## 3 Related Work
The proposed antenna design exhibited a satisfactory operation bandwidth for both frequency bands. [PERSON] et al. [60] introduced a novel hybrid algorithm based on Jaya [61] and GWO. Based on the proposed algorithm, the authors designed and fabricated two modified E-shaped circularly-polarized patch antennas operating in the 5G frequency bands of 3.7 GHz and 26 GHz. Simulated and measured results for both antennas were in good agreement. The presented antennas exhibited wideband operation in the desired frequency bands and satisfactory current distribution for circular polarization. The binary GWO has been applied in [62] to design and optimize an arbitrary-shaped dual-band patch antenna. Numerical results demonstrated the effectiveness of the utilized algorithm to the application of discrete-valued problems in antenna design. Finally, [PERSON] et al. [63] designed and presented a Vivaldi antenna by applying an improved GWO to minimize the radar cross section (RCS), and therefore, to enhance the gain performance. The WOA [35] has also been employed recently in various optimization problems of antenna design. The optimization problem of sidelobe suppression has been addressed in [64; 65; 66; 67; 68]. In detail, [PERSON] et al. [64] applied the WOA to the synthesis of a sparse antenna array. Their objective was to achieve a significantly lower peak sidelobe level (pSSL) value in the radiation pattern of the antenna array. Simulated results showed the effectiveness of the applied algorithm in the suppression of SLL. [PERSON] et al. [65; 66] introduced the WOA to the synthesis of broadside linear aperiodic arrays with uniform excitation. From their presented results, the superiority of the WOA to suppress the pSLL combined with NDL is revealed, compared to other state-of-the-art algorithms. An improved WOA has been proposed in [67]. The authors applied the proposed algorithm to optimize the pattern of the MIMO radar system. Numerical results demonstrated the effectiveness of the algorithm and its ability to achieve pSLL and NDL at the desired levels. Additionally, the authors in [68] designed and optimized, in terms of amplitude, position and phase an antenna array structure in smart antenna technology by utilizing the WOA. Their objective was to obtain radiation patterns achievable SLL reduction by optimizing amplitude excitations, inter-element distances, and phases for each element of the array. Numerical results exhibited a relatively improved performance of the WOA against other popular algorithms. The problem of error mitigation in the radiation pattern of an antenna array has also been addressed with the use of WOA in [69]. [PERSON] et al. studied the failure correction of the radiation pattern in a linear array by applying the WOA and the Chaotic WOA (CWOA). Simulated results showed the efficacy of the algorithm to re-optimize the amplitude excitations of powered elements in a failed antenna array. A modified WOA has been employed by [70] for pattern synthesis of a linear antenna array. Computed results demonstrated the efficacy of the selected algorithm against other popular algorithms in the literature. The problem of scattering in a MIMO system is also of importance since it is related to the system channel capacity. The authors in [71] designed and optimized an antenna element of a MIMO system by applying a binary WOA with a crossover operator. Numerical results demonstrated the improvement of system capacity even for poor scattering environments. Moreover, the WOA has been utilized in the design of compact and planar antennas. In [72], the authors applied the WOA as an optimization technique to design and fabricate a quad H-slotted antenna at ISM (Industrial Scientific Medicine) frequency band of 2.45 GHz. The authors in [73] applied the WOA to design a planar inverted-F antenna (PIFA) for wearable wireless applications. Numerical results exhibited the validity of the proposed design structure.