), and the X-band satellite communication (7.9-8.4 GHz) spectrum. The presence of these notch bands affects the efficiency of the communication link using the FCC-UWB spectrum. The solution to this issue is to utilize UWB antennas with single-, dual-, or triple-band notches at these narrow unlicensed spectra [3; 4; 5]. In [3], a printed dongle antenna used for ultra-wideband networks with a single narrow band rejection (i.e., WLAN) was reported. The radiator element was designed based on the self-complementary technique. A patch antenna with a Von Koch fractal shape at its boundary was designed. A rejected WLAN band was achieved by etching a fractal slot on the patch radiator near the CPW feed line. The reported monopole antenna was fabricated on FR-4 substrate material. In [4], an annular-ring monopole-printed antenna was reported to achieve ultra-wideband characteristics. The radiating element consists of an annular-ring-shaped monopole antenna. A pair of split ring resonators (SRRs) is placed on a superstrate over the CPW feed line to obtain dual band notches. In [5], an UWB-printed circular monopole patch radiator with a triple notch band was reported. The notch bands were achieved by loading triple split ring resonators (SRRs) on the opposite side of the CPW feeding line. One SSR is used for each notch band (i.e., 3.5 GHz WiMAX, 5.5 GHz WLAN, and 7.9 GHz X-band for satellite communication link). The printed antenna and SSRs are designed and fabricated on FR4-Epoxy material. Since the UWB antenna uses an RF signal with low power and in the presence of some obstacles causing multipath fading, the multiple-input multiple-output (MIMO) network was introduced as a promising solution to solve this issue.