Abstract
In this paper, a meander-lines-based epsilon negative (ENG) metamaterial (MTM) with a high effective medium ratio (EMR) and near-zero refractive index (NZI) is designed and investigated for multiband microwave applications. The metamaterial unit cell is a modification of the conventional square split-ring resonator in which the meander line concept is utilized. The meander line helps to increase the electrical length of the rings and provides strong multiple resonances within a small dimension. The unit cell of proposed MTM is initiated on a low-cost FR4 substrate of 1.5 mm thick and electrical dimension of 0.06λ × 0.06λ, where wavelength, λ is calculated at the lowest resonance frequency (2.48 GHz). The MTM provides four major resonances of transmission coefficient (S21) at 2.48, 4.28, 9.36, and 13.7 GHz covering S, C, X, and Ku bands. It shows negative permittivity, near-zero permeability, and near-zero refractive index in the vicinity of these resonances. The equivalent circuit is designed and modeled in Advanced Design System (ADS) software. The simulated S21 of the MTM unit cell is compared with the measured one and both show close similarity. The array performance of the MTM is also evaluated by using 2 × 2, 4 × 4, and 8 × 8 arrays that show close resemblance with the unit cell. The MTM offers a high effective medium ratio (EMR) of 15.1, indicating the design's compactness. The frequency hopping characteristics of the proposed MTM is investigated by open and short-circuited the three outer rings split gaps by using three switches. Eight different combinations of the switching states provide eight different sets of multiband resonances within 2–18 GHz; those give the flexibility of using the proposed MTM operating in various frequency bands. For its small dimension, NZI, high EMR, and frequency hopping characteristics through switching, this metamaterial can be utilized for multiband microwave applications, especially to enhance the gain of multiband antennas.
Highlights
In this paper, a meander-lines-based epsilon negative (ENG) metamaterial (MTM) with a high effective medium ratio (EMR) and near-zero refractive index (NZI) is designed and investigated for multiband microwave applications
The results show a close similarity with each other though Advanced Design System (ADS) output deviates from the Computer Simulation Technology (CST) in the sense of two small resonances near 7.5 and 12 GHz
An ENG metamaterial based on meaner line resonators is presented that shows near-zero permeability and refractive index
Summary
The metamaterial property of the proposed MTM is extracted, and analysis has been done on the obtained result to identify the characteristic of the intended design. The effect of shorting the gap of the outer ring changes the total resonance phenomena due to the change of the total capacitance and inductance of the MTM unit cell, and three major resonances are observed at 5.85, 7.6, and 13.6 GHz, respectively, covering C and Ku bands. In the step, when switch S2 of the second outmost ring is closed, keeping unaffected by the other split gaps, four major resonances are observed near 2.9, 7, 10.8, 12.5 GHz covering S, C, X, and Ku bands This switching effect is noticed with the transformation of the capacitive effect of second ring to the inductive one that causes a change in resonance frequencies compared to the result obtained by the proposed MTM without any switch.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
