Dielectric Constant Substrate Research Articles

Sensitivity Modeling of an RFID-Based Strain-Sensing Antenna With Dielectric Constant Change

An radiofrequency identification (RFID)-based folded patch antenna has been developed as a novel passive wireless sensor to measure surface strain and crack, for the structural health monitoring of metallic structures. Up to 2.5 m of read range is achieved by a proof-of-concept prototype patch antenna sensor with a strain sensitivity around −760 Hz/ $\mu \varepsilon $ , which is equivalent to a normalized strain sensitivity of −0.74 ppm/ $\mu \varepsilon $ . In this paper, we propose to consider the change of the substrate dielectric constant due to strain when modeling the antenna sensor. An enhanced strain sensitivity model is introduced for more accurately estimating the strain sensing performance of the hereby introduced smart skin antenna sensor. Laboratory experiments are carried out to quantify the dielectric constant change under strain. The measurement results are incorporated into a mechanics–electromagnetics coupled simulation model. Accuracy of the multi-physics coupled simulation is improved by integrating dielectric constant change in the model.

Effect of charged impurity scattering on the electron diffusivity and mobility in graphene

The influence of charged impurities on the transport properties of graphene, including the diffusion coefficient at low and high electric fields, is investigated by means of an ensemble Monte Carlo simulator. Three different possible substrates are considered, h-BN, SiC and SiO2. The results show the importance of impurity scattering in degrading the diffusion coefficient, electronic mobility and drift velocity, particularly at low and intermediate electric fields. The influence of the substrate dielectric constant in relation to impurities and surface polar phonon scattering is also evidenced; this turns SiC into the most suitable substrate of choice from this point of view.

Microstrip Patch Antenna Temperature Sensor

The resonant frequencies of a microstrip patch antenna are dependent on the dielectric constant of its substrate and the physical dimensions of its radiation patch. Both of these parameters are temperature-dependent. In this paper, we investigated the effects of temperature on the antenna resonant frequencies for the purpose of studying the microstrip patch antenna as a temperature sensor. First, the relationship between the antenna resonant frequency shift and the temperature change is derived based on the transmission line model. To validate the theoretical prediction, antenna sensors bonded on different metal bases were tested in a temperature chamber. By comparing the measured temperature-frequency relationship with the theoretical predictions, we discovered that the dielectric constant of the substrate is not only dependent on temperature but also influenced by the base material. After calibrating the thermal coefficient of the substrate dielectric constant using the measurement data, the differences between the measurements and the theoretical predictions were within the expected systematic error of the reference thermocouple, validating that a microstrip patch antenna can serve as a temperature sensor.

Anisotropic Intervalley Plasmon Excitations in Graphene* *Supported by the National Basic Research Program of China (973 Program) under Grant No. 2013CB934001, the State Key Laboratory of Software Development Environment under Grant No. SKLSDE-2013ZX-28

We investigate theoretically the intervalley plasmon excitations (IPEs) in graphene monolayer within the random-phase approximation. We derive an analytical expression of the real part of the dielectric function. We find a low-energy plasmon mode with a linear anisotropic dispersion which depends on the Fermi energy and the dielectric constant of substrate. The IPEs show strongly anisotropic behavior, which becomes significant around the zigzag crystallographic direction. More interestingly, the group velocity of IPE varies from negative to positive, and vanishes at special energy.

IJIREEICE - Electrical, Electronics, Instrumentation and Control

In this paper, analyses and design of slotted Rectangular patch antenna for high speed wireless local area network at 5-6 GHz frequency has been done. A parametric study of the antenna has been carried out, to analyze and understand the effects of dimensional parameters. Main disadvantage of the microstrip patch antenna is its narrow bandwidth. However, in this paper slotting technique has been used to increase the bandwidth of the patch antenna. In this design, four slots are incorporated into Rectangular patch antenna. It gives fractional bandwidth of 0.202% with the center frequency of 5.4345GHz & 0.334% with center frequency of 5.681GHz.The antenna frequency band, with -10 db return loss covers the frequency range of 5.431-5.442 &5.675-5.68 GHz. The design of patch antenna has been completed using IE3D software. The antenna is designed on 0.5mm RT duroid 5880 substrate with dielectric constant of 2.2 and loss tangent 0.0004 operating at 5.25 GHz. A substrate of low dielectric constant is selected to obtain a compact radiating structure that meets the demanding bandwidth specification.

MEMS patch antenna array with broadband and high-gain on double-layer silicon wafers

A MEMS patch antenna which can be integrated with RF module easily was designed to improve the bandwidth and gain of the traditional microstrip antenna. The equivalent dielectric constant of substrate of the microstrip antenna was optimized to greatly increase the bandwidth of the antenna by a high resistivity silicon being bonded to a low resistivity silicon to form a double-layer silicon substrate under the MEMS technology. Defected ground structure was also used on ground plane in order to restrain the harmonic radiation of antenna. Based on the above aspects, a 22 antenna array was designed with a center frequency of 10 GHz. The simulation results show that the antenna array has an impendence bandwidth of 15.9% and a gain of 10.9 dB, significantly better than traditional antennas and meets the anti-interference requirements of antennas in the fuze.

Comparative Study of Transmission Line and Cavity Model of Rectangular Microstrip Antenna

In this paper a comparative study is carried out to estimate the performance of transmission line and cavity models of rectangular microstrip antenna mounted on six dielectric substrate materials with variable substrate heights. An artificial intelligence technique, namely: MATLAB based Adaptive Neuro-Fuzzy Inference System is used to optimize the length and width of the antenna. Random data sets are generated and experimental data are used to carry out the optimization of various antenna parameters to cover almost entire cellular spectrum. With operating frequency of 2.1GHz, we analyze the bandwidth of the antenna of both the models. The simulation results predict that the cavity model of rectangular microstrip antenna perform well over transmission line model with thick substrate while transmission line model is better at low dielectric constant and thin substrate.

Artificial Neural Network Model for Suspended Rectangular Microstrip Antennas

The broadband microstrip antenna is more commonly realized by fabricating the patch on lower dielectric constant thicker substrate. While using thicker substrate, close form expressions for calculating edge extension length due to fringing fields is not available. In this paper, an artificial neural network model for suspended rectangular microstrip antenna is proposed. The resonance frequency calculated by using the proposed neural network model closely agrees with simulated and measured results over wide frequency range and for varying thicker substrates. Thus the proposed model can be used to accurately calculate the side length of rectangular microstrip antenna.

Design and Investigation of Disk Patch Antenna with Quad C-Slots for Multiband Operations

An investigation into the design and fabrication of multiband disk patch antenna with symmetrically quad C-slots is presented in this paper. The proposed antenna shows multiband resonance frequencies which highly depend on substrate thickness, dielectric constant, and radius of the disk patch. By incorporating two pairs of C-slots in optimum geometry on the radiating patch, the proposed antenna operates between 2 and 12 GHz at different frequency bands centered at 2.27, 7.505, 9.34, 10.33, and 11.61 GHz. The other antenna parameters are studied like gain, antenna efficiency, and radiation pattern. The proposed antenna may find applications in S-, C-, and X-band. The results are carried out with the aid of HFSS and MOM-based IE3D simulator. The measured and simulated results are in good agreement with each other.

A planar UWB monopole antenna with dual band notched function

ABSTRACTA printed monopole antenna for UWB applications with dual band notch property is proposed in this letter. The UWB monopole consists of modified circular patch with an elliptical slot to reject WiMAX frequencies (3.3–3.8 GHz). The modified ground plane is introduced to attain the wide impedance UWB bandwidth with G‐shaped slot below the feed line to reject 5.15–5.85 GHz WLAN frequencies. The length of embedded slot not only depends on notch frequency and substrate dielectric constant but also depends on substrate thickness and slot width. In this letter, we have presented a technique to calculate accurately the slot length of the embedded slot. The simulated and measured result shows that the designed antenna is expected to be good candidate for UWB applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:99–104, 2015

Substrate Height and Dielectric Constant Dependent Performance of Rectangular Micro Strip Patch Antenna

In this paper, Rectangular Microstrip patch antenna has been designed for different substrate heights and dielectric constants of substrate. This paper proposes a new generation of antenna that applies Meta material properties at ground Plane. The paper analyzes the performance of Micro strip Patch Antenna with and without using the Meta material structure. Effect of bandwidth due to change of substrate height and dielectric constant have been investigated. Finally, bandwidth for each substrate height and dielectric constant is measured for selecting the optimal patch antenna.

Research progress in the application of biosensors by using metamaterial in terahertz wave

In the present paper, the recent progress in terahertz metamaterials-based sensing is reviewed with the principle of metamaterial biosensor,metamaterial substrate, and structure design, respectively. The paper introduces the principle in detail, analyzes the sensitivity of the biosensor with the material and the thickness of the substrate and the structure of metamaterial. The analysis shows that we can enhance the sensitivity and resolution of biosensor by designing specific metamaterial structure, using low dielectric constant and low loss thin substrate, especially many materials have a specific response in the terahertz frequency. So, there is a large potential application for label-free sensing by using the terahertz metamaterials. This paper also presents the future development of THz metamaterial sensors.

Excitons in anisotropic two-dimensional semiconducting crystals

The excitonic behavior of anisotropic two-dimensional crystals is investigated using numerical methods. We employ a screened potential arising due to the system polarizability to solve the central-potential problem using the Numerov approach. The dependence of the exciton energies on the interaction strength and mass anisotropy is demonstrated. We use our results to obtain the exciton binding energy in phosphorene as a function of the substrate dielectric constant.

On the performance of microstrip antenna embedded in composite laminated substrates

AbstractFiber‐reinforced composite structures can be tailored to desire mechanical properties and to embed microstrip antenna in aerospace applications. The electromagnetic characteristics of a microstrip antenna on isotropic and uniaxial substrates have been known, but that embedded in composite laminated substrates remain unavailable to date. This work aims at analyzing the performance of microstrip antenna embedded in composite laminated substrates by spectral domain analysis. Parameter studies are conducted to investigate the effects of the substrate's dielectric constants, the fiber directions (the orientation between the antenna and the laminate layers), and the stacking sequence on antenna's resonant frequency and radiation pattern. The antenna size when embedded in composite laminated substrates is larger than that when attached on isotropic substrates, or conversely, the resonant frequency will deviate lower if assuming the substrate as isotropic. The far‐field pattern in composite laminated substrates is more ‘directional’ than that in isotropic substrates. The antenna gain in the substrates of symmetric stacking with ±45° fiber direction is 20 dB better than that in isotropic substrates in some elevations. Copyright © 2014 John Wiley & Sons, Ltd.

Quantum friction controlled by plasmons between graphene sheets

We theoretically study quantum friction between two infinite graphene sheets, which is controlled by plasmons excited at the interfaces of graphenes and dielectrics. In near-field regime, quantum friction can be enhanced due to the coupling of plasmons between two graphene sheets. Dependences of friction coefficient on distance, chemical potential of graphene, temperature of environment, and dielectric constant of substrate have been investigated in detail. Friction coefficient can be increased by increasing temperature or dielectric constants of substrates, and can be reduced by increasing distance or chemical potential.

Multiband-coupled sectoral antenna using high and low dielectric constant substrates

Design analysis of multiband-coupled stacked sectoral antenna array with finite ground plane using high low dielectric constant substrates is proposed in this paper for modern communication systems and applied physics. Multiband planar antennas have been extensively developed due to demands for integration of wireless communication systems. In this paper, we present the design and development of a multiband microstrip antenna array with parasitic coupling and stacking using two different substrates. The stacked designed antenna resonates at three different frequencies: 3.8, 5.4, and 10 GHz; therefore, showing a multiband property with good radiation (far-field) characteristics. A significant comparison study is also presented considering different dielectric constant substrates. The proposed antenna is an attractive solution for different wireless communication systems such as mobile systems, satellite systems, etc.

A CPW-fed reconfigurable patch antenna with circular polarization diversity

This paper presents a simple and compact coplanar waveguide (CPW)-fed circular-shaped reconfigurable patch antenna with a switchable circular polarization (CP) sense. The circular patch is cut at the ends vertically and switches are introduced to connect the patch ends. By controlling the ON/OFF status of the two switches, the polarization of the antenna can be switched between two states: left-hand circular polarization and right-hand circular polarization. The patch is designed on a very thin RT Duroid substrate of dielectric constant (εr) of 2.2 and thickness of 0.254 mm. The overall antenna dimensions are 35 × 30 mm. The antenna is designed and simulated using finite-element method -based EM simulator, HFSS. For each switching condition the return loss curve, radiation pattern are obtained. Axial ratio curves for polarization diversity cases are also plotted. Parametric studies have been made in order to get optimized values for certain antenna dimensions such as thickness, CPW ground to feed gap, etc.

The formation of a dielectric SiNxCy sealing layer using an atomic layer deposition technique

We investigated the growth of a SiNxCy dielectric sealing layer on a porous low dielectric constant (low-k) substrate using plasma-enhanced atomic layer deposition (PE-ALD). A porous low-k substrate was repeatedly exposed to bis(dimethylamino)dimethylsilane (BDMADMS) and a hydrogen plasma. A SiNxCy sealing layer grown by PE-ALD was formed without any penetration of the pores within the porous low dielectric substrate. Our technique provides for the deposition of a dielectric sealing layer that prevents pore penetration of a low-k material.

An efficient tuning method for narrowband superconducting filters with interdigital capacitor resonators in the time domain

This article proposes an effective tuning method based on the time domain for improving the performance of high-temperature superconducting (HTS) bandpass filters with interdigital capacitor resonators (ICRs). Analysis of the causes of HTS filter performance deterioration reveal that such deterioration is primarily caused by the resonant frequency deviation of the resonator of the HTS filter; this deviation results from fabrication errors and from the non-uniformity of the thickness and dielectric constant of the substrate. The sensitivity of the filter, which arises from the non-uniformity of the substrate thickness and dielectric constant, is related to the type of the resonator and the group delay characteristic of the filter. A 0.4% fractional bandwidth HTS filter with ICRs at the UHF band is fabricated and tuned using mechanical rods in the time domain. By applying this method, the resonant frequency deviation of each resonator and the coupling coefficient between resonators can be measured and tuned individually. The insertion loss of the HTS filter is improved from 1.06dB to 0.43dB, whereas the return loss is improved from 9.57dB to 15.1dB.

A COMPACT PRINTED DIPOLE ANTENNA FOR WIDEBAND WIRELESS APPLICATIONS

A compact printed dipole antenna with wide impedance bandwidth is proposed in this paper. This antenna consists of a pair of radiation metal arms and a microstrip-to-slotline transition structure. At the end of the feeding slotted line, a beveled slot with stepped connection structure is designed to realize an ofiset feeding structure for feeding the dipole antenna. By using the beveled ofiset feeding structure, the bandwidth of the dipole antenna is signiflcantly improved. The microstrip-to- slotline transition is used as an integrated balun to realize a balanced feeding for the dipole antenna. To demonstrate the efiectiveness of the proposed design, a prototype of the designed antenna is fabricated and measured. The measured results show that the designed dipole antenna achieves a gain of 2.2{4.4dBi across a wide impedance bandwidth from 2.65GHz to 17.5GHz with a compact size (33mm£16mm). The performance of the proposed dipole antenna is also compared with some similar printed dipole antennas with respect to overall size, substrate dielectric constant, impedance bandwidth and antenna gain.