Numerical analysis of the concentric ring number for electric field sensing with a Split-Ring Resonator metamaterial

Wireless communications have experienced a tremendous development during the last decade. The interaction of the electromagnetic waves as a function of the frequency and intensity with physical objects remains largely unknown. This poses the challenge to study the physical mechanisms involved to actually quantify the impact of the interaction with other objects caused by various electromagnetic waves-emitting sources. Here, we proposed the design of a plane SRR (Split-Ring Resonator) with metamaterial circular rings for S-Band frequency range. To guide the construction of the SRR prototype, simulations of the bandwidth were conducted using the Finite Integral technique. A logarithmic function describes the dependence of the simulated resonant frequency. The maximum simulated bandwidth of the SRR can be reached with an even number of concentric rings. 1.Introduction Metamaterials with electrical negative indexes have had a great impact in the field of optics and electromagnetism [1]. These artificially metal-dielectric composites with periodic structures whose maximum dimension is less than the wavelength of interest have had a major impact in communications systems. In particular, the development of miniaturized antennas to improve the directivity, radiation pattern and efficiency has gained a great deal of interest due to the growing demand of more efficient communications systems. Multiband antennas can be designed with different structures such as the Split Ring Resonators (SRR) [2-5]. The experimental development of this type of antennas has been not fully investigated. In this paper, a metamaterial effect was obtained using a pair of concentric circles having a slot, one ring geometrically opposite to the other [6-7], and we studied the dependence of the number of concentric ring pairs for a flat SRR, the bandwidth and resonance frequency. The proposed design could be employed for electric field sensing in communications working in the S-Band (2-4GHz). 2.Methods and Results A flat SRR metamaterial with circular rings was designed. This geometry minimizes the leakage currents caused by discontinuities at right angles. Figure 1 shows the schematics of an elementary structure. Table 1 summarizes the dimensions of the antenna prototype. The Finite integration technique (FIT) was used to simulate the S11-parameters with the Software Tool CST (CST Microwave Studio, VIII International Congress of Engineering Physics IOP Publishing IOP Conf. Series: Journal of Physics: Conf. Series 792 (2017) 012086 doi:10.1088/1742-6596/792/1/012086 International Conference on Recent Trends in Physics 2016 (ICRTP2016) IOP Publishing Journal of Physics: Conference Series 755 (2016) 011001 doi:10.1088/1742-6596/755/1/011001 Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1 Darmstadt, Germany). This software is able to determine the reflection coefficients based on a time domain solver, which obtains the frequency response due to a temporary stimulus. Table 1 data was also used for all electromagnetic simulations. Figure 2 shows the simulated S11-parameter for the resonance frequency as a function of the number of concentric ring pairs. Figure 1. Design of the flat metamaterial SRR with circular rings. a) primary structure, b) current feeding microstrip. Table 1. Physical characteristics of a flat metamaterial SRR used for the numerical analysis of finite integration in the time domain (FITD), and a FR4 substrate with an electrical permittivity εr=4.3. Name [mm] Description delta_sep 0.3 Separation of the track h 2 Height of the substrate lg 1.0 Length of the wave-guide lm 5.0 Length of the Microstrip-line lrmax 17.0 Length of the maximum radius Ls 40.0 Length of the substrate Mt 0.035 Thickness of the microstrip-line wg 0.5 Width of the wave guide wm 1.8 Width of the microstripline x_sep 2.0 Separation of the split ring y_sep 0.1 Separation between each pair of rings VIII International Congress of Engineering Physics IOP Publishing IOP Conf. Series: Journal of Physics: Conf. Series 792 (2017) 012086 doi:10.1088/1742-6596/792/1/012086