Split Ring Resonator Research Articles

Millimeter-wave wideband filtering on-chip antenna based on IPD technology

ABSTRACT A millimeter-wave wideband filtering on-chip antenna is proposed in this paper. Its operation frequency covers 32 GHz to 63 GHz, and the impedance fractional bandwidth reaches 63%. Based on the corner-fed patch antenna, the antenna in this work has a quasi-omnidirectional radiation pattern, and peak efficiency reaches 91.7%. By square slotting on the four sides of the patch and cross slotting on the center of the patch, the high-order mode is suppressed, which supports the wide operating frequency range with filtering characteristics. Split ring resonators are etched on the ground to strengthen filtering characteristics. Based on thin-film integrated passive device (IPD) technology, the proposed structure is applicable to the on-chip wideband and high-efficiency antenna array.

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.

Miniaturization of antenna using metamaterial loaded with CSRR for wireless applications

This paper proposes a compact decagon antenna for wireless applications based on inspired metamaterial (MTM) loaded with a modified complementary split ring resonator (CSRR). A MTM loaded with CSRR is used to achieve a size reduction of 50% when compared to a traditional antenna. The suggested decagon antenna's ground plane has been loaded with CSRR. The antenna was made on an FR4 substrate with a thickness of 1.6 mm and εr=4.4 and has a very small dimension of 0.288 λ_0x0.272 λ_0x0.013 λ_0 (where λ_0 represent center frequency at 2.4 GHz). The given antenna has a 90 MHz bandwidth (2.40-2.50 GHz) with a peak gain of 2.36 dB. The presented design is validated by showing simulated results of the S parameter, VSWR, gain, surface current, and radiation pattern. The proposed antenna is well suited for wireless applications.

All‐metal wide‐angle and polarization‐independent microwave metamaterial absorber

AbstractAn innovative all‐metal self‐support microwave metamaterial absorber (MMA) based on a continuous complementary split ring resonator (CSRR) array frequency selective surface (FSS) is constructed. The CSRR‐based FSS has a selected frequency of 23 GHz and is proved to be polarization insensitive. And the all‐metal MMA has the same response frequency as the FSS, showing convenience in the geometrical scaling process. Additionally, in both transverse electric and transverse magnetic modes, the all‐metal MMA shows stable response at oblique incidences with an incident angle as large as 50°. Along with lightweight, easy fabrication and high cost‐performance ratio, the new proposed all‐metal FSS‐based MMA has good potential to serve in many practical applications.

Broadband high-efficiency plasmonic metalens with negative dispersion characteristic

Controlling the dispersion characteristic of metasurfaces (or metalenses) along a broad bandwidth is of great importance to develop high-performance broadband metadevices. Different from traditional lenses that rely on the material refractive index along the light trajectory, metasurfaces or metalenses provide a new regime of dispersion control via a sub-wavelength metastructure, which is known as negative chromatic dispersion. However, broadband metalenses design with high-performance focusing especially with a reduced device dimension is a significant challenge in society. Here, we design, fabricate, and demonstrate a broadband high-performance diffractive-type plasmonic metalens based on a circular split-ring resonator metasurface with a relative working bandwidth of 28.6%. The metalens thickness is only 0.09λ0 ( λ0 is at the central wavelength), which is much thinner than previous broadband all-dielectric metalenses. The full-wave simulation results show that both high transmissive efficiency above 80% (the maximum is even above 90%) and high average focusing efficiency above 45% (the maximum is 56%) are achieved within the entire working bandwidth of 9–12 GHz. Moreover, an average high numerical aperture of 0.7 ( NA=0.7 ) of high-efficiency microwave metalens is obtained in the simulations. The broadband high-performance metalens is also fabricated and experimental measurements verify its much higher average focusing efficiency of 55% (the maximum is above 65% within the broad bandwidth) and a moderate high NA of 0.6. The proposed plasmonic metalens can facilitate the development of wavelength-dependent broadband diffractive devices and is also meaningful to further studies on arbitrary dispersion control in diffractive optics based on plasmonic metasurfaces.

Meta-atom loaded circularly polarized triple band patch antenna for Wi-Fi, ISM and X-band communications

Microstrip antennas usually suffer from high losses, gain, and efficiency degradation. It is a challenging task to miniaturize the patch antenna without degrading the performance parameters. To mitigate the above problems, a microstrip patch antenna loaded with stubs and printed on the ground plane loaded with dumbbell meta-atom is presented in this paper. The proposed double dumbbell meta-atom consists of two complementary split ring resonator (CSRR) cells loaded with rectangular rings. This exhibits the Double Negative (DNG) characteristic at 2.45 GHz. The devised meta-atom possesses dimensions of 0.05λ x 0.03λ at lower giga-hertz range. The meta-atom is further analyzed in CST-Microwave Studio and the corresponding S-parameters are extracted in MATLAB using the Nicolson Ross Weir (NRW) method. The electrical model of the meta-atom is also analyzed using Agilent ADS simulator. Further, two models of the proposed antenna with FR-4 and RT/Duroid-5880 are designed and compared. The proposed patch antenna resonates at three different frequency bands i.e. 2.445 GHz with a 3-dB bandwidth of 110 MHz (2.4 GHz–2.51 GHz), at 5.85 GHz with a 3-dB bandwidth of 730 MHz (5.13 GHz–5.86 GHz), and at 8.83 GHz with a 3-dB bandwidth of 1.83 GHz (7.7 GHz–9.53 GHz). This exhibit peak gains of 2.75dBi, 3.53dBc and 4.36dBi with low cross polarization levels at the said frequencies of operation. Further, the antenna possesses circular polarization in the frequency band (5.15 GHz–5.63 GHz). This antenna is used for Wi-Fi, ISM and X-band communications. The designed prototype is fabricated and tested and bears resemblance to the simulated results.

Local oscillator port integrated resonator for Rydberg atom-based electric field measurement enhancement

Rydberg atom-based superheterodyne with additional local oscillator (LO) signal is a novel approach to detect electric field with high measured sensitivity. However, the LO signal is often supplied to the atomic vapor cell by free-space illumination, which lacks mobility and integration for practical applications. Here, we present a LO port integrated split-ring resonator for realizing high sensitivity-enhanced electric field measurements. The LO signal is sent directly to the resonator through a parallel-plate waveguide, which is shown to achieve a sensitivity enhancement of 32 dB. The integrated resonator has an electrical size of 0.088λ and the feed port S11 reaches −38.2 dB.

Metamaterial Inspired Varactor-Tuned Antenna with Frequency Reconfigurability and Pattern Diversity.

A metamaterial-inspired varactor-tuned antenna with frequency reconfigurability and pattern diversity is designed. Two different versions of a reconfigurable structure are integrated into a single antenna to excite two different orthogonal patterns, which realizes pattern diversity for MIMO applications. The outer annular Composite Right-/Left-Handed Transmission Line (CRLH-TL) works at the 1 mode and provides a broadside pattern, and the inner circular radiator loaded with split ring resonators (SRR) operates at the 0 mode and radiates an omnidirectional pattern, which realizes pattern diversity. By using surface-mounted varactors, the operating frequencies for the two radiation patterns can be tuned over a wide frequency range, from 1.7 GHz to 2.2 GHz, covering the 1.71-2.17 GHz LTE band, and a low mutual coupling between the two radiators is achieved. The antenna has also been prototyped. The measured results are in good agreement with the simulation results, verifying the proposed concept. The dual-mode MIMO system equipped with the proposed antenna elements is discussed within the context of a 3-D channel model, and it shows a superior array compactness and spectral efficiency (SE) performance compared to scenarios with single-mode elements.

UWB TAPERED-SLOT PATCH ANTENNA WITH RECONFIGURABLE DUAL BAND-NOTCHES CHARACTERISTICS

An ultra-wideband patch antenna (UWB) that makes use of tapered slot technology is designed and analyzed in this article. Coplanar waveguide feeds the projected antenna. The presented antenna displayed superior UWB performances with -10 dB return-loss bandwidth, ranging from 1.9 to 12 GHz. The projected slot antenna has another benefit of minimizing the interference effect of the narrow band communications conducted by two notch bands operating at 3.3–3.8 GHz (WiMAX) and 5.1-6 GHz (WLAN and HIPERLAN/2), respectively. The Dual-Bands rejection is generated by etching out a complementary split ring resonator (CSRR) from the patch and placing a trapezoidal split ring resonator (TSRR). Adaptable single or dual-band rejection characteristics have been added to the behavior of the UWB antenna, by mounting electronic switching across SRR and CSRR. Furthermore, the presented UWB slot antenna is printed on an FR4-epoxy substrate (εr = 4.4) and it has an overall size of . 55x48x1.5 mm3

An Analysis of Split-Ring Resonators and Potential Barcode Application

This paper presents an analysis of various split-ring resonator (SRR) configurations coupled with coplanar waveguides (CPW). Three distinct resonant structures are presented, namely, the S-shaped split-ring resonator (S-SRR), the conventional split-ring resonator (SRR), and a pair of SRR. Among the examined resonant structures, it is observed that the S-SRR exhibits the smallest electrical size with the corresponding resonant frequency of 1.37 GHz, while the conventional SRR has the largest electrical size with the corresponding resonant frequency of 3.34 GHz. On the other hand, the resonant frequency of a dual SRR is 2.37 GHz. However, the transmission coefficient of a dual SRR is -11.43 dB, which is higher than S-SRR (-10.02 dB) and SRR (-8.18 dB). Furthermore, this study extends the analysis between a square dual SRR and a circular dual SRR with retained area. The square SRR demonstrates a lower resonance frequency (2.23 GHz) relative to its circular counterpart (2.37 GHz). The comparison also shows that the transmission coefficient of the square configuration is -13.88 dB, which is higher than its circular counterpart (-11.43 dB). The realization of a barcode application is achieved by loading multiple S-shaped split ring resonators (S-SRRs) with varying geometric parameters adjacently onto the transmission line. By individually rotating each of these S-SRRs, it becomes possible to alter the notch magnitude, thereby positioning it within a specific designated range corresponding to a particular code. In the case of a configuration involving rotations of (0°, 45°, 90°, 0°, 45°, 90°), this approach results in the creation of a barcode denoted as "100 010 000 100 011 000". This methodology enables the encoding of information in the form of distinctive resonant responses, providing a versatile and compact means of realizing barcode 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.

Compact terahertz harmonic generation in the Reststrahlenband using a graphene-embedded metallic split ring resonator array

Harmonic generation is a result of a strong non-linear interaction between light and matter. It is a key technology for optics, as it allows the conversion of optical signals to higher frequencies. Owing to its intrinsically large and electrically tunable non-linear optical response, graphene has been used for high harmonic generation but, until now, only at frequencies < 2 THz, and with high-power ultrafast table-top lasers or accelerator-based structures. Here, we demonstrate third harmonic generation at 9.63 THz by optically pumping single-layer graphene, coupled to a circular split ring resonator (CSRR) array, with a 3.21 THz frequency quantum cascade laser (QCL). Combined with the high graphene nonlinearity, the mode confinement provided by the optically-pumped CSRR enhances the pump power density as well as that at the third harmonic, permitting harmonic generation. This approach enables potential access to a frequency range (6-12 THz) where compact sources remain difficult to obtain, owing to the Reststrahlenband of typical III-V semiconductors.

Non‐Hermitian Broadside Coupled Split Ring Resonators with Directional Sensitivity

AbstractDirectional radiofrequency (RF) sensing, also known as radio direction finding, is essential in various applications that involve localizing RF sources. However, existing RF sensing technologies face challenges due to their large antenna sizes and complex RF signal processing circuits, which hinder the realization of miniaturized subwavelength direction sensors. In this article, a non‐Hermitian broadside coupled split ring resonators (BC‐SRRs) are presented, which can identify the direction of an incident RF signal with angles ranging from 0° to 180°. The non‐Hermitian Hamiltonian of the system, which can be interpreted by the temporal coupled mode theory, gives rise to asymmetric resonant modes of the BC‐SRRs. The asymmetry allows the direct measurement of RF wave incident angle by probing the resonant strength of the two BC‐SRRs. For the proof of concept, a one‐stage Dickson voltage multiplier is employed to rectify the RF signals and demonstrate angle sensing ability by relating the rectified voltage to the incident angle. The results showcase the potential of the proposed technique using non‐Hermitian BC‐SRRs as a pathway toward subwavelength antenna‐based radio direction finding.

Dual-Notched UWB Orthogonal MIMO Antenna with Improved Gain Characteristics Using Frequency Selective Surfaces for Wireless Communication Applications

In this paper, a complementary split ring resonator (CSRR) loaded compact CPW-fed circular shaped monopole UWB antenna with dual band notch characteristics is designed on an FR-4 substrate. The propounded band-notched UWB antenna is integrated with two frequency selective surface layers referred as bandpass frequency selective surface (FSS-1) and reflector (FSS-2) to offer enhanced radiation performance. Bandpass FSS-1 enhances the gain of the antenna by improving directivity and reflector FSS-2 reflects back the backside radiation of the proposed antenna towards the forward direction thereby increasing gain and directivity of the proposed antenna. Furthermore, a two-element orthogonal MIMO antenna is proposed with improved gain using two FSS layers. The complete configuration of the proposed two-element MIMO antenna consists of CSRR-based radiating patches, monopole ground planes and two integrated FSS layers. The proposed MIMO antenna operates in UWB range from 3.46[Formula: see text]GHz to 16.02[Formula: see text]GHz with dual notches at 3.9[Formula: see text]GHz and 7.2[Formula: see text]GHz. Isolation between MIMO elements is greater than 23 dB. Both antennas are fabricated and investigated at 5.9[Formula: see text]GHz for vehicular communications. Maximum gain improvements of 8 dB and 6.4 dB are observed in case of the presented single element and MIMO antenna within the entire operating band due to the integration of dual FSS layers. The diversity performance of the suggested MIMO antenna is investigated by analyzing mean effective gain, envelope correlation coefficient, channel capacity loss and diversity gain parameters. The proposed MIMO antenna is a suitable candidate for vehicular and UWB wireless communication applications.

Development of CPW Fed Slot Antenna with CSRR for Biomedical Applications

This paper presents a complementary split-ring resonator (CSRR) loaded coplanar waveguide (CPW) fed with a circular shape, miniaturized diamond slot planar monopole antenna. The proposed antenna for healthcare monitoring biomedical applications uses the industrial medical and scientific band. The antenna design and development to implant the human phantom are proposed. The primary goal of this work is to continuously monitor the patient’s ability to detect abnormal conditions as soon as possible as a result of improvements in quality of life. In this case, an antenna design methodology must prioritize features such as miniaturization, increased gain and bandwidth, and biocompatibility. Simulated and measured antenna characteristics for biomedical applications are performed at ISM Band frequency.

Highly Sensitive Microwave Sensors Based on Open Complementary Square Split-Ring Resonator for Sensing Liquid Materials.

This paper presents high-sensitivity sensors based on an open complementary square split-ring resonator and a modified open complementary split-ring resonator operating at 4.5 GHz and 3.4 GHz, respectively. The sensors are designed for the detection of multiple liquid materials, including distilled water, methanol, and ethanol. The liquid under test is filled in a glass container loaded using a pipette. Compared to the conventional OCSSRR, the modified OCSSRR with multiple rings exhibits a higher frequency shift of 1200 MHz, 1270 MHz, and 1520 MHz for ethanol, methanol, and distilled water, respectively. The modified sensor also demonstrates a high sensitivity of 308 MHz/RIU for ethanol concentration which is the highest among the existing microwave sensors. The sensors in this manuscript are suitable for multiple liquid-material-sensing applications.

Dual-band dual-polarized sub-6 GHz phased array antenna with suppressed higher order modes

This manuscript proposes a dual-band dual-polarized 64-element phased array antenna (PAA) with suppressed higher order modes (HoMs). Each array element is a microstrip patch structure with complementary split ring resonator (CSRR) loading, allowing for simultaneous dual-band and dual-polarization performance at 3.45 GHz and 3.87 GHz. The proposed PAA exhibits impedance matching of ≤-20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le - 20$$\\end{document} dB at 3.45 GHz and 3.87 GHz while limiting the mutual coupling below -19\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$- 19$$\\end{document} dB between the adjacent elements at both the operating bands. The proposed design includes a plated through hole placed near the CSRR loading to suppress any higher-order modes (HOMs). Two antenna prototypes, without and with HOMs suppression techniques are fabricated and measured. In addition, we demonstrate the beam steering of the proposed PAA up to ±600\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 60^0$$\\end{document} using an off-the-shelf 6-bit phase shifter module. The proposed 64 -element array achieves a gain of 23 dBi, and shows a minimal steering loss of ≃3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\simeq 3$$\\end{document} dB over the steering angle.

Enhanced accuracy and high sensitivity in dielectric characterization through a compact and miniaturized metamaterial inspired microwave sensor

This academic paper introduces a novel sensor known as the Planar Microstrip-based Triple Ring Bridge Complementary Split Ring Resonator (TRB-CSRR) sensor. The main objective of this sensor is to determine the permittivity and thickness of solid dielectric substances. The TRB-CSRR sensor is meticulously designed to resonate precisely at a frequency of 4.86 GHz, achieving a significant notch depth of −33.5 dB. This configuration displays an enhanced average relative sensitivity of 20.2%. The study undertakes numerical assessments across various scenarios, encompassing situations where the sensor interacts with diverse dielectric materials. These assessments yield insights into alterations in resonant frequencies. By meticulously refining the design, the sensor's capability to confine electric fields precisely at the resonant frequency is amplified, ultimately resulting in heightened sensitivity towards dielectric characteristics. The sensor's efficacy is tested using materials featuring relative permittivity values spanning from 1.006 to 12.9, while consistently adhering to dimensions of 5 mm×5 mm×1.6 mm. To validate the conceptual frame-work, a physical sensor is fabricated, and its response is gauged through the utilization of a vector network analyzer (VNA-AV3672D). Employing curve fitting methodologies, alterations in resonance frequencies due to interactions with the tested materials are presented, underscoring the impact of permittivity and thickness. The outcomes derived from simulations, empirical measurements, and calculations display a robust alignment.

Toroidal metamaterial-assisted terahertz biosensor with high sensitivity

In this paper, a toroidal metamaterial for achieving highly sensitive sensors in the terahertz (THz) frequency range is proposed. Such a subwavelength structure consists of a pair of mirror-symmetric metal split-ring resonators and a single metal wire. By exciting the structure with vertically incident electromagnetic waves, high-Q transmission peaks are generated at 2.40 and 2.44[Formula: see text]THz. Near-field analysis reveals that the reverse-flowing currents in the metal split-ring resonators and the metal wire create a pair of magnetic dipoles connected end to end, resulting in a vortex-like magnetic field known as a toroidal dipole. Calculations of multipole scattering energy further confirm that the rapidly enhanced toroidal dipole is the primary factor responsible for the high-Q transmission peaks. This toroidal metamaterial can be used to design refractive index sensors with a sensitivity of up to 20[Formula: see text]GHz/RIU, enabling the detection of subtle changes in the surrounding environment’s parameters. Our strategy paves an alternative route to the development of highly sensitive sensors for biological and chemical molecules in the THz frequency range.

Terahertz Lattice enhanced Quasi-Anapole Immunosensor assisted by protein antibody and AuNPs

Terahertz (THz) metasurface immunosensor has the characteristics of label-free detection, good biocompatibility and high specificity because the antibody-modified of biomarkers has the ability to specifically recognize corresponding biomarkers and increase the detection sensitivity to the concentration of the recognized antigen. The limit of detection (LoD) of THz metasurface immunosensor is highly dependent on resonant field enhancement of metasurface. The anapole mode shows a radiationless state with nontrivial oscillating current configuration. To observe such mode in farfield, in this work, the concept of quasi-anapole (QA) mode is presented which is induced when the electric and toroidal dipoles with identical intensity radiate in antiphase on the metasurface with the unit cell of two split ring resonators (SRRs) on both sides of the central cut-wire. In addition, by coupling the first-order lattice mode to the QA mode, lattice-enhanced QA mode (LQA) was investigated and observed to further enhance field confinement and decrease radiative loss. As a practical application, immunosensor was designed and fabricated by functionalized gold nanoparticles conjugated with the specific monoclonal antibody onto the LQA metasurface to detect the cell concentration of SARS-CoV-2 spike protein. The experimental results indicate that the response of LQA immunosensor depends heavily on the concentration of the Anti-S modified on its surface. When the concentration of Anti-S is 50 pg/ml, the LoD reaches to 3 pg/ml (39 fmol). Such THz LQA immunosensor also shows good specific identification and validates its effectiveness in biomedical sensing.