# Miniaturized Antenna Array-Based Novel Metamaterial Technology for Reconfigurable MIMO Systems
## 2 Antenna Array Design Details  
This antenna array is designed from two antenna elements printed on the same substrate for MIMO system design. Each antenna element is structured from three main parts: a printed monopole, an interdigital capacitor array, and a meander line. The proposed antenna is fed with CPW to eliminate the ground plane on the same patch side as well as ensure harmonics generation by accumulating the electrical charge on the ground plane [12]. Therefore, the proposed meander line is fetched to the ground plane of the proposed CPW structure. In such a structure, the effects of field gradients can be enhanced altimetry to realize bandwidth enhancements [3]. For this, the antenna gain bandwidth would be enhanced to realize the desired frequency resonances with maximum size reduction [5]. Nevertheless, the proposed antenna performance can be controlled by switching the connections between the antenna meander line and the ground plane through four LDR resistors. The proposed antenna array occupies an area of 50 \(\times\) 30 mm\({}^{2}\) when printed on an FR4 substrate of 1 mm thickness.  
For the MIMO configuration, the authors applied the design of two elements that are mounted on the same substrate with the same direction, as shown in Figure 1. The antenna array is defective with an MTM structure at the center position between the antenna elements to ensure surface wave sprucing at the desired frequency bands [6]. The proposed MTM structure is constructed using Minkowski fractal design with the third iteration. In such a structure, a high capacitive load is coupled near the edges of the proposed monopoles; in it, most fringing effects are initiated [3]. Logically, positioning such an MTM at the center of the proposed array would be an excellent option. In another aspect, the proposed MTM is structured to provide a single negative performance in which a high coupling redaction can be achieved [7]. Therefore, the surface wave mitigation between the antenna elements would vanish smoothly without significant phase reflections [11]. Simultaneously, a high diversity can be achieved by directing most antenna radiation away from the array center through the inductive imposing effect from the proposed MTM fractal structure [14].  
It is important to note that the introduction of the meander line has the effect of producing a frequency band that is distinct from the band emitted by the monopole, as will be demonstrated later. To regulate the mobility of the antenna surface current, an LDR switch is used to link the planned meander line to the antenna ground plane. The key benefit of including the interdigital capacitor in the design is that it may be used to balance the monopole antenna structure's induction effect and match the electromagnetic aperture coupling to the free space impedance. As will be demonstrated later [8], this would considerably increase the antenna radiation efficiency. The suggested antenna is then printed on an RF-4 substrate that is 1 mm thick. Ultimately, an RF-4 substrate with a 1 mm thickness and 4.4 dielectric constants is used to print the suggested antenna. Table 1 contains the remaining geometrical information about the proposed array.  
Figure 1: Antenna geometrical details in mm scale: (**a**) front view and (**b**) back view.