Inductively tuned modified split ring resonator based quad band epsilon negative (ENG) with near zero index (NZI) metamaterial for multiband antenna performance enhancement

Abstract

An inductively tuned modified split-ring resonator-based metamaterial (MTM) is presented in this article that provides multiple resonances covering S, C, X, and Ku-bands. The MTM is designed on an FR-4 substrate with a thickness of 1.5 mm and an electrical dimension of 0.063λ × 0.063λ where wavelength, λ is calculated at 2.38 GHz. The resonator part is a combination of three squared copper rings and one circular ring in which all the square rings are modified shaped, and the inner two rings are interconnected. The resonance frequency is tuned by adding inductive metal strips in parallel two vertical splits of the outer ring that causes a significant shift of resonances towards the lower frequencies and a highly effective medium ratio (EMR) of 15.75. Numerical simulation software CST microwave studio is used for the simulation and performance analysis of the proposed unit cell. The MTM unit cell exhibits six resonances of transmission coefficient (S21) at 2.38, 4.24, 5.98, 9.55, 12.1, and 14.34 GHz covering S, C, X, and Ku-bands with epsilon negative (ENG), near-zero permeability, and near-zero refractive index (NZI). The simulated result is validated by experiment with good agreement between them. The performance of the array of the unit cells is also investigated in both simulation and measurement. The equivalent circuit modeling has been accomplished using Advanced Design Software (ADS) that shows a similar S21 response compared to CST simulation. Noteworthy to mention that with the copper backplane, the same unit cell provides multiband absorption properties with four major absorption peaks of 99.6%, 95.7%, 99.9%, 92.7% with quality factors(Q-factor) of 28.4, 34.4, 23, and 32 at 3.98, 5.5, 11.73 and 13.47 GHz, respectively which can be applied for sensing and detecting purposes. The application of an array of the unit cells is investigated using it as a superstrate of an antenna that provides a 73% (average) increase of antenna gain. Due to its simple design, compact dimension with high EMR, ENG property with near-zero permeability, this multiband NZI metamaterial can be used for microwave applications, especially for multiband antenna gain enhancement.

Gap coupled symmetric split ring resonator based near zero index ENG metamaterial for gain improvement of monopole antenna

“…Coupling reduction in MIMO antenna system 2. Meander line-based diagonally coupled MTM 17 2021 8 × 8 0.063λ × 0.063λ 2.38, 4.24, 5.98, 9.55, 12.1, 14.34 15.75 S, C, X, Ku 1. Symmetric about the vertical axis 2.…”

“…Moreover, the presented MIMO system with MTM helps to achieve size reduction and good diversity gain 16 . In another work, a metamaterial with near zero index is used to improve gain of a multiband antenna using MTM as a superstrate 17 . The metamaterial is also utilized by Das et al to increase the bandwidth and gain of monopole antenna 18 , whereas Ke et al .…”

Meta-atom Microfluidic Sensor for Highly Sensitive Cell Detection

“…From a circuit theory perspective, a SRR can be considered as a resonator, which is coupled with illuminated electromagnetic wave. It can be modeled using an LC circuit and the resonance frequency of this LC circuit is as follows [17]:…”

Modeling of a Negative Refractive Index Metamaterial Unit-Cell and Array for Aircraft Surveillance Applications

“…Despite these discrepancies, the fabricated result closely resembles the simulated outcome. The difference between simulated and measured results is also affected by the type of substrate material, with approximately 5% experimental error being acceptable for lossy substrate materials [38] [39].…”

“…As seen in Figure 17(e), the scattered H-field begins to flow in the same direction and accumulates at the split or gap between the circular and square SRRs. As shown in Figure 17(b) & (d), the E and H-fields display opposite excitation at the resonant frequency, hence the proposed NRI-MTM (unitcell, 1×2 SCM array, and 2×2 SCM array) fulfils the Maxwell equation [42][43] [44].…”