T-shaped Resonator Research Articles

Highly narrowband miniaturized microstrip diplexer for qubit mobile communication networks utilizing SIR and T-shaped resonators with negative group delay performance

Highly narrowband miniaturized microstrip diplexer for qubit mobile communication networks utilizing SIR and T-shaped resonators with negative group delay performance

A tunable narrow single-mode bandpass filter using graphene nanoribbons for THz applications

This paper presents a tunable, single-mode narrowband optical filter designed for terahertz applications utilizing graphene nanoribbons. To attain optimal conditions, the filter was devised in three steps. It is composed of two input and output waveguides and a T-shaped resonator with nanoscale dimensions. The transmission spectrum analysis employs the three-dimensional finite difference time domain and coupled mode theory methods. Tunability is achieved through the adjustment of the nanoribbon size and the chemical potential of graphene. The filter demonstrates remarkable performance metrics, including a maximum transmission spectrum efficiency of 99%, a full width at half maximum (FWHM) of 0.115 THz, a quality factor (Q-factor) of 100, and a free spectral range (FSR) of 45 THz. The presented structure holds significant promise for integrated optical components and compact optical devices, showcasing its applicability in the terahertz frequency range. Furthermore, the inherent sensitivity of this structure to changes in the refractive index of the substrate positions it as a potential sensor.

Resonator-based nanoscale plasmonic sensor made of metal–graphene–insulator interfaces

We present a nanoscale refractive index plasmonic sensor based on Fano resonance. We simulate and numerically analyze a novel double T-shaped resonator structure made of conductor–insulator waveguides. Our simulation results show that two Fano resonance peaks can be achieved by the interference between a broadband mode in the straight waveguide and a narrowband mode in the T-shaped resonator. The shifts of Fano resonance peaks by changing the sample refractive index in the resonator structure facilitates the design of a refractive index sensor. To attain a sensor with high sensitivity and figure of merit we employ different geometrical parameters for the resonator structure and analyze the transmission spectra of the sensor. By optimizing the sensor structural parameters we achieve a maximum sensitivity of 523.5 nm/RIU and figure of merit of 2×105 for the sensor made of metal–insulator waveguide. By employing graphene at the core–cladding boundary of the waveguides we attain a high sensitivity of 662.3 nm/RIU and figure of merit of 6.6×105 compared to the literature. We employ samples with refractive indices ranging from 1.0 to 1.05 to analyze the sensor capabilities and employ blood plasma samples to analyze the applications of our sensor structure as a biosensor. Simple fabrication, compactness and high sensitivity are the main advantages of the proposed sensor structure.

Tunable perfect meta-absorber with high sensitivity for refractive index sensing application

An infrared (IR) tunable perfect meta-absorber (TPM) is presented, which is configured of metal-insulator-metal (MIM) structure. The unit cell of the TPM device is composed of two opposite T-shaped and two rod-shaped Au resonators on the reflective mirror layer. The optimized feature size of TPM can achieve perfect absorption and the resonant wavelength can be tuned from blue-shift first and then red-shift by increasing the gap size between two T-shaped resonators continuously. The tuning process of red shift is linear. By changing the distance between two rod-shaped resonators, the TPM device exhibits red shift linearly. Moreover, TPM device shows polarization-dependent characteristic that the main absorption resonance can be attenuated from 100% to 0% by changing polarization angle from 0° to 90° of incident IR light. The resonance of TPM device has an excellent linear relationship with the ambient refractive index, and the sensitivity and maximum figure of merit (FOM) are calculated as 1249 nm/RIU and 21 RIU−1, respectively. These results prove that the design of the proposed TPM device is very suitable for the use of IR sensing, polarization switching, and refractive index sensing applications.

Collaboratively Far-Field and Near-Field Regions for Dual-Modalities Microwave Permittivity Sensor Using T-Shaped Resonator Embedded With IDC

Collaboratively Far-Field and Near-Field Regions for Dual-Modalities Microwave Permittivity Sensor Using T-Shaped Resonator Embedded With IDC

E-Plane dual band bandstop waveguide filter for possible X-band applications

ABSTRACT This paper presents, a novel second order E-plane planar insert based dual band bandstop waveguide filter. The circular shape with two T-shape resonators are printed on Roger RO4350 dielectric substrate to form planar insert. The insert are placed in such a way that positioned in E-plane of the standard WR-90 rectangular waveguide. The independent resonant frequency and bandwidth of the stopband can be adjusted by tuning the resonators. To achieve second order dual band bandstop filter response four asymmetrical circular shape with two T-shape resonators are designed on dielectric substrate to form different stopbands and separated by some specific distance to eliminate the unwanted coupling between them. The numerical analysis of the proposed filter is carried out using CST microwave studio. To validate the numerical analysis of the proposed filter, resonator, WR-90 rectangular waveguide is fabricated and measured. The measured results shows stopband characteristics having centre frequencies f 01g = 8.56 GHz and f 02 = 11.21 GHz and exhibits the bandwidth of 0.4146 GHz and 0.3824 GHz. The simulated and measured result are in good agreement.

Acoustics performance of compact micro-perforated panel absorber with grazing flow

This paper presents numerical and experimental investigations into the acoustic behaviour of a micro-perforated panel (MPP) backed by a shallow cavity under a fully developed grazing flow. A three-dimensional time-domain computational fluid dynamics approach is applied alongside hybrid evaluation methods to accurately capture the acoustic behaviour variations of an MPP orifice. Meanwhile, a hybrid Rayleigh's end correction model for T-shaped resonators is utilized to calculate the acoustic reactance of a very shallow cavity and an acoustics impedance model of an orifice backing with shallow cavity at grazing flow is established. The proposed acoustic impedance model of orifice has been validated by experimental study. The practical significance of this study is that it elucidates the influence of cavities upon the acoustic behaviour of MPPs in the presence of grazing flows; furthermore, it proposes an impedance model that is more suitable for predicting the acoustic performance of booming compact meta-structures.

Graphene electromagnetically induced transparent polarization-insensitive sensors inthe mid-infrared frequency band.

In this paper, a polarization-insensitive sensor based on graphene electromagnetically induced transparency (EIT) is proposed. The device consists of two graphene orthogonal T-shaped structures. This T-shaped resonator produces transparent windows that largely overlap under x and y polarizations, and the results demonstrate its good polarization insensitivity. The device can accomplish detection performance with sensitivity higher than 4960nm/RIU and figure of merit (FOM) greater than 11.4. Meanwhile, when the Fermi energy level of graphene changes from 0.5to 0.8eV, it enables arbitrary modulation of the operating frequency over a wide frequency range of about 4.5terahertz in the mid-infrared band. Our work has the potential to significantly advance the area of biological molecular detection.

An efficient, compact, wide-angle, wide-band, and polarization-insensitive metamaterial electromagnetic energy harvester

This paper introduces a metamaterial energy harvester that is compact, highly efficient, and capable of operating at wide angles. The proposed design has an outer ring resonator housing inverted T-shaped resonators, and it can operate at two distinct frequencies, 3.2 GHz and 5.4 GHz. The structure's impedance is carefully designed to align with that of free space, ensuring efficient capture of incident electromagnetic power with minimal reflection. This enables the resistor load to receive power in the most efficient manner. Based on the simulation findings, the proposed harvester exhibits a notably higher conversion efficiency of around 97 %. To ensure the accuracy and reliability of the simulation outcomes, we fabricated a 3x3 cell array of the proposed design and conducted experimental tests within an anechoic chamber. The simulation and experimental results exhibit a strong correlation. Existing metamaterial-based energy harvesting designs frequently confront size, absorption band, and polarization sensitivity limitations. Our compact design is distinguished by its ability to accomplish near-unity absorption and greater power conversion efficiencies at the desired frequency bands. This makes it an ideal option for energy harvesting systems for wireless sensor networks prioritizing efficiency and size.

Acoustic behaviour of micro-perforated panel backed by shallow cavity under fully developed grazing flow

This paper presents numerical and experimental investigations into the acoustic behaviour of a micro-perforated panel (MPP) backed by a shallow cavity under a fully developed grazing flow. A three-dimensional time-domain computational fluid dynamics approach is applied alongside hybrid evaluation methods to accurately capture the acoustic behaviour variations of an MPP orifice, considering the interaction of flow dynamics and the acoustics in the orifice and cavity. Meanwhile, a hybrid Rayleigh's end correction model for T-shaped resonators is utilized to calculate the acoustic reactance of a very shallow cavity. The numerical results show that the vertical shear layer is observed alongside the hole and cavity and impinges the bottom of shallow cavity. Subsequently it alters acoustic and flow interaction significantly that leads to variation of acoustic behaviour of orifice. In this regard, an acoustic impedance model of an orifice backing with shallow cavity at grazing flow is established. The proposed acoustic impedance model of orifice has been validated by experimental study. The transmission loss predictions for a compact MPP absorber with single or double cavities agree well with the experimental results for the grazing flow condition. The practical significance of this study is that it elucidates the influence of cavities upon the acoustic behaviour of MPPs in the presence of grazing flow; furthermore, it proposes an impedance model that is more suitable for predicting the acoustic performance of booming compact meta-structures.

Tunable bandstop filter using spoof surface plasmon polaritons for terahertz applications

This paper presents the design and analysis of a spoof surface plasmon polaritons (SSPP)-based bandwidth tunable bandstop filter (BSF) operating at 0.26 THz frequency. The proposed filter is comprised of SSPP T-shape resonators which are coupled to the spoof transmission line. Odd and even mode analysis is carried out for the proposed design, and using Co-EM simulation, it is shown that the designed band stop filter is capable of offering tunable bandwidth at THz frequency using a variable capacitor. In order to experimentally validate the proposed approach, design studies are carried out at microwave frequencies and the BSF is developed on a Rogers R4003C substrate of thickness 1.524 mm. The proposed filter designs have a 3 dB bandwidth tunability of 3 GHz (0.038–0.041 THz) and 50 MHz (0.55–0.60 GHz) in the THz and microwave frequency regimes, respectively. The proposed terahertz filter has the potential to be used as an ultra-compact BSF in future applications of photonic integrated circuits in terahertz imaging.

Integrated Microwave Sensor and Antenna Sensor Based on Dual T-Shaped Resonator Structures for Contact and Noncontact Characterization of Solid Material

This paper proposes the integration of microwave sensors (MS) and antenna sensors (AS) for contact and non-contact characterization of solid materials. Integration between MS and AS were determined based on the reflection coefficient (S11) where S11 of ≥ -10 dB was proposed as MS and S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> of ≤ -10 dB was proposed as AS. The proposed sensor consists of a dual T-Shaped resonator with single port operating at a resonant frequency of f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r1</sub> = 1.81 GHz for MS and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r2</sub> = 2.34 GHz for AS using FR-4 substrate with ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> of 4.3, tan δ of 0.0265 and thickness of 1.6 mm. Furthermore, the two resonant frequencies had independent characteristics with different sensing hotspots. MS are proposed for permittivity detection of the Material Under Test (MUT) for contact detection while non-contact detection is proposed by utilizing AS. The procedure for contact detection was carried out by placing the material under test on the surface of the sensor while non-contact detection was carried out by placing the MUT with an air gap between the MUT (d) and the AS was 0.5 - 1.5 mm. The measurement results showed that the average accuracy was 99.30% and 99.31% for the MS and AS for the permittivity range of 1 - 6.15 while the normalized sensitivities of the proposed sensors were 1.15 % and 0.16%, respectively. The results of this research are novel and can be recommended for several purposes related to biomedical and pharmaceutical industries requiring contact and non-contact detection of material characterization.

Multifunctional of dual-band permittivity sensors with antenna using multicascode T-shaped resonators for simultaneous measurement of solid materials and data transfer capabilities

This paper proposes multifunctional of a dual-band independent permittivity sensor with anantenna for data transfer capabilities. The proposed sensor consists of multicascode T-shaped resonators withsingle port operating at frequencies of fr1 = 2.45 GHz, fr2 = 2.00 GHz and fr3 = 1.50 GHz, respectively. The 1st resonant frequency was used as anantenna while the 2nd and 3rd resonant frequencies were used as sensors to determine the permittivity of solid materials simultaneously. Based on the measurement results obtained an average accuracy of 96.81% and 97.54%, while the normalized sensitivityof the proposed sensor was 0.66% and 1.77% with a permittivity range of 1 – 6.15, respectively. Furthermore, the higher resonant frequencyis used as anantenna to transmit and receive data via wireless network. This research is beneficial to be applied in food, biomedical, and pharmaceutical industries to support the industry 4.0 in which the integration between sensors and the internet is required.

SARS-CoV-2 detecting rapid metasurface-based sensor.

We have proposed a novel approach to detect COVID-19 by detecting the ethyl butanoate which high volume ratio is present in the exhaled breath of a COVID-19 infected person. We have employed a refractive index sensor (RIS) with the help of a metasurface-based slotted T-shape perfect absorber that can detect ethyl butanoate present in exhaled breath of COVID-19 infected person with high sensitivity and in-process SARS-CoV-2. The optimized structure of the sensor is obtained by varying several structure parameters including structure length and thickness, slotted T-shape resonator length, width, and thickness. Sensor's performance is evaluated based on numerous factors comprising of sensitivity, Q factor, detection limit, a figure of merit (FOM), detection accuracy, and other performance defining parameters. The proposed slotted T-shape RIS achieved the largest sensitivity of 2500 nm/RIU, Q factor of 131.06, a FOM of 131.58 RIU-1, detection limit of 0.0224 RIU.

Machine learning assisted hepta band THz metamaterial absorber for biomedical applications

A hepta-band terahertz metamaterial absorber (MMA) with modified dual T-shaped resonators deposited on polyimide is presented for sensing applications. The proposed polarization sensitive MMA is ultra-thin (0.061 λ) and compact (0.21 λ) at its lowest operational frequency, with multiple absorption peaks at 1.89, 4.15, 5.32, 5.84, 7.04, 8.02, and 8.13 THz. The impedance matching theory and electric field distribution are investigated to understand the physical mechanism of hepta-band absorption. The sensing functionality is evaluated using a surrounding medium with a refractive index between 1 and 1.1, resulting in good Quality factor (Q) value of 117. The proposed sensor has the highest sensitivity of 4.72 THz/RIU for glucose detection. Extreme randomized tree (ERT) model is utilized to predict absorptivities for intermediate frequencies with unit cell dimensions, substrate thickness, angle variation, and refractive index values to reduce simulation time. The effectiveness of the ERT model in predicting absorption values is evaluated using the Adjusted R2 score, which is close to 1.0 for nmin = 2, demonstrating the prediction efficiency in various test cases. The experimental results show that 60% of simulation time and resources can be saved by simulating absorber design using the ERT model. The proposed MMA sensor with an ERT model has potential applications in biomedical fields such as bacterial infections, malaria, and other diseases.

Inverse Design of Nonlinear Polaritonic Metasurfaces for Second Harmonic Generation

Enabling strong nonlinear optical phenomena requires carefully designed photonic devices to maximize light–matter interactions. In recent years, topology optimization has become an increasingly popular tool to optimize photonic devices, due to its efficiency in dealing with extremely large parameter spaces. The focus has largely been on two-dimensional linear optical devices, particularly in integrated photonic settings, with a limited number of studies extending topology optimization to nonlinear effects in dielectric structures. Here, we apply topology optimization to metal–multiple quantum well–metal structures supporting intersubband transitions. In past years, the combination of photonic engineering and material design has enabled extremely efficient ultrathin second harmonic generating metasurfaces, based on L- and T-shaped resonators. Topology optimization enables novel designs that exceed the state-of-the-art nonlinear metasurfaces to date, with the promise of further improvement. The same approach may be extended to other frequency mixing phenomena, such as sum-frequency or difference-frequency generation.

Design and Simulation of MIM Optical Filter Structure Based on Plasmonic Diagonal T-Shaped Resonators Using ANN Method

Design and Simulation of MIM Optical Filter Structure Based on Plasmonic Diagonal T-Shaped Resonators Using ANN Method

Low Complexity Compact Lowpass Filter Using T-Shaped Resonator Loaded With a Stub

A novel miniaturized microstrip low pass filter (LPF) with a wide stopband and sharp roll-off is presented. The designed filter is developed by realizing a T-shaped structure loaded with a stub as a resonator and open-stubs as suppressor cells to achieve a simple structure for ease of fabrication process. The new filter with a symmetrical structure has a 3 dB cut-off frequency of 2.15 GHz, the transition band is 123 dB/GHz from -3 dB to -40 dB, a stopband with an attenuation level better than -20 dB from 2.4 up to 22.1 GHz with a compact size of 0.0132λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>g</i></sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The insertion loss in the passband is less than 0.3 dB and return loss is lower than -20 dB. The filter is fabricated, and the results show agreement between the simulation and measurement.

Designing ultra-small Wilkinson power divider with multi-harmonics suppression

ABSTRACT This paper presents a miniaturized Wilkinson Power Divider (WPD) with the capability of attenuating unwanted harmonics up to the 19th harmonic. In this study, a low pass filter was embedded as the quarter-wavelength transmission lines of the conventional WPD. To reduce the size of the proposed structure, the high impedance line is meandered. A simple T-shape resonator is added to suppress the high frequency. The even and odd mode analysis were reported as the analytical descriptions. The operational frequency of the presented WPD is 1.95GHz, and S21, S11, S22, and S23 in this frequency are -3.79dB, -15.56dB, -14.15dB, and -10.89dB, respectively. The overall size of implemented WPD is only 8.8 mm × 8.02 mm, and its normalized circuit size equals 0.078 × 0.071. The designed structure has been fabricated and measured on the RT-5880 substrate with a thickness of 20mil. The desired matching between the simulation results and the measurement ones has been evident.

Experimental investigation of mechanical, acoustic and hybrid metamaterial designs for enhanced and multi-band electric motor noise dissipation

Acoustic metastructures exhibit an unprecedented ability to arbitrarily manipulate the properties of sound waves, including amplitude and phase modulation which has attracted much attention in both the academic and industrial communities. Design of metastructures has been extensively investigated for the purpose of the independent manipulation of acoustic and elastic waves. It is up to now unclear however if the optimal dissipation approach involves locally resonant structural elements, or locally resonant acoustic cavities or a hybrid mix of both noise abatement mechanisms. To study this problem, we investigate numerically and experimentally the noise reduction performance of acoustic and mechanically locally resonant structures and how they perform when integrated into the same application scenario. Taking the noise emission of an electric motor as the excitation regime for our study, the acoustic and mechanical metamaterial structures with respective C-shape and T-shaped resonators are judiciously designed to maximize noise dissipation within two targeted frequency bands where the motor noise peaks. A hybrid structure with a mix of both resonators is also designed. The results demonstrate that all three metastructure designs improved the noise attenuation performance with an additional sound insertion loss of up to 16 dB when compared to a flat wall structure of equivalent mass. The findings in this work demonstrate that significant noise attenuation can be obtained by incorporating these acoustic and mechanical meta-atoms into a wall architecture which may have great potential for real world applications such as surrounding electric motors which tend to emit monotonic and irritating noise.