Dielectric Height Research Articles

Achieving desired characteristic impedances in customized coplanar waveguide transmission line design

Coplanar waveguide (CPW) transmission lines are valued for their planar design, low radiation, and minimized signal loss, but controlling their characteristic impedance remains a challenge. This study employs the Taguchi method, a statistical approach, to optimize the characteristic impedance by adjusting eight control factors: track width, track thickness, gap width, dielectric height, backplane thickness, conductor material conductivity, dielectric conductivity, and operational frequency. The analysis evaluates these factors across three levels to find optimal conditions, with dielectric height and track width identified as most influential. Additional assessments using main effect screening, Analysis of Variance (ANOVA), and multivariable linear regression validate the Taguchi method's effectiveness. The results of this effort encompass a distributed resistance of 133.69 Ω/m, a distributed inductance of 2.6676E-7H/m, a shunt conductance of 2.8880E-16 S/m, a capacitance of 7.4103E-11 F/m, a propagation constant of (1.1141 + 279.36i) m-1, and a characteristic impedance of (59.999 - 0.23928i) Ω. A CPW transmission line with a characteristic impedance of 60 Ω was successfully designed and simulated using COMSOL Multiphysics, showing promising results for efficient CPW designs tailored to specific applications. The paper describes•Applied the Taguchi method to assess control factors that affect the Characteristic Impedances of the coplanar waveguide Transmission Lines.•Conducted additional validations with ANOVA and regression analysis.•Simulated designs based on optimized parameters using COMSOL Multiphysics.

WITHDRAWN: Fano-modulated chiral metasurface for near-infrared sensing via bound states in the continuum

Here, we report polarization-sensitive chiral metasurface with broken in-plane inverse symmetry to exploit symmetry-protected quasi-bound states in the continuum (quasi-BIC) for highly sensitive and sharply resonant surface interactions enabling refractive index sensing in near infrared region. Chirality is induced by rotating silicon nanofins placed on top of dielectric spacer with a gold backplate, creating a chiral arrangement that results in a strong chiroptical response. Our chiral metasurface offers controllable spectral linewidth and chiral selectivity in dual-wavelength bands where each band can be excited simultaneously or independently by controlling meta-atom geometry offering multispectral index sensing. We report a novel phenomenon of controlling interplay of chirality between two closely positioned wavelength bands to tailor symmetry breaking for a specific resonant mode (chiral) while preserving symmetry for other mode (achiral). Additionally, we report the phase-sensitive evolution of Fano resonance from pure reflectance dip when controlled by dielectric spacer height, and further demonstrated phase-insensitive control of Fano resonance amplitude. We divided Fano resonance into distinct spectral peak and dip to improve light manipulation within the metasurface. Our proposed sensor demonstrates sensitivity and a quality factor of about 435 nm/RIU and 3888, respectively. Furthermore, we compared different phenomenon (chiral selectivity, quasi-BIC, Fano) and sensing parameter values for different metasurface configurations (including single nanofin and absence of a spacer) and observed that the configuration without a spacer achieved the highest sensitivity of approximately 640 nm/RIU.

Design and analysis of multiple beams phased array microstrip antenna for 5G applications

The paper presents a novel and compact antenna array design fed through a 3 dB BLC for producing phase shift in the array. Beam steering is an attractive design feature for avoiding obstacles in the path of the beam. It is achieved by switching the beam to another path by simply varying the phase shift between elements. The proposed structure exhibits resonance in the frequency having range of 27.6 GHz −29.6 GHz with a minimal return loss value of −45 dB for frequency applications of 28 GHz, which can be further employed for 5G frequency applications, there are two multiple beams observed, with main beam at theta equal to −35 degrees, the main beam shifts to +28 degrees by changing the feed port of the coupler. A stable gain of around 11.5 dB is obtained for the entire frequency range. The input phase has been varied for different elements in the array, and best results were obtained for a 90 degree phase difference, which required the use of a 3 dB BLC. Rogers RT Duroid 5880, having a dielectric of 2.2 and a 0.51 mm dielectric height, was used as a substrate for antenna fabrication. The simulations were performed on the CST Microwave studio and the measurements were done on VNA (Agilent N5247A).

High FOM Refractive Index Sensor Based on Quasi-Bound States in the Continuum of Tri-Prism Metasurface

Due to the inevitable ohmic losses and radiation losses from metal materials and nanoparticles, the figure of merit (FOM) of plasmon sensors is usually very low. The all-medium material combined with bound states in the continuum (BIC) can effectively improve the FOM of sensors. In this article, a single-layer tri-prism metasurface sensor based on quasi-BIC (Q-BIC) was first proposed and simulated. Some meaningful results were obtained by adjusting and optimizing the structural parameters. By reducing duty ratio (DR) and dielectric column height, the sensor was sensitive to refractive index (RI) changes and had an excellent spectral performance. The results showed the sensitivity and full width at half maximum (FWHM) of the single-layer tri-prism sensors were 680.7 nm/RIU and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times 10^{-{2}}$ </tex-math></inline-formula> nm, respectively, and the FOM could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.36\times 10^{{4}}$ </tex-math></inline-formula> RIU−1. On this basis, we proposed a novel double-layer metasurface sensor model to improve the sensing performance and simulate it further. Because of the complete symmetry of the two-layer metasurfaces, the sensor had perfect phase matching condition. Under the same conditions, double-layer sensor had higher sensitivity and narrower FWHM in Q-BIC. The results showed the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> and FWHM of the sensor were 715.6 nm/RIU and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7\times 10^{-{5}}$ </tex-math></inline-formula> nm, respectively, and the FOM could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{7}}$ </tex-math></inline-formula> RIU−1, detection limit (DL) could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.89\times 10^{-{9}}$ </tex-math></inline-formula> RIU. FOM had been improved by three orders of magnitude than the single-layer sensor. It provided ideas for sensors with ultralow DLs in the future.

Dual-band rectenna system for biomedical wireless applications

- This paper proposes a dual-band RF energy harvester to power biomedical wireless devices for various health applications. Biomedical devices may be implantable medical devices or wearable devices. The proposed system's novelty is that it can work in widespread operating power ranges with good conversion efficiencies. The Pi impedance matching network is used in the projected dual-band rectifier that is practicable for RF energy harvesting within the existing band of frequencies. The proposed antenna is simulated and designed using CST MW Studio 2018, while for the designing and simulation of the rectifier, ADS 2020 is used. Also, for the DC pass filter and matching network, ADS 2020 is used. For fabrication, an FR-4 lossy substrate having a dielectric constant of 4.4 and dielectric height of 1.6 mm is used. The projected result shows that the conversion efficiency is greater than 50% (capable of 78%), with an input power range of 8.5–10 dBm. At an input power of 8 dBm, the typical DC voltage was increased to 1.8 V. With the use of matching circuits, the maximum conversion efficiency is 78%, while without a matching circuit, the maximum conversion efficiency is only 37%. The matching circuit was critical for conversion efficiency.

Reconfigurable switching between reflecting/absorbing modes in VO2 assisted graphene-coated hemispherical dielectric hole arrays

In this paper, a graphene-coated dielectric hole array is used to design a reconfigurable switchable optical reflector/absorber device. The design benefits from the collective excitation of localized surface plasmon resonances of graphene-coated hole array, providing simpler fabrication fellow and more compact structure with respect to graphene-coated spherical nanoparticle array with similar plasmonic behavior. Geometrical parametric study of the reflecting mode shows that the device has lots of degrees of freedom for spectrum tuning and can highly tolerate fabrication imperfections. Moreover, the reflection rate is slightly affected by the dielectric substrate height, which can be tuned to achieve strong absorption by backing it with a metallic mirror. The designed absorber efficiently captures a wide range of obliquely incident transverse electric (TE) and transverse magnetic (TM) waves. Also, the operating frequency of both reflecting and absorbing modes can be tuned after fabrication, thanks to the two-dimensional nature of graphene material. Finally, using vanadium dioxide (VO2) phase change material, the switchable reflector\\absorber mode of the device is also exhibited.

Effects of dielectric substrate material microstrip antenna for limited band applications

In this paper, an analysis of dual frequency resonance antenna is achieved by OM-shape microstrip patch antenna. The proposed antenna is analyzed using IE3D simulation software. The analysis of proposed structure is done by varying the dielectric constants and height of the substrate as well as gain and radiation pattern of the antenna is obtained. It observed that on varying the dielectric substrate the effect on proposed antenna is very effective.

Design and Fabrication of a Novel Ultra Compact Microstrip Diplexer Using Interdigital and Spiral Cells

A dual-band bandpass-bandpass microstrip diplexer with very small size and good performance is designed in this work. The proposed diplexer has a novel structure which is introduced for the first time in this paper. In comparison with the previously reported diplexers, it occupies the most compact size of 0.002 λg2 (226.7 mm2), fabricated on 0.787 mm dielectric substrate height. The resonance frequencies of the presented diplexer are located at 0.76 GHz and 1.79 GHz making it suitable for the global system for mobile communications (GSM) applications. It has a wide flat channels with two fractional bandwidths (FBWs) of 41.1% and 50%. Another feature of the proposed diplexer is its ability to suppress the harmonics. It can attenuate the 1st to 7th harmonics. Moreover, it has low insertion losses and low group delays at both channels while the isolation and return losses are acceptable. Finally, the proposed diplexer is fabricated and measured to verify the simulation results, where a good agreement between the simulation and measurement results is obtained.

Drain current characterization of dielectric modulated split gate TFET for bio-sensing application

This paper presents an analytical surface potential and drain current model of split gate (SG) Tunnel Field Effect Transistor (TFET) for label free detection of biomolecules e.g. protein, biotine, DNA, etc., utilizing the concept of underlap and dielectric modulation approach. A portion of the device channel is left open in between the splitted gates with a thin layer of silicon dioxide as adhesive layer. This open cavity acts as the binding site for the biomolecules to be detected which alters the effective capacitance of the region and hence modulates the device characteristic trend. The device electrostatics are developed by solving two dimensional Poisson’s equation and Young’s parabolic approximation and consequent drain current is then formulated applying Kane’s model. To assess the sensing ability of the device, both neutral and charged biomolecules with different dielectric values are immobilized within the cavity and the impact of variation in dielectric constant, charge density and height of biomolecules on device characteristics is analyzed. In addition to this, drain current sensitivity of the device is also investigated by varying the permittivity, charge density (both positive and negative) and height of the bio-species. All the analytical results are evaluated with corresponding Sentaurus TCAD simulated data to corroborate the accuracy of the derived model.

Study of the Super Directive THz Photoconductivity Antenna

The photoconductivity antenna is a promising technology to generate THz wave. However, the technology is problematic in THz low antenna gain. The improvement of efficiency and directive is very important to the photoconductivity antenna. Here, a super directivity THz photoconductivity antenna (PCA) is proposed. The antenna uses the dielectric resonator to enhance the directivity which yields the super directivity in radiation. The eigen mode analysis is performed to the super directivity antenna, which is used to help design the antenna and understand the mechanism for the super directivity. The spherical cap is used as the dielectric resonate antenna (DRA), and the relationship between the radius of sphere and the height of cap and super directivity is surveyed. The dielectric cap height and sphere radius are found both playing an important role in enhancing the directivity of the antenna. To validate the proposed design, a THz photoconductivity antenna is designed. The simulations are performed using FDTD and FEM method. Both results show that the designed THz antenna has the super directivity value above 9.0 at 2.0 THz.

An Ultra-Wideband Terahertz Metamaterial Absorber Based on the Fractal Structure

In this paper, we propose an ultra-wideband terahertz (THz) metamaterial absorber (MA) based on a fractal structure, and the main structure of the MA includes the upper metal patch, the bottom metal reflector, and a single dielectric substrate between the two. The surface metal patch is the gold designed by fractal and topology theory to constitute the basic resonant unit, and then the surface base resonant unit is reduced and amplified at different scales. By approaching the resonance frequencies of each other, MA with an operating range of 6.39 to 9.47 THz was obtained, and its relative bandwidth (RB) is 38.8%. The absorption bandwidth can be extended by adjusting the ratio between the four groups of resonators, and the dielectric height can be adjusted to improve the efficiency of the absorption spectrum. In addition to the discussion of the above influencing factors, we are also curious about the principle behind absorption. Therefore, the distribution of the electric field strength and magnetic field strength of the designed MA and the influence of the polarization angle and incidence angle on the absorption bandwidth are simulated.

A novel miniaturized microstrip lowpass-bandpass diplexer using patch and interdigital cells for wireless networks

This paper presents a novel design of lowpass-bandpass microstrip diplexer using patch and interdigital cells. In comparison with the previously reported lowpass-bandpass diplexers, the proposed design has the most compact size with the overall area of 0.018 λg2 (351.7 mm2) fabricated on 0.787 mm dielectric substrate height. The lowpass channel has a cut-off frequency (fc) at 1.57 GHz. The resonance frequency of the bandpass channel is located at 3.35 GHz, which is suitable for WiMAX applications. Having low insertion losses at the lowpass and bandpass channels is another feature of this work. For the frequencies above the bandpass channel, the harmonics are attenuated up to 2.8 fc. A theory method is presented to show the behavior of the proposed structure. Finally, the designed diplexer is fabricated and measured, where the simulation results match well with the measurements.

A very compact microstrip diplexer fabrication with superior performance for broadband wireless applications

AbstractThis study presents a planar dual‐channel bandpass microstrip diplexer based on a novel structure. It has the very compact size of 0.0081 λ g2 (95.7 mm2) fabricated on 0.787 mm dielectric substrate height. Due to the use of close microstrip sections, several coupling capacitors are created. These capacitors can increase the degree of freedom for controlling the diplexer performance while it is optimized easily. Accordingly, the designed diplexer has a high performance in terms of wide fractional bandwidths, attenuated harmonics, flat channels, high return losses and low insertion losses. The wide fractional bandwidths (FBWs%) of 34.3% at the first channel and 38.6% at the second channel make the proposed diplexer appropriate for the broadband applications. The resonance frequencies are located at f1 = 1.6 GHz for the L‐band and f2 = 3 GHz for WiMAX applications. The maximum harmonic level is less than −20 dB for the frequencies up to 6.5 GHz (4f1). The maximum group delays are &lt;1.26 ns at the first passband and 0.56 ns at the second passband. The proposed diplexer is fabricated and measured for verification. The comparison shows that both measured and simulated results are in a reasonable agreement.

Graphene-based highly efficient and broadband solar absorber

We propose graphene-based solar absorber for broadband absorption response. The absorber is designed by sandwich graphene layer between the dielectric layer and resonator layer. The use of graphene layer improves the absorption in the dielectric layer. The design results in the form of absorption, reflection and normalised electric field are analysed for graphene-based design and simple design (without graphene layer). The design with the graphene layer is giving better absorption behaviour in the range of 100 THz to 1600 THz. The design results are also analysed for the different physical design parameters like gold resonator width (G_W), silver resonator width (S_W), gold dielectric layer height (G_H) and total structure width (W). The increase in the gold resonator and silver resonator width reduces the absorption and increase in height of gold dielectric layer increases the absorption. The designed structure is absorbing not only visible energy but also infrared energy and ultraviolet energy. The designed graphene-based broadband solar absorber is applicable in solar energy harvesting, light trapping and photovoltaic devices.

Broadbeam Cylindrical Dielectric Resonator Antenna

A novel widebeam aperture-coupled cylindrical dielectric resonator antenna is proposed, which consists of multi-layered cylindrical ceramic disks joined together to achieve the required height. The proposed antenna is fed by wide aperture slot, which, along with optimum dielectric resonator height, excites fundamental and high order hybrid modes inside the DR to achieve wide beamwidths in the two principal planes simultaneously. Then, a new frequency, which is called the limited frequency and denoted as $f_{\mathrm {L}}$ , is defined. Based on $f_{\mathrm {L}}$ , dimensions of the wide slot are determined. Finally, the antenna is manufactured and measured. Its operating frequency band ranges from 5.49 GHz to 7.2 GHz. The antenna yields broadbeam in the frequency band from 6.1 to 6.7 GHz and achieves a 3-dB beamwidth from 124° to 149° in the E-plane and from 112° to 126° in the H-plane.

Tunable Coplanar Waveguide

The tuning methods of transmission line based on coplanar waveguide presented. Tuning is achieved by moving signal electrode of the line above the substrate or by moving additional dielectric plate above the electrodes of the line. Signal electrode lifting or presence of additional dielectric plate leads to redistribution of the electromagnetic field and therefore to changing of transmission line effective parameters, such as effective dielectric permittivity and characteristic impedance. Calculation of effective parameters was performed by using finite elements method. Proposed method of calculation is in good agreement with well-known analytical expression for coplanar waveguide based line without tuning. Experimental verification for tunable line based on coplanar waveguide was performed. The values of effective dielectric permittivity were extracted from measured S-parameters by solving an approximation task. The measured and calculated effective dielectric permittivity are in good agreement. Effective dielectric permittivity decreases with increasing of air gap between the signal electrode and dielectric substrate or between the additional dielectric plate and electrodes of the line. Required displacement are up to hundred micrometers, that allows to use MEMS or piezo actuators as control elements. The influence of electro physical and geometrical parameters on the tuning efficiency is shown. There are several ways for improving of the tuning efficiency. First is to decrease distance between the signal electrode and ground electrode, which is applicable for both methods. Another way for method with signal electrode lifting is to increase dielectric permittivity or height of the substrate. In method with moving dielectric plate above the electrodes, dielectric plate is the defining element. Therefore, increasing of dielectric permittivity and height of the dielectric plate or decreasing of dielectric permittivity or height of the substrate leads to the improving of the tuning efficiency and tuning range. The results of the paper allow to effectively design resonant elements and phase shifters based on coplanar waveguide line.Ref. 16, fig. 13, table 4.

Utilising graphene antidots for implementation of a broadband terahertz absorber

In this work, a broadband absorber is designed for application in the terahertz region using graphene antidots array. The proposed absorber consists of an Au substrate, a polyethylene dielectric layer and a graphene sheet with antidot resonators. The geometrical dimensions of the antidot resonator and its array period, the graphene conductivity parameters and the dielectric layer height and refractive index are the parameters that determine the characteristics of the absorber such as bandwidth, centre frequency, the amount of the absorption and sensitivity to the incident wave incident angle and polarisation. The circuit theory and a broadband matching technique of the transmission lines are utilised in some steps of the design approach. Moreover, some rules of thumb are extracted for the absorber design in different frequencies. The designed absorber has a normalised bandwidth of 80% in the terahertz region, low sensitivity to incident angle and an absorption peak of 100%.

Understanding of post deposition annealing and substrate temperature effects on structural and electrical properties of Gd2O3 MOS capacitor

The purpose of this study is to understand the effects of substrate temperature (ST) and post deposition annealing (PDA) on the structural-electrical properties of Gd2O3 film and to evaluate the electrical performances of the MOS based devices formed with this dielectric. The Gd2O3/Si structures were annealed at 500, 600, 700, and 800 °C under N2 ambient after the films were grown on heated p-Si substrate at various temperatures ranged from 20 to 300 °C by RF magnetron sputtering. For any given ST, the crystallization/grain size increased with increasing PDA temperature. The bump in the accumulation region or continuous decrease in the capacitance values of the inversion region of the C–V curves for 800 °C PDA was not observed. The lowest effective oxide charge density (Qeff) value was obtained to be − 1.13 × 1011 cm−2 from the MOS capacitor with Gd2O3, which is grown on heated Si at 300 °C and annealed at 800 °C. The density of the interface states (Dit) was found to be in the range of 0.84 × 1011 to 1.50 × 1011 eV−1 cm−2. The highest dielectric constant (e) and barrier height $$({\Phi _B})$$ values were found to be 14.46 and 3.68, which are obtained for 20 °C ST and 800 °C PDA. The results show that the negative charge trapping in the oxide layer is generally more than that of the positive, but, it is reverse of this situation at the interface. The leakage current density decreased after 20 °C ST, but no significant change was observed for other ST values.

A fast solution of TM wave scattering by a coated 2D partially filled rectangular crack

An analytical technique of kobayashi potential (KP) method is applied to study the TM plane wave scattering by a coated 2D partially filled rectangular crack in a ground plane. Initially, by expanding a summation of waveguide modal eigenfunctions, the electric field inside the coating layer is found. Then, the crack contribution is taken into account by addition of the Bessel eigenfunctions in both the coating layer and the semi-infinite half space. By applying the KP method and utilizing the Weber–Schafheitlin discontinuous integrals, the governing equations of an infinite summations with unknown coefficients are derived. Then, by imposing the boundary conditions, the unknown coefficients are determined. The proposed method is validated by comparisons made with the finite element method results. Finally, the effect of a progressively filling crack and the dielectric layer height increase on the far-field scattered field is investigated. The permittivities and permeabilities of the coating and the filling dielectric could be lossy or lossless. The proposed method is applicable to both narrow and wide cracks and is accurate and computationally efficient.

Impact of Wire Geometry on Interconnect &lt;italic&gt;RC&lt;/italic&gt; and Circuit Delay

We investigate the impact of wire geometry on the resistance, capacitance, and RC delay of Cu/low-k damascene interconnects for fixed line-to-line pitch. The resistance is computed by applying a semiempirical resistivity model, calibrated to Cu damascene wires, integrated with a Ru-based liner, currently investigated for the 7 nm logic technology node. The capacitance is simulated by means of a 2D field solver (Raphael) by Synopsys. The impact of line dimensions is analyzed for the case of 32 nm pitch interconnects, which are representative of the 7 nm logic technology node. We show that for aspect ratios greater than 1, the resistance is more sensitive to variations of the line width rather than of the line height, because of the higher surface scattering induced by the sidewall interfaces, which are closer to each other compared with the top and bottom interfaces. For capacitance, low-k sidewall damage exacerbates capacitance sensitivity to line dimensions and, for typical interconnect schemes, the impact of line width variations dominates over variations of the line height. We demonstrate that for a given pitch and dielectric stack height, the RC delay can be significantly reduced by targeting wider and deeper damascene trenches, that is, by trading capacitance for resistance, and that an optimal wire geometry for RC delay minimization exists. In addition, we show that a given RC delay can be achieved with several geometries and, therefore, R and C pairs, which represents a useful degree of freedom for designers to optimize system-level performance. As an application, we analyze a possible 7 nm technology scenario and show that wide and deep damascene trenches can mitigate the impact of the increased wire resistance on circuit delay.