# Metamaterial Integrated Folded Dipole Antenna with Low SAR for 4G, 5G and NB-IoT Applications
## 1 Introduction
39 and 44 were designed by [8] respectively. In addition, [9] designed a band no. 44 antenna using ferrite as a substrate with permeability and permittivity of 3.7 and 7.8, respectively, with an optimized dimension of \(55\times 110\times 7\) mm\({}^{3}\). In comparison to [9], a ceramic-based antenna was proposed by [10] and resulted in a diminution of volume by 22% compared to the one not using the ceramic substrate, covering LTE band nos. 39, 40 and 44 with low correlation coefficients, to be used as MIMO antennas. The well-known IFA (Inverted F Antenna) [11] was modified for LTE band nos. 41 and 44 on a realistic PCB with dimensions of 100 \(\times\) 40 mm\({}^{2}\) for MIMO operations. In comparison to this [11], a MIMO antenna for the LTE band no. 7/17/13/20 was presented by [12], which requires a T-shaped dc line with two pin diodes for a reconfigurable frequency with the overall dimensions of 5 \(\times\) 125 \(\times\) 1 mm\({}^{3}\) to be used for laptop applications. A reconfigurable triple band tablet computer antenna for the LTE operation was proposed using the IFA/loop antenna [13] to cover the TDD LTE low, middle and high bands with an overall dimension of 160 \(\times\) 200 \(\times\) 3 mm\({}^{3}\). The research work of [13] was further improved for miniaturization in [14] with a wide band operation to cover the same TDD LTE low, middle and high bands that were previously used [13], but without the use of MIMO or frequency reconfigurable operations. The overall dimensions of [14] were reduced to 75 \(\times\) 140 \(\times\) 5.8 mm\({}^{3}\). The dimensions of the antenna can be reduced to 38.5 \(\times\) 25 mm\({}^{2}\) with the use of an asymmetric ground plane [15] with the band coverage of 40, 42 and 43. LTE base station antenna with MIMO operations was introduced by [16] to switch between LTE bands of 2.39-2.52 GHz and 1.825-2.925 GHz. The MIMO requirements can be avoided with the use of parasitic components [17] that can cover LTE low and high band applications with overall dimensions of 140 \(\times\) 70 \(\times\) 5 mm\({}^{3}\). Although the majority of designs available in the literature are compact, they focus only on some of the frequency bands, and those supporting a large number of bands are complex in design. Currently, most of the telecom operators are working in the 4G LTE service on the 2300 MHz TDD LTE band, i.e., band no. 40, and are in the process of including more bands for their growing data services. Thus, there will be high demand for small-size antennas in the near future that can support 4G, 5G and IoT bands to solve the problem of band congestion. Metamaterial integrated antennas can be an excellent solution for meeting such demands. Double Negative (DNG) metamaterials are unnatural materials that may mimic the negative behavior of permittivity and permeability. This negative behavior leads to a negative refractive index, which may exhibit many unnatural properties, such as backward wave propagation, negative refraction, inversion of the Doppler effect and Snell's law [18]. These extraordinary properties may be useful in controlling the wave radiation behavior of electromagnetic waves [19]. The integration of metamaterial with a patch antenna can be used to address many of the limitations [20; 21]. The designed antenna presented in this research work focuses on achieving a wide bandwidth to cover 4G/5G/IoT bands with a compact size to meet the requirements of radio equipment. The proposed antenna design is simple and planar in structure, and can be used in any radio device for LTE, NR and NB-IoT operations. Moreover, the design supports LTE bands from 33 to 43, NR-IoT bands B1, B2 and B25, and the 5G NR n78 band on a single chip for 4G/5G/IoT applications with a compact size of 35 \(\times\) 48 \(\times\) 1.62 mm\({}^{3}\). The remainder of the paper is structured in four sections. The metamaterial design and its specifications are addressed in Section 2. Section 3 discusses the detailed designing methodology for wideband achievement and results analysis.