Complementary Split Ring Resonator Structure Research Articles

Highly sensitive DS-CSRR based microwave sensor for permittivity measurement of liquids

In this work, a low-cost double split complementary split ring resonator (CSRR) microwave sensor has been designed and fabricated on an FR4 substrate for permittivity characterization of liquids. This modified CSRR structure is proposed to make use of the benefits of the dielectric resonator technique compared to other types of microwave methods. The resonator structure comprises two slits in each of the rings normal to each other while maintaining one slit in each ring along the feed line for maximum excitation of the resonator. The resonator with substrate dimensions of acts like an inductance-capacitance-resistance (LCR) circuit and operates at of the industrial scientific and medical band. Eleven different liquid samples (each with of volume) covering a wide permittivity range of have been used to measure the transmission coefficient using vector network analyzer. In comparison with many recently reported works, the sensitivity of the sensor is found to be higher with average and normalized sensitivity of permittivity and respectively. Fit equations are developed for both real and imaginary parts of permittivity, and using the fit equations the permittivity of three unknown samples are determined with less than error. The sensor adopts a unique orientation of the slits to enhance the E-field intensity for better interaction of the samples with the sensor. A compact form factor, low production cost, future integration possibilities, and high sensitivity are the distinct highlights of the sensor. The sensor promises to be a potential candidate for situations that demands low-cost and highly accurate measurements and may be a good alternative to commercial sensors for dielectric characterization, concentration analysis, and impurity measurement of liquids.

Design of Miniaturized SIW Filter Loaded with Improved CSRR Structures

In recent years, Split-Ring Resonators (SRRs) and Complementary Split-Ring Resonators (CSRRs) have gained significant attention for their unique electromagnetic properties, such as negative permeability and negative permittivity, making them promising candidates for advanced microwave devices. This paper presents the design and analysis of a substrate-integrated waveguide (SIW) filter using CSRR structures for miniaturization. The improved CSRR unit can be easily integrated on the surface of the SIW, making it an ideal candidate for the design of compact SIW filters. In this paper, an improved CSRR-loaded SIW filter is designed and analyzed based on its equivalent lumped parameter model. A filter with a center frequency at 22.6 GHz is designed. Several transmission zeros (TZs) are also realized to improve the skirt selectivity of the filter. The design process involves theoretical analysis and electromagnetic simulations to optimize the dimensions of the CSRR resonators to achieve the desired filter characteristics. The measured and simulated results show good agreement, confirming the effectiveness of the proposed improved CSRR-loaded SIW filter. The successful implementation of the improved CSRR-loaded SIW filter demonstrates its potential for achieving miniaturization and enhanced performance in advanced microwave applications.

Multi-Beam Luneburg Lens with Reduced Size Patch Antenna

This paper describes the integration of a plate Luneburg lens with a microstrip patch antenna (MPA) with a complementary split ring resonator (CSRR) at 17 GHz frequency. The main advantage of the method is the compact size of the optimized MPA with CSRR such that the radiation pattern of the antennas successfully overlaps at −3 dB. The overlapping is achieved by positioning multiple MPA with CSRR structures around the plate Luneburg lens with 0.408λ distance between the elements. To test the performance of the lens, CST simulations are carried out using a classical WR62 open-ended waveguide to feed the structure, then adding more waveguides rotated at focal points of the lens. After that, the waveguide is substituted with the MPA with CSRR structure. The superiority of the proposed method over the conventional waveguide or regular patch antenna is confirmed by an overlap in radiation pattern at −3 dB with a narrow beamwidth of 10.9°.

CSRR Structure Design for NV Spin Manipulation with Microwave Strength and Fluorescence Collection Synchronous Enhancement.

In this work, we designed, simulated, and tested a complementary split ring resonator (CSRR) for the purpose of applying a strong and uniform microwave field for the manipulation of nitrogen vacancy (NV) ensembles. This structure was fabricated by etching two concentric rings on a flat metal film that was deposited on a printed circuit board. A metal transmission on the back plane was used as the feed line. The fluorescence collection efficiency was improved by about 2.5 times with the CSRR structure compared to that without CSRR. Furthermore, the maximum Rabi frequency could reach 11.3 MHz, and the Rabi frequency variation was smaller than 2.8% in an area of 250 × 75 μm. This could pave the way to achieving high-efficiency control of the quantum state for spin-based sensor applications.

A Miniaturized and Highly Sensitive Microwave Sensor Based on CSRR for Characterization of Liquid Materials.

In this work, a miniaturized and highly sensitive microwave sensor based on a complementary split-ring resonator (CSRR) is proposed for the detection of liquid materials. The modeled sensor was designed based on the CSRR structure with triple rings (TRs) and a curve feed for improved measurement sensitivity. The designed sensor oscillates at a single frequency of 2.5 GHz, which is simulated using an Ansys HFSS simulator. The electromagnetic simulation explains the basis of the mode resonance of all two-port resonators. Five variations of the liquid media under tests (MUTs) are simulated and measured. These liquid MUTs are as follows: without a sample (without a tube), air (empty tube), ethanol, methanol, and distilled water (DI). A detailed sensitivity calculation is performed for the resonance band at 2.5 GHz. The MUTs mechanism is performed with a polypropylene tube (PP). The samples of dielectric material are filled into PP tube channels and loaded into the CSRR center hole; the E-fields around the sensor affect the relationship with the liquid MUTs, resulting in a high Q-factor value. The final sensor has a Q-factor value and sensitivity of 520 and 7.032 (MHz)/εr) at 2.5 GHz, respectively. Due to the high sensitivity of the presented sensor for characterizing various liquid penetrations, the sensor is also of interest for accurate estimations of solute concentrations in liquid media. Finally, the relationship between the permittivity and Q-factor value at the resonant frequency is derived and investigated. These given results make the presented resonator ideal for the characterization of liquid materials.

Design of Hybrid Fractal Integrated Half Mode SIW Band Pass Filter with CSRR and Minkowski Defected Ground Structure for Sub-6 GHz 5G Applications

A compact and wide-stop band half mode substrate integrated waveguide (HMSIW) filter, incorporated with a hybrid fractal on the upper plane and a complementary split ring resonator (CSRR), along with a defected ground structure (DGS) etched on the bottom plane, is proposed for 5G sub-6 GHz application. A CSRR reduces the resonant frequency causing size miniaturisation by approximately 40% by augmenting the equivalent inductance and capacitance of the CSRR. Further, the low-pass characteristics of the DGS aid in suppressing out-of-band spurious harmonics. A two-pole band pass filter (BPF) is fabricated using FR4 (flame retardant) to validate the design. The results confirm that the proposed filter has a pass band from 3.75 GHz–5.12 GHz with spurious response below −20 dB > 4f0.

Inverse Modeling and Optimization of CSRR-Based Microwave Sensors for Industrial Applications

Design optimization of multivariable resonators is a challenging topic in the area of microwave sensors for industrial applications. This article proposes a novel methodology for rapid redesign and parameter tuning of complementary split-ring resonators (CSRRs). Our approach involves inverse surrogate models established using preoptimized resonator data as well as analytical correction techniques to enable rapid adjustment of geometry parameters and CSRR optimization over broad ranges of operating frequencies. The tuning process is arranged to precisely allocate the operating frequency while maximizing the quality factor of the circuit. The procedure is generic and characterized by an extremely low computational cost of up to two electromagnetic (EM) analyses of the circuit at hand (not counting the inverse model setup). The presented technique is demonstrated using a circular CSRR coupled to a microstrip transmission line (MTL) and optimized to operate between 5 and 20 GHz. The design optimized for 15 GHz is fabricated and experimentally validated using a vector network analyzer. The sensor works in the transmission mode and senses the shift in resonance frequency determined by the properties of the material under test (MUT). Furthermore, an inverse regression model is developed that allows for directly finding the unknown permittivity of the MUT based on the measured resonant frequencies of the sensor. The obtained results corroborate the design utility of the proposed optimization method, as well as the practical usefulness of the specific CSRR structure developed with the aid thereof.

Low phase noise oscillator employing miniaturized shielded-EMSIW resonators embedded with CSRRs structure

In this paper, a parallel-feedback oscillator exploiting miniaturized shielded eighth mode substrate integrated waveguide (SD-EMSIW) resonators embedded with complementary split-ring resonators (CSRRs) structure is proposed. The phase noise performance of the designed oscillator can be efficiently enhanced by employing the SD-EMSIW resonators. Meanwhile, the physical size is prominently miniaturized by loading the CSRRs. The proposed oscillator is designed at 3.5 GHz by utilizing a four-order quasi-elliptic bandpass filter (BPF), combining the shielding metallized walls and etched CSRR techniques on the EMSIW cavities. The proposed prototype has been designed, fabricated and experimented. The experimental results indicate that the oscillator operates at 3.52 GHz with an output signal of 4.2 dBm. The second-harmonic suppression reaches to 25.2 dBc. The phase noise performance of the proposed oscillator features −134.8 dBc/Hz at 1-MHz frequency-offset. In addition to the property of the low phase noise, the proposed prototype exhibits the merits of miniaturized dimension and effective shielding characteristic.

UWB MIMO ANTENNA DESIGN AND FABRICATION WITH PROTRUDED STUB BASED ISOLATION

A compact planar closely placed ultra-wideband circular-patch antenna with multiple-input/multiple-output technology is discussed in this paper. A complementary split-ring resonator structure was introduced between the antennas and a protruded strip-like structure was added to the antenna itself to improve the isolation between the antennas. The defected ground structure was used to further improve the S-parameters. Slots were introduced in the antenna structure to improve the bandwidth. A FR-4 substrate was used in the simulations. The overall cross section of the antenna was 16 × 26 mm<sup>2</sup>. The antenna was simulated using the computer simulation technology software program, CST Studio Suite. In this paper, several antenna parameters are also discussed, such as voltage standing wave ratio (VSWR), gain, envelope correlation coefficient (ECC), radiation pattern, and various other characteristic parameters. The proposed design resonates at 5.34, 8.63, 9.8, and 10.48 GHz with return losses of -33.5, -28.3, -51.9, and -43 dB, respectively. In addition, it has a bandwidth of 4.33-11.419 GHz, an ECC close to zero throughout the band, and has VSWR of less than 1.6 throughout the band.

Electrical Size Reduction of Microstrip Antennas by Using Defected Ground Structures Composed of Complementary Split Ring Resonator

In this study the effects of using defected ground structures (DGS) composed of a complementary split ring resonator (CSRR) and CSRR with dumbbell (CSRR-D) for rectangular microstrip antennas are investigated. On this aim, two different antennas, which are Antenna B having CSRR etched DGS and Antenna C having CSRR-D etched DGS are designed and fabricated in comparison with the ordinary rectangular patch antenna, which is Antenna A. In both Antennas B and C, CSRR structures are etched in the same position of the ground planes. On the other hand, another ordinary microstrip antenna, called Antenna D, is designed at resonance frequency of Antenna C. For the characterization; resonance frequencies, voltage standing wave ratios, percentage bandwidths, gains, ka values and gain radiation patterns are investigated both in simulations and experiments. The numerical analyses show that 29.39% and 44.49% electrical size reduction (ESR) ratios are obtained for Antenna B and Antenna C, respectively in comparison to Antenna A. The experimental results verify the ESR ratios with 29.15% and 44.94%. Supporting, Antenna C promises 68.12% physical size reduction (PSR) as it is compared with Antenna D. These results reveal that Antenna C is a good alternative for DGS based microstrip electrically small antennas.

A compact low frequency dual band liquid crystal polymer antenna for VHF and UHF band applications

This article presents a compact low frequency dual band Liquid crystal polymer (LCP) antenna for Very High Frequency (VHF) and Ultra High Frequency (UHF) band applications. The proposed antenna is having dimensions of 19 × 19 × 0.1 mm 3, which is compact in size and designed on FR4, Rogers/ RT Duroid, Polyimide and LCP substrate materials with CPW (Coplanar Waveguide) feed having CSRR (Complementary Split Ring Resonator) structure placed on ground plane. Simulation results of the designed antennas are compared with each other and finally LCP substrate material exhibits better properties compared with all other substrate materials. The designed antenna on LCP operates in frequency ranges of VHF and UHF (0.085–0.29 GHz and 0.805–2.58 GHz) respectively. The designed antenna on LCP is resonating at 0.14 GHz and 1.425 GHz frequencies with reflection coefficient of −24.29 dB and –33.39 dB respectively. The designed antenna on LCP has the gain of 12. 82 dB at 0.14 GHz and 6.27 dB at 1.425 GHz respectively. The designed antenna on LCP is fabricated and analyzed by using combinational analyzer. Measured results of proposed antenna on LCP are in good agreement with simulated results.

A wireless slot-antenna integrated temperature-pressure-humidity sensor loaded with CSRR for harsh-environment applications

In this study, a wireless slot-antenna integrated temperature-pressure-humidity (TPH) sensor loaded with complementary split ring resonator (CSRR) for harsh-environment applications was presented. The sensor is a multi-resonance structure with three separate resonant frequencies, which renders simultaneous measurements of temperature, pressure and humidity by placing sensitive elements in the corresponding CSRR structures. The sensitivity mechanisms for the temperature, pressure and humidity sensing are described in detail. The sensor was customized and fabricated on the high temperature co-fired ceramics (HTCC) using the three-dimensional co-firing and screen-printing technology. The humidity-sensitive graphene oxide modified polyimide (GO@PI) was used and characterized by the scanning electron microscope (SEM) and energy dispersive spectrometry (EDS). The as-prepared TPH sensor can stably work at the ambient environment of 25–300 ℃, 10–300 kPa, and 20–90 %RH. The temperature sensitivity of the TPH sensor is 133 kHz/℃. The frequency shift of the pressure sensor is 30 MHz with a highest sensitivity of 107.78 kHz/kPa at 60 %RH, and 300℃. The humidity sensor realizes a sensitivity of 389 kHz/%RH in the low humidity of 20–60 %RH and 1.52 MHz/%RH in the high humidity of 60–90 %RH at 10 kPa, and 25 ℃. The sensor described in this study has the advantages of simple structure, higher sensitivity, and lower environmental interference and has the potential for utilization in simultaneous TPH monitoring in harsh environments.

A novel wideband bandpass filter based on CSRR‐loaded substrate integrated folded waveguide

A novel wideband bandpass filter based on folded substrate integrated waveguide (FSIW) is presented in the article. Five square complementary split-ring resonators (CSRRs) are etched in the middle layer of the FSIW. By adjusting the physical size of the CSRR structure, the resonant frequency of the CSRRs can be tuned at the same time and the stopband performance can be changed. As transverse electromagnetic (TEM) mode can be transmitted in the stripline, FSIW excited by stripline shows wider passband than that excited by microstrip line directly. To achieve perfect impedance matching, two microstrip lines to stripline transitions are added in two ports of the filter. The proposed bandpass filter exhibits compact size, high selectivity, good stopband rejection, lower radiation loss, and wideband performances. The measured results show that the fractional bandwidth of the filter is about 35.5%. The measured return loss is better than 15 dB from 4.84 GHz to 6.90 GHz, and the insertion loss is less than 1.2 dB. The comparison between the simulated results and the measured ones validate the possibility of the technology that combines the FSIW and CSRR.

Complimentary split ring resonator sensor with high sensitivity based on material characterization

A new model of microwave planar sensor established on the complementary split ring resonator (CSRR) as well as an air hole in substrate of the structure is introduced for a precise measurement of materials permittivity. The hole is filled into substrate of the planar microstrip line. The CSRR structure with hole is selected for the sensitivity analysis, the result is established to hold over quite sensitive compared with CSRR structure without hole and thus evidence to be more suitable for the sensor design. The sensor in the form of CSRRs operating at a 1.74–3.4 GHz band is explained. At resonance, it is found that the electric field produced straight the plane of CSRR being highly sensitive for the characterization of sample resident with the sensor. The minimum transmission frequency of sensor shifts from 3.4 to 1.74 GHz as the sample permittivity varies from 1 to 10. A numerical model is introduced here for the computation of the system resolution as a function of resonance frequency and sample permittivity using electromagnetic simulator. It is found that the proposed sensor provides 35% increment in sensitivity more than conventional sensor for same permittivity of the sample under test.

A microwave SIW sensor loaded with CSRR for wireless pressure detection in high-temperature environments

In this study, a microwave substrate integrated waveguide (SIW) sensor loaded with complementary split ring resonator (CSRR) for wireless pressure detection in high-temperature environments was presented. The CSRR structure is placed directly above a substrate with an embedded sealed cavity, which is sensitive to pressure. The resonant frequency of sensor is in response to pressure because the strongest electromagnetic field is mainly concentrated on the CSRR. The working principle of the pressure sensor is elaborated via circuit analysis and simulation optimization of high frequency structure simulator (HFSS). The designed sensor worked at about 2.4 GHz to avoid use of expensive measurement equipment. The sensor was customized, and fabricated on the high temperature co-fired ceramics (HTCC) using the three-dimensional co-firing and screen printing technology. The as-prepared sensor can stably work at the ambient environment of 25 °C–800 °C, and 10–300 kPa with a highest pressure sensitivity of 206.89 kHz kPa−1 at 800 °C. The sensor described in this study has the advantages of simple structure, higher quality and sensitivity, and lower environmental interference and has the potential for utilization in multi-site pressure testing or multi-parameter testing (temperature, pressure, gas) in high-temperature environments.

Design of ZnO/N-Doped Graphene Nanohybrid Incorporated RF Complementary Split Ring Resonator Sensor for Ammonia Gas Detection

The integration of nanomaterials with the micro-wave technology is a significant step toward the development of low-cost and low-power RF gas sensors. But, the issues associated with materials like insignificant surface area and poor conductivity, are barriers for the rapid detection of wide range of gas concentrations. In this paper, we demonstrate the proof-of concept using an RF complementary split ring resonator (CSRR) integrated ZnO/N-doped graphene (NGN) nano-hybrid to study the gas sensing properties. This RF device senses the presence of ammonia based on the change in the electrical conductivity of the nanohybrid material upon gas exposure. For this, we have designed and fabricated various new CSRR structures, namely, the meander (M-CSRR) and the CSRR, with the concentric-etched square pattern (SP-CSRR) other than the conventional CSRR (C-CSRR). The fabricated CSRRs are coated with the solvothermal methodically prepared ZnO/NGN nanomaterials and a comparison among them is also made. The comparison revealed that the SP-CSRR coated ZnO/NGN sensor had the maximum shift in the S21 resonance frequency ( $\Delta \text {f}_{\mathbf {S21}} = 13$ MHz at 100 ppm) among all at room temperature. Furthermore, the SP-CSRR-ZnO/NGN sensor exhibited a large-S21 frequency shift of 133 MHz for 500 ppm of ammonia and has shown excellent reproducibility with 0.05% of variation. We have also projected the plausible sensing mechanism for this RF sensing device.

Multiple‐input‐multiple‐output/diversity antenna with dual band‐notched characteristics for ultra‐wideband applications

AbstractDesign and implementation of a four‐port ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO)/diversity antenna with dual band‐notched characteristics are presented. The proposed diversity antenna is composed of four identical rhombic‐shaped monopole radiators arranged orthogonally to achieve better interelement isolation and polarization diversity. At each port, the MIMO antenna shows an impedance bandwidth (S11 ≤ –10 dB) of 10.5 GHz (2.8‐13.3 GHz) and an interelement isolation larger than 18 dB. Furthermore, in order to eliminate 3.5 GHz (Wi‐MAX) and 5.5 GHz (WLAN) bands from the UWB range, the antenna radiators are loaded with elliptical complementary split ring resonator structures. The MIMO performance metrics such as isolation, envelope correlation coefficient, and apparent diversity gain are calculated and presented. The MIMO/diversity antenna prototype is fabricated, and experimental results are verified with simulated results.

Caracterização numérica e experimental de estruturas CSRR em antenas de microfita

<p>This work aims to perform the numerical and experimental characterization of CSRR (Complementary Split Ring Resonator) structures in the ground plane of microstrip antennas, for the use in 4G/LTE wireless systems in the 2.5 GHz band. Two geometries for the radiating elements of the antennas were used, the circular and the rectangular ones. Some initial equations were used to design the CSRR structures, followed by a numerical optimization process. This way, numerical and experimental analyzes of the changes in antennas characteristics were carried out, mainly in resonance frequency, bandwidth and radiation pattern. The simulated results were obtained using the commercial software ANSYS, which uses the Moment Method (MoM). The simulated and measured results of the antennas with the CSRR structures printed on their ground plane were compared with those obtained by circular and rectangular patch antennas with a conventional ground plane, we could observe a reduction in their resonant frequency, enabling the miniaturization process.</p>

Multiband hairpin-line bandpass filters by using metamaterial complimentary split ring resonator

Telecommunication systems for the new generation have greatly stimulated the demand for multi-band bandpass filters with compact dimensions, low insertion loss, robust, low cost and less complex design. In this paper, a compact multi-band bandpass filter, with the fractional bandwidth of 40% and 20% at resonant frequency 3.5 and 5.5 GHz respectively with the response of Chebyshev passband ripple of 0.1 dB is presented. This bandpass filter is suitable for WiMAX application. The design is based on the hairpin-line configuration and metamaterial of complementary split ring resonator structure. The hairpin-line is used for the compact structure design and easy to fabricate because it has open-circuited ends that require no grounding. While the complementary split ring resonator structure is easy to design and can provide multi-band without affecting of size and performance of the filter. The simulated results show the dual-band bandpass response with the insertion loss is 0 dB and high attenuation at stopband. The proposed filter provides a compact, low insertion loss, and less complex structure design that are promising candidates in order to meet the demands of the new generation of communication systems.

Multiband hairpin-line bandpass filters by using metamaterial complimentary split ring resonator

Telecommunication systems for the new generation have greatly stimulated the demand for multi-band bandpass filters with compact dimensions, low insertion loss, robust, low cost and less complex design. In this paper, a compact multi-band bandpass filter, with the fractional bandwidth of 40% and 20% at resonant frequency 3.5 and 5.5 GHz respectively with the response of Chebyshev passband ripple of 0.1 dB is presented. This bandpass filter is suitable for WiMAX application. The design is based on the hairpin-line configuration and metamaterial of complementary split ring resonator structure. The hairpin-line is used for the compact structure design and easy to fabricate because it has open-circuited ends that require no grounding. While the complementary split ring resonator structure is easy to design and can provide multi-band without affecting of size and performance of the filter. The simulated results show the dual-band bandpass response with the insertion loss is 0 dB and high attenuation at stopband. The proposed filter provides a compact, low insertion loss, and less complex structure design that are promising candidates in order to meet the demands of the new generation of communication systems.