Split Ring Resonator Research Articles

Multichannel full-space coding metasurface with linearly-circularly-polarized wavefront manipulation

Abstract Achieving independent multitasked wavefront control by using an ultrathin plate is a challenge to increase information capacity in integration optics and radar applications. Transmission-reflection-integrated metasurface provides an efficient recipe primarily for multifunctional meta-device, however it is challenging to synergize both linear polarization (LP) and circular polarization (CP) using a single meta-plate. Here, a multichannel full-space coding metasurface composed of interleaved shared-aperture meta-atom is proposed to achieve large information capacity by capsulating judiciously engineered high efficiency triple sub-elements (modes) in four-layer scheme. By rotating dual-gap split ring resonator and varying size of “L” type structure insulating by a metallic ring with electrostatic-analogue shielding effect, both Pancharatnam–Berry (PB) and dynamic phases are independently realized under CP and LP waves, respectively. Such an extraordinary insulating strategy completely suppresses crosstalk among three modes and unprecedentedly increases the capability in yielding kaleidoscopic wavefront control. To verify the significance, a proof-of-concept metadevice is devised and experimentally demonstrated with tri-channel wavefront manipulations, exhibiting reflective dual-vortex beam and Bessel beam for forward and backward CP wave, respectively at high frequency, while transmissive polarization beam splitting for 45°-LP wave at low frequency. Our finding in polarization-direction multiplexing is expected to generate great interest in electromagnetic integration with emerging degree of freedoms.

Electrically switchable metamaterial analogue to electromagnetically induced transparency

In this paper, we propose an active electromagnetically induced transparency-like (EIT-like) metamaterial to investigate the electrically switchable behaviors. The EIT-like metamaterial is constructed by a “bright” comb-line resonator side-coupled with a “dark” split-ring resonator. The “bright” and “dark” resonators are individually or simultaneously soldered with PIN diodes. The diodes are connected with DC voltage sources through conducting wires. By adjusting the bias voltage within the range of 0.0–1.2 V, the resistance of PIN diode can be changed from 9000 to 1 Ω, thereby dynamically modulating the EIT-like spectrum. Both simulation and experiment results indicate that this active configuration can generate remarkable multi-band amplitude modulations on the EIT-like spectrum, and a significant modulation depth of up to 18.3 dB was achieved on the tested transmission through the metamaterial. Moreover, the transformation of transparency-to-absorption and slow light on-to-off switching actions are also obtained via electric biasing the proposed sample. These findings resulted from the EIT-like mechanism, which may promote the development of actively controlled photonic devices.

Design and analysis of a multi-modal refractive index plasmonic biosensor based on split ring resonator for detection of the various cancer cells

Design and analysis of a multi-modal refractive index plasmonic biosensor based on split ring resonator for detection of the various cancer cells

Unveiling photon–photon coupling induced transparency and absorption

Abstract This study presents the theoretical foundations of an analogous electromagnetically induced transparency (EIT) and absorption (EIA) which we are referring as coupling induced transparency (CIT) and absorption (CIA) respectively, along with an exploration of the transition between these phenomena. We provide a concise phenomenological description with analytical expressions for transmission spectra and dispersion elucidating how the interplay of coherent and dissipative interactions in a coupled system results in the emergence of level repulsion and attraction, corresponding to CIT and CIA, respectively. This theory comprehensively captures both the phenomena while modelling the microstripline loaded resonators and their couplings systematically. The model is validated through numerical simulations using a hybrid system comprising a split ring resonator (SRR) and electric inductive-capacitive (ELC) resonator in planar geometry. We analyse two cases while keeping ELC parameters constant; one involving a dynamic adjustment of the SRR size with a fixed split gap, and the other entailing a varying gap while maintaining a constant SRR size. Notably, in the first case, the dispersion profile of the transmission signal demonstrates level repulsion, while the second case results in level attraction, effectively showcasing CIT and CIA, respectively. These simulated findings not only align with the theoretical model but also underscore the versatility of our approach. Subsequently, we expand our model to a more general case, demonstrating that a controlled transition from CIT to CIA is achievable by manipulating the dissipation rate of individual modes within the hybrid system, leading to either coherent or dissipative interactions between the modes. The results provide a pathway for designing hybrid systems that can control the group velocity of light, offering potential applications in the fields of optical switching and quantum information technology.

Green Wearable Sensors and Antennas for Bio-Medicine, Green Internet of Things, Energy Harvesting, and Communication Systems.

This paper presents innovations in green electronic and computing technologies. The importance and the status of the main subjects in green electronic and computing technologies are presented in this paper. In the last semicentennial, the planet suffered from rapid changes in climate. The planet is suffering from increasingly wild storms, hurricanes, typhoons, hard droughts, increases in seawater height, floods, seawater acidification, decreases in groundwater reserves, and increases in global temperatures. These climate changes may be irreversible if companies, organizations, governments, and individuals do not act daily and rapidly to save the planet. Unfortunately, the continuous growth in the number of computing devices, cellular devices, smartphones, and other smart devices over the last fifty years has resulted in a rapid increase in climate change. It is severely crucial to design energy-efficient "green" technologies and devices. Toxic waste from computing and cellular devices is rapidly filling up landfills and increasing air and water pollution. This electronic waste contains hazardous and toxic materials that pollute the environment and affect our health. Green computing and electronic engineering are employed to address this climate disaster. The development of green materials, green energy, waste, and recycling are the major objectives in innovation and research in green computing and electronics technologies. Energy-harvesting technologies can be used to produce and store green energy. Wearable active sensors and metamaterial antennas with circular split ring resonators (CSSRs) containing energy-harvesting units are presented in this paper. The measured bandwidth of the matched sensor is around 65% for VSWR, which is better than 3:1. The sensor gain is 14.1 dB at 2.62 GHz. A wideband 0.4 GHz to 6.4 GHz slot antenna with an RF energy-harvesting unit is presented in this paper. The Skyworks Schottky diode, SMS-7630, was used as the rectifier diode in the harvesting unit. If we transmit 20 dBm of RF power from a transmitting antenna that is located 0.2 m from the harvesting slot antenna at 2.4 GHz, the output voltage at the output port of the harvesting unit will be around 1 V. The power conversion efficiency of the metamaterial antenna dipole with metallic strips is around 75%. Wearable sensors with energy-harvesting units provide efficient, low-cost healthcare services that contribute to a green environment and minimize energy consumption. The measurement process and setups of wearable sensors are presented in this paper.

Novel metamaterial array-based dual port MIMO antenna using low profile substrate with feature multiband, and high isolation for sub-6G, IoT, and WiMAX applications

This article represents a single-layered two-port MIMO antenna loaded into a compact plane-patterned metamaterial (MTM) structure for a 5G communication system. The antenna operates at three bands to investigate metamaterial properties in addition to diversity parameters, an arrangement of a series of arrays suggested a 2-port design antenna and a circular-shaped split ring resonator unit cell was developed. The design of a single port antenna utilizes 1 × 3 MTM unit cells for each component. This antenna operates within a frequency range ranging from 1 GHz to 15 GHz. Additionally, the suggested MIMO antenna offers a dominant isolation of –55dB. The measurement’s results show that, with an entire antenna size of 112 mm × 26.5 mm and a 3.33 GHz bandwidth, the MIMO antenna is achieved with good efficiency and CCL < 0.35, considerable DG > 9.97dB, ECC < 0.18, and TARC <–9.97. The presented design is suitable for medical imaging, RFID, Bluetooth, Wi-Fi, WiMAX, IOT, satellite communication systems, and the 5G and sub-6 GHz spectrum.

Microelectromechanical System-Based Reconfigurable Terahertz Metamaterial for Polarization Filter, Switch, and Logic Modulator Applications.

The terahertz (THz) metamaterials integrated with microelectromechanical systems (MEMS) have led to the realization of dynamic control in amplitude, phase, polarization, and spin angular momentum of the THz wave. In this study, we demonstrate an MEMS-based reconfigurable THz metamaterial (RTM) composed of a split ring resonator (SRR) for real-time modulation of THz wave. By gradually increasing the polarization angle of the incident THz wave, the resonant frequency of SRR switches from 0.74 to 1.16 THz, and the maximum modulation depth is more than 70%. When the MEMS-based RTM is actuated by different DC bias voltages, the polarization-dependent transmission intensity and resonant frequency of the device can be actively tuned. MEMS-based RTM shows logical function characteristics that can be used for logic modulators by performing the driving voltages and polarization states as 2-bit input signals and quantizing the transmission response as "on" and "off" states. The logic gates of "NAND" are at 0.439 THz and "AND" is at 0.732 THz. These results offer potential applications for the proposed MEMS-based RTM in tunable and reconfigurable polarization filters, optical switches, programmable logic modulators, and so on.

Fabrication of compact substrate integrated waveguide dual band bandpass filter using complementary split-ring resonators for C and X band applications

This article presents a compact dual-band Bandpass Filter(BPF) based substrate integrated waveguide(SIW) used for C and X band applications. Complementary split-ring resonators(CSRR) are loaded into the waveguide surface to obtain more advantages of compactness and good performance. The SIW cavity undergoes initial optimization utilizing the powerful genetic algorithm, renowned for its robustness in solving complex problems, before proceeding to simulation with Ansys HFSS software with loaded CSRRs. The filter displays two passbands: the first has a bandwidth of 2 GHz and resonates at 6.8 GHz, while the second has a bandwidth of 5,55 GHz and resonates at 10.3 GHz. Moreover, with two resonance frequencies, the developed BPF has the benefit of low insertion loss(S21=-1.7dB and -1.9 dB) and improved return loss: (S11=-24dB and -22 dB) respectively. Furthermore, the proposed combination not only allows the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide but also exhibits good rejection, demonstrated by the presence of two transmission zeros with rejection of -16 dB and -19 dB, attained at 7.4 GHz and 14.8 GHz respectively. The proposed SIW BPF was designed using a 0.6mm thick FR4 dielectric substrate measuring 13mm × 15mm. The filter is manufactured to validate the concept and the measured results agree well with the simulation. With all these advantages: compact size, high rejection, and good filtering response, the proposed SIW BPF became suitable for microwave applications.

Designer Metasurfaces via Nanocube Assembly at the Air-Water Interface.

The advent of metasurfaces has revolutionized the design of optical instruments, and recent advancements in fabrication techniques are further accelerating their practical applications. However, conventional top-down fabrication of intricate nanostructures proves to be expensive and time-consuming, posing challenges for large-scale production. Here, we propose a cost-effective bottom-up approach to create nanostructure arrays with arbitrarily complex meta-atoms displaying single nanoparticle lateral resolution over submillimeter areas, minimizing the need for advanced and high-cost nanofabrication equipment. By utilizing air/water interface assembly, we transfer nanoparticles onto templated polydimethylsiloxane (PDMS) irrespective of nanopattern density, shape, or size. We demonstrate the robust assembly of nanocubes into meta-atoms with diverse configurations generally unachievable by conventional methods, including U, L, cross, S, T, gammadion, split-ring resonators, and Pancharatnam-Berry metasurfaces with designer optical functionalities. We also show nanocube epitaxy at near ambient temperature to transform the meta-atoms into complex continuous nanostructures that can be swiftly transferred from PDMS to various substrates via contact printing. Our approach potentially offers a large-scale manufacturing alternative to top-down fabrication for metal nanostructuring, unlocking possibilities in the realm of nanophotonics.

Passive Wireless Porous Biopolymer Sensors for At-Home Monitoring of Oil and Fatty Acid Nutrition.

Dietary oils─rich in omega-3, -6, and -9 fatty acids─exhibit critical impacts on health parameters such as cardiovascular function, bodily inflammation, and neurological development. There has emerged a need for low-cost, accessible method to assess dietary oil consumption and its health implications. Existing methods typically require specialized, complex equipment and extensive sample preparation steps, rendering them unsuitable for home use. Addressing this gap, herein, we study passive wireless, biocompatible biosensors that can be used to monitor dietary oils directly from foods either prepared or cooked in oil. This design uses broad-coupled split ring resonators interceded with porous silk fibroin biopolymer (requiring only food-safe materials, such as aluminum foil and biopolymer). These porous biopolymer films absorb oils at rates proportional to their viscosity/fatty acid composition and whose response can be measured wirelessly without any microelectronic components touching food. The engineering and mechanism of such sensors are explored, alongside their ability to measure the oil presence and fatty acid content directly from foods. Its simplicity, portability, and inexpensiveness are ideal for emerging needs in precision nutrition─such sensors may empower individuals to make informed dietary decisions based on direct-from-food measurements.

Design and development of a compact, wide-angle metamaterial electromagnetic energy harvester with multiband functionality and polarization-insensitive features

This article presents a compact, wide-angle, polarization-insensitive metamaterial harvester that can efficiently harvest electromagnetic (EM) energy in the S, C, X, and Ku bands. The harvester's unit cell consists of a split ring resonator, two strip lines, and two split strip lines, giving it a total size of (10 × 10) mm2. Each split gap is filled with a 50 Ω resistive load. The input impedance of the harvester is precisely designed to match that of free space, allowing for efficient absorption of EM power and appropriate redirection towards the resistive loads. The harvester's performance is also evaluated for various polarization and incident angles, considering the Transverse Electric and Transverse Magnetic modes. The simulation results reveal that the proposed harvester exhibits a notably greater conversion efficiency of around > 95%. The simulation outcomes were carefully validated through experimental tests conducted in an anechoic chamber using a 3 × 3 cell array of the proposed design. This ensured the accuracy and reliability of the results. The strong correlation between the experimental data and the full-wave simulations strongly supports the effectiveness of the proposed harvester. Therefore, the demonstrated efficiency and compact size make it a perfect fit for energy harvesting systems in wireless sensor networks.

Complementary split ring resonator-inspired multi-HCN for implementation of an efficiency-enhanced inverse class-F2,3 PA

This article introduces a conceptual framework for enhancing the efficiency of an inverse class-F2,3 (F2,3−1) power amplifier (PA) through the incorporation of an innovative metamaterial-based multi-harmonic control network (multi-HCN). In the recommended approach, the multi-HCN comprises two resonant cells inspired by square-shaped complementary split ring resonator (CSRR), which are configured to suppress unwanted harmonics and to obtain the desired waveforms. The primary focus is to showcase how CSRRs can be effectively employed to form a shunt resonator through the etching of the conductive pattern of the proposed multi-HCN. Apart their harmonic tunability, CSRRs offer various noteworthy attributes such as impressive wave restoration capabilities and the capacity to address spatial limitations. To assess the efficacy of the proposed methodology, a class-F2,3−1 PA is devised and constructed utilizing a commercially available 10 W GaN HEMT device. The presented class F2,3−1 PA yields a commendable drain efficiency (DE) ranging from 50.3 % to 84 % and achieves an output power within the range of 38 dBm to 41.2 dBm across the bandwidth of 3.3 GHz to 3.7 GHz. These significant performance metrics serve as compelling evidence, validating the effectiveness of the proposed approach. Furthermore, this achievement establishes the design as a promising path for creating high-performance, affordable PA suitable for emerging communication systems.

Microwave detection towards marine climate monitoring: fog and humidity

Sea fog severely impacts marine operations and coastal transportation due to the low visibility, metal corrosion, and unpredictable effects. This paper introduces a microwave detection technique for monitoring the sea fog generation in-time, as well as the salt-content within sea fog. Besides, in the fogless time, the microwave sensor can also work for humidity detection. The proposed sensor doesn’t use the sensitive materials which assure the reliability and stability. In humidity detection, the nested split-ring resonator (NSRR) sensor achieves a maximum sensitivity with a 1.19 MHz/% RH frequency shift, 0.034 dB/% RH return-loss change, and 0.24°/% RH phase change. For NaCl content, the 2NSRR sensor exhibits a significantly higher sensitivity of 4.42 MHz/% compared to the 1NSRR sensor. This paper firstly introduces four non-resonant detection parameters (FWHM, HPI, FSI, and IF) to avoid high loss due to the fog. This microwave sensor and non-resonant parameters offer a comprehensive solution for accurate and timely sea fog monitoring, enhancing safety and efficiency in maritime and coastal operations.

Microstrip Patch Antenna Array Inspired by Split Ring Resonators for 5.8 GHz Applications

Microstrip Patch Antenna Array Inspired by Split Ring Resonators for 5.8 GHz Applications

Fast and slow waves in a chain of superconducting split-ring resonators with staggered coupling strengths

The transmission and reflection spectra of a linear chain comprising superconducting split-ring resonators operating at 6 GHz, with staggered coupling strength are investigated. The collective mode and the associated transmission and reflection on resonances can be fully analyzed by employing finite-element simulations focused on the unit cell structure and an effective hopping model. Robust coupling energies, equivalent to approximately 4% of the resonant frequency, enable significant transmission through the collective modes. Furthermore, the resonance modes exhibit substantial quality factors, leading to distinct superluminal and retarding propagation effects for reflected and transmitted microwaves, respectively. The chain configuration allows for 200 ns in either advance or delay for a 1 µs microwave pulse at the resonance frequency. These findings shed light on the unique behavior of superconducting split-ring resonator arrays and their potential applications in microwave signal manipulation.

A new miniaturized Split-Ring Resonator-Based inverse double Sigma-Shaped artificial material for Penta-Band wireless communication

This paper discusses a study on creating and confirming the authenticity of an artificial material with a SNG (Singular Negative) attribute. The artificial material was constructed using a metamaterial structured around split-ring resonators forming an inverse double sigma shape. Advanced electromagnetic simulation tools like CST (Computer Simulation Technology) Microwave Studio, Ansys HFSS (High Frequency Structure Simulator) and ADS (Advanced Design System) were employed to extensively analyze the electromagnetic characteristics of the artificial material. Notably, the proposed artificial material exhibits five distinct resonance frequencies spanning L-, S-, C-, X-, and Ku-band operations, specifically at 1.560 GHz, 2.232 GHz, 4.350 GHz, 8.095 GHz, and 17.370 GHz. Achieving an optimal EMR (Effective Medium Ratio) of 23.45, with a compact unit cell size of 8.2 mm × 8.2 mm and a substrate thickness of 1.905 mm, underscores its innovative design attributes. Of significance, the compact size, SNG characteristics, high EMR, and resonant frequencies render this structure particularly noteworthy. The utilization of the L-band for GPS (Global Positioning System), S-band for Wireless LAN (Local Area Network), C-band for Satellite communication, X-band radar system, and the Ku-band for VSAT (Very Small Aperture Terminal) communication applications is well-documented. This article elucidates the intricacies of the design process and conducts various parametric analyses. Remarkably, the simulation results obtained from Ansys HFSS 3D software closely align with those from CST. Furthermore, a comprehensive examination of surface current, E-field, and H-field distributions is provided. Importantly, comparative assessments indicate the superior performance of the proposed structure across multiple metrics, including EMR, SNG frequency range, and compactness, positioning it as an ideal candidate cellular phone, satellite, and radar-based applications.

A novel configuration of a microstrip metamaterial reconfigurable bandstop filter

This paper presents the design, simulation, and test measurements of a microstrip bandstop filter operating at 1.5 GHz, incorporating six split ring resonator (SRR) unit cells. The substrate employed is an FR-4 with a thickness of 1.6 mm and tangent losses of 0.025. In the initial phase, the design is conceptualized, simulated using computer simulation technology (CST) studio and advanced design system (ADS) Agilent simulators, and validated through test measurements. Building upon this foundation, the filter is transformed into a reconfigurable variant by integrating four SMV2019 varactor diodes. These varactors are modeled to ensure the reconfigurability of the bandwidth. The integration of varactors introduces dynamic tuning capabilities to the considered bandstop filter.

Design and analysis of a metamaterial based biosensor to determine blood glucose concentration

In this paper, a biosensor utilizing metamaterials is designed and simulated to detect blood glucose concentration. The proposed sensor comprised of a microstrip patch antenna designed on a Rogers RT5880 substrate. A circular-shaped complementary split ring resonator (CSRR) cell is integrated onto the patch of the antenna which acts as the sensing region. The sensor is analyzed in order to ascertain the blood glucose concentration ranging from 50-300 mg/dL in a human finger model. The sensing parameter is amplitude of reflection coefficient, which exhibits variation in response to alterations in the dielectric characteristics of the sample being tested. The Cole-Cole relaxation model is employed to predict the dielectric properties of different finger tissues. An analysis of the characteristics of the CSRR was conducted to illustrate its significance in the realm of glucose detection. The glucose level is determined through the utilization of a linear regression model that describes the relationship between the reflection coefficient of the sensor and glucose level. The sensor demonstrates an impressive sensitivity of 1.792 dB per (mgdL&lt;sup&gt;-1&lt;/sup&gt;) and has the ability of determining glucose levels with a good accuracy, as verified by the application of Clarke error grid. This sensor exhibits enhanced performance compared to some other recent glucose sensors.

Switchable VO₂ Metamaterial Based on Planar and Vertical Split Ring Resonators for High-Performance Sensing

Switchable VO₂ Metamaterial Based on Planar and Vertical Split Ring Resonators for High-Performance Sensing

Deciphering split ring resonators: understanding theoretical validation and simulation implications

This study presents a comparative analysis of analytical calculations and simulation results of a single-ring split ring resonator (SRR). A simulated SRR made of aluminum, designed in high frequency structure simulator (HFSS), with the resonant frequency of 3.97 GHz with transmission loss of −47.7 dB. The initial gap, width, and thickness of the ring are set at 1 mm, 1 mm, and 3 mm, respectively. These geometrical parameters are subsequently varied in simulations, and theoretical calculations are conducted for each variation using Python 3.10 code to facilitate comparative analysis. The analytical calculations reveal certain limitations in accurately modeling the impact of fringing and radiation, particularly when dealing with smaller dimensions. Although there exist slight disparities between the simulated and calculated outcomes, it is evident that the theoretically derived results exhibit a close correspondence with simulated responses, particularly for dimensions that are not excessively small. This observation underscores the confirmation that an augmentation in the gap of the Split Ring Resonator (SRR) leads to an elevation in the resonant frequency. Furthermore, by maintaining a constant inner radius and adjusting the outer radius to modulate the width of the SRR, a decrease in the resonant frequency is noted with an increase in the width of the metallic ring. Similarly, an increase in the thickness of the ring contributes to a reduction in the resonant frequency This comprehensive investigation provides a valuable methodology for corroborating theoretically derived results with simulation data. Additionally, the research underscores the diverse resonances that can be achieved by fine-tuning the gap, width, and thickness of the split ring resonator, highlighting the significance of selecting these dimensions carefully to attain specific resonant frequencies.