HFSS Results Research Articles

Triple band terahertz absorption based fractal ring shaped ultrathin mustard oil adulteration sensor

A tri-band terahertz (THz) absorber for sensing the adulteration percentage in mustard oil is proposed in this paper. It consists of a gold based metallic resonating geometry and metallic ground plane on the top and bottom layers of the dielectric material respectively. It has three absorption peaks with peak absorptivity of 99.74%, 99.96% & 99.94% and Full Width at Half Maxima (FWHM) of 0.57, 0.862 & 1.112 THz at 4.6296, 8.295 & 12.6309 THz respectively. The proposed absorber’s unit cell volume has an overall volume of 10 μm×10μm×1.61μm (0.15432λL×0.15432λL×0.024846λL where λL is wavelength at lowest operating frequency i.e. 4.6296 THz). It has polarization insensitive absorption performance under normal incidence and incident angle (θ∘) stability up to 50° for A≥90%. The proposed structure is simulated through by using CST & HFSS. The results are validated by developing an equivalent circuit model (ECM). The results of CST, HFSS and ECM are found to be in good agreement. A sensitivity varying from ∼0.23 THz/RIU to ∼1.62 THz/RIU is achieved for Refractive Index (RI) sensing case, whereas a high sensitivity in the range of ∼0.4 THz/RIU to ∼2 THz/RIU is achieved for mustard oil adulteration sensing case by mounting the absorber’s top surface with a polyimide based container filled with an analyte (either refractive index material or mustard oil). During the validation, a maximum ∼0.16% error in mustard oil adulteration estimation is achieved. The proposed sensor has advantages of simple & ultra compact dimensions, high sensitivity and minimal error in impurity concentration estimation with respect to other absorber-based sensors.

Beamforming with 1 × N Conformal Arrays.

The rapid growth of wireless spectrum access through cellular and IoT devices, for example, requires antennas with more capabilities such as being conformal and self-adapting beamforming. In this paper, the adaptive beamforming patterns of microstrip patch antenna arrays on changing flexible (or conformal) curved surfaces are developed by deriving array coefficients based on the projection method that includes the mutual coupling between elements. A linear four-element microstrip patch antenna array is then embedded on two deformed conformal surfaces to investigate the projection method for desired beamforming patterns. The generated beamforming radiation patterns using the computed weighting coefficients are validated with theoretical equations evaluated in MATLAB, full-wave simulations in HFSS and measurement results. The measured results of the fabricated system agree with the simulated results. Furthermore, new guidelines are provided on the effects of mutual coupling and changing conformal surfaces for various beam-forming patterns. Such demonstrations pave the way to an efficient and robust conformal phased-array antenna with multiple beam forming and adaptive nulling capabilities.

Metamaterial Based Circularly Polarized Parasitic Element Driven DRA for Sub 6 GHz Wireless and 5G Communication Applications

Billions of wireless devices are directly communicating with each other and exchanging data worldwide. The 5G communication provides broad scope to this data exchange with low latency, high data rate, and efficient utilization of the EM spectrum. This paper articulates designing and developing a multiband Dielectric Resonator Antenna (DRA) with circular polarization for sub-6 GHz applications. The designed DRA of alumina occupies the dimension of radius ten and height of twenty mm on the FR4 substrate. The proposed DRA resonates at the quad-band with good impedance bandwidth covering the 5G band under the sub 6 GHz range. The designed antenna provides moderate gain and radiation efficiency of more than ninety-six percent. The prototype measured results show excellent matching with the simulation results of HFSS.

3D-FDTD analysis of fractal antenna using PML boundary conditions

In this paper, a rectangular fractal patch antenna for satellite communication is presented. The antenna is designed at frequency 20GHz. The antenna structure is depicted and inspected using 3-D finite difference time domain (FDTD) method and the results are compared with obtained by commercial software Ansys HFSS and experimental results. It is found that FDTD simulation results along with fabricated and HFSS simulations are agreed adequately. The return loss of the antenna operating is -33.14 dB and gain is 17dB. These results infer that the proposed antenna is well suitable for Satellite communication at Ku band and has large bandwidth.

Epoxy resin based composite filled with low-loading LRGO@AC and CoFe2O4 for excellent electromagnetic absorption performance

In this work, large-sized reduced graphene oxide@activated carbon (LRGO@AC) and CoFe2O4 were prepared by thermal reduction and solvothermal method. The epoxy resin based composites were successfully synthesized via a simple physical mixing way. Its complex permittivity, permeability, and reflection loss (RL) were characterized by using an Agilent N5234A vector network analyzer. The results showed that the LRGO@AC/CoFe2O4/epoxy composite presented excellent EM wave absorption performance at a 5 wt% loading of LRGO@AC/CoFe2O4. The minimum RL value reached − 42.70 dB at 11.24 GHz and the effective absorption bandwidth (RL < − 10 dB) reached 5.45 GHz with a matching thickness of 3.0 mm. The excellent EM wave absorption performance was due to the unique 3D conductive network structure of LRGO which is conducive to the uniform dispersion of LRGO@AC and CoFe2O4 in the matrix, which facilitates the interaction of the filler in the epoxy resin and promotes the synergistic effect of electromagnetic loss. Moreover, the results of HFSS show that the radar cross section (RCS) can be reduced rapidly. Therefore, the LRGO@AC/CoFe2O4 would be a useful absorbing material.

A Metallic WBAN Dielectric Resonator Antenna for ISM Band Applications

A compact cylindrical dielectric resonator antenna (CDRA) for Industrial, Scientific and Medical (ISM) applications is proposed in this article. The simple microstrip feeding system can be used to stimulate a certain CDRA. An implemented dielectric resonator delivers the functionalities for an efficient radiator with the feeding specifications. The permitted band can be accumulated by varying the design specifications. The standardized design comprises the resonator to attain frequency of 2.4 GHz. The ISM band is used in wireless body area networks (WBAN) technology for transmission of real time traffic such as video and information to monitor the health conditions. A U-shaped metal strip is located over the dielectric resonator material in order to miniaturize the size and enhance the resonator appearance. The consequences on antenna appearance for various radio wire specifications are explored. The intended model has competitive prices, lower volumes, and adequate containment. The evaluation of antenna illustrates the optimal bandwidth, coefficient of reflection (&lt; -10 dB) as well as substantial gain across the specified bands. Coefficients of reflection, voltage standing wave ratio (VSWR) and radiation structure were discovered in each scenario. Architecture content and simulated results of Ansoft's HFSS are demonstrated. For ISM band implementations, the constructed antenna is sensible.

Miniaturized triple band-notched quasi-self complementary fractal antenna with improved characteristics for UWB applications

This paper is a continuation and extension of a previous work [1]. In this paper, an enhanced UWB microstrip-fed quasi self-complementary fractal (QSCF) antenna with triple band notches is presented. These band notches are allocated at 3.5, 5.5 and 7.8 GHz. The proposed design supports coexistence with narrow band applications IEEE 802.16 WiMAX, IEEE 802.11 WLAN and X-band of satellite communications, respectively. Both slot and parasitic loading techniques are utilized to achieve this goal. A guided half wavelength U-shape slot is etched in the ground for creating band rejection at the WiMAX frequency band. To attain the WLAN band rejection, another half wavelength U-shape slot is inserted to the feed line. A split ring resonator (SRR) is embedded to the left and right of the feed line for avoiding interference with X-band. The prospective antenna is designed using low cost FR4 substrate of miniaturized size 32 × 16.5 × 1.5 mm3 which empowers it to be embedded in assorted portable devices. Nearly omnidirectional radiation patterns and stable gain are accomplished over the operating bandwidth from 2 to 11 GHz. For further clarification of the operating principle, an equivalent circuit model is considered showing good agreement with CSTMWS, HFSS and experimental results. Furthermore, a time domain analysis is investigated presenting satisfactory distortion performance between excited and received pulse validating it for diversified UWB applications.

Design and analysis of seven-bands-slot-antenna with small frequency ratio for different wireless applications

In this paper, a low profile planar multiband slot antenna covering numerous wireless applications is presented. The proposed antenna resonates for seven frequency bands corresponding to centre frequencies 2.54 GHz, 3.48 GHz, 4.02 GHz, 4.34 GHz, 5.1 GHz, 5.54 GHz and 6.24 GHz. The antenna also shows circular polarization in the two frequency bands ranging from 3.42 to 3.68 GHz and 6.2 to 6.94 GHz. A very small frequency ratio of 1.37007, 1.15517, 1.0796, 1.17511, 1.0862 and 1.1263 is realized between the two consecutive bands. The designing of the proposed antenna is carried out by means of Ansys HFSS and simulated results are found in good agreement with the measured results.

Triple-notch UWB monopole antenna with fractal Koch and T-shaped stub

In this study, a triple-notch ultra-wideband (UWB) monopole antenna with fractal Koch and T-shaped stub is presented. The prototype antenna is based on a circular monopole antenna with a back-plane feed line modified for 2–11GHz in an omnidirectional pattern. By implementing a combination of fractal Koch and T-shaped stub on the antenna, a triple-notch band occurred at 2, 3.5, and 5.8GHz for rejecting personal communication services (PCS), worldwide interoperability for microwave access (WiMAX), and wireless local area network (WLAN). In addition to the UWB application frequency range of 3.1–10.6GHz, the final antenna covers a frequency range of 1.78–1.91GHz for GSM 1800, 2.28–3.120GHz for Wi-Fi, and 2.4GHz for Bluetooth applications with a voltage standing wave ratio (VSWR)<2. Simulated results of HFSS and CST are compared with experimental results. The dimensions of the antenna are 50mm×50mm×1.6mm. The current distribution and efficiency at notch frequency are noted for the whole frequency band, and the maximum antenna gain is between −3.5 and 6.5dBi. In this study, methods using Koch structure and T-shaped stub to achieve triple-notch antenna are implemented in three steps. In addition, the effects of T-shaped stub and fractal Koch on the magnitude of the antenna (S11) are studied.

하이브리드 방법을 이용한 다층 미앤더선로 구조의 3:1 광대역 원편파 편파기 설계

Abstract In this paper, a wideband circular polarizer operating in the frequency range of 6<18 GHz is designed and fabricated using a multilayer structure with meanderlines. A T matrix expression for the unit structure, which consists of meanderline, dielectric substrate and spacer, was derived using the boundary value solution. A proposed meanderline structure was modeled as an array of unit meanderline cell in order to apply the waveguide model with PEC and PMC boundary conditions. The calculation procedures to obtain an equivalent susceptance of the unit meanderline cell using HFSS was also suggested. Using a hybrid method, which combines the T matrix with the HFSS results, and cut-and-try method, a wideband circular polarizer with low insertion loss and good AR performance was designed. The fabricated polarizer has the return loss less than 10 dB within 92 % bandwidth, the average insertion loss less than 0.24 dB, and the average AR below 2.6 dB for full 3:1 bandwidth. Key words: Wideband Circular Polarizer, Meanderline „in oCS(Agency for Defense Development) *†‡ ˆ ‰ n(Department of Radio Science & Engineering, Chung-Nam National University) 8Manuscript received July 31, 2015 ; Revised August 26, 2015 ; Accepted August 26, 2015. (ID No. 20150731-053)8Corresponding Author: Jeong-Ki Pack (e-mail: jkpack@cnu.ac.kr)

Tunable and dual band rectangular microstrip antenna for bluetooth and WiMAX applications

ABSTRACTA rectangular microstrip antenna (RMSA) with two slots placed close and parallel to nonradiating edges for tunable and dual band operation with single feed has been demonstrated. A tunable operation can be achieved by the adding electrically small slots along the patch edges. For two frequencies TM10 and TM30 are the first two modes of simple RMSA are perturbed and two frequencies with same polarization, broadside radiation, and impedance characteristics. Dual frequency operations easily obtained if two slots placed together and are of same dimensions, which equals to greater than half of length. The proposed design is suitable for dual band operation for Bluetooth 2450 MHz–WiMAX 3500 MHz. Slot dimensions was taken identical for the symmetry. The performance parameters of the proposed RMSA with and without slots were compared. Furthermore, a parametric analysis carried out by taking variations in the length (Ls), width (d) and spacing (S) between the two slots, the frequency ratio is tuned in the range 1.41 to 1.45. The dimensions of the proposed antenna 50 × 54 × 1.6mm3 with the size reduction compared with conventional microstrip antenna (MSA).The proposed antenna is simulated using HFSS based on finite element method and simulated return loss, radiation pattern and impedance were presented. Finally fabrication and measurement of VSWR of the proposed antenna has been taken. The HFSS results and measured results are in good agreement. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1986–1991, 2015

Wideband and compact slot loaded annular ring microstrip antenna using L-probe proximity-feed for wireless communications

A wideband orthogonally slot cut annular ring microstrip antenna fed by L-shaped probe is investigated using modal expansion cavity model and circuit theory approach. Simulation of the proposed antenna is performed using Ansoft HFSS and simulated results are compared with the measured and theoretical results. The impedance bandwidth of about 37.46% is observed at resonant frequency 3.15 GHz. The proposed antenna realizes an improvement in bandwidth of 13.46% and miniaturization in physical dimension about 10% from earlier reported structures. An improvement in bandwidth and miniaturization is due to thick substrate, L-probe feed, and orthogonally loaded slots. The measured results of fabricated antennas are in good agreement with simulated and theoretical results.

Strip-Width and Slot-Gap Dependent Equivalent Isotropic Substrate and Dispersion Characteristics of Asymmetric Coplanar Waveguide, Symmetric Coplanar Waveguide and Micro-Coplanar Strip Line on Anisotropic Substrates

In this paper, we reformulate the quasi-static spectral-domain approach, using the partial capacitance method (PCM), to compute the W/h and S/h dependent equivalent isotropic substrates corresponding to the anisotropic substrate asymmetric coplanar waveguide (ACPW), coplanar waveguide (CPW), micro-coplanar strip line (MCS), and microstrip line. We have used the closed-form dispersion relations over equivalent substrates to obtain the dispersion in these line structures. For this purpose, the ACPW and MCS structures are converted to the equivalent symmetrical CPW and the available closed-form dispersion model for the CPW is adapted to the ACPW and MCS structures. The dispersion results for these lines are compared against the results of the HFSS with average deviations in the range of 1%-4%. We get nearly the same range of deviations in the results of HFSS against the experimental results on the isotropic substrates.

Radiation-Enhancement Properties of an X-Band Woodpile EBG and Its Application to a Planar Antenna

A woodpile Electromagnetic Bandgap (EBG) material has been designed, by using an in-house code that implements the Fourier Modal Method (FMM). A couple of alumina-woodpile samples have been fabricated. Several results have been collected for the transmission behaviour of the woodpile and of resonators with woodpile mirrors, in a shielded anechoic chamber, by using a vector network analyzer, in the 8–12 GHz range. These new experimental data highlight interesting properties of 3D EBG resonators and suggest possible innovative applications. Comparisons of the collected results with FMM show a satisfactory agreement. An application of the EBG resonator has been considered, for gain enhancement of a microstrip antenna: an increase of about 10 dB in the broadside gain has been measured; experimental data and numerical results obtained with the commercial software HFSS show a good agreement. A comparison is presented between EBG resonator antennas and two-dimensional uniform arrays. Finally, HFSS results are provided for EBG resonator antennas working at higher frequencies or with a more selective superstrate: a gain enhancement of more than 18 dB is achieved by such antennas.

Triple Band Annular Ring Loaded Stacked Circular Patch Microstrip Antenna

In this paper a novel structure of annular ring loaded stacked circular patch microstrip antenna is theoretically analysed to observe various parameters such as return loss, input impedance, gain, directivity and radiation pattern. It is found that antenna possess three band of operation which signify the compactness and multiband operation of antenna. The antenna is resonating at three operating frequencies 1.720, 2.950, 3.060 GHz. The proposed theory is verified by simulation using Ansoft's HFSS and theoretical results are in good agreement with simulated results. The antenna is useful for multi-services operations such as WLAN, GSM, UMTS, and WiMAX services.

A compact wideband planar microstrip‐fed quasi‐yagi antenna with a C‐shape reflector

ABSTRACTA compact wideband planar microstrip‐fed quasi‐Yagi antenna is presented. Through optimizing the structure of the C‐shape reflector, a broadband impedance bandwidth of 75.3% (1.83 ∼ 4.04 GHz) for return loss less than −10 dB and a gain of 3.83 ∼ 8.48 dBi are obtained. Simulation based on HFSS and measurement results are provided and discussed. The agreements between the simulation and measurement results indicate that the antenna is suitable for wireless communication applications and phased arrays. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:241–244, 2014

A micro compact coplanar power divider at X-band with finite-width ground plane based on GaAs MMIC technology

A micro coplanar Wilkinson power divider at X-band on GaAs substrate is presented in this paper. The proposed power divider introduces a size reduction method, and the length of the transmission line is reduced to λ/8 (at 10 GHz). Since the two segments of the two edge coupled quarter-wave asymmetric coplanar striplines (ACPSs) with finite-width ground plane are closed to each other, their characteristic parameters, such as characteristic impedance and attenuation coefficient, are obtained using the quasi-static conformal mapping technique (CMT) of coupled coplanar waveguide (CCPW) with finite-width ground plane. S-parameters for the power divider are deduced in the case of quasi-static TEM even–odd mode. The fabrication process is compatible with the GaAs MMIC process. The measured S-parameters are compared with the simulated results of HFSS v.11 and the calculated results of TEM even–odd analysis. Simulated results show that it has reflection loss less of 16.5 dB and insertion loss less of 3.6 dB. Measured results show that the divider has reflection loss less of 15.0 dB and insertion loss less of 3.5 dB. Compared with conventional Wilkinson power divider, the length of the power divider is shortened from 2,620 to 1,570 μm.

Computation of static and frequency-dependent line parameters of multilayer CPW using static SDA and single layer reduction method

We reformulate the quasi-static SDA applicable to a lossy multilayer CPW that also incorporates two-layer model of a conductor thickness and the concept of effective permeability due to magnetic field penetration in an imperfect conductor. The present static SDA formulation accounts for the effect of conductor thickness and low frequency dispersion on computation of quasi-static effective relative permittivity and characteristic impedance. The paper also presents the single layer reduction (SLR) formulation and circuit model to compute frequency dependent line parameters of a lossy multilayer CPW. The accuracy of formulation is comparable to that of HFSS and CST, without using complex and time consuming full-wave methods. The results of CST for εeff, Z0, αd, αc of multilayer CPW, in the frequency range 1–100 GHz, deviate from results of HFSS up to 1.26%, 2.78%, 11.75%, and 18.7%, respectively; whereas corresponding deviations of present formulation are up to 1.56%, 2.4%, 3.04%, and 7%. The results of the present formulation and HFSS are also compared against the available experimental results. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:18–29, 2014.

MODELING FOR DISPERSION AND LOSSES OF MULTILAYER ASYMMETRIC CPW ON ISO/ANISOTROPIC SUBSTRATE

In this paper, we reformulate the quasi-static spectral domain analysis (SDA) applicable to a lossy anisotropic multilayer asymmetric coplanar waveguide (ACPW). The SDA formulation also incorporates two-layer model of a conductor thickness and the concept of efiective permeability to account for the low frequency dispersion due to the magnetic fleld penetration in an imperfect conductor. The paper further presents the single layer reduction (SLR) formulation and circuit model to compute frequency dependent line parameters of a lossy anisotropic multilayer ACPW. The accuracy of formulation is comparable to that of the HFSS and CST, without using complex and time consuming full-wave methods. The results of CST for efi , Z0, fid, fic of multilayer ACPW, in the frequency range 1GHz{100GHz, deviate from results of HFSS up to 0.49%, 1.53%, 2.06% and 10.73% respectively; whereas corresponding deviations of the present SDA and SLR combined formulation are up to 1.38%, 2.09%, 3.57% and 8.87%.

IMPROVED ANALYTICAL METHOD FOR PLASMA ELECTRON DENSITY MEASUREMENT BY RESONANT CAVITY PERTURBATION THEORY

A method of plasma density measurement based on microwave resonant cavity perturbation (by Kornegay (14)) is described. Resonant cavity theory was analyzed and a resonant cavity with special structure was designed for measuring the low density plasma. In the middle of the closed cavity, there were cut-ofi tubes which were extended a little into the cavity to get through the plasma. It was found that the distribution of the electrical fleld intensity was the densest near the cut-ofi tubes when the cylindrical cavity operating with TM010 mode. By using the method of resonant equivalent circuit analysis, both the amplitudes and phases of the Scattering matrices (S matrices) were obtained before the plasma came and at the time of the plasma passing through. Then the electron line density (Ne) and the electron-molecule collision frequency for momentum transfer (vm) were calculated. A modifled formula was proposed based on our simulation which was conducted in HFSS and experimental results. With the comparison of our results and Kornegay's, it was found that the accuracy of the plasma dielectric constant calculation was improved about 5 percent.