Advanced Electromagnetics (E-Journal)
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High Efficiency Ka-Band Spatial Combiner
No full textA Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC) is proposed in this paper, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS) transitions. At the date of this paper and at the Author's best knowledge no such FLuS innovative transitions have been reported in literature before. These transitions are inserted into a WR28 waveguide T-junction, in order to allow the integration of 16 Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifiers (SSPA's). A computational electromagnetic model using the finite elements method has been implemented. A mean insertion loss of 2 dB is achieved with a return loss better the 10 dB in the 31-37 GHz bandwidth
Broadband Spectroscopy of Nanoporous-Gold Promoter
No full textThe efficiency of UV photocatalysis on TiO2 particles was increased by mixing TiO2 particles with nanoporous gold (NPG) with pore diameters of 10–40 nm. This means that NPG acts as a promoter in the photocatalytic reaction of TiO2. Broadband spectroscopic results from millimeter wave to ultra violet of NPG membrane are discussed to estimate plasmonic effect on the catalysis
Realization of THz Band Mixer Using Graphene
No full textIn this article a new method for creating mixer component in infrared and THz is suggested. Since the nonlinear property of admittance creates frequency components that do not exist in the input signal and the electrical conductivity is associated with admittance, in our work we have proven and simulated that the nonlinear property of graphene admittance can produce mixer component. The simulation results show that the mixer component is larger than other components, therefore the mixer works properly. Because of nano scale of graphene structure, this method paves the road to achieve super compact circuits
Dual-Band Coherent Perfect Absorption/Thermal
No full textDual-band perfect absorption/thermal emission is shown to be a general property of an ultrathin bilayer consisting of a dielectric and a totally reflective layer if the permittivity of the dielectric can be described by Drude-Lorentz (DL) model. The two bands coexist and reside on opposite sides of the Lorentzian resonant frequency where the material loss is small. However, the perfect absorption mechanism for the two bands is distinguishably different. One band is related to Fabry-Perot phenomenon and the surge of refractive index near the Lorentzian resonance. This band is polarization insensitive. The other band is associated with excitation of Brewster-type mode at the ϵ-near-zero (ENZ) wavelength and occurs only for p-polarized wave at oblique incidences. This mode has a fast-wave non-radiative character and propagates along the ultrathin ENZ layer superimposed on the highly reflective surface. Both bands exhibit wide-angle high emission with a small shift in their center frequencies which can be tuned by tuning the Lorentzian resonance. The resonance-enhanced dual band absorption occurs in the ultrathin DL layer at the weakly absorbing wavelengths as a consequence of an interaction between the total transmission and the total reflection. We demonstrate this phenomenon in a silicon carbide/copper bilayer. The suggested structure may have applications in biological and chemical sensors, IR sensors, thermal emission controls, thermophotovoltaics, and photodetectors
Effects of RF/MW Exposure from Mobile-phone Base-Stations on the Growth of Green Mint Plant using Chl a Fluorescence Emission
No full textWe report on the effects of RF/MW on plants.Green Mint plant exposed to different levels ofradiation (from 0.5 to 10.5 μW/cm2) for thispurpose. A USB2000 spectrophotometer wasused to record fluorescence signals from intactleaves.Spectroscopic data (P.I.R and A.R)together with vegetative data (leafdimensions and weight), revealed stressingeffects on plant due to RF/MW in all groupsexcept the control which was free of exposure
Investigation of surface roughness influence on hyperbolic metamaterial performance
No full textThe main goal of this work was to introduce simple model of surface roughness which does not involve objects with complicated shapes and could help to reduce computational costs. We described and proved numerically that the influence of surface roughness at the interfaces in metal-dielectric composite materials could be described by proper selection of refractive index of dielectric layers. Our calculations show that this model works for roughness with RMS value about 1 nm and below
Investigations and Simulations of All optical Switches in linear state Based on Photonic Crystal Directional Coupler
No full textSwitching is a principle process in digital computers and signal processing systems. The growth of optical signal processing systems, draws particular attention to design of ultra-fast optical switches. In this paper, All Optical Switches in linear state Based On photonic crystal Directional coupler is analyzed and simulated. Among different methods, the finite difference time domain method (FDTD) is a preferable method and is used. We have studied the application of photonic crystal lattices, the physics of optical switching and photonic crystal Directional coupler. In this paper, Electric field intensity and the power output that are two factors to improve the switching performance and the device efficiency are investigated and simulated. All simulations are performed by COMSOL software
New SERS-active junction based on cerium dioxide facet dielectric films for biosensing
No full textFurther enhance of the Raman scattering is the priority for the development of the modern molecular diagnostic methods. Expected increasing in detection sensitivity of the biological and chemical agents provides substantial progress in such areas as: proteomics (discovery of new disease markers), pharmacokinetics of drugs, analysis of toxins and infections agents, drug analysis, food safety, and environmental safety.
In this paper we investigated the possibility of the facet structures, based on cerium dioxide to further enhance the SERS signal. During the studies a new metamaterial was developed. The metamaterial is based on the facet cerium dioxide films and plasmonic nanoparticles that are immobilized on its surface. The new metamaterial provides additional SERS signal amplification factor of 211. Thus developed material offers the prospect of increasing the sensitivity and selectivity of biochemical and immunological analysis
Synthesis of RF Circuits with Negative Time Delay by Using LNA
No full textA demonstration of the negative time-delay by using active circuit topologies with negative group delay (NGD) is described in this paper. This negative time delay is realized with two different topologies operating in base band and modulated frequencies. The first NGD topology is composed of an RL-network in feedback with an RF/microwave amplifier. Knowing the characteristics of the amplifier, a synthesis method of this circuit in function of the desired NGD values and the expected time advance is established. The feasibility of this extraordinary physical effect is illustrated with frequency- and time-domain analyses. It is shown in this paper that by considering an arbitrary waveform signal, output in advance of about 7 ns is observed compared to the corresponding input. It is stated that such an effect is not in contradiction with the causality. The other NGD topology is comprised of a microwave amplifier associated with an RLC-series resonant. The theoretical approach illustrating the functioning of this NGD circuit is established by considering the amplifier S-parameters. Then, synthesis relations enabling to choose the NGD device parameters according to the desired NGD and gain values are also established. To demonstrate the relevance of the theoretic concept, a microwave device exhibiting NGD function of about -1.5 ns at around 1.19 GHz was designed and analyzed. The NGD device investigated in this paper presents advantages on its faculty to exhibit positive transmission gain, the implementation of the bias network and matching in the considered NGD frequency band
Tunable Nanoplasmonics
No full textIn this paper, we present novel mechanisms for tuning and controlling the response of novel plasmonic filter using metal-insulator-metal (MIM) configuration. These mechanisms allow for full control on the transmission response from these waveguide based structures. This control can be done electrically or mechanically. The applications and advantages of these novel schemes are discussed in details. Wideband tuning range has been obtained using these schemes