Complementary Single Split Ring Resonator Research Articles

Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation

The application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing based on planar microwave resonators, especially defective ground structures (DGS) including complementary split ring resonators (CSRRs). The analysis is carried out from the equivalent circuit model as well as the electromagnetic (EM) field perspectives, and guidelines for the design of crack sensors with high sensitivity are developed. Numerical and experimental validation of the provided theoretical analysis is another aim of this article. With this aim, the developed guidelines are used to design a crack sensor based on a single-ring CSRR. It is shown that the sensitivity of the proposed sensor is almost three times higher than the sensitivity of a conventional double-ring CSRR. Moreover, it is demonstrated that folded dumbbell-shape DGS resonators can be used to achieve even higher sensitivities. The CSRR-based crack sensors presented in this study and other studies available in the literature are only sensitive to cracks with a specific orientation. To address this limitation, a modified version of the DGS is proposed to sense cracks with arbitrary orientations at the cost of lower sensitivity. The performance of all the presented sensors is validated through EM simulation, equivalent circuit model extraction, and measurement of the fabricated prototypes.

Design of a High-Sensitivity Microstrip Patch Sensor Antenna Loaded with a Defected Ground Structure Based on a Complementary Split Ring Resonator.

A comparative study to determine the most highly sensitive resonant frequency among the first four resonant frequencies of a conventional patch antenna and defected ground structure (DGS)-loaded patch antennas using commonly used DGS geometries in the literature, such as a rectangular slit, single-ring complementary split ring resonators (CSRRs) with different split positions, and double-ring CSRRs (DR-CSRRs) with different locations below the patch, for relative permittivity measurement of planar materials was conducted. The sensitivity performance for placing the DGS on two different locations, a center and a radiating edge of the patch, was also compared. Finally, the effect of scaling down the patch size of the DGS-loaded patch antenna was investigated in order to enhance the sensitivities of the higher order resonant frequencies. It was found that the second resonant frequency of the DR-CSRR DGS-loaded patch antenna aligned on a radiating edge with a half scaled-down patch size shows the highest sensitivity when varying the relative permittivity of the material under test from 1 to 10. In order to validate the simulated performance of the proposed antenna, the conventional and the proposed patch antennas were fabricated on 0.76-mm-thick RF-35 substrate, and they were used to measure their sensitivity when several standard dielectric substrate samples with dielectric constants ranging from 2.17 to 10.2 were loaded. The measured sensitivity of the second resonant frequency for the proposed DGS-loaded patch antenna was 4.91 to 7.72 times higher than the first resonant frequency of the conventional patch antenna, and the measured performance is also slightly better compared to the patch antenna loaded with a meander-line slot on the patch.

Ultra-Wideband Metamaterial-Loaded Microstrip Array Antennas using Fibonacci & Fractal Geometric Patterns, Design and Modelling

In this study; theory, design and modeling of a new topology of ultra-wideband (UWB) metamaterial (MTM) loaded microstrip array antenna using Fibonacci & fractal geometric patterns are analyzed. This antenna is made basically from many monopole elements which are loaded by complementary metamaterial transmission line (CMTL) unit cells. The distributed CMTL element, contains a Koch-shaped expanded complementary single split ring resonator (CSRR) pair. At first step, the UWB microstrip array antenna designed with two CMTL-loaded monopole element. So, using an iterative method based on the Fibonacci and fractal geometry patterns, the array antenna is expanded. As the order of iteration increases, the impedance bandwidth of the proposed array antennas improve more, and the radar cross section (RCS) decreases. the impedance bandwidth of the proposed third-order Fibonacci and fractal CMTL-loaded array antennas are 250 MHz and 539 MHz more than the two-element CMTL-loaded array antenna, respectively. Finally, this paper presents an improved method to extract the parameters of an equivalent circuit model of the proposed MTM-loaded array antenna. Verification of the equivalent model have been validated utilizing ADS software. The obtained model, in addition to numerically efficient in comparison with the full wave analysis utilizing the moment method, gives a good physical insight to the mutual coupling mechanism of the array antenna.

Simulation and fabrication of a high-isolation very compact MIMO antenna for ultra-wide band applications with dual band-notched characteristics

In this paper a very compact dual band-notched two-port multiple-input multiple-output antenna with low mutual coupling is presented for portable ultra-wideband systems. This antenna with overall size 18 × 35 × 1.6 mm3, consist of two identical monopole elements which fed by two 50 Ω coplanar waveguide lines and fabricated adjacent to each other on the top side of a FR-4 substrate with shared ground plane. To reduce the mutual coupling between elements, a rectangular stub was introduced between them and then it modified to a T-shaped stub. For further reduction, a rectangular slot etched out of the connected ground plane. Due to the results, proposed antenna achieves wide impedance bandwidth at each port, from 2.3 to 12 GHz covering the whole UWB spectrum except at two eliminating bands. Although this antenna has small size and simple structure, the mutual coupling between elements is lower than −20 dB. By etching out two rectangular single complementary split-ring resonators from the radiating patch, dual band-notched characteristics are obtained in WiMAX and WLAN bands. Envelope correlation coefficient of less than 0.035, nearly omnidirectional pattern, 90% radiation efficiency despite lossy substrate, high multiplexing efficiency (>−1 dB) except at two notches and peak gain near 6dBi are some other characteristics of this design.

CSRR Based Sensors for Relative Permittivity Measurement With Improved and Uniform Sensitivity Throughout [0.9–10.9] GHz Band

This paper proposes miniaturized, lightweight and high sensitivity planar metamaterial based sensors for relative permittivity measurement within [0.9–10.9] GHz band. Each proposed sensor is designed using a thin-substrate microstrip line loaded with a single complementary split ring resonator (CSRR). The loaded resonator is excited using maximum electric/magnetic (cross polarization) excitation to maximize the sensors’ sensitivity. Each proposed sensor operates at different frequency range within [0.9–10.9] GHz band based on the size of the loaded resonator. Compared to similar state-of-the-art sensors, the proposed ones are at least 30% more sensitive. The minimum transmission frequency shifts (50)% as the sample’s relative permittivity changes from 1 to 10. The paper proposes a condition of sensitivity uniformity to maintain a uniform sensitivity over the specified band irrespective of the resonator size. Utilizing the proposed condition, the sensitivity of all sensors remains uniform throughout [0.9–10.9] GHz band for all dielectric samples with relative permittivity between 1 and 10. This vital feature allows the practical realization of resonant probes with less computational operations and consistent measurements over a wide dynamic range of the sensing-related frequency. Experimental measurements are in good agreement with the numerical findings. The paper includes a comprehensive sensitivity analysis which investigates the effect of resonator’s excitation scheme, resonator’s order (i.e. single or double CSRR) and substrate thickness on the sensitivity of CSRR based sensors. The proposed sensing platforms are recommended for the development of highly sensitive, consistent and reliable planar sensors such as microfluidics, displacement, nondestructive and biomedical sensors.

A metamaterial hepta‐band antenna for wireless applications with specific absorption rate reduction

Present article embodies the design and analysis of slotted circular shape metamaterial loaded multiband antenna for wireless applications with declination of SAR. The electrical dimension is 0.260 λ × 0.253 λ × 0.0059 λ (35 × 34 × 0.8 mm3) of proposed design, at lower frequency of 2.23 GHz. The antenna consists of circular shape rectangular slot as the radiation element loaded with metamaterial split ring resonator (SRR) and two parallel rectangular stubs, etched rectangular single complementary split-ring resonator (CSRR) and reclined T-shaped slot as ground plane. Antenna achieves hepta bands for wireless standards WLAN (2.4/5.0/5.8 GHz), WiMAX (3.5 GHz), radio frequency identification (RFID) services (3.0 GHz), Upper X band (11.8 GHz—for space communication) and Lower KU band (13.1 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The SRR is responsible for creating an additional resonating mode for wireless application as well as provide the declination in SAR about 13.3%. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.

Low Sidelobe Level CSRR Loaded Weighted Array Antenna

A novel complementary split-ring resonator (CSRR) loaded amplitude tapering technique is proposed to create a low sidelobe level array antenna. Low sidelobe levels are realized by loading single, double, and hybrid CSRRs couplets, in the ground plane of a uniformly excited array antenna. Design curves are created for various amplitude taper values to achieve low sidelobe levels. Amplitude tapering is accomplished by varying CSRRs parameters in the ground plane of the array. The method is demonstrated on a $6 \times 2$ rectangular microstrip patch array antenna configuration operating at a center frequency of 10.9 GHz. Three array configurations incorporating single CSRRs couplets, double CSRRs couplets, and hybrid (combination of single and double CSRR couplets) CSRRs couplets are analyzed to create low sidelobe level array. Single CSRR couplet loaded configuration exhibits a measured first sidelobe level of 24 dB and second sidelobe level of 19.5 dB. Hybrid CSRR couplet loaded array antenna provides the first sidelobe level of 23 dB and the second sidelobe level of 25 dB. Measured gain of the proposed antenna at 10.9 GHz is 16.1 dB. The proposed method exhibits an improvement of nearly 10 and 4 dB of first and second sidelobe suppressions, respectively.

Dual‐mode bandpass filter based on substrate‐integrated waveguide loaded with complementary split ring resonators

AbstractA compact dual‐mode bandpass filter adapted from circular substrate‐integrated waveguide (SIW) is presented in this paper. The excited modes of the cavity are controlled by introducing metal vias and loading complementary split ring resonators (CSRRs) to the cavity. Higher order dual resonant modes are used to generate the passband response. Single ring CSRRs with double splits are loaded in the SIW cavity to provide independent control over the passband resonant modes. The loading of CSRRs contributes to further size reduction of the cavity. The fundamental mode of the cavity is controlled by using optimally configured metal vias. Thus, a nearly symmetric passband response and an improved out‐of‐band response below the dual‐mode passband are achieved by suppressing the fundamental mode. The modified SIW cavity loaded with CSRRs reduces the size of the standard circular cavity by 83%. The proposed bandpass filter has center frequency at 8.7 GHz with 14% fractional bandwidth. 0.7 dB is the measured minimum insertion loss with a return loss better than 20 dB.

Metamaterial-inspired rotation sensor based on complementary single split-ring resonator (CSSRR)

In this paper, a new rotation sensor based on a complementary single split-ring resonator (CSSRR) coupled to a circularly shaped microstrip line is designed, simulated and verified by experiment. Rotating the upper resonator, the measurement results reveal the relationship of the rotated angles and the transmission characteristics. Compared to the previously published rotation sensors, the sensor proposed benefits from a well immunity to ambient conditions and nearly same resonance frequency responses at the relatively symmetrical angles. It even can get a high sensitivity around 100 MHz per 10° with a wide dynamic range of 0°–90°. The configured device is quite compacted with respect to the operational wavelength and will have tremendous potential applications in the micro-electromechanical systems technology.

Non-Invasive Millimeter-Wave Profiler for Surface Height Measurement of Photoresist Films

This paper presents a low-cost non-invasive millimeter-wave surface-height measurement sensor of dielectric and polymer films on glass and quartz substrates. The surface-height profiler utilizes near-field resonance measurement technique operating at 96 GHz implemented by using a single complementary split-ring resonator (CSRR) integrated with a tailor-made WR10 rectangular waveguide. By placing a glass or quartz substrate uniformly coated with SU-8 photoresist on top of the CSRR, the thickness of the SU-8 polymer can be extracted based on the reflected and transmitted electromagnetic-wave energy interacting at the electrical boundary between the substrate and polymer film. Uniform single layers of SU-8 polymer with thicknesses from 3 to $13~\mu \text{m}$ coated on top of the glass substrate are measured and characterized. The extracted polymer-film thicknesses from the sensor in this paper show an agreement of higher than 95% as compared with the commercial surface profiler instrument, while offering various advantages, such as non-invasion, ease of measurement setup, low-cost, and miniaturization.

Topology optimization-based design of metamaterial-inspired sensor with improved sensitivity

Sensitivity is of great importance for a Metamaterial (MTM)-inspired sensor in many detecting and sensing applications. In this paper, a new improved sensitivity method for a metamaterial-inspired sensor is proposed, which is based on MTM microstructure topology optimization. The metamaterial-inspired sensor consists of a microstrip-lined excitation and a coupled MTM microstructure, and can be used to dielectric sensing by tracking the resonant frequency shift. The optimization model is established to improve the sensitivity of the sensor where the MTM microstructure is topologically optimized in the design domain. To validate the improved sensitivity, a sensor is designed to monitor the dielectric film thickness. Compared with the complementary split ring resonator (CSRR), complementary single split ring resonator (CSSRR) based sensors, the novel sensor with an optimized MTM exhibits more frequency shift for a tiny variation of the dielectric thickness. The relationship between the dielectric thickness and the resonant frequency is established through polynomial interpolation fitting.

A CPW-fed circular patch antenna inspired by reduced ground plane and CSRR slot for UWB applications with notch band

A coplanar waveguide (CPW) fed ultra-wideband antenna is proposed for UWB applications. The proposed antenna consists of circular monopole with single complementary split ring resonator (CSRR) slot and reduced ground plane. The overall size of an antenna is 20 × 25 × 1.6 mm3. The prototype antenna is designed, fabricated and tested. It provides good return loss characteristics and radiation pattern. The measured −10 dB impedance bandwidths are 1.06 GHz (3.9–4.96 GHz) and 4.5 GHz (6.7–11.2 GHz) with resonance frequencies at 4.4 and 9 GHz, respectively. An appropriate dimension of CSRR slot has been etched on patch to notch 5–6 GHz band to avoid interference with WLAN and WiMAX devices which is one of the crucial issues to be solved in UWB antenna. Parametric studies on width of ground plane and dimension of CSRR slot are done to investigate the effect of various geometrical values on antenna characteristics. The simulated and measured results of the antenna are in close agreement with each other which will confirm the applicability of the proposed antenna. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:745–749, 2017

Triple band‐notched UWB monopole antenna on ultra‐thin liquid crystal polymer based on ESCSRR

A triple band-notched UWB monopole antennas is presented for flexible electronics. To enhance the flexibility, ultra-thin liquid crystal polymer with 50 μm thickness is used as the substrate. The antennas are constituted by swallow tail radiation patch and trapezoid ground. Moreover, band-notched characteristic is realised by etching different sized elliptic single complementary split-ring resonators on the radiation patch. An improved triple band-notched UWB antenna with notched-frequency bands at 3.7–4.2 GHz, 5.15–5.35 GHz, and 5.725–5.825 GHz are designed by a novel capacitance compensation method. The measured radiation patterns indicate that the antennas are an omni-directional antenna both at flat and bent circumstances. The occupied area of antenna is 27 × 21 mm.

Effect of Complementary Split Ring Resonator Structure on PIFA Antenna

This paper proposes a new design of Planar Inverted-F Antenna with complementary split ring resonators (CSRRs). The operating frequency of this antenna is 2.425 GHz for Wireless Local Area Network (WLAN) application. The method is to incorporate a single CSRR cell and a periodic array CSRRs on the radiating patch. We studied the effect of this method on the characteristics of antenna in free space and in the presence of the user. We used a homogeneous model of a human head near our antenna. The parameters that considered in these works are gain, electric field, magnetic field, return loss, radiation pattern, power loss density and Specific Absorption Rate. The addition of CSRRs on to PIFA antenna will improve the gain from 4.76 dB to 4.81 dB and will reduce the Specific Absorption Rate from 3.57 W/kg to 2.95 W/kg.

Single-Compound Complementary Split-Ring Resonator for Simultaneously Measuring the Permittivity and Thickness of Dual-Layer Dielectric Materials

This paper presents the design and analysis of a single-compound complementary split-ring resonator (SC-CSRR) that induces two resonance frequencies for simultaneously measuring the thickness and permittivity of dual-layer dielectric structures. Two resonance frequencies were generated using two distinct embedded resonator current lengths in a single complementary split-ring resonator. These two resonance frequency responses were combined to determine the thickness and permittivity of a dual-layer dielectric sample. Methods proposed in this paper were used to analyze the equivalent permittivity relationship, and thus, determine the thickness and permittivity of the material under test. The proposed simple low-cost SC-CSRR measurement method for assessing the permittivity of materials in a compact area was experimentally analyzed and verified in experiments. The experimental results indicated that the average thickness and permittivity measurement errors were 6.26% and 4.63%, respectively, for single-layer samples, and 5.26% and 6.48%, respectively, for dual-layer samples.

Compact wideband antenna based on novel composite right/left handed transmission line

Based on a new type of composite right/left handed transmission line (CRLH TL), a novel compact wideband antenna is proposed. The CRLH TL is composed of a ground player with an etched complementary single split-ring resonator and a patch with two series gaps and two metal vias. Consistent simulated and measured results of the proposed antenna are shown that it operates at 3.46 GHz extended to 3.97 GHz (10 dB return loss bandwidth is 13.7%). The electrical size of the patch at the center frequency f = 3.72 GHz is only 0.25λ0 × 0.22λ0 × 0.01λ0, a 52.7% reduction in size comparing to the conventional patch antenna. The measured radiation efficiency was higher than 80% over the 10 dB return loss bandwidth. Additionally, the antenna attained a gain extended from 3.1 to 4.76 dB.

A Compact Microstrip-Fed Triple Band-Notched UWB Monopole Antenna

In this letter, a novel low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed. Notch bands around the 3.3-3.8-GHz WiMAX and 5.15-5.85-GHz WLAN frequencies are obtained by etching out two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna. Furthermore, by placing two rectangular split-ring resonators near the feedline-patch junction of the antenna, rejection for the 7.9-8.4-GHz X-band frequencies is achieved. Design guidelines for implementing the notch-bands at the desired frequency regions are provided. The match between the simulated and experimental results suggests that the proposed antenna can be a good candidate for application in UWB communication systems.

MULTIFREQUENCY MONOPOLE ANTENNAS BY LOADING METAMATERIAL TRANSMISSION LINES WITH DUAL-SHUNT BRANCH CIRCUIT

The theory and design of a new family of multifrequency monopole antennas by smartly loading a set of complementary metamaterial transmission line (CMTL) unit cells are investigated. The distributed CMTL elements, epsilon negative (ENG) or double negative (DNG) through incorporating additional capacitive gaps, contain a Koch-shaped extended complementary single split ring resonator pair (K-ECSSRRP) etched on the signal strip. The K- ECSSRRP features dual-shunt branches in the equivalent circuit model, rendering a distinguished resonator with dual zeroth-order resonant (ZOR) modes. By smartly controlling the element layout and loading difierent numbers of unit cells, ten antennas covering difierent communication standards (GSM1800, UMTS, Bluetooth, DMB and WIMAX) are designed and four of them are fabricated and measured. At most of operating frequencies, the antennas exhibit impedance matching better than i10dB and normal monopolar radiation patterns. Numerical and experimental results both conflrm that the single-cell or dual-cell ENG and DNG CMTL-loaded monopoles exhibit almost identical dual ZOR modes. Moreover, the loaded elements also contribute to the radiation, which is the major advantage of this

Harmonic suppressed bandpass filter using composite right/left handed transmission line

A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equiva-lent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR). The characterization is performed by theory analysis, circuit simulation, and full-wave electromagnetic (EM) simulation. The negative refractive index (NRI) and backward wave propagation performance of the CRLH TL are demonstrated. For application, a bandpass filter (BPF) with enhanced out-of-band selectivity and harmonic suppression operating at the wireless local area network (WLAN) band is designed, fabricated, and measured by combining the CRLH TL with a complementary electric inductive-capacitive resonator (CELC). Three CELC cells with wideband stopband performance in the conductor strip and ground plane, respectively, are utilized in terms of single negative permeability. The design concept has been verified by the measurement data.

Dual-shunt branch circuit and harmonic suppressed device application

A new type of planar left handed transmission line (LH TL) circuit was investigated theoretically and experimentally. It consists of a capacitive gap and Koch-shaped extended complementary single split ring resonator pair (K-ECSSRRP) etched on the host conductor line and ground plane, respectively. Distinguished from any previous counterparts possessing only one shunt branch, the current K-ECSSRRP features dual-shunt branches in the capacitive–inductive equivalent circuit. As a consequence, an additional attenuation pole is introduced above the upper edge passband of the LH TL, which is a very desirable characteristic. For verification and illustration of potential applications, a compact diplexer is designed and fabricated with an enhanced harmonic suppression. The dual-shunt branch circuit is of reference value and suggests a variety of device implementations where miniaturization and harmonic suppression are major concerns.