Dual Resonance Frequency Research Articles

A Stable-Gain Millimeter-Wave Fabry-Perot Antenna Based on Circular Polarizer-Integrated PRS with Positive Reflective Phase Gradient

In this paper, we present a millimeter-wave Fabry-Perot antenna with dual resonances, circular polarization, and stable gain. To achieve circularly polarized radiation, we integrate a receiver-transmitter circular polarizer into the partially reflective surface (PRS) of the antenna. The PRS is specifically designed with a positive reflective phase gradient, which contributes to a stable gain in the dual-resonance frequency band. For the radiation source, we adopt a linearly-polarized substrate-integrated waveguide cavity-backed slot fed by a printed ridge gap waveguide. Experimental measurements conducted on a fabricated prototype of the proposed antenna demonstrate its impedance and axial ratio bandwidths of 28.6–30.0 GHz and 28.6–29.6 GHz, respectively. Furthermore, the antenna exhibits a peak gain of 12.1 dBi and a gain fluctuation lower than 0.6 dB within the operational frequency band.

Graphene-Based Tunable Dual-Frequency Terahertz Sensor.

A tunable dual-band terahertz sensor based on graphene is proposed. The sensor consists of a metal bottom layer, a middle dielectric layer, and single-layer graphene patterned with four strips on the top. The numerical simulations results show that the proposed sensor exhibits two significant absorption peaks at 2.58 THz and 6.07 THz. The corresponding absorption rates are as high as nearly 100% and 98%, respectively. The corresponding quality factor (Q) value is 11.8 at 2.58 THz and 29.6 at 6.07 THz. By adjusting the external electric field or chemical doping of graphene, the positions of the dual-frequency resonance peak can be dynamically tuned. The excitation of plasma resonance in graphene can illustrate the mechanism of the sensor. To verify the practical application of the device, the terahertz response of different kinds and different thicknesses of the analyte is investigated and analyzed. A phenomenon of obvious frequency shifts of the two resonance peaks can be observed. Therefore, the proposed sensor has great potential applications in terahertz fields, such as material characterization, medical diagnosis, and environmental monitoring.

Dual low pressure plasma process for SiCN:H thin films deposition: A comparative study

SiCN:H thin films have large possibilities of applications due to their versatile chemical and physical properties. Plasma Assisted Chemical Vapor Deposition (PACVD) process is widely used for SiCN:H deposition. Here we discuss on the potentialities of dual Electron Cyclotron Resonance (ECR) and Radio Frequency Magnetron Sputtering (rf MS) plasmas coupling for SiCN:H deposition in Ar/N2/Si(CH3)4 gas mixture. The study is carried out by varying the autopolarisation voltage Vbias of the silicon target. ECR plasma gives low deposition growth rate about 50 nm/h. The films are transparent. SiCN nanopillars with high aspect ratio are obtained. Rf MS plasma gives high deposition growth rate up to 2200 nm/h. The films are opaque in the near UV and transparent in the visible depending on their thickness. The optical index at 630 nm is 1.95, the Tauc's band gap is 3.0 eV and do not change with Vbias. Dual ECR/rf MS plasma gives high deposition growth rate up to 2300 nm/h. The films are transparent. The optical index varies between 1.7 and 2.05 at 630 nm and the Tauc's band gap decreases linearly between 4.75 and 3.4 eV with Vbias. Dual ECR/rf MS plasma coupling is a very promising PACVD process for thin films deposition.

A novel approach to measuring local mechanical properties via photothermal excitation of an atomic force microscope probe using an optical pump–probe inspired design

Obtaining and improving measurements of mechanical properties at the nanoscale has been made possible through the continuous advancement of atomic force microscopy (AFM) techniques over the past several decades. Among these advancements include implementing multifunctional AFM probes and developing new detection schemes that enable sensitivity to local mechanical properties. In this work, we demonstrate a proof-of-concept for a detection scheme that enables a standard AFM configuration to produce qualitative local mechanical property maps through the use of an optical pump–probe scheme, alleviating a common requirement of incorporating additional piezoelectric actuators. Data from this work are presented for silicon carbide and epitaxially grown graphene on silicon carbide. Through preliminary analysis of resonant frequency maps acquired through dual-frequency resonance tracking, the local stiffness and elastic modulus can be estimated at each point. This work contributes to the field of scanning probe microscopy by providing a new opportunity for AFM systems that are not currently equipped for a mechanical mode to obtain local mechanical property data.

Single crystal piezoelectric motor operating with both inertia and ultrasonic resonance drives

This study presents a novel piezoelectric motor based on a single crystal material with orthorhombic mm2 symmetry class, in which piezoelectric coupling coefficients in sign and magnitude at transverse directions are different, implying that the value of d32 is positive whilst d31 is negative. The single crystal piezoceramic plate in the shape of a truncated rhombus has three conducting electrodes. While two active electrodes dividing one main surface into two equal sections, the common electrode covers the other main surface uniformly. When a signal is applied between one of the active and the common electrodes, the excited section expands and contracts with a larger magnitude. The expansion and shrinkage on one side causes an oblique movement of the side surface, on which a friction tip is attached. The oblique movement is then transferred to a moving element through frictional coupling. The proposed piezoelectric motor design is simpler and less susceptible to manufacturing tolerances as it does not rely on dimensional aspect ratios to couple two eigenmodes to get a useful movement at the friction tip of the stator. The motor can be operated both inertia (stick–slip) and resonance drive principals. In the case of sawtooth voltage excitation, the smallest motion steps are in the range of 100 nm. Using the ultrasonic excitation of both single source and dual source dual frequency resonance (DSDFR) drives, the piezoelectric motor reached a maximum no load velocity higher than 220 mm/s, and a push–pull force capacity of 2.5 N.

A Dual Resonance Frequency-Selective Surface Temperature Sensor With Linear Frequency–Temperature Behavior

Metamaterial temperature sensors are receiving increasing attention due to the wireless and passive operation. Unfortunately, the frequency response of most metamaterials sensors to temperature is nonlinear, which increases the complexity of signal processing. A dual resonance frequency selective surface (FSS) temperature sensor with linear frequency-temperature characteristic is proposed in this work. The dual frequency resonance of the sensor is realized by introducing the circular slot unit cell into the substrate integrated waveguide (SIW) structure. The linear relationship between the temperature and the difference in the two resonance frequencies can be achieved at specific condition. The proposed sensor was fabricated and measured from room temperature to 120 °C. Measured resonance frequency of the sensor decreases from 12.658 GHz to 12.57 GHz in SIW cavity resonance mode and from 13.787 GHz to 13.727 GHz in circular slot resonance mode. The experiment result shows that wireless temperature sensing is feasible and that the difference in resonance frequency has a good linear relationship with temperature. The sensitivity of the sensor is 0.309 MHz/°C. This design method can be extended to a wider temperature range and the sensor can be potentially applied in temperature sensing in industrial systems.

A super asymmetric cross antenna structure with tunable dual-frequency resonances.

The detection performance of traditional infrared spectroscopy can be very limited in the case of molecular vibrational modes with low absorption cross-sections. On account of its electric field enhancement, plasmonic antenna can be combined with infrared spectroscopy to realize surface enhanced infrared detection and characterization of molecules. In this work, a super asymmetric cross antenna structure with tunable dual-frequency resonance and a high enhancement factor is designed. By systematically studying the transmission spectrum and charge distribution of this super asymmetric cross antenna structure, the physical origin of the dual-frequency resonance and its tunability are characterized in detail. In addition, in order to target desired molecular ensembles, the relationship between the resonance frequency and electric-field intensity of the two resonance modes and the parameters of structure and incident light are examined, yielding an enhancement factor close to 100 in the desired frequency region. Finally, the experimental results show that the proposed super asymmetric cross antenna structure can indeed generate dual-frequency resonances, agreeing reasonably with the theoretical results. It is believed that the super asymmetric cross antenna structure can be widely used to sensitively detect trace molecules, and in monolayered chemistry and bio-molecules, allowing their structures and dynamics to be studied using nonlinear infrared spectroscopy.

Tuning of dual frequency resonance analysis of circular and rectangular patch UWB antenna used for wireless sensor networks

In our modern digital world, communication plays a most important role in research of new designs and novel findings. The proposed analysis is based on Ultra-wide band microstrip patch antenna with two methods of circular and rectangular patch. The design analysis and comparison of various antenna parameters are used for wireless sensor networks. The V-shaped slot is introduced on top of the circular patch and the horizontal T-shaped slot on rectangular patch using jeans substrate material, the design gives good resonance frequency of 9.5GHz and 7.7GHz for wireless communication networks. At resonance the receiver of UWB antenna has a frequency sensing element and the antenna parameters were analyzed using High Frequency Structural Simulator. From the analysis, gain of an antenna, VSWR, return loss as well as radiation pattern, Specific Absorption Rate SAR values are in the acceptable range. The VSWR value of both rectangular and circular patch is 1.05, return loss below -11dB determined in order to avoid surface wave propagation, the specific absorption rate SAR value should be below 2W and gain of each antenna consists of positive value. Hence the antenna meets the requirement suitable for wireless sensor network application.

An Oval-Square Shaped Split Ring Resonator Based Left-Handed Metamaterial for Satellite Communications and Radar Applications.

Development of satellite and radar applications has been continuously studied to reach the demand in the recent communication technology. In this study, a new oval-square-shaped split-ring resonator with left-handed metamaterial properties was developed for C-band and X-band applications. The proposed metamaterial was fabricated on 9 × 9 × 0.508 mm3 size of Rogers RO4003C substrate. The proposed metamaterial structure was designed and simulated using Computer Simulation Technique (CST) Microwave Studio with the frequency ranging between 0 to 12 GHz. The simulated result of the proposed design indicated dual resonance frequency at 5.52 GHz (C-band) and 8.81 GHz (X-band). Meanwhile, the experimental result of the proposed design demonstrated dual resonance frequency at 5.53 GHz (C-band) and 8.31 GHz (X-band). Therefore, with a slight difference in the dual resonance frequency, the simulated result corresponded to the experimental result. Additionally, the proposed design exhibited the ideal properties of electromagnetic which is left-handed metamaterial (LHM) behavior. Hence, the metamaterial structure is highly recommended for satellite and radar applications.

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.

Intelligent mine vehicle terminal antenna based on LTCC technology

A new type of laminate antenna for smart mining vehicle terminal based on low temperature co-fired ceramic (LTCC) technology is proposed. This antenna adopts a simple structure on an LTCC substrate which consists of two layers of rectangular radiating patches with cut corners and a gap inserted in the middle. A laminate structure is designed to cause dual-frequency resonance in order to expand working bandwidth further. A good circular polarization performance can be obtained by adjusting the gap and cut corner size of the upper and lower radiation patches. The software HFSS is used for simulation design. It can be seen form simulation results that the impedance bandwidth(IBW)of the antenna with return loss less than-10dB is 102MHz, ranging from 2.507 to 2.609GHz, and the size of the antenna is 25 × 28×4.6 mm3.

A circular microstrip patch antenna to operate in dual band for wireless communications

A dual band circular micro-strip patch antenna is designed and simulated to obtain electronic circuit miniaturization of an antenna in high speed wireless local area networks (IEEE 802.11a standard). The proposed antenna contains a substrate layer (FR-4 lossy) with a dielectric constant of 4.9 and there is a circular patch on the upper layer of the substrate. The coaxial probe feed is used to excite the desired antenna which reduces the spurious radiation and hence obtained good efficiency. Also the cavity model is used for larger bandwidth while maintaining the lower size of the antenna. An ‘E’ shaped slot is introduced in the radiating patch to obtain dual band resonance frequency with maximum current distribution on the surface. Finally the simulated results using Computer Simulation Technology (CST) microwave studio 2009 in this design are compared with manual computation results and are found to be suitable for WLAN applications.

Bar-shaped Magnetoelectric Gyrator

This paper reports a dual-resonance power transfer effect and a dual-resonance I-V conversion for a bar-shaped ME gyrator made from a hard Pb(ZrxTi1−x)O3 (PZT) ceramic bar having a transverse polarization and a Tb0.3Dy0.7Fe1.92 (Terfenol-D) magnetostrictive alloy bar having a longitudinal magnetization bonded along their cross-section areas. A bar-shaped provides several advantages to a ME gyrator; such as dual resonance frequency along its length direction, as well as half-wave and full-wave vibration modes; reduced laminate bonding area avoiding adhesive breakdown; and ease of fabrication. The reported magnetoelectric gyrator effect originates from the mechanically mediated resonance piezoelectric and magnetostrictive effects in the PZT and Terfenol-D bars, respectively. We studied the influence of the length ratio between the Terfenol-D and piezoelectric bars. A power efficiency of 69.4% was obtained at the half wavelength resonance of 21.47kHz under optimal HBias=1000 Oe and low power conditions. Under higher power drive of 8W/in3, an efficiency of 60.2% was found. This dual-resonance ME gyrator effect offers much promise in power transfer devices for power electronic applications.

Unbalanced and Low-Order Harmonic Voltage Mitigation of Stand-Alone Dual-Stator Brushless Doubly Fed Induction Wind Generator

This paper presents the control strategy of power winding voltage for performance improvement of the dual-stator brushless doubly fed induction generator (BDFG) under stand-alone nonideal load conditions. The control target is to eliminate the unbalanced fifth- and seventh-order components so that a pure and sinusoidal voltage at the point of common coupling can be obtained. Considering the existence of both dc and ac components in the control winding current reference, a proportional-integral dual frequency resonance current regulator is adopted and tuned. The dynamic performances of voltage and current loop are also analyzed. Finally, the effectiveness of the proposed control strategy under various load conditions is verified by steady-state and dynamic performance tests.

Simulation of the simultaneous dual-frequency resonance excitation of ions in a linear ion trap.

The process of ion resonance dipolar excitation in a linear ion trap by 2 ejection waveforms with close frequencies is studied. The physical mechanism of increasing the resolving power using the ion excitation is a nonlinearity of the electric radio frequency fields caused by space charge. Using 2 resonance forces with 2 close frequencies leads to the completion of 2 excitation processes. In the case of the perfect quadrupole electric field, the ion motion equations are linear, and as a result, the respondent ion ensemble is also a linear and valid superposition principle. Nevertheless, the resolution increases (20%) in the case of lack of a space charge in an operating mode with a dual-frequency. The numerical simulations show that the mass shift is removed, and the mass resolution is increased via dual-frequency resonance excitation when the frequency difference (approximately 2.5kHz) is relatively small and the phase difference of 2 harmonic signals is 0-π3 even at a high linear ion density of up to 50000 ions per radius field r0 .

Stain-free Histopathology of Basal Cell Carcinoma by Dual Vibration Resonance Frequency CARS Microscopy.

Basal cell carcinoma (BCC) is the most common malignancy in Caucasians. Nonlinear microscopy has been previously utilized for the imaging of BCC, but the captured images do not correlate with H&E staining. Recently, Freudiger et al. introduced a novel method to visualize tissue morphology analogous to H&E staining, using coherent anti-Stokes Raman scattering (CARS) technique. In our present work, we introduce a novel algorithm to post-process images obtained from dual vibration resonance frequency (DVRF) CARS measurements to acquire high-quality pseudo H&E images of BCC samples. We adapted our CARS setup to utilize the distinct vibrational properties of CH3 (mainly in proteins) and CH2 bonds (primarily in lipids). In a narrowband setup, the central wavelength of the pump laser is set to 791nm and 796nm to obtain optimal excitation. Due to the partial overlap of the excitation spectra and the 5-10nm FWHM spectral bandwidth of our lasers, we set the wavelengths to 790nm (proteins) and 800nm (lipids). Nonresonant background from water molecules also reduces the chemical selectivity which can be significantly improved if we subtract the DVRF images from each other. As a result, we acquired two images: one for "lipids" and one for" proteins" when we properly set a multiplication factor to minimize the non-specific background. By merging these images, we obtained high contrast H&E "stained" images of BBC's. Nonlinear microscope systems upgraded for real time DVRF CARS measurements, providing pseudo H&E images can be suitable for in vivo assessment of BCC in the future.

628 Dual vibration resonance frequency CARS microscopy imaging of basal cell carcinoma to achieve stain free histopathology

628 Dual vibration resonance frequency CARS microscopy imaging of basal cell carcinoma to achieve stain free histopathology

Dual Band Gap Coupled Patch Antenna for Wireless Communications

A dual frequency resonance antenna is proposed by means of a rectangular microstrip patch antenna with parasitic elements. Analysis is made using concepts of circuit theory and the measured and theoretical results are compared with simulation results obtained with IE3D simulation software. Error between experimental and theoretical and simulated values is within 1.5% and frequency ratio of the simulated, theoretical and experimental values is found to be 2.0

Super scattering phenomenon in active spherical nanoparticles**Project supported by the National Natural Science Foundation of China (Grant Nos. 11174222 and 91230203).

Localized surface electromagnetic resonances in spherical nanoparticles with gain are investigated by using the Mie theory. Due to the coupling between the gain and resonances, super scattering phenomenon is raised and the total scattering efficiency is increased by over six orders of magnitude. The dual frequency resonance induced by the electric dipole term of the particle is observed. The distributions of electromagnetic field and the Poynting vector around nanoparticles are provided for better understanding different multipole resonances. Finally, the scattering properties of active spherical nanoparticles are investigated when the sizes of nanoparticles are beyond the quasi-static limit. It is noticed that more high-order multipole resonances can be excited with the increase of the radius. Besides, all resonances dominated by multipole magnetic terms can only appear in dielectric materials.

Single Molecule Fluorescence and Atomic Force Microscopy Studies of DNA Repair

DNA polymerases that are responsible for replication make approximately one error for every 107 bases copied, but the human genome contains ∼6 billion bases, which results in ∼600 errors per round of replication. The DNA mismatch repair (MMR) system corrects these DNA synthesis errors that occur during replication. MMR is initiated by the highly conserved MutS and MutL homologs, which are both dimers and contain DNA binding and ATPase activities that are essential for MMR in vivo. MutS homologs initiate repair by binding to a mismatch and undergoing an ATP-dependent conformational change that promotes its interaction with MutL homologs. This complex signals the initiation of excision and resynthesis of the newly synthesized DNA strand containing the incorrect nucleotide. We have been using a combination of atomic force microscopy (AFM) and single molecule fluorescence to characterize the stoichiometries and the conformational and dynamic properties of MutS and MutL homologs and their assembly on DNA containing a mismatch. We have also developed a new dual resonance frequency enhanced electrostatic force microscopy (DREEM), in which we simultaneously collect the AFM topographic image and an image of the electrostatic potential of the surface. The DREEM images reveal the path of DNA inside individual protein-DNA complexes, yielding unprecedented details about DNA conformations within simple and complicated complexes. I will discuss our studies on the assembly of MutS and MutL homologs on mismatches, with a focus on how AFM, DREEM, and single-molecule fluorescence can be powerful tools to study the stoichiometries, conformations, and dynamic assembly of multi-component complexes.