Stealth characteristic of two dimensional cylinder plasma envelopes is studied. Three cases about plasma refraction effect, reflection characteristic and attenuation by absorbing electromagnetic wave (EMW) are concerned synthetically. As for plasma refraction stealth, EMW traces equation in cylinder plasma is deduced; a novel concept of plasma refraction deviation angle is presented; the relation between refraction deviation angle and incidence angle of EMW is yielded; the relation between refraction deviation angle and plasma density distribution is made out. As for reflection stealth and attenuation stealth, reflection calculation of multi-layer plasma is presented first, and plasma collision frequency as well as corresponding collision absorption is taken into account simultaneously, then EMW reflectivity with double-path attenuation is obtained. It is shown that cylinder plasma envelopes considering the three cases above could make distinct stealth.

This paper presents the simulation study of a wideband modified fractal rectangular curve iteration-1 (FRC-1) dielectric resonator antenna (DRA) along with conventional FRC DRAs of different iteration levels for WiMAX application. The simulation study has been carried out using CST Microwave Studio software. The design procedure and radiation performance characteristics of modified and conventional FRC DRAs are described and the simulation results for modified FRC-1 DRA are compared with those of a conventional FRC-1 DRA of identical outer dimensions. The simulation results for the material dielectric constant dependent radiation characteristics of both the FRC-1 DRAs are also presented. The results presented here may be useful in designing portable personnel communication device antennas and in analyzing the performance of these antennas for wireless communication.

With the aim to improve the performance of Bulk Acoustic Wave resonators, the thickened edge load can be included on the top electrode. Using this solution, the energy trapping concept is forced, and lateral unwanted resonances are not present in the electrical behavior of the resonator. The way to design such a thickened edge load entails, on one hand, the presence of a resonant mode given by the thickened edge load; on the other hand, the degradation of the electromechanical coupling coefficient of the main thickness mode. In order to study the previous phenomena, the electric equivalent circuit has been developed. The obtained results have been validated with the three-dimensional simulations and compared with manufactured resonators.

We have developed a proof-of-concept low power free electron maser that is compact and low cost. The design, set-up and results of a novel (without wiggler) low power X-band rectangular waveguide pre-bunched free electron maser (PFEM) are presented in this paper. Our device operates at 10 GHz, with 10 mWatt seeding input power and employs two rectangular waveguide cavities (one for velocity modulation and the other for energy extraction). The electron beam used in this experiment is produced by Thoria coated Iridium filament which can operate at 3 kV and up to 5 mA beam current. The effect of the aperture on the power leaking out of the waveguide is also analyzed. The TE10 mode propagation of the EM standing wave is used to pre-bunch the electron beams in the input cavity. The bunched electron beams are in the same phase as the TE10 mode propagation of the EM wave in the output cavity. This free electron maser could be useful industrially, as it could be used with the commercially available accelerating voltage supplies.

The properties of a lossless Veselago lens is examined when the material parameters epsilon and mu are frequency dispersive. A complete solution is presented that is based on the use of Fourier transforms in the frequency domain and is obtained in terms of the residues at the poles and branch cut integrals. It is shown that for an incident field with a finite frequency spectrum the excited evanescent field consists of resonant even and odd surface wave modes that do not grow exponentially within the slab. For a lossless slab and a sinusoidal signal of finite duration, at a single frequency corresponding to that where the relative values of epsilon and mu equal -1, Pendry's solution is obtained along with excited surface wave modes and other interfering waves that makes it impossible to obtain a coherent reconstruction of the spatial spectrum of the object field at the image plane. If the slab material is lossy the excited interfering surface wave modes will decay away in a relatively short time interval, but as shown by other investigators the resolution of the lens will be reduced in a very substantial way if the losses are moderate to large.

A systematic derivation of the Coupled Nonlinear Schrodinger Equations (CNLSE) governing nonlinear pulse propagation in a weakly birefringent monomode optical fiber based on a multiple-scale perturbation solution of the semilinear vector wave equation for the electric field in a (randomly) birefringent fiber medium is presented. The analysis of the nonlinear propagation characteristics of optical pulses based on a numerical solution of the CNLSE is deferred to the second part of this contribution.

This paper presents a novel approach for designing planar multimode wideband bandpass filters with good selectivity. The multimode resonator is composed of an open-ended microstrip line with length of half-wavelength (λ/2) and several radial-line stubs. By using different kinds of radial-line stub-loaded, different kinds of responses including three-pole and four-pole bandpass filters can be realized. Depending on electric field distribution and equivalent circuit model, the characteristics of the filter are analyzed. To verify the proposed method, two filters are implemented. The measured results exhibit good agreement with the simulation.

A polarized 3D-electromagnetic wave propagating from an aperture source into a lossy medium can be modeled by an astigmatic Gaussian beam model (GBM) of complex source coefficients that characterize a radiating antenna uniquely. The source coefficients are determined numerically from phantom experiments, and then used in simulations of specific absorption rates (SAR), in both homogeneous and layered biological media, resulting in good agreement with experimental data. This paper shows that for an x-polarized E-field the GBM simulations of SAR enhancement or focus in the axial, z-directed, paraxial region are accurate, but approximate in the transverse, y-directed, non-paraxial regions due to a focal shift.

In this study, electromagnetic (EM) pollution measurements in crowded residential areas were performed and statistical analysis of values recorded for the EM sources causing pollution was carried out. The actual measurement values and the estimated values by the analysis model obtained through the statistical analysis were compared. Also, amplitude fluctuations of the electromagnetic radiations from EM pollution sources were detected for a long time and statistical analyses were made. EM field levels were measured in the districts of Turkish capital, Ankara where cellular base stations and TV/Radio stations are densely populated. EM radiation levels were measured for the GSM900, GSM1800, FM, UHF4, VHF4 and VHF5 stations for certain spectrum ranges under far-field conditions by utilizing isotropic field probe and selective spectrum analyzer. The measurements were fulfilled by using NARDA SRM3000 radiation meter with isotropic antenna that can be utilized in 100 kHz-3 GHz frequency range. The obtained measurement levels were compared with the limit values given by International Commission for Non-Ionizing Radiation Protection (ICNIRP). The measurement results for each pollution sources were compared and their contributions to the combined radiation were analyzed. The values for the EM pollution in the measurement regions were embedded over the digital maps created for the related places. During this process, comparisons of the pollution maps were made by utilizing Natural Neighbour (NN) interpolation technique.

An optical code generating device has been developed based on 1×2 and 1×4 asymmetric plastic optical fiber (POF) couplers. The code generating device provides a unique series of output power which are successively used as an optical code in a portable optical access-card system. The system is designed where the asymmetric POF coupler is embedded in an all passive portable unit. This device utilizes a tap-off ratio (TOFR) technique based on a simple variation of the tap width of an asymmetric Y-branch splitter design. A hollow-type waveguide structure is used where it eliminates the use of polymeric material for the waveguide core and allows simple fabrication and assembling of the device. The asymmetric POF coupler has been fabricated on metal-based materials using machining technique. The results for the simulated and fabricated 1×2 asymmetric couplers show the same linear characteristics between the TOFR and the tap width. The simulated devices shows a TOFR variation from 18.6% to 49.9% whereas the TOFR for the fabricated metalbased devices varies from 10.7% up to 47.7%, for a tap width of 500 um to 1 mm. The 1×4 coupler designed using simple cascading of a Y-branch splitter with two 1×2 asymmetric couplers has been fabricated and shows similar characteristics as that of the designed 1×4 devices. The insertion loss for the 1×2 asymmetric coupler at the tap line varies from 9 dB to 16 dB whereas for the bus line, the insertion loss is about 9±0.8 dB. The insertion loss for the 1×4 asymmetric coupler at the output ports varies from 14 dB to 22 dB.

The paper discusses fabrication of homogenous and heterogeneous breast phantoms to simulate the dielectric properties of human breast over the microwave frequency range from 0.5 GHz to 13.5 GHz. The breast phantoms have stable mechanical configuration and dielectric properties suitable for microwave imaging experiments particularly ultra-wideband microwave imaging for breast cancer detection.

The paper presents an analytical approach to treat the problem of transient oscillations in a cavity uniformly filled with nonstationary medium, which is characterized by time-varying permittivity and conductivity. Closed-form solutions are found for some transient excitations and medium parameters.

The anisotropic spherical Wigner-Seitz (WS) cell model --- introduced to describe colloidal plasmas --- is investigated using the linearized Poisson-Boltzmann (PB) equation. As an approximation, the surface potential of the spherical macroparicle expanded in terms of the monopole (q) and the dipole (p) is considered as an anisotropic boundary condition of the linear PB equation. Here, the "apparent" moments q and p are the moments 'seen' in the microion cloud, respectively. Based on a new physical concept, the momentneutrality, the potential around the macroparticle can be solvable analytically if the relationship between the actual moment and the "apparent" moment can be obtained according to the momentneutrality condition in addition to the usual electroneutrality. The calculated results of the potential show that there is an attractive region in the vicinity of macroparticle when the corresponding dipole part of the potential dominates over the monopole part, and there is an attractive region and a repulsive region at the same time, i.e., a potential well, when the corresponding dipole part of the potential just comes into play. It provides the possibility and the conditions of the appearance of periodic structure of the colloidal plasmas, although it is a result of a simple theoretical model.

In this paper, a novel dual-band rectangular slot antenna for wireless local area network (WLAN) applications in IEEE 802.11b/g/a systems is presented. The proposed antenna, fed by a 50Ω microstrip line, has size of 32 mm×28 mm×1.6 mm. By introducing a pair of U-shaped strips, the proposed antenna can generate two separate impedance bandwidths. The prototype of the proposed antenna has been successfully constructed and tested. The low-band resonant frequency is located at about 2.4 GHz, with -10 dB impedance bandwidth from about 2.3 to 2.5 GHz. The high-band resonant frequency is located at about 5.7 GHz, with -10 dB impedance bandwidth from about 4.9 to 6.0 GHz. In addition, the measured results show good radiation characteristics at the two operating bands, proving the dualband operation of the proposed antenna.

A new modification of the method of Mode Expansion in Time Domain is proposed for studying transient signals propagation in conical lines (including multi-connected ones) with inhomogeneous and time-dependent medium. The method is based on expanding the fields in spherical coordinate system into series of angular dependent modes with mode amplitudes being governed by a system of coupled evolutionary equations. The medium parameters (permittivity and permeability) are taken in a factorized form as a product of angular dependent factor and a factor that depends on time and radial coordinate. The introduced method can be applied to analysis of propagation and radiation in conical-like antennas with dielectric filling.

A multiresonance double cross element is used to design a dual-band reflectarray with dual linear polarization. The proposed element has a single conductive layer structure which makes it easy to manufacture. The results presented in this paper show that the mutual effect between the elements of the two bands is negligible. Hence, it is easy to achieve the phase compensation for each band separately. The simulated and measured results for an element designed to cover the X- and K-bands have confirmed the suitability of the proposed element to build a dual-band reflectarray.

This paper shows that L-shaped monopole antenna on PPS manufactured by inkjet printing of nano silver ink is able to produce very competitive overall antenna performance against Rogers copper foil structures if the thickness of the printed conductor layer is about the skin depth at the operating frequency multiplied by four.

We have investigated elliptical annular ring microstrip antennas having a sine wave periphery both theoretically and experimentally. The proposed antenna gives a good circular polarization at the center frequency of 1.296 GHz, with measured 3 dB axial ratio bandwidth of about 0.73% (9.5 MHz) and impedance bandwidth of about 1.7% (22.0 MHz). Input and radiation characteristics are also examined for different sine wave amplitudes applied to the periphery of elliptical ring patch antenna.

This work proposes the use of Non-Bianisotropic Split Ring Resonators (NB-SRRs) as building blocks for dual-band response filters. Design parameters will be evaluated in order to characterize coupling mechanisms for both the particle and filter structure. A ready-to-use dual-band filter for a multiconstellation Galileo/GPS global positioning receiver is manufactured in order to validate and test the proposed design. The device transmission response measurement agrees with both circuital and electromagnetic simulations, as well as with theoretical insertion losses, which are 2.4 dB and 3.5 dB at center passbands for L5 and L1 bands respectively.

Physical agents such as non-ionizing continuous-wave 2.45 GHz radiation may cause damage that alters cellular homeostasis and may trigger activation of the genes that encode heat shock proteins (HSP). We used Enzyme-Linked ImmunoSorbent Assay (ELI-SA) and immunohistochemistry to analyze the changes in levels of HSP-90 and its distribution in the brain of Sprague-Dawley rats, ninety minutes and twenty-four hours after acute (30 min) continuous exposure to 2.45 GHz radiation in a the Gigahertz Transverse Electromagnetic (GTEM cell). In addition, we studied further indicators of neuronal insult: dark neurons, chromatin condensation and nucleus fragmentation, which were observed under optical conventional or fluorescence microscopy after DAPI staining. The cellular distribution of protein HSP-90 in the brain increased with each corresponding (0.034 ± 3.10^-3, 0.069 ± 5.10^-3, 0.27 ± 21.10^-3 W/kg), in hypothalamic nuclei, limbic cortex and somatosensorial cortex after exposure to the radiation. At twenty-four hours post-irradiation, levels of HSP-90 protein remained high in all hypothalamic nuclei for all SARs, and in the parietal cortex, except the limbic system, HSP-90 levels were lower than in non-irradiated rats, almost half the levels in rats exposed to the highest power radiation. Non-apoptotic cellular nuclei and a some dark neurons were found ninety minutes and twenty-four hours after maximal SAR exposure. The results suggest that acute exposure to electromagnetic fields triggered an imbalance in anatomical HSP-90 levels but the anti-apoptotic mechanism is probably sufficient to compensate the non-ionizing stimulus. Further studies are required to determine the regional effects of chronic electromagnetic pollution on heat shock proteins and their involvement in neurological processes and neuronal damage.