Metamaterial Unit Cell Structure Research Articles

Telemetric angle and position sensing using millimeter-wave metamaterial and a frequency-modulated continuous-wave (FMCW) chip

Abstract. We present a fully telemetric sensor concept for angle and position measurement. It is based on single-layer millimeter-wave metamaterials that exhibit an anisotropic resonant behavior in interaction with incident electromagnetic waves. The angle of rotation is determined from the reflected millimeter waves of the metamaterial target using a millimeter wave chip transceiver. We use a metamaterial geometry exhibiting anisotropic Fano-type resonant behavior. The Fano-type resonance shows a distinct minimum in the reflection spectrum, even with a single layer of metamaterial. The metamaterial target is manufactured on a printed circuit board (PCB) laminate with low-cost standard manufacturing methods. We present an analytical model estimating the resonance frequency of the metamaterial used. The model allows us to assess whether with the Fano-type metamaterial unit cell structure resonance frequencies in the millimeter wave regime are achievable and compliant with standard PCB manufacturing design rules. We performed proof-of-principle experiments with the metamaterial targets and a vector network analyzer, assisted by a detailed analysis of the sensor effect by means of finite-element method calculations. Finally, we implemented a demonstrator setup containing a state-of-the-art frequency-modulated continuous-wave (FMCW) radar chip and a metamaterial target manufactured with standard PCB manufacturing processes.

Metamaterial as perfect absorber for high sensitivity refractive index based biosensing applications at infrared frequencies

In this paper, we introduce a novel design of a metamaterial unit cell absorber, which is based on a metal/insulator/metal sandwich structure. The design is subjected to comprehensive finite element method computational analysis to ensure accurate and reliable results. The proposed metamaterial sandwich structure demonstrates exceptional absorption performance, achieving a nearly perfect absorption rate of 99.996% at the resonance infrared frequency of 39.8 THz. To provide a detailed theoretical explanation of nearly perfect absorption, we employ the effective medium theory, impedance matching, and field distribution analysis. Additionally, we have optimized the structural parameters of the sensor to maximize its absorption peak. This includes optimizing the thickness of the gold (Au) layer (from 0.03 to 0.28 μm), the distance between the L shape corners (from 0.60 to 0.90 μm), and the thickness of SiC dielectric spacer (from 0.20 to 0.45 μm). Furthermore, we showcase the remarkable sensitivity of the proposed metamaterial unit cell in detecting subtle changes in the refractive index through the implementation of a sensing medium setup in our model. Remarkably, we achieve a frequency shift sensitivity of 3.74 THz/RIU, along with a quality factor of 10.33, for a wide range of refractive indices (1.0–2.0). Moreover, for cancer detection, we attain a sensitivity of 3.5 THz/RIU. These findings highlight the exceptional performance of our approach in accurately detecting changes in refractive index, making it a promising candidate for various sensing applications. The novelty of our work lies in the design of a metamaterial unit cell structure. This configuration exhibits several noteworthy features, including wide incident angle () coverage up to 60°, polarization insensitivity, exceptional frequency shift sensitivity, high absorption peaks across a wide range of refractive indices, and the ability to distinguish cancer cells from healthy ones.

Compact triple band-stop filter using novel epsilon-shaped metamaterial with lumped capacitor

This paper presents the design of a novel epsilon-shaped metamaterial unit cell structure that is applicable for single-band and multi-band applications. A closed-form formulas to control the resonance frequencies of the proposed design are included. The proposed unit cell, which exhibits negative permeability at its frequency bands, is etched from the ground plane to form a band-stop filter. The filter design is constructed to validate the band-notched characteristics of the proposed unit cell. A lumped capacitor is inserted for size reduction purpose in addition to multi-resonance generation. The fundamental resonance frequency is translated from 3.62 GHz to 2.45 GHz, which means that the filter size will be more compact (more than 32% size reduction). The overall size of the proposed filter is 13 × 6 × 1.524 mm3, where the electrical size is 0.221λg × 0.102λg × 0.026λg at the lower frequency band (2.45 GHz). Two other resonance frequencies are generated at 5.3 GHz and 9.2 GHz, which confirm the multi-band behavior of the proposed filter. Good agreement between simulated and measured characteristics of the fabricated filter prototype is achieved.

Design of miniaturized, low-loss and flexible multi-band metamaterial for microwave application

In this paper, a novel miniaturized low-loss metamaterial unit cell structure, called circular spiral split ring resonator (CSSRR), operating at microwave frequency regime is introduced. The miniaturization is realized with inductive loading by increasing the length of metallic spiral strips inside the structure. Due to inductive loading, the effective inductance-to-capacitance ratio, L/C, is increased as a consequence, low-loss behaviour is also obtained along with the compactness. Despite of miniaturization and low loss, the introduced structure exhibits multi-resonance property with two distinct e-negative (ENG) regions and one µ-negative (MNG) region over the X, Ku, and K microwave frequency bands. Particularly, the low-loss behaviour is observed for all three resonance frequencies of the proposed structure. Furthermore, the presented metamaterial is flexible and provides stable characteristics to bending as well as twisting effect.

Analogue Electromagnetically Induced Transparency Based on Low-loss Metamaterial and its Application in Nanosensor and Slow-light Device

In this paper, we demonstrated a low-loss and high-transmission analogy of electromagnetically induced transparency based on all-dieletric metasurface. The metamaterial unit cell structure is composed of two mutually perpendicular silicon nanoscale bars. Under the joint effects of the neighboring meta-atoms’ coherent interaction and significant low absorption loss, the transmission and the Q-factor can reach up to 93 % and 139, respectively. Moreover, we use the coupled harmonic oscillator model to analyze the near field interaction between the two elements in the electromagnetically induced transparency (EIT) metamaterial unit cell qualitatively and the effects of parameters on EIT. The figure-of-merit of 42 and the group delay of 0.65 ps are obtained. These characteristics make the metamaterial structure with potential to apply for ultrafast switches, sensor, and slow-light devices.

Active plasmonic band-stop filters based on graphene metamaterial at THz wavelengths.

Active plasmonic band-stop filters based on single- and double-layer doped graphene metamaterials at the THz wavelengths are proposed and investigated numerically by using the finite-difference time-domain (FDTD) method. The metamaterial unit cell structure is composed of two parallel graphene nanoscale ribbons. Simulated results exhibit that significant resonance wavelength shifts can be achieved with a slight variation of the doping concentration of the graphene ribbons. Besides, the asymmetry double-layer graphene metamaterial device has two apparent filter dips while the symmetry single-, double-layer and asymmetry single-layer graphene metamaterial devices just only one. The metamaterials with symmetry single-layer and asymmetry double-layer graphene can be used as a high-sensitivity refractive sensor with the sensitivity up to 5100 nm/RIU and a two-circuit switch, respectively. These prospects pave the way towards ultrafast active graphene-based plasmonic devices for THz applications.

Metamaterial Inspired Microstrip Antenna Investigations Using Metascreens

A dual layer periodically patterned metamaterial inspired antenna on a low cost FR4 substrate is designed, simulated, fabricated, and tested. The eigenmode dispersion simulations are performed indicating the left handed metamaterial characteristics and are tunable with substrate permittivity. The same metamaterial unit cell structure is utilized to fabricate a metascreen. This metascreen is applied below the proposed metamaterial antenna and next used as superstrate above a simple patch to study the effects on impedance bandwidth, gain, and radiation patterns. The experimental results of these antennas are very good and closely match with the simulations. More importantly, the resonance for the proposed metamaterial antenna with metascreen occurs at the left handed (LH) eigenfrequency of the metamaterial unit cell structure. The measured −10 dB bandwidths are 14.56% and 22.86% for the metamaterial antenna with single and double metascreens, respectively. The metascreens over the simple patch show adjacent dual band response. The first and second bands have measured −10 dB bandwidths of 9.6% and 16.66%. The simulated peak gain and radiation efficiency are 1.83 dBi and 74%, respectively. The radiation patterns are also very good and could be useful in the UWB wireless applications.

High Gain Resonant Cavity Antenna with Meta-material Inspired Superstrate

Abstract A high gain planar Resonant Cavity Antenna (RCA) inspired by metamaterial superstrate is proposed operating at C-band. The RCA is modelled using simple ray tracing method. The unit cell metamaterial consists of Artificial Magnetic Conductor (AMC) and square patch laminated on either side of magneto-dielectric material, is used as the superstrate to design RCA. Square patch is capacitive type and that AMC as inductive. Effects of the reflection phase of the substrate decides the gain of the antenna. A cylindrical dielectric resonator antenna (CDRA) has been used as the primary radiator. The metamaterial unit cell structure is characterized and its effective material parameters are extracted through its S-parameters simulation. The proposed antenna achieves 12.5dBi gain with only 2x2 array superstrate.The results of upto 12 x 12 array superstrate with multiple layers can be demonstrated for higher gain over wide frequency range.

Design of a Single Negative Metamaterial based Microstrip Patch Antenna

paper describes the design and simulation of the new Ɛ negative metamaterial unit cell structure and then the unit cells are combined to form 3D array which use as metamaterial cover with a single microstrip patch antenna. The new Ɛ negative metamaterial is based on the ELC resonator structure, which is used for obtaining the negative value of permittivity and positive value of permeability. Simulation result shows that the gain of the antenna has been increased with metamaterial cover up to 1.46db .This has to proven that metamaterial as a cover enhance the directive properties of conventional microstrip patch antenna. Keywordsial (MTM), Epsilon negative (ENG) metamaterial, Microstrip Antenna (MSA), Electric-LC (ELC) Resonator, HFSS.

The Design and Analysis of a Novel Split-H-Shaped Metamaterial for Multi-Band Microwave Applications.

This paper presents the design and analysis of a novel split-H-shaped metamaterial unit cell structure that is applicable in a multi-band frequency range and that exhibits negative permeability and permittivity in those frequency bands. In the basic design, the separate split-square resonators are joined by a metal link to form an H-shaped unit structure. Moreover, an analysis and a comparison of the 1 × 1 array and 2 × 2 array structures and the 1 × 1 and 2 × 2 unit cell configurations were performed. All of these configurations demonstrate multi-band operating frequencies (S-band, C-band, X-band and Ku-band) with double-negative characteristics. The equivalent circuit model and measured result for each unit cell are presented to validate the resonant behavior. The commercially available finite-difference time-domain (FDTD)-based simulation software, Computer Simulation Technology (CST) Microwave Studio, was used to obtain the reflection and transmission parameters of each unit cell. This is a novel and promising design in the electromagnetic paradigm for its simplicity, scalability, double-negative characteristics and multi-band operation.

A New Double Negative Metamaterial for C-Band Microwave Applications

Metamaterials are artificial materials that show extra ordinary electromagnetic properties which are not available in nature. It has opened a new era in the field of material science. It can be defined as an exotic electromagnetic structure that may show both negative permittivity and negative permeability simultaneously within a frequency range. Metamaterials with simultaneous negative permeability and permittivity are called Double Negative Metamaterials (DNG). In this paper, a new metamaterial unit cell structure has been proposed that exhibits resonance within frequency of C-band and shows a negative permeability and permittivity at that resonant frequency. In the proposed structure, two separate split ring resonators and a metallic bar has been used. A commercially available simulation software CST Microwave Studio has been used to get the reflection and transmission parameters for the unit cell.

A new double negative metamaterial for multi-band microwave applications

This paper reveals the design and analysis of a new split-H-shaped metamaterial unit cell structure that is applicable for multi-band frequency range, and it shows negative permeability and permittivity at those frequency bands. In the basic design, the two separate split square resonators have been added by a metal link to form H-shape unit structure. Moreover, the analyses and comparison of the 1 × 1-array, 2 × 2-array structures and 1 × 1, 2 × 2 unit cell configurations have been investigated. All these configurations demonstrate its multi-band operating frequency (S-band, C-band, X-band, K u -band) with double negative characteristics. The equivalent circuit model for the unit cell is presented to demonstrate the validation of the resonant behavior. The commercially available finite-difference time-domain based simulation software CST microwave studio has been used to get the reflection and transmission parameters of the unit cell. In summation, the material also exhibits single negative characteristics in the multi-band frequency range if it is projected on the 20 × 20 mm2 substrates. The simplicity, scalability, double negative characteristics, and multi-band operations have made this design novel in the electromagnetic paradigm.