Open Complementary Split Ring Resonators Research Articles

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.

An Angular Displacement Sensor-Based Active Feedback Open Complementary Split-Ring Resonator

This letter presents an active feedback microwave sensor with a wide dynamic range and high sensitivity for detecting angular displacement. The sensor comprises two types of movable ring resonators (the rotor), split-ring resonator (SRR) and complement SRR (CSRR), and a modified convex-shaped open complementary split-ring resonator (the stator). The stator is designed with an active circuitry to enhance the quality factor over 4.7 K, and the feedback loop surrounds the sensing zone to enhance the mutual coupling for tracking a finite rotation of rotors in a wide dynamic range. The stator uses the separation between two reflection coefficients or the decibel magnitude variation at a fixed frequency, which is generated from its resonance frequency shift and whose values vary as a function of the rotation angle to be measured. After rotor loading, the average decibel sensitivity in terms of variation in reflection was calculated as 0.32 and 0.13 dB/degree for the SRR and CSRR, respectively, within a dynamic range of 0°–90°.

Highly Sensitive Reflective-Mode Phase-Variation Permittivity Sensor Based on a Coplanar Waveguide Terminated With an Open Complementary Split Ring Resonator (OCSRR)

This paper presents a one-port reflective-mode phase-variation microwave sensor consisting of a coplanar waveguide (CPW) transmission line terminated with a grounded open complementary split ring resonator (OCSRR). The sensor is useful for measuring the dielectric constant of the so-called material under test (MUT), which should be placed in contact with the OCSRR, the sensitive element. The output variable is the phase of the reflection coefficient. Design guidelines for the implementation of highly sensitive sensors are derived in the paper, and validated through simulation and experiment. As compared to other reflective-mode phase-variation sensors based on open-ended sensing lines, the designed and fabricated devices exhibit a very small sensitive region by virtue of the use of an electrically small resonant element, the OCSRR. The relevant figure of merit, defined as the ratio between the maximum sensitivity and the size of the sensing area (expressed in terms of the squared wavelength), is as high as FoM $= 5643^{\circ }/\lambda ^{2}$ in one of the reported prototypes. Moreover, the paper analyzes the effects of losses. From this study, it is concluded that MUT losses do not significantly affect the output variable, provided losses are small. It is also demonstrated that the sensor is useful to estimate the loss tangent of the considered MUT samples.

Super compact dual-band substrate integrated waveguide filters and filtering power dividers based on evanescent-mode technique

AbstractThis paper proposes a series of novel super compact dual-band substrate integrated waveguide (SIW) filters and filtering power dividers (FPDs) using two new compact metamaterial unit-cells. The proposed unit-cells, called COCSRRs, consist of a complementary split-ring resonator (CSRR) and an open CSRR (OCSRR). The working principle of the proposed filters and FPDs is based on the evanescent-mode technique.Based on the theory of evanescent mode, an additional passband below the waveguide cut-off can be achieved by etching the electric dipoles on the metal surface of the SIW structure. The CSRR and OCSRR unit-cells, behave as electric dipoles when excited by an axial electric field and are able to generate a forward-wave passband region below the cut-off frequency of the SIW configuration. Therefore, the proposed COCSRR unit-cells can be interpreted in term of electric dipoles, which can generate two forward-wave passbands below the cut-off frequency of the SIW structure. Although, the center frequencies of each passband can be independently controlled by changing the dimensions of the CSRR and OCSRR sections in the proposed COCSRR unit-cells. Accordingly, by loading the proposed COCSRR unit-cells on the waveguide surface, two arbitrary passbands below the waveguide cut-off frequency are achieved for WLANs and WiMAX applications. The designed SIW filters and FPD are fabricated and measured. Good agreement is observed between the simulated and measured results of the proposed filters and FPD. The proposed dual-band filters and FPD have many benefits like compact size, high selectivity, tunable passband frequencies, and easy integration with other planar technologies.

Open Complementary Split-Ring Resonator Sensor for Dropping-Based Liquid Dielectric Characterization

A microwave sensor with a coplanar waveguide semilumped meander open complementary split-ring resonator (MOCSRR) is proposed to analyze the dielectric properties of liquid. The proposed method operates at subgigahertz frequencies and uses a small volume of liquid (>0.08 mL) on a substrate-integrated slot container. A resonance reflection coefficient notch frequency and its magnitude in decibels are observed for complex permittivity ( $\varepsilon'+j \varepsilon $ ”) characterization. A strong electric field distributed on the edge of the designed MOCSRR slot provides a sensitive compact area to detect small variations in the liquid sample or concentration. Operations need not be constrained to micropipette operations or microfluidic channel fabrication. A specific volume of the sample liquid must be dropped in the detection zone to analyze complex permittivity. To test the proposed methods, binary mixtures of ethanol and water were loaded, and a 58.7 MHz shift in resonant frequency and a variation of 6.77 dB were attributed to a complex permittivity perturbation phenomenon when ethanol concentration was varied from 0% to 100%. Different concentrations of ethanol and liquid were evaluated and analyzed. The proposed sensor exhibited repeatability and easy operation in detecting liquids with high relative permittivity, such as water and lossy liquids.

Microwave Resonator for Eye Tracking

This article presents a novel microwave resonator for eye tracking. The system is implemented using coplanar waveguide technology and consists of two identical configurations with a pair of mirror-symmetrical open complementary split-ring resonators. These two sensors are combined with a wearable device placed on the eye and glass frame corners. The proposed evaluation uses two uncoupled and separate reflection magnitudes for differential cross modes. Each sensor has two resonance frequencies, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{L}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{H}$ </tex-math></inline-formula> , to detect horizontal and vertical eye sweeping, respectively. As the user’s focus sweeps left to right or up and down with the wearable device, the asymmetrical conditions of the eyelid and cornea enhance the variation in differential reflection magnitude. The paired sensors provide information for tracking eye action. By applying the resonator perturbation theory, the eyelid and eye cornea locations above the planar resonator location were analyzed using the equivalent permittivity and conductance loss relationship, respectively. The experimental results indicate that the resonator tracker can detect relative changes in eye gaze from 50° to 130° horizontally (average 8.81-dB variation) and from 40° to 140° vertically (average 9.43-dB variation). These eye sweeping directions, thus, connect at 90°. Initial calculations reveal that the optimal eye tracking function is achieved and that the tracking method is suitable for individual users.

Compact low‐pass/band‐pass filters based on quarter‐mode substrate integrated waveguide and a connected network of CSRRs

In this study, a compact low-pass filter (LPF) and two compact dual-wideband band-pass filters (BPFs) are proposed based on a connected network of complementary split-ring resonators (CSRRs) and open CSRRs (OCSRRs). The LPF is designed based on microstrip structure, and then the structure is changed to quarter-mode substrate integrated waveguide for designing the dual-band BPFs. The 3 dB cutoff frequency of the LPF is 1.84 GHz and its size is 0.094λ g × 0.094λ g , where λ is the guide wavelength at 3 dB cutoff frequency. The LPF has a wide stop-band, up to 16 GHz. The first proposed dual-wideband BPF has the centre frequencies of 3.85 and 8.03 GHz, with 3 dB fractional bandwidths of 31.69 and 13.7%, respectively. Finally, a sharper dual-band BPF is obtained by cascading two proposed dual-wideband BPFs and optimising them for the desirable response. The measured centre frequencies of the second dual-band BPF are 3.65 and 7.15 GHz with 3 dB fractional bandwidths of 28.21 and 12.52%, respectively. The measurement results of the fabricated filters are in good agreement with the simulation ones. The filters are compared with similar reported filters in the literature, which confirm the compactness of the proposed filters..

A compact open complementary split ring resonator inspired triband reconfigurable coplanar waveguide fed antenna

AbstractThis paper presents the implementation of open complimentary split ring resonator (OCSRR) structure in small rectangular radiating elements to achieve triple band and dual band reconfigurability using PIN diode. The proposed design is a coplanar waveguide fed structure and consists of three small radiating elements, whereas two OCSRR structures are coupled with the two‐radiating elements. The third radiating element embedded with OCSRR is connected using a PIN diode. Under DC biasing conditions the whole design resonates at three frequencies, that is, , , and , whereas the proposed design switches to dual band operation at and in the diode ‘OFF’ state. The proposed structure is designed and fabricated on a single sided ungrounded FR substrate. Overall, a good agreement between simulated and measured results is observed. It is also observed that the radiation patterns of the proposed antenna are the same with gains of , , and at , and in the PIN diode ‘ON’ state, respectively, whereas in the diode ‘OFF’ state, at the gain is and at the gain is .

Miniaturized substrate integrated waveguide filter using fractal open complementary split-ring resonators

A miniaturized substrate integrated waveguide (SIW) bandpass filter using fractal open complementary split-ring resonators (FOCSRRs) unit-cell is proposed. The proposed structure is realized by etching the proposed FOCSRR unit-cells on the top metal surface of the SIW structure. The working principle of the proposed filter is based on the evanescent-mode propagation. The proposed FOCSRRs behave as an electric dipoles in condition of the appropriate stimulation, which are able to generate a forward-wave passband region below the cutoff frequency of the waveguide structure. Since, the electrical size of the proposed FOCSRRs unit-cell is larger than the conventional OCSRRs unit-cell; therefore, the FOCSRR unit-cell is a good candidate to miniaturize the SIW structure. The proposed filter represents high selectivity and compact size because of the utilization of the sub-wavelength resonators. The introduced filter is simulated by a 3D electromagnetic simulator. In order to validate the ability of the proposed topology in size reduction, 1- and 2-stage of the proposed filters have been fabricated based on the standard printed circuit board process. The measured S-parameters of the fabricated filters are in a good agreement with the simulated ones. The proposed SIW filters have many advantages in term of compact size, low insertion loss, high return loss, easy fabrication and integration with other circuits. It is the first time that the FOCSRR unit-cells were combined with the SIW structure for miniaturization of this structure. Furthermore, a wide upper-stopband with the attenuation >20 dB in the range of 3–8 GHz is achieved. The results show that, a miniaturization factor about 75.5% has been obtained.

Highly-Sensitive Microwave Sensors Based on Open Complementary Split Ring Resonators (OCSRRs) for Dielectric Characterization and Solute Concentration Measurement in Liquids

Differential permittivity sensors based on a pair of uncoupled microstrip lines, each one loaded with an open complementary split ring resonator (OCSRR), are proposed in this paper. The sensing principle is based on the measurement of the cross-mode insertion loss, very sensitive to asymmetric loading. Thus, by loading one of the OCSRRs with the reference sample, and the other one with the sample under test (SUT), the difference in the complex permittivity between both samples generates an asymmetry that gives rise to mode conversion. From the measurement of the cross-mode transmission coefficient, the dielectric properties of the SUT can be determined, provided those of the reference sample are well known. It is shown that by adding fluidic channels on top of the OCSRRs, the proposed sensor is useful for the measurement of the complex dielectric constant of liquids, and experimental results in mixtures of ethanol and deionized (DI) water and methanol in DI water, as a function of the ethanol/methanol content, are provided. Due to the high sensitivity of the proposed differential sensor to detect small perturbations (asymmetries), the structure is also of interest for the accurate measurement of solute concentrations in liquid solutions. In this paper, the structure is applied to monitor sodium content in aqueous solutions, and it is found that sodium concentrations as small as 0.25 g/L can be resolved.

Miniaturized filtering SIW power divider with arbitrary power-dividing ratio loaded by open complementary split-ring resonators

A miniaturized substrate-integrated waveguide (SIW) power divider with embedded filter response and arbitrary power-dividing ratio loaded by open complementary split-ring resonators (OCSRRs) is presented. In the proposed power divider, the miniaturization and filtering response are realized by a pair of OCSRRs, which are etched on the metal cover of the SIW structure. The design procedure indicates that the power division ratio can be adjusted by changing the locations of the output ports. In this study, three miniaturized filtering SIW power dividers with different power division ratios (1:1, 1:4, and 1:8) are implemented to evaluate the performance of the proposed structure on the size reduction. These power dividers (1:1, 1:4, and 1:8) have the overall sizes of 0.31λg× 0.14λg, 0.25λg× 0.17λg, and 0.25λg× 0.18λg, respectively. The measured results also agree well with the simulated results.

A low‐cost compact antenna design on a paper substrate for near‐field passive UHFRFID tags

ABSTRACTA significant cost in the widespread deployment of UHF radio frequency identification (RFID) systems has been the passive RFID tags. To address some of this expense, this paper presents an antenna design for UHF RFID tags that can be printed on inexpensive paper substrates and operate in the near field of the UHF reader. This antenna design is based on meander line miniaturization techniques and open complementary split ring resonator (OCSRR) elements to reduce the amount of conducting material required to manufacture the antenna by 30%. For demonstration purposes, a prototype near‐field UHF RFID tag was manufactured on a paper substrate and the read‐range was measured at 920 MHz. It was shown that useful read‐ranges could be achieved while reducing the overall cost and size of the antenna on the RFID tag. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1052–1056, 2017

Compact dual‐band bandpass filters using complementary split‐ring resonators with closely spaced passbands

Two compact dual-band bandpass filters based on open complementary split-ring resonators (OCSRRs) with stub loaded are presented. Both of the stub-loaded open-loop resonators can achieve two resonant modes, and each of the resonators generate a passband. Thus, a small ratio of two passbands central frequencies can be obtained. Moreover, the two resonant modes of the outer ring are λ /4 resonators, so the OCSRR exhibits a compact size. Meanwhile, the characteristics of dual-mode resonators can be discussed by using even-/odd-mode analysis. The proposed filters exhibit four transmission zeros, one or two of which can be introduced between the two passbands. To verify the theory, two filters with zeros of different locations are designed, fabricated and measured. The test results indicate good agreement with simulated ones.

Compact bandpass filter based on SIW loaded by open complementary split-ring resonators

A compact substrate integrated waveguide (SIW) with open complementary split-ring resonators (OCSRRs) loaded on the waveguide surface is proposed. The OCSRRs can be interpreted in terms of electric dipoles and they are good candidates to behave as electric scatterers. By loading OCSRRs on the waveguide surface, a forward-wave pass-band propagating below the waveguide cutoff frequency is generated. The resonance frequency of the OCSRRs is approximately half of the resonance frequency of the complementary split ring resonator (CSRR). Therefore, the electrical size of this particle is larger than the CSRRs and the OCSRRs are more appropriate for the SIW miniaturization. A bandpass response with a sharp rejection frequency band is obtained by properly manipulating the structure of the elements. By changing the orientation of the OCSRRs, two types of unit cell are proposed. Moreover, by resizing the OCSRRs, resonance frequency can be easily moved and the bandwidth can be tuned by the coupling between two OCSRRs. Compared with some other reported bandpass filters (BPFs) with SIW technique, the presented BPF has great improvements on size reduction and selectivity. To verify the methodology, two filters with center frequency of 5.5 GHz are designed and measured. The measured results are in good agreement with the simulated ones. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:674–682, 2016.

Automated design of bandpass filters based on open complementary split ring resonators (OCSRRs) using aggressive space mapping (ASM) optimization

AbstractThis paper is focused on the design of bandpass filters based on open complementary split ring resonators (OCSRRs) in microstrip technology. The filters are obtained by coupling the corresponding shunt resonators (OCSRRs) through admittance inverters (quarter wavelength transmission line sections). Different undesirable effects derived from the chosen topology are taken into account and are compensated at the design level. These effects include the reduction in bandwidth (caused by the narrowband functionality of the line sections acting as admittance inverters), and the presence of a spurious band above the filter passband. The proposed technique is based on the well‐known aggressive space mapping algorithm, which is a powerful tool for the synthesis and design of microwave components. The design of the OCSRR‐based filter is provided in a fully automated way as the main result of this paper. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Compact and Wide Stopband Lowpass Filter Using Open Complementary Split Ring Resonator and Defected Ground Structure

Abstract. A compact (0.16  g × 0.08  g ) and wide stop-band lowpass filter design using open complementary split ring resonator (OCSRR) and defected ground structure (DGS) is presented in this paper. Low pass filter is con-structed using two cascaded stages of OCSRR. Since the rejection bandwidth of the OCSRR is narrow, tapered dumbbell shaped DGS section is placed under the OCSRR to enhance the bandwidth. The cutoff frequency (f c ) of the proposed lowpass filter is 1.09 GHz. The rejection band-width of the filter covers the entire ultra wideband spec-trum. Hence the spurious passband suppression is achieved up to 10 f c . The designed filter has been fabri-cated and validated by experimental results. Keywords Lowpass filter, defected ground structure (DGS), open complementary split ring resonator (OCSRR) 1. Introduction On the motive of conventional filter design methods such as stepped impedance and open stub suffering from poor skirt characteristics and spurious passband, re-searchers have paid great attention over the past few years in designing a compact and sharp cutoff lowpass filters with spurious free wide stopband. Lowpass filter using different defected ground structures (DGS), photonic bandgap (PBG) structures and electromagnetic bandgap structures have been proposed in various literatures [1–9]. Sharp cutoff and low insertion loss lowpass filter using a complementary split ring resonator (CSRR) is reported in [3]. Cascaded stages of CSRR with open stub configura-tion, exhibiting sharp cutoff lowpass response are pre-sented in [4]. Planar photonic bandgap (PBG) structures involving compact microstrip resonating cell (CMCR) are utilized to design a lowpass filter with wide stopband [5]. Recently, a lowpass filter with very sharp transition band using OCSRR is demonstrated in [6]. In this paper, a new technique is proposed to reduce the size of the lowpass filter and to obtain the wide spurious free stopband. The lowpass filter is designed using open complementary split ring resonator and a tapered dumbbell shaped DGS is placed under the OCSRRs to extend the stopband. The proposed lowpass filter is smaller and outperforming the existing filters in terms of insertion loss level, roll off rate and rejection bandwidth. Figure 1 shows the schematic of OCSRR printed on the microstrip line. This structure is first proposed in [6] for designing a sharp cutoff lowpass filter with compact size. OCSRR is a negative image of the open split ring resonator. To study the frequency response characteristics of the OCSRR, this structure is designed on Rogers 5880 substrate with a dielectric constant of 2.2 and a substrate thickness of 0.381 mm and simulated using an Ansys full wave simulator.

A CPW‐fed triple band OCSRR embedded monopole antenna with modified ground for WLAN and WIMAX applications

ABSTRACTA coplanar waveguide fed triple band antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WIMAX) applications. The proposed antenna consists of rectangle monopole with modified ground plane and open complementary split ring resonator (OCSRR) loading. The overall size of the antenna is 30 × 40 × 0.8 mm3, which provides Omnidirectional pattern in all three bands. The prototype of antenna is designed, fabricated, and measured. The measured −10 dB impedance bandwidths are 300 MHz (2.40–2.70 GHz), 680 MHz (3.32–4.00 GHz), and 1040 MHz (4.76–5.8 GHz) with resonance frequency at 2.6 GHz,3.4GHz, and 5GHz, respectively, which is suitable for WLAN/WiMAX applications. Parametric study on OCSRR is discussed to validate the results. Simulated and measured results of the antenna are presented and discussed. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2413–2418, 2015

Wideband three section branch line coupler using triple open complementary split ring resonator and open stubs

This paper presents the design of a wideband three section branch line coupler using three cascaded open complementary split ring resonator structures and open stubs connected between them. The slow wave effect offered by the open complementary split ring resonator is utilized to achieve size reduction. The low impedance lines of the conventional three section branch line coupler are replaced by the proposed structure which is 50–52% less in length. The fabricated prototype gives a bandwidth of 53% and occupies an area of 17.46% of the conventional one.

Automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs) through aggressive space mapping (ASM)

This paper is focused on the application of space mapping optimization to the automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs). These structures are of interest for the implementation of resonant-type metamaterial transmission lines and for the design of planar microwave circuits based on such complementary resonators. The paper presents a method to generate the layouts of CSRR- and OCSRR-loaded microstrip lines from the elements of their equivalent circuit models. Using the so-called aggressive space mapping, a specific implementation that uses quasi-Newton type iteration, we have developed synthesis algorithms that are able to provide the topology of these CSRR- and OCSRR-loaded lines in few steps. The most relevant aspect, however, is that this synthesis process is completely automatic, i.e., it does not require any action from the designers, other than initiating the algorithm. Moreover, this technique can be translated to other electrically small planar elements described by lumped element equivalent circuit models.

Common-mode suppressed differential bandpass filter based on open complementary split ring resonators fabricated in microstrip technology without ground plane etching

A differential (or balanced) bandpass filter based on open complementary split ring resonators (OCSRRs) coupled through admittance inverters is presented in this article. Pairs of OCSRRs are symmetrically placed in a mirror configuration between the strips of the differential line and are modeled by means of two series connected parallel resonators. For the differential (odd) mode, there is a virtual ground at the connecting plane between the OCSRR pairs, and the structure is roughly described by the canonical model of a bandpass filter, consisting of a cascade of shunt resonators coupled through admittance inverters. It is demonstrated that, through a proper design of the OCSRR stages, the common mode noise in the vicinity of the differential filter pass band can be efficiently suppressed. Due to the differential mode operation of the filter, it is not necessary to incorporate metallic vias to ground the OCSRRs. Moreover, as compared to other differential filters based on OCSRRs, defected ground structures are not present in the proposed filters. To illustrate the potential of the approach, two balanced bandpass filters are designed, fabricated, and characterized. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:910–916, 2014