The transmittance is studied for a Cantor-like multibarrier system. The calculation are made in the framework of effective mass theory. Some typical values of effective masses and potentials are used in order to have an experimental reference. The techniques of Transfer Matrix are used to calculate the transmittance of the entire structure having some dozens of layers. The results display a complex structure of peaks and valleys. The set of maxima is studied with the tool of the q-dependent dimension D(q). The set of transmittance maxima exhibits a fractal structure, or more exactly, a multifractal structure, i.e., a q-dependent dimension, characterized as usually with limit one when q parameter tends to -∞ but witha limit between 0 and 1 when tends to +∞. This numerical experiment demonstrate that spatially bounded potential may exhibit spectrum with fractal character.

Two compact CPW-fed band-pass filters using dual-mode resonator are proposed and studied - one resonator with two unequal corner-cut elements located at two diagonal corners of a conventional micro-strip patch and the other with unequal crossed slots at the center of a conventional micro-strip patch. In this paper, adjusting the length of corner-cut element and the crossed slot are mainly studied. By use of HFSS, the simulation results are given and analyzed. The simulation results show that the pass-band of the filter(a) may be adjusted over the bandwidth range from 4.9% to 16%, and the pass-band of the filter(b) may be adjusted over the bandwidth range from 5.4% to 8.2%, and filter(b) with cross-slot has smaller size than filter(a) with corner-cut to meet the same application demand. According to the simulation results, to design a filter which works at 1.65 GHz, the configuration of filter(b) is adopted owning to smaller size. finally, filter(b) with len1=20.2mm and len2=20.4mm is fabricated and measured, which has a minimum insertion loss of 2.48 dB in its pass-band.

A hybrid method is introduced for analysis of the H-plane waveguide discontinuities. It combines multimode contour integral and mode matching techniques. The process is based on dividing the circuit structure into key building blocks and finding the multimode scattering matrix of each block individually. The multimode scattering matrix of the whole structure can be found by cascading these blocks. Also contour integral method is developed for analysis of multi-media circuits. Therefore, it is possible to analyze H-plane waveguide filters with dielectric resonators using this method. The accuracy and run time of the purposed method is compared with those reported in literatures and/or Ansoft HFSS software.

Multiresolution Time Domain (MRTD) techniques based on wavelet expansions can be used for adaptive refinement of computations to economize the resources in regions of space and time where the fields or circuit parameters or their derivatives are large. Hitherto, standard wavelets filter coefficients have been used with the MRTD method but the design of such filter itself may enable to incorporate desired properties for different applications. Towards this, in this paper, a new set of stencil coefficients in terms of scaling coefficients starting from a half band filter, designed by window method and deriving a physically realizable filter by spectral factorization using cepstral technique, for the MRTD method is presented. These stencil coefficients for the MRTD are found to give good agreement with similar MRTD schemes such as those obtained using Daubechies orthogonal wavelets.

Method proposed by Maslov has been used, to remedy the problem of geometrical optics, for a two dimensional Perfect electromagnetic conductor (PEMC) Gregorian system. It generates an integral form of solution near the caustic that can be evaluated analytically/numerically, or withuniform asymptotic techniques. Away from the caustic it recovers the geometrical optics field. Numerical computations are made to calculate the field around the caustic of a Gregorian system.

In this paper, the radar target recognition is given by projected features of frequency-diversity RCS (radar cross section). The frequency diversity means signals are collected by sweeping the frequency of the incident illumination. Initially, the frequencydiversity RCS data from targets are collected and projected onto the PCA (principal components analysis) space. The elementary recognition of targets is efficiently performed on the PCA space. To achieve well separate recognition of targets, the features of the PCA space are further projected onto the LDA (linear discriminant algorithm) space. Simulation results show that accurate results of radar target recognition can be obtained by the proposed frequencydiversity scheme. In addition, the proposed frequency-diversity scheme has good ability to tolerate noise effects in radar target recognition.

This paper presents a general inequality for the grating lobes of the planar phased array, whether rectangular lattice or triangular lattice. And for the planar phased array with grating lobes, the maximum scanning angle is given.

Taking the advantage of common waveguide filters and SIW technology, a new filter structure is proposed.This structure can be implemented for various microwave frequencies by choosing appropriate low loss substrates.An example of suggested structure in Ku band is presented in this paper.The filter is designed and simulated on a low loss RT/Duroid 5880 laminate.The resulted filter has a Quality factor around 150.The main advantage of the structure is low size and cost, simplicity in fabrication, and the ability of integration with other elements of the circuit.

The translational addition theorems for the spherical scalar and vector wave functions are derived in a novel, unified way based on the simple and well-known concepts of the radiation and incoming wave patterns. This approach makes the derivation simpler and more transparent compared to the previous approaches. As a result, we also obtain alternative and partly simpler expressions for the translation coefficients in the vector case.

In this paper, the angular side-play amount created by radiation pressure acting on active space object has been detailed investigated based on the physical optics, and the results are compared with the results by Mie theory; the correctness of the physical optics model is validated. The curves of angular side-play amount varied with the energy density of incident wave, mass of the object, and the angular between the direction of incident wave and initial velocity of the space etc. Using the results having been calculated, we analyzed the detectable conditions of angular side-play amount. A new method, which identifies different active object in space, has been taken out.

This article discusses the-state-of-the-art of the vaneloaded gyrotron traveling wave tube (gyro-TWT) amplifier, which is device of increasing importance for high resolution radar and high information density communication systems because of its high-power and broad bandwidth capabilities. Vane loading is identified as a means to achieve a low-beam energy, high-harmonic, low-magnetic field, mode-selective and stable operation of a gyro-TWT. Thus, the development of a simple approach to the analysis of the interaction structure of vane-loaded gyro-TWT has been identified as a problem of practical relevance.

In this paper a method of moment based analysis of an H-plane 1:3p ower divider has been presented using Multi Cavity Modeling Technique (MCMT) in transmitting mode. Finally attempt has been made to improve the frequency response characteristic of the above mentioned waveguide circuit using a sorting post to diversify the power equally in all the ports. Codes have been written for analyzing the frequency response characteristic of the structure, mentioned above. Numerical data have been compared with the data obtained with laboratory measurement, and CST Microwave Studio simulation. In the present analysis global basis function has been used. The existence of cross polarization components of the field inside the waveguide structures if exists, have also been considered to obtain an accurate result. The proposed power divider has good agreement with the theoretical; CST microwave studio simulated data and measured data. The power divider can be used in the input at 9.8 GHz frequency band, over 800 MHz.

In this paper, design and analysis of a novel broadband V-shaped monopole antenna is presented. The proposed antenna has a simple configuration to fabricate with low cost. The antenna is composed of two elliptical conducting plates connected to the two edges of a small horizontal rectangular plate and placed over a small circular ground plane. The designed antenna has a very wide bandwidth range of 3-18 GHz, low cross polarization, relatively high gain and good far-field radiation characteristics in the entire operating bandwidth. To obtain the broad bandwidth, the antenna dimensions have been optimized. A comprehensive parametric study has been carried out to understand the effects of various parameters and to optimize the performance of the final design. The designed antenna is simulated with software packages CST microwave studio and Ansoft' HFSS in the operating frequency range. Simulation results for VSWR and far-field radiation patterns of the antenna over the frequency band 3-18 GHz are presented and discussed.

A prototype of dual polarized ultra wideband antenna-feed was fabricated (200 MHz-2000 MHz) for usage in low frequency radio astronomy at the GMRT (Giant Meterwave Radio Telescope). The feed was mounted on one of the GMRT dish antennas and tested using signals from the radio galaxy Cygnus A and zenith sky. Modeling of the GMRT dish with the antenna-feed mounted at its focus has been done. With the use of simulated radiation patterns of the antennafeed and the measured results, the system independent deflections at various frequencies were computed. The performances of the GMRT dish with present mesh and RMS (root mean square) efficiencies have been studied. Performance of the GMRT dish with 100% mesh and RMS efficiencies were computed. Future guidelines of ultra wideband antenna-feed design for GMRT have been indicated. Improvements of the GMRT dishes have also been suggested.

A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on the same ground plane and with defected ground structure between them has been investigated. The microstrip patch array with defected ground structure has the advantage of a low mutual coupling compared with the classic one. The Finite-Difference Time-Domain (FDTD) is used to simulate the sensor for landmines detection.

Conventional interferometric inverse synthetic aperture radar three dimensional imaging only consider broadside imaging condition. In this paper, squint model imaging configuration is discussed and the coordinate transform equation is given. The ISAR range profile envelope alignment problem among different antennas are also discussed. Simulation results show the effectiveness of our proposed method.

In this paper, the vector parabolic equation method (VPEM) is used to investigate the Shannon capacity of multiple-input multiple-output (MIMO) communication systems in indoor corridors. This deterministic three-dimensional (3-D) full-wave method is capable to demonstrate the effects of antennas and propagation environment on the channel capacity. The VPEM can model any field depolarization effects which are caused by the corridor walls. This method is particularly useful for evaluation of MIMO channel capacity in corridors with local narrowing of cross section. The channel capacity is computed for both single and hybrid polarizations and simulation results are compared with those obtained by the ray tracing method.

In this paper, a virtual cathode oscillator (VCO) is simulated based on FDTD algorithm. The geometrical structure is coaxial. Electromagnetic fields and current graphs are calculated. For the first time it has been shown that the delay between input pulse and output microwave signal originate from the waveguide transition delay time and the virtual cathode generation loop delay time.

Data recording on biological tissues and prostheses with femtosecond laser processing for personal identification is demonstrated. The target materials are human fingernails (fingernail memory) and dental prostheses (dental memory). Because they have unexpected movements and individual three-dimensional shapes, the processing system is required an adaptive focusing and highthroughput recording capability. The adaptive focusing is performed with a target surface detection. The high throughput is realized by parallel laser processing based on a computer-generated hologram displayed on a spatial light modulator. Two-dimensional and threedimensional parallel laser processing of glass is demonstrated.

In this paper a moment method simulation of electromagnetic scattering problem is presented. An effective numerical method for solving this problem based on the method of moments and using block-pulse basis functions is proposed. Some examples of engineering interest are included to illustrate the procedure. The scattering problem is treated in detail, and illustrative computations are given for some cases. This method can be generalized to apply to objects of arbitrary geometry and arbitrary material.