###### Abstract  
A compact triple-band operation ultra-wideband (UWB) antenna with dual-notch band characteristics is presented in this paper. By inserting three metamaterial (MTM) square split-ring resonators (MTM-SSRRs) and a triangular slot on the radiating patch, the antenna develops measured dual-band rejection at 4.17-5.33 GHz and 6.5-8.9 GHz in the UWB frequency range (3-12 GHz). The proposed antenna offers three frequency bands of operation in the UWB range, which are between 3-4.17 GHz (-12 GHz bandwidth), 5.33-6.5 GHz (-1.17 GHz bandwidth), and 8.9-12 GHz (-3.1 GHz bandwidth), respectively. The higher resonating frequency band can be tuned/controlled by varying the width of the triangle slot, while the medium operational band can be controlled by adjusting the width of the SSRR slot. Initially, the simulated S-parameter response, 2D and 3D radiation patterns, gain, and surface current distribution of the proposed UWB inverted triangular antenna has been studied using epoxy glass FR4 substrate having parameters \(\varepsilon_{r}\) = 4.3, \(h\) = 1.6 mm, and tan \(\delta\) = 0.025, respectively. In order to validate the simulation results, the proposed UWB antenna with dual-notch band characteristics is finally fabricated and measured. The fabricated antenna's return-loss and far-field measurements show good agreement with the simulated results. The proposed antenna achieved the measured gain of 2.3 dBi, 4.9 dBi, and 5.2 dBi at 3.5 GHz, 6.1 GHz, and 9.25 GHz, respectively. Additionally, an in-depth comparative study is performed to analyze the performance of the proposed antenna with existing designs available in the literature. The results show that the proposed antenna is an excellent candidate for fifth-generation (5G) mobile base-stations, next-generation WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications. Ultra-wideband (UWB); metamaterial (MTM); square split-ring resonator (SSRR); fifth-generation (5G); WiFi-6E; indoor distributed antenna systems (IDAS); C-band; X-band +
Footnote †: journal:  
0000-0001-7111-1111-1111-1111-1111-1111-1111-11111-1111-11111-1111-11111-11111-11111-11111-111111-111111-111111-1111111-111111-1111111-1111111-1111111-11111111-1111111-11111111-1111  
media platforms, artificial intelligence (AI) applications, and live streaming websites will bring a 1000-fold upsurge in the network capacity which cannot be fulfilled by the currently deployed wireless technologies [1; 2]. It is anticipated that currently deployed 5G wireless technology can handle this demand because it offers massive low signal latency and power consumption, and increased bandwidth with data-transmission speeds comparable to an optical fiber by offering ~10 GB/s data rates, and several billion-user connection capacity [4]. Although the researchers and technology companies have already started exploring the possibilities for next-generation wireless technologies such as Beyond 5G (B5G) and sixth-generation (6G) wireless systems as well as broadband Wi-Fi technologies above 6 GHz frequency band such as WiFi-6E [1; 2; 3; 4]. In modern and upcoming wireless systems, the most important component in the radio frequency (RF) transceivers is the antenna, which plays a critical part in the way the signal is transmitted to the end-user. Antennas have been assigned functions such as beam-steering/beam-scanning [5; 6], multi-band operation [7; 8; 9], reconfigurability [10], band-notch characteristics [11; 12; 13], and gain-filtering [14]. Moreover, the need for antennas that can operate in multiple frequency bands has exponentially increased in recent years because of the introduction of new and different variants of Wi-Fi standards [2; 3; 4]. For example, IEEE 802.11 ac Wi-Fi standard offers 5 GHz single-band operation, whereas IEEE 802.11 ax (WiFi-6) offers 2.4 GHz/5 GHz dual-band operation, and future standards like WiFi-6E, which will be deployed in the years to come, will offer 2.4 GHz/5 GHz and 6 GHz triple-band operation with ultra-wide bandwidth [2; 3; 4; 15].