A novel dualband frequency selective surface (FSS) with both a dielectric substrate and superstrate constructed by double-fourlegged loaded slots (DFLLSs) is investigated, in which each periodic cell consists of two neighboring DFLLSs with different dimensions, its resonant frequencies occur at 183 GHz and 220 GHz. Good selectivity performance can be easily achieved both in lower passband and higher passband by tuning the dimensions of the DFLLSs. Besides, the passbands are mainly determined by the neighboring perturb cells and can be designed independently. According to the explicit physical concept and some formulas, the design process become straightforward and simple. Its frequency performance is obtained by using numerical simulation software CST based on finite difference time domain method (FDTD). The simulated results show the good stability of the resonant frequencies and bandwidths at different polarization states and various incident angles.

This paper presents the design of a dual stacked microstrip antenna over the frequency range of 9.5-16 GHz. Investigations show that in the new structure the impedance bandwidth of the antenna is increased to 44% and the thickness of the antenna decreases to 0.14λ. Furthermore, the gain bandwidth of the antenna (above 8 dB) is increased to 5.1 GHz (40%).

This paper presents a novel elliptic shape defected ground structure (DGS) for low pass filter (LPF) applications. An equivalent RLC circuit model is presented and its corresponding parameters are also extracted from the measured S-parameters. The filter presents the advantages of compact size,high selectivity; low insertion loss and high out-band suppression from 5.15 GHz to 10 GHz below -31 dB. Good agreement with response of equivalent circuit, electromagnetic simulation, and measurement is demonstrated.

The permittivity tensor of an anisotropic material can be predicted with use of the presented technique. A slab of this substance possessing infinitesimal thickness is illuminated by a normally incident plane wave and rigorous expressions for the transmission coefficients are obtained. The derived formulas are linearly expanded with respect to the small thickness of the slice, while simple approximations of the material permittivities are produced by measuring the transmission coefficients for suitable polarizations. These simplified expressions provide a physical intuition about the use and the function of the anisotropy parameters which cannot be achieved via more precise but also more complex patterns. Some diagrams of the prediction error with respect to the dielectric constants, the size of the slab and the operating frequency are included and discussed.

In RFID system, tag collision is a main problem for fast tag identification. On the base of binary search algorithm of backtracking, an enhanced binary anti-collision search algorithm for radio frequency identification (RFID) system is presented in this paper. By dynamically transferring the ID of the tag, the length of the data transferred can be decreased dramatically. Mathematical simulation result shows that compared with the binary search algorithm of backtracking, the proposed algorithm can save channel by more than 43.75% when handling multiple RFID tags simultaneously. Finally the proposed algorithm is successfully applied to a RFID device, which validates itself.

In this paper, an integrated and manifold study of the combined electromagnetic and thermal effects, caused by human exposure to microwave radiation is carried out. In essence, we numerically calculate the amount of electromagnetic power absorbed by biological tissues for various exposure conditions and types of emitting sources, utilizing a detailed model of the human head. The severity of the obtained results is evaluated via comparisons with the guidelines of international safety standards, while further insight is gained by investigating the induced thermal effects. The latter are properly quantified through the solution of the bioheat equation, when combined with the outcome of the electromagnetic simulations. Spatial distributions of the corresponding temperature changes are thus calculated, their relation to the dissipated power is established, and the thermal response of human tissues in marginal cases of exposure is predicted.

Fractional curl operator has been used to derive solutions to the Maxwell equations for fractional rectangular cavity resonator. These solutions to the Maxwell equations may be regarded as fractional dual solutions. Behavior of field lines and surface current density in fractional cavity resonator have been investigated with respect to the fractional parameter. Fractional parameter describes the order of fractional curl operator.

Anechoic chambers are used for both emission and immunity testing but the ferrite tiles used to line the inside of the chamber are extremely expensive. This paper describes a method of reducing the number of tiles, whilst ensuring a reliable test environment. In this paper, the ray-tracing method for waves propagation is used for evaluation of the reflectivity level of an anechoic chamber, and genetic algorithms are used. And use genetic algorithms to optimize the layout of ferrite tile absorber in a partially lined enclosure to produce a best performance. The results show that it is possible to cover just 80% of the surface of the enclosure with ferrite absorber and obtain good agreement by fully lined enclosure with an error of less than 3 percent over the whole test points.

In this article the details of Erbium doped Fiber Amplifier (EDFA) in presence of Silicon nanocrystal (Si-Nc) is investigated. In this analysis Si-Nc and Er ions in matrix of fiber are assumed two and five levels respectively. For this structure rate equation for transient and steady state analysis is considered. The range of Er⁽⁺³⁾ concentration and pump intensity at 488nm are considered [10¹⁷ - 10²¹]1/cm³ and [10¹⁷ - 10²³] photon/cm^{2 .} sec respectively in this paper. Based on numerical simulation of this problem we observed that with increasing of concentration of the Si-Nc the fiber length for given optical gain is decreased. For example in the case of 40 dB optical gain, we calculated fiber length to be 1.1 × 10⁵ cm without Si-Nc and 5 × 10² cm for σ_CCa = 1 × 10^-17 cm² (confined carrier absorption cross-section) and 5 cm for σ_CCa = 1 × 10^-19 cm² respectively. Our simulations show that for second level with increasing pump intensity the population rise and fall times are decreased. But, for third level the population rise time is decreased and fall time is depends to level of Er ion interactions. We observed that with increasing Er ions optical net gain is increased and finally has a maximum. After this special value of Er ions because of increasing in interaction between ions the net gain finally begin to decrease. In this analysis we let to Er ions have inhomogeneous distribution. Also, we observed that in this case with increasing of the distribution peak, the net gain is increased, interaction between ions is increased, the coupling coefficient to the Si-Ncs is increased and losses due to Si-Ncs are decreased. Finally effect of K_exiton (maximum number of exciton in single Si-Nc) on amplification process is considered and we observed that in the case of K_exiton = 2 the optical gain considerably and introduced losses due to Si-Nc are increased.

To investigate the effect of forest spatial structure on SAR interferometry (InSAR) data requires an electromagnetic scattering model capable of expressing radar observation in terms of parameters describing forest spatial structure. In this paper, we propose an electromagnetic scattering model for mixed-species forest which includes the coherent effect of forest structure and preserves phase information of radar backscattering signal. Interferometric SAR images of three-dimensional (3-D) scenes are simulated based on this model and the heights of scattering phase centers are estimated from the simulated InSAR data. The results show that the model is suitable for simulating interferometric SAR response to forest canopies and for investigating the forest spatial structure. We also compare the backscattering coefficients predicted by the proposed electromagnetic scattering model with the JERS-1 L-band SAR and ENVISAT ASAR C-band data acquired at forest stands of Changqing test site in Daxinganling, Northern China. Good agreements are obtained between the model results and measurement data.

In this paper, a folded substrate integrated waveguide (FSIW) cavity is analyzed theoretically. Formulae for the determination of the dimensions of the FSIW cavity have been deduced. To verify the proposed formulae, simulated results are compared with the results of the formulae and good agreement has been observed between them. An example filter working at 8 GHz is designed and fabricated. Good agreement between the simulated and the measured results has been obtained. Result shows the advantage of wide out-of-band rejection and compact size.

The full MIMO radar and the partial MIMO one are introduced. The performance analysis of beamforming for MIMO (Multiple-input Multiple-output) radar and comparisons with the phased-array radar are given. The expressions of beamwidth, gain loss and detection range for MIMO radar are derived. Theoretical analysis and simulations show that the beam of the full MIMO utilizing all virtual array elements is identical to the two-way beam of the phasedarray radar, and that the beam of the partial MIMO selecting elements with different phase centers (phase shifts) is narrower, but has a gain loss. Additionally, the partial MIMO can avoid aliasing in space when the transmitting antennas are spaced at greater than half-wavelength spacing. As scanning radar, the partial MIMO radar has smaller detection range than the phased-array radar, and the full MIMO radar has the same range as the phased-array radar.

The measurement of inhomogeneity and irregularity of dielectric plate requires metering equipments with high spatial resolution power and contactless method. As we know, a measurement system with thin beam has high spatial resolution power. In this paper, a beam compressed system (BCS) is proposed to improve the spatial resolution power for measuring inhomogeneity and irregularity of dielectric plate at millimeter wave band. The beam shape of the BCS has to be carefully designed to achieve a very thin shape which has to be constant over a long range. The BCS can be applied to detect inhomogeneity and irregularity of a dielectric plate from cell to cell with its thin beam. Simulations with FDTD and FEM and experiments are carried out to confirm the performance of the designed BCS, both simulation and experimental results have good agreement. And the images of the permittivity or thickness variance of dielectric plate are given to demonstrate the advantages of the BCS over traditional Gaussian beam measuring method.

This paper presents a compact dual-band slot antenna for 2.4/5 GHz WLAN applications. The radiating elements of the proposed antenna are composed of a square ring slot and a circular ring slot, operating at 2.4 GHz and 5 GHz bands respectively. The antenna size is very compact (40mm × 40mm × 1mm), and can be integrated easily with other RF front-end circuits. It is demonstrated that the proposed antenna can completely cover the required bandwidths of IEEE 802.11b/g (2.4-2.485 GHz) and IEEE 802.11a (5.15-5.825 GHz) with satisfactory radiation characteristics. Good agreement is achieved between the simulated and measured results.

The sensitivity of cylindrical and spherical transformation cloak to several factors has been carefully studied in this paper. We find that the performance of the transformation cloak is quite sensitive to the crevice in the shell. When an obstacle is not completely wrapped inside the cloaking shell,noticeable scattering will be induced outside. It is also shown that if the shape of the cloak is changed in certain ways while the material parameters remain the same,the backward scattering is still zero. In addition,the combination of parts of cylindrical cloak can only achieve perfect invisibility in one direction,while combining the cylindrical cloak with two halves of spherical cloak can still make a perfect 3-dimensional (3D) invisible cloak. The findings are verified with finite element based simulations as well as theoretical calculations. Our discussion results are valuable to the implementation of cloak in engineering.

A novel compact dual-band electromagnetic band-gap (EBG) structure is proposed in this paper. The major contribution to this dual-band design is using cascaded mushroom-like units which operate at different frequencies. The position of via is moved off the center of the metal patch to get a lower resonant frequency and the effects of the radius of via are considered at the same time. The method of suspended microstrip is utilized to measure the band-gap characteristics of the EBG structures. Several dual-band EBG structures are designed and compared. Results show that this novel cascaded structure offers additional flexibility in controlling the frequencies of the stopband over a wide range. The cascaded dualband EBG structure has potential application to dual-band antenna and circuit.

The third generation promises increased bandwidth up to 384 Kbits/s for wide area coverage up to 2Mbits/s for local area coverage. A smart antenna technique has been developed specifically to meet the bandwidth needs of 3G [5, 7, 12, 14]. Smart beamforming provides increased data throughput for mobile high speed data application. Here in this paper we worked on MVDR Beamforming scheme for continuing demand for increased bandwidth & better quality of services. Adaptive minimum variance beamforming can be easily implemented to increase capacity as well as suppressing co-channel interference & to enhance the immunity to fading. The computer simulation carried out in MATLAB platform shows the signal processing technique optimally combines the components in such a way that it maximizes array gain in the desired direction simultaneously minimize it in the direction of interference [1, 3, 15, 16].

The modifiedWatson transform is applied to the Mie series expression of the electromagnetic field scattered by a high frequency plane wave incident on an infinitely long double negative cylinder. The Debye expansion is applied to the Mie series coefficients to obtain a physical insight into the scattering mechanisms and achieve an efficient approach for the computation of the scattered field. The first two terms of the Debye series are computed using the residue series in the geometrical shadow regions and using the steepest descent method in the geometrically lit regions. It is observed that the results obtained from the series and from the modified Watson transform are in good agreement. The angular boundaries for the geometrically lit and the geometrical shadow regions of the double negative cylinder corresponding to the first two terms of the Debye series are determined. These are compared with the corresponding angular boundaries for a double positive cylinder. It is observed that the spatial extent of the geometrical shadow of the double negative cylinder corresponding to the second term of the Debye series is very small compared to that of the double positive cylinder due to the negative refraction in the double negative cylinder when the magnitude of the refractive index n is greater than √2.

This paper talks about the adiabatic parameter dynamics of Gaussian and super-Gaussian optical solitons that propagate through dispersion-managed optical fibers. These parameter dynamics are useful in further study of various aspects of optical solitons, including the quasi-particle theory of optical solitons, collision induced timing jitter, the four-wave mixing and various other features. These perturbation terms and its corresponding adiabatic dynamics also can be used to study the aspects of ghost pulses and the effects of randomness in dispersion-managed optical fibers.

The imaging method when a lossy layer (e.g., a defected metallic slab or a plasma layer) is present between the target and the sensor is demonstrated using the concept of active left-handed material (LHM). The effect of the lossy layer to the reflection coefficients measured by the receiver can be cancelled by imaginatively adding an active LHM layer, which has a same thickness as the lossy layer but an opposite sign of the constitutive parameters. Therefore, the updated reflection coefficients obtained after this data process look like the lossy layer has been removed, which leads to a significant improvement of the target imaging. When the lossy layer is inhomogeneous due to the existence of small defects, we use a homogenization procedure based on the Drude model to characterize its effective constitutive parameters. Our simulation examples shows the effectiveness of the proposed method.