Split Ring Resonator Structure Research Articles

A Microwave Sensor With Split-Ring Resonator Structure for the Detection of Lubricating Oil Contaminants

A Microwave Sensor With Split-Ring Resonator Structure for the Detection of Lubricating Oil Contaminants

A compact, low‐loss, and wide passband ratio substrate integrated waveguide triplexer based on complementary split ring resonators for multiband applications

SummaryIn this paper, a design of a substrate‐integrated waveguide (SIW) triplexer with improved low‐loss performance, passband ratio, and compactness based on the complementary split ring resonator (CSRR) structure is presented. The proposed triplexer operates at three passbands of 6, 8, and 10 GHz that correspond to the passband ratios of 1.33 and 1.67. By appropriately designing square CSRRs on the surface of the SIW structure, the low‐loss and compact resonator filters below the cut‐off frequency of the SIW at each operation frequency can be realized. The wide passband ratio is obtainable by adjusting the dimensions of the T‐junction. The measured results show the minimum insertion losses of 1.5, 1.4, and 1.9 dB at 6, 8, and 10 GHz, respectively. In addition, the minimum measured return losses are −9.33, −11.3, and −12.4 dB at the corresponding three passbands. The measured isolation between output ports is better than −17 dB in the frequency range from 5 to 11 GHz. The measured results agree well with simulations which are conducted by the CST Microwave Studio simulator. The proposed triplexer is designed on a cost‐effective RO4003C substrate with a compact size of 35 25 mm2

Tuneable double negative (DNG) Tri-Hexagonal split ring resonator metamaterial for 5G application

This paper introduces a compact tuneable metamaterial (MTM) unit cell featuring a tri-hexagon and tri-square split ring resonator (THTSSSR) structure designed for 5G communication applications. Metamaterials are employed to achieve unique electromagnetic properties not found in natural materials. The design process involves the arrangement of three square rings and three hexagon rings as metallic patches on a Rogers substrate (RT 5880), measuring 7 x 7 mm2 with a thickness of 1.575 mm. The proposed design exhibits double negative (DNG) properties, with resonances in the transmission coefficient (S21) at 3.493 GHz and a bandwidth of −10 dB covering frequencies between 3.057 and 3.711 GHz. Numerical simulations conducted using finite-integration techniques (FIT) in CST Microwave Studio validate the design's effectiveness, with confirmation through the Advanced Design System (ADS). The MTM unit cell demonstrates tuneable attributes, including negative permittivity ranging from 3.39 to 5 GHz and negative permeability from 3.39 to 3.86 GHz. These findings highlight the compactness and tunability of the proposed design, making it promising for 5G communication applications.

A reconfigurable band‐notched wearable super ultra‐wideband antenna utilizing a split‐ring resonator

AbstractThis article presents a flexible ultra‐wideband (UWB) antenna that can be used in wireless body area networks (WBAN). The antenna has a switchable slotted split ring resonator (SRR) structure on the radiating patch, which creates band‐notch functionality. The antenna has three switchable states: UWB and two band‐notched states at central frequencies of 5.5 and 3.5 GHz. The antenna has compact dimensions of 30 × 38 × 0.38 mm3 and is fabricated on an RT5880 substrate. Its impedance bandwidth ranges from 2.7 to 50 GHz (a relative bandwidth of 180%). The antenna's performance has been evaluated under deformation, and its impact on the human body has been assessed using the specific absorption rate (SAR) parameter. The antenna has been manufactured, and its key features have been measured, demonstrating good agreement with simulations. Due to its low SAR, minimal thickness, and UWB performance, the antenna is a good candidate for WBAN applications.

Polarization insensitive multiband metamaterial absorber for bio-plastic sensing application

This article introduces a microwave multiband metamaterial absorber (MA) with high potential for bio-plastic sensing applications. The innovative design is realized through a compact unit cell dimension of 1.33λο × 1.33λο × 0.22λο, employing a state-of-the-art split-ring resonator structure. Strikingly, this absorber demonstrates polarization insensitivity and can be characterized by five distinct absorption peaks at 18.69 GHz, 23.34 GHz, 25.72 GHz, 32.94 GHz, and 35.40 GHz. The corresponding absorption rates are exceptionally high, ranging from 92.82% to 99.95%. To elucidate the underlying absorption mechanism, detailed analyses of the electric field, magnetic field, surface current distribution, and input impedance are provided, showcasing the absorber's effective MA structure. The designed MA sensor exhibits outstanding performance metrics for bio-plastic detection, including an average quality factor (Q-factor) of 210 and sensitivity of 0.888 GHz/RIU (refractive index unit), marking a significant advancement in the field. Additionally, the sensor's linearity, output variation, and sensitivity are considerably improved for bio-plastic sensing. The research confirms the proposed MA absorber's functionality by comparing measured results and simulation outcomes, indicating a high degree of accuracy and reliability. The potential applications of this MA are manifold, extending to microwave absorption and enhanced plastic sensing techniques. Its compact and thin design facilitates seamless integration with various sensor equipment, broadening the scope of its utility. Furthermore, the article delves into the relevance of this research to several Sustainable Development Goals (SDGs), particularly highlighting its alignment with SDG 9 (Industry, Innovation, and Infrastructure), SDG 12 (Responsible Consumption and Production), and SDG 14 (Life Below Water). Thus, the innovative MA design signifies a technological leap in the field of metamaterial absorbers and contributes to the pursuit of sustainability and environmental protection.

Highly sensitive refractive index sensing with a dual-band optically transparent ITO-based perfect metamaterial absorber for biomedical applications

In this paper, a dual-band optically transparent square-shaped perfect metamaterial absorber operating in the frequency range from 2 to 4 terahertz (THz) is proposed. The structure consists of an indium tin oxide (ITO)-based split ring resonator (SRR) structure with additional splits and rectangular inner strips to form the top layer over the lead glass substrate. Perfect absorption is attained in the frequencies of 2.089 and 3.892 THz with absorbances of 99.99% and 99.98% in TE polarization mode, respectively. Perfect absorption is also achieved in TM polarization mode at 2.23 THz. Broadband absorption is found in TM polarization mode with full width half maximum (FWHM) of 1.1742. The proposed structure has one polarization-insensitive band in TE polarization mode. Absorbance is greater than 80% and 90% in the successive absorption peaks even at 60° and 75° of incidence, respectively. The resonance frequency is sensitive to the refractive index of the medium. As a result, the proposed metamaterial structure may be implemented as a refractive index (RI) sensor with a high sensitivity of 1109 GHz/RIU and 1954 GHz/RIU in both absorption bands for a refractive index range of 1.34 to 1.40. It's interesting to note that the refractive index of most biological samples ranges from 1.3 to 1.39. The figure of merit (FOM) of the proposed sensor can reach as high as 10 and 14 for the 1st and 2nd frequency bands. As a result, the proposed sensor has a high sensitivity and can be employed in medical applications. Potential applications of the proposed absorber include imaging, biomedical sensing, etc.

A planar DGS sensor for moisture analysis in civil construction aggregates

The need for effective methods for analyzing water content in aggregates used in construction materials is important to ensure durability and structural excellence. The realization of the intrinsic limitations of conventional approaches to moisture analysis in aggregates instigates the search for more effective and precise solutions, especially in samples with varying percentages of water. This study innovates by presenting a compact device, using the Defect Ground Structure (DGS) technique, for the precise determination of the water content in aggregates used in civil construction. The proposed sensor is based on a modified Complementary Split Ring Resonator (CSRR) structure, operating at a resonance frequency of 2.38 GHz. The operating method consists of measuring aggregated samples with different percentages of water to establish an equation relating the resonance frequency to the water content of the material. The results indicate an effective analysis of moisture in aggregated samples, with an average sensitivity of 1.83% and reduced error levels with an average of 2.01%, validating the potential of this sensor to contribute significantly to advances in the area and improving precision and reliability in determination of water content in aggregates used in construction materials.

Miniaturized electronically controlled notched band filter based on spoof surface plasmon polaritons

In this paper, a novel miniaturized electronical controlled notch band filter based on spoof surface plasmon polaritons (SSPPs) with inverted “山”-shaped unit is designed and experimentally demonstrated. The notch band filter is mainly composed of four parts: microstrip transmission line, transition structure, inverted “山”-shaped SSPPs, and split ring resonator (SRR) structure, and a varactor diode is embedded in the slit notch of the SRR structure to realize electronic control. Comparing with the traditional SSPP unit with the same lateral size, the dispersion curve of the proposed inverted “山”-shaped unit shows better slow wave characteristics, and the asymptotic frequency is reduced to 55%. The frequency of the notch band can be dynamically controlled by adjusting the external bias voltage at both ends of the varactor diode. As the external bias voltage increases from 0.5 V to 30 V, the notch band frequency can be changed from 2.1 GHz to 2.3 GHz and achieve easily electronic regulation. The simulation results show that the notched band filter achieves low insertion loss (<i>S</i><sub>21</sub> < –1 dB) and great return loss (<i>S</i><sub>11</sub> > –10 dB) in the pass band, which has the advantage of miniaturization with the size only 0.78<i>λ</i><sub>g</sub> × 0.35<i>λ</i><sub>g</sub>. It is worth noting that when the equivalent capacitance of the slit notch is changed, the transmission coefficient of the notched band is always less than –15 dB, showing superior band-stop performance. At the same time, by comparing and analyzing the electric field distribution of notch band filter, the transmission mechanism of microwave signal is further verified. In order to verify the its effectiveness, the traditional printed circuit board technology is used to fabricate notch band filter. The measurement results are in good agreement with the simulation ones, verifying the feasibility of the design. The electronically controlled notch band filter has higher integration and can effectively suppress the interference frequency band.

Low-Profile UWB-MIMO Antenna System with Enhanced Isolation Using Parasitic Elements and Metamaterial Integration

A new compact UWB multiple-input–multiple-output (MIMO) antenna is presented in this paper. The proposed antenna, with a compact size of 30 × 20 × 1.6 mm3, consists of a two-element microstrip line-fed pentagonal-shaped patch associated with a parasitic element and a partial ground plane. Three complementary split-ring resonator (CSRR) structures are integrated into the defected ground with the aims of reducing the mutual coupling and enhancing the bandwidth. A UWB impedance bandwidth is achieved covering the FCC band (3.1–10.6 GHz), corresponding to a reflection coefficient below −10 dB and a reduced mutual coupling below −22 dB. Additionally, acceptable limits of the diversity performance parameters are obtained. Furthermore, all the simulated outcomes of the suggested antenna are convenient for UWB-MIMO wireless applications. Measures carried out on the fabricated prototype of the antenna demonstrate good agreement between both the simulation and measurement results of the optimized two-port MIMO antenna.

A low-profile metamaterial absorber with ultrawideband reflectionless and wide-angular stability

An ultrawideband reflectionless metamaterial absorber (MA) is proposed by replacing the metallic ground with the complementary split-ring resonator (CSRR) structure. The proposed MA exhibits −10 dB reflectivity spectrum from 1 GHz to 20 GHz, which maintains more than 90% absorption from 1.5 GHz to 20 GHz. Furthermore, it achieves angle stability for TE and TM polarization at oblique incident angles up to 40° and 65°, respectively. To achieve broadband absorption spectrum, we have adopted a single-layer high-impedance surface (HIS) loaded with a double-layer magnetic material (MM) structure. To further realize the RCS reduction into a lower frequency range, we have employed the scattering cancellation technology into the traditional metallic ground. Finally, we have fabricated a sample exhibiting the 10 dB RCS reduction from 1 GHz to 20 GHz with a thickness of 10 mm. Measurement and simulation results confirm that the proposed MA exhibits excellent comprehensive performance, making it suitable for many practical applications.

Meta-material inspired penta-band decagon fractal antenna for wireless applications

In this article, a meta-material inspired penta-band fractal antenna is proposed for wireless applications. It is constructed by integrating the Complementary Split Ring Resonator (CSRR) and decagon fractal structure. The decagon is the regular polygon with 10 sides. Three layers are constructed in the proposed design to obtain the multiple operating frequencies with better performance. Top layer has the decagon structure with ten slots and second-order Koch loop radiating element. The rectangular patch layer and CSRR layer are the bottom layers. Dielectric material FR4 is selected to design the suggested antenna. The measurement results reveal that the projected antenna has five resonant frequencies at 2.63 GHz, 3.98 GHz, 4.78 GHz, 5.52 GHz and 5.91 GHz with a bandwidth of 230 MHz, 300 MHz, 80 MHz, 200 MHz, and 290 MHz. Gain is observed about 3.29 dB, 4.44 dB, 5.71 dB, 4.22 dB and 3.99 dB at the corresponding resonant frequencies.

Compact SCSRR‐based quad‐band antenna for Bluetooth, WiMAX, WLAN, and fixed‐satellite services

SummaryThis research describes the detailed analysis and design of the compact complex‐free structural metamaterial quad band radiating element applicable for Bluetooth, WiMAX, WLAN, and fixed‐satellite service. The radiating element designed is composed of an inner angle‐rotated circular Split Ring Resonator (SRR) placed within the outer square‐shaped SRR interlinked by a strip to design the multiband operational characteristics and is fed by a coplanar waveguide. Suggested radiating element is imprinted over the FR4 substrate material with the electrical dimension of 28 × 31.26 × 0.8 mm3. The initial outer‐closed square ring offers dual‐band operation by resonating at 2.8 and 8.5 GHz frequencies, and the incorporation of a circular SRR offers quad‐band operation. The unique negative permeability feature of the proposed Square and Circular Split Ring Resonator (SCSRR) structure is extracted, and its band characteristics are analyzed. Results obtained from the simulated radiating element are validated with the fabricated antenna. The measured E plane pattern resembles a numeric eight shape, and the H plane pattern is omnidirectional. Suggested SCSRR antenna offers a gain of above 3.2 dBi in all the operating bands.

A Metasurface-Based LTC Polarization Converter with S-Shaped Split Ring Resonator Structure for Flexible Applications.

This paper presents a metasurface-based linear-to-circular polarization converter with a flexible structure for conformal and wearable applications. The converter consists of nested S- and C-shaped split ring resonators in the unit cell and can convert linearly polarized incident waves into left-handed circularly polarized ones at 12.4 GHz. Simulation results show that the proposed design has a high polarization conversion rate and efficiency at the operating frequency. Conformal tests are also conducted to evaluate the performance under curvature circumstances. A minor shift in the operating frequency is observed when the converter is applied on a sinusoidal wavy surface.

Independently Tunable Triband Patch Antenna with Band-Notched Characteristics for X-Band Applications

This paper presents a triband antenna with a simple design for X-band applications. The proposed antenna is designed based on a patch with a truncated corner slot and complementary split-ring resonators in the ground plane. In this way, the antenna exhibits three operating bands and its resonant frequencies can be controlled independently by changing dimensions of the slot in the patch and the resonator structures in the ground plane. In addition, due to the antiresonant behavior of the complementary split-ring resonator structures, the antenna exhibits a notch-band characteristic at 10.7 GHz. A parametric study is performed to provide a detailed understanding of the independent resonance tuning behavior of the antenna. Both simulated and measured results of the proposed antenna are presented, which are in good agreement. The proposed antenna shows three operating bands in the X-band including (with absolute and relative bandwidths) 9.4–9.7 GHz (300 MHz, 3.14%), 10.3–10.6 GHz (300 MHz, 2.86%), and 11.05–11.32 GHz (297 MHz, 2.66%). In addition to that, a notched band of 10.6–11.05 GHz is introduced to exclude operation in the frequency bands of radiometric observation systems (10.6–10.7 GHz). To the best of our knowledge, this work is unique in its combination of independent tuning of three frequency bands of operation with single-layer implementation in the X-band. Such a structure provides additional degrees of freedom to the antenna design, customizing operation in the required bands while avoiding operation in other bands.

Alignment-free twisted-split-ring metasurface on single substrate with 2π phase range for linearly polarized sub-terahertz wave.

To achieve high-speed, large-capacity communication, next-generation mobile communication systems will require manipulation of the propagation of sub-terahertz waves in the propagation channel. In this paper, we propose the use of a novel split-ring resonator (SRR) structure as a metasurface unit cell for manipulating the linearly polarized incident and transmission waves used in mobile communication systems. In this SRR structure, the gap is twisted by 90° to efficiently use cross-polarized scattered waves. By changing the twist direction and gap size of the unit cell, 2π phase designability can be achieved, which enables linear polarization conversion efficiencies of -2 dB with a backside polarizer and -0.2 dB with two polarizers. In addition, a complementary pattern of the unit cell was fabricated, and a measured conversion efficiency of more than -1 dB at the peak with only the backside polarizer on a single substrate was verified. In the proposed structure, the 2π phase designability and efficiency gain are obtained independently by the unit cell and polarizer, respectively, thus enabling alignment-free characteristics, which are highly advantageous from an industrial viewpoint. Metasurface lenses with binary phase profiles of 0 and π were fabricated using the proposed structure with a backside polarizer on a single substrate. The lenses' focusing, deflection, and collimation operations were experimentally verified with a lens gain of 20.8 dB, which agreed well with our calculated results. Our metasurface lens has the great advantages of easy fabrication and implementation, and it has the potential to enable dynamic control by combining it with active devices because of the simple design methodology, which entails only changing the twist direction and the gap's capacitance component.

Flexible microwave sensor films based on nested-complementary split ring resonator for liquid dielectric constant detection

This paper proposes a flexible double-sided attached microwave sensor film for real-time measurement of the liquid dielectric constant, and proposes a nested-complementary split ring resonator（NCSRR）structure with high sensitivity and quality factor values that is based on the structure evolution of a complementary split ring resonator（CSRR）. The sensor films are composed of a ground film with an NCSRR structure and a U-shaped microstrip line film. By taking a borosilicate glass beaker and a polypropylene beaker as examples, two types of microwave sensors are formed by attaching films to both sides of the beakers. Lubricating oil with 0%− 25% water content is added to the beakers separately, and the dielectric constants of the mixture are characterized nondestructively by the transmission coefficient (S21) of the device. According to the mathematical model established from the measurement results, the resonant frequencies of both sensors are linearly and negatively correlated with the dielectric constant of the liquid to be measured, which proves that the sensor film can be attached to a substrate with arbitrary curvature to form a microwave resonant sensor.

Electromagnetic absorption enhancement of concrete using metamaterials

Electromagnetic wave (EMW) pollution adversely affects information, facilities safety, and human health, leading to the development of EMW absorbing materials, especially absorbing concrete. Here, the influence of arrangement ways of concrete iron on microwave reflectivity was analyzed, and a split ring resonator (SRR) was designed and introduced to steel-reinforced concrete to improve the EMW absorbing performance of the concrete. The simulation results show that by tuning the diameter and arrangement ways of concrete iron and introducing SRR structure, an EMW absorption concrete which can display 0.3% reflection loss ([Formula: see text]% absorption) at 2.34[Formula: see text]GHz was designed and realized. The reflectivity of concrete iron and EMW absorption capacity of concrete were investigated by a vector network analyzer, and the experimental results almost agree with the simulation results. The reflection and absorption of EMW are caused by magnetic resonance and conductive loss, magnetic loss, respectively.

A Multi-Frequency Omnidirectional Antenna Based on a Ring-Shaped Structure.

A multi-frequency microstrip antenna loaded with a ring-like structure has been proposed. The radiating patch on the antenna surface consists of three split-ring resonator structures, and the ground plate consists of a bottom metal strip and three ring-shaped metals with regular cuts to form a defective ground structure. The proposed antenna works in six different frequency bands covering 1.10, 1.33, 1.63, 1.97, 2.08, and 2.69 GHz and works entirely when connected to 5G NR (FR1, 0.45-3 GHz), 4GLTE (1.6265-1.6605 GHz), Personal Communication System (1.85-1.99 GHz), Universal Mobile Telecommunications System (1.92-2.176 GHz), WiMAX (2.5-2.69 GHz), and other communications frequency bands. Moreover, such antennas also have stable omnidirectional radiation properties across different operating frequency bands. This antenna meets the needs of portable multi-frequency mobile devices and provides a theoretical approach for the development of multi-frequency antennas.

Design of Sub-6 GHz Antenna using Negative Permittivity Metamaterial for 5G Applications

Abstract: The objective of the presented article is to design a compact metamaterial-based dual-band antenna that meets the frequency requirement of 5G. The antenna consists of a Circular Split Ring Resonator structure with a defective ground plane and slots to enhance the bandwidth and gain parameters. Metamaterial-based Microstrip patch antenna produces unique electromagnetic properties that allow us to control over the antenna parameters with a compact size. FR-4 epoxy is used as a substrate its dielectric constant is 4.4 and its loss tangent is 0.02. Dimensions of the antenna are 20 x 12 x 1.6mm3 with a very compact size and cost-effective. The proposed metamaterial-based antenna resonates at dual bands at 3.24GHz and 5.46 GHz respectively. The peak gains at resonant frequencies 3.45GHz and 5.46 GHz are 0.9 dB and 2dB respectively. The proposed antenna shows S-parameters at S11, which is -12.13dB at frequency of 3.45 GHz and -15.165 at a frequency of 5.46 GHz. The proposed antenna can effectively work for WLAN and WiMAX applications. The antenna covers the frequency spectrum from 2 GHz to 8 GHz with a centre frequency of 5 GHz. The proposed antenna is cost-effective

A Miniaturized, Dual-Port, Multiband MIMO with CSRR DGS for Internet of Things Using WLAN Communication Standards

A compact, dual-port, triband MIMO antenna is designed and tested for three sub-6 GHz WLAN bands for IoT applications. The size and performance of the antenna make it versatile for the emerging IoT applications communicating using the 2.4 GHz, 5.2 GHz, and 5.8 GHz WLAN frequencies. The single radiating element of antenna geometry includes a pair of modified and optimized rectangular patches. A complimentary split ring resonator (CSRR) structure is incorporated in the ground plane as a defect (defected ground structure) to attain the third operational band. The orientation of the elements, orthogonally arranged, along with DGS, enhances the isolation between the radiating elements keeping it below 18 dB throughout the three operating frequency bands. The size of the final antenna is as small as 0.32 λ 0 × 0.32 λ 0 mm2 build on commercially available and cheap FR4 substrate of thickness 1.5748 mm. A peak gain of 7.17 dBi is attained for the proposed MIMO system. This MIMO antenna also satisfies the diversity parameter requirements including DG > 9.8 , ECC < 0.5 , TARC < − 10 dB, and CCL < 0.5 bits/s/Hz. This makes the proposed antenna a good candidate for IoT applications employing WLAN frequencies.