## 1 Introduction  
Exploring new physicochemical phenomena that arise, when materials are confined to the nanoscale, as surface energy becomes relevant or dominates the volume energy, is one of the fundamental strengths of the multifunctional applied materials science. However, there are different compositional and shape configurations that belong to the microscalethat dazzle by their high versatility and variability in their properties, when they are subjected to an external stimulus (i.e., an applied electric and/or magnetic field, mechanical stresses, temperature, and a gas exposure) [1; 2; 3; 4; 5; 6; 7]. Specifically for the electromagnetic microwave technology, multifunctional materials with tunable properties by external stimuli are essential to progression in the field of sensing applications [4; 8; 9], microwave shielding systems [7; 10; 11; 12], wireless communication [13; 14], antenna engineering [15; 16], hyperthermia [17], and biomedical engineering [18; 19; 20]. The crossed control of the electromagnetic properties is appealing for advanced performances, involving the ability of modulating the electrical response by means of a magnetic field and conversely. Such cross-modulation requires materials with strong magneto-electric coupling [21]. In this scenario, Fe\({}_{2.25}\)Co\({}_{72.75}\)Si\({}_{10}\)B\({}_{15}\) amorphous ferromagnetic microwires (Co-based MWs) are excellent candidates for hosting the multifunctionality for microwave sensing applications, because they exhibit a high-frequency giant magneto-impedance (GMI) effect, being highly sensitive to those external stimuli [2; 3; 22]. The Co-based microwires (MWs) with a small addition of Fe or Mn present a near-zero negative magnetostriction of the order of \(10^{-7}\) and show a predominant circumferential magnetic anisotropy [23]. The latter is the result of the coupling between the negative magnetostriction and the large internal tensile along the MWs induced by the Taylor-Ulitovsky technique [24; 25; 26; 27]. [PERSON] et al. [28] theoretically demonstrated for the first time a giant GMI effect with a peak in the longitudinal component of the MW impedance at the magnetic anisotropy field (\(H_{\mathrm{K}}\)), when the easy direction of the magnetization is circumferential. Since then, many works have been made studying the evolution of their mechanical, electrical, and magnetic properties as a function of a thermal annealing [29], mechanical stress under annealing [30; 31], and twisting the MW a certain angle [32] (among others). Furthermore, tunable and enhanced physical properties are obtained when the MWs are distributed in an array with interesting and powerful results [33; 34; 29; 35]. In this line, wireless systems that are composed by MWs with GMI effects in the microwave range have been recently reported [36]. In the presence of electromagnetic waves, the frequency that is associated to the maximum scattering is determined by the length of the MW through a dipole electric resonance [37]. The scattering coefficient (\(S_{21}\)) can be modulated by means of the application of a DC or AC magnetic field in the presence of GHz-ranged electromagnetic wave due to the GMI effect observed in Co-based MWs. The present work is conceived to identify novel configurations of MW arrangement to obtain strong microwave scattering effects adjustable by DC or AC magnetic fields. In such a scenario, a parallel Co-based MWs arrangement (equidistantly spaced) presents substantial improvements of the scattering coefficient \(S_{21}\) as a function of their distribution and number of MWs. The physical mechanism behind is based on the high-frequency electric current that is induced in the MW due to the incident electric field component (\(E^{\mathrm{inc}}\)) and parallel to the axis of the MW coming from the electromagnetic wave with frequencies in the GHz range. Here, the MW polarization depends strongly on the surface impedance and the magnetic skin depth (\(\delta_{\mathrm{m}}\)) near the MW resonance.