###### Abstract
Modern 5G antenna systems are required to have ultra-wideband (UWB) behavior with multi-band coverage and operation to adapt quickly to the newly released standards and their frequency bands [16; 17]. This allows for an easy transition to the new wireless standards for the end-users with enhanced data rates, and more bandwidth. It also allows for maintaining the sustainability and competitiveness of wireless communication systems. UWB antennas are preferred for such systems because of their huge bandwidth characteristics. The Federal Communication Commission (FCC), USA [18] has designated a frequency spectrum ranging from 3.1-10.6 GHz (7.5 GHz bandwidth) for UWB antennas for low-power emission applications. For modern wireless communication systems, microstrip patch antennas (MPAs) [19] are typically preferred and have gained popularity due to their small size and weight, low-cost, ease of fabrication, and compatibility with other transceiver components. The MPAs are also sometimes referred to as planar antennas [19]. The MPAs have some inherent disadvantages: they offer narrow bandwidth, and they typically resonate at a single frequency, although these shortcomings can be overcome by adding slots [7; 11; 20] and slits [9; 12] in the main resonating patch. The UWB antenna can be realized using several techniques. For example, researchers have designed UWB antennas using (1) planar wideband antenna technique, (2) fractal structure oriented UWB antenna technique, (3) MTM inspired UWB antenna technique, and (4) wearable UWB antenna techniques using planar antenna concepts [11; 12; 13; 17; 18; 21; 22; 23; 24; 25; 26]. One of the serious constraints in the design and operation of UWB antennas is the interference with other neighboring communication systems that use the frequency bands within the UWB range. It is therefore critically important for the researchers and the systems designers to reject or filter these interfering bands, which leads to the concept of filtering, and notch-band characteristics [18]. A number of researchers have proposed and investigated different UWB filter designs with band-rejection capabilities and selectivity at different frequency bands to solve this problem [27]. On the other hand, antennas with band-rejection characteristics can also be designed using different techniques to select certain frequency bands and reject others. This behavior in antennas is also referred to as notch-band characteristics and it can be realized by using techniques like (1) introduction of slots in the resonating patch, and (2) introduction of MTM-oriented structures such as electromagnetic bandgap (EBG) structures, split-ring resonator (SRR) structures, parasitic elements, frequency selective surfaces (FSS)/meta-surfaces, meander-line structures, etc. in the resonating patch [11; 12; 13; 18; 26; 27; 28; 29; 30; 31; 32; 33]. Depending on the technique employed, the antenna can be made to reject single as well as multiple frequency bands. In some cases, both the slot- as well as MTM-based techniques can be exploited together to implement effective and useful notch-band characteristics. Most of the researchers had faced difficulties in controlling each operational and rejection band individually. Therefore, in this paper, the authors exploit both MTM and slot-based techniques and propose a MTM square split-ring resonator (SSRR) structure inspired triple-band operation UWB inverted triangular antenna with dual-notch band characteristics for the currently deployed 5G mobile base-stations (BSs), upcoming WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications, respectively. The antenna operates in the frequency range of the 3-12 GHz band. The radiating patch of the antenna is based on the inverted modified triangular patch.