The purpose of this paper is to present a complete design and analysis of a new integrated balanced transmitter operated at 4 GHz using microstrip technology. It comprises a 4-GHz two-port negative resistance oscillator and a microstrip-patch antenna resonated at 4 GHz. Three different modules are designed and analyzed. The first one used a Lange coupler as a power splitter while the second and third used a one (two)-section branch couplers. The components of the three modules are designed using full-scale computer simulation program named with MSDES; performed by the author; which takes fully into account all the discontinuities included in the microstrip lines, while the modules are analyzed and optimized using APLAC V7.61 software. The design methodologies of the two-port negative resistance oscillator and microstrip patch antenna are introduced and explained. The analyses of the designed modules show a better efficiency and good performance. The modules give a transmit-antenna gain of 15.7 dB with antenna beam widths 91.7^o and 18.2^o in E-and H-planes, respectively. The complete schematic diagrams of the transmitter modules are drawn. These modules can be used in satellite communication, Doppler and other radars, active and semi-active seekers, radio altimeters, missile technology, weapon fuzing, manpack equipment, remote sensing, feed elements in complex antennas, satellite navigation receivers, and biomedical radiators.

The PMCT probe, saying, one kind of open-ended coaxial probe adopted widely in microwave coagulation therapy of cancer, has been used to measure the complex permittivity of freshly excised specimens of normal animal tissues. The RFM model for PMCT probe is developed to extract the anticipant permittivity of specimens under test. In addition, the effects of several factors on the measurement results have been considered and discussed, including different temperature and reference materials, as well as the sampling frequency range and intervals of the rational function model. All the experiments have been conducted at the microwave frequency range from 450 MHz to 14.5 GHz.

A generalized GPS (GGPS) algorithm is proposed for the problem of reducing the bandwidth and profile of the stiffness matrix in finite element problems. The algorithm has two key-points. Firstly and most importantly, more pseudo-peripheral nodes are found, used as the origins for generating more level structures, rather than only two level structures in the GPS (Gibbs-Poole-Stockmeyer) algorithm. A new level structure is constructed with all the level structures rooted at the pseudo-peripheral nodes, leading to a smaller level width than the level width of any level structure's in general. Secondly, renumbering by degree is changed to be sum of the adjacent nodes codes to make a better renumbering in each level. Simulation results show that the GGPS algorithm can reduce the bandwidth by about 37.63% and 8.91% and the profiles by 0.17% and 2.29% in average for solid models and plane models, respectively, compared with the outcomes of GPS algorithm. The execution time is close to the GPS algorithm. Empirical results show that the GGPS is superior to the GPS in reducing bandwidth and profile.

This paper presents a novel method to enhance the pattern characteristics of the TEM horn antenna for 2-14 GHz frequency band. The conventional TEM horn antenna introduces some fluctuations in the main lobe radiation pattern over the higher frequencies, i.e., 10-14 GHz. This motivated us to propose a new method to remove the aforementioned impact by carving an arc shape to the open end of exponentially tapered plates. The associated curvature of this arc is optimized to completely remove the aforementioned fluctuation. The measurement results show that the improved TEM horn antenna structure exhibits low VSWR as well as good radiation pattern over 2-14 GHz frequency band.

This paper studies the loss effect of the line and the validity of a SPICE model for lossless transmission lines excited by an incident plane wave by using a simple structure --- a single line over an infinite perfectly conducting ground excited by an incident electromagnetic field. The frequency domain current responses calculated by the Baum-Liu-Tesche (BLT) equation with the loss ignored are compared with those through the BLT equation with loss considered to study the loss effect of transmission lines. The loss effect study shows that the SPICE model for lossless transmission line can be used for electromagnetic pulse interaction with electronic systems when the frequency is not very high or the systems are not very large. But for a sine wave of which the frequency equals the pole frequency of the line, the SPICE model may lead to significant error.

We review the research progress in reversed Cherenkov radiation in double- negative metamaterials (DNMs) starting from the first experimental verification of the DNMs reported in 2001, including theories, numerical computation and simulation and experiments. We also discuss the potential applications to particle detectors and highpower microwave or millimeter-wave devices, including the oscillators and amplifiers, and the formidable challenges needed to be resolved before the benefits of using such artificial materials can be harvested.

A heuristic particle swarm optimization (PSO) based algorithm is presented in this work and the novel hybrid approach is applied to linear array synthesis considering complex weights and directive element patterns so as to analyze its usefulness and limitations. Basically, classical PSO schemes are modified by introducing a tournament selection strategy and the downhill simplex local search method, so that the hybrid algorithms proposed combine the strengths of the PSO to initially explore the search space, the pressure exerted by the genetic selection operator to manage and speed up the search, and finally, the ability of the local optimization technique to quickly descend to the optimum solution. Four classical real-valued PSO schemes are taken as reference and synthesis results for a 60-element linear array comparing those classical schemes and the hybridized ones are reported and discussed in order to show the improvements achieved by the hybrid approaches.

A novel CPW-fed antenna having a frequency band-notched function for UWB applications is proposed and studied. By inserting a pair of inverted-T-shaped slots on the radiation element, the narrow frequency band notch has been created to cover the desired frequency varying from 3.4 to 3.69 GHz and the required UWB bandwidth is also acquainted. Good monopole-like radiation patterns and antenna gains have also been obtained.

A configuration for a miniaturized band-pass filter on a coplanar waveguide (CPW) is proposed in this communication. Parametric studies conducted for various geometrical parameters suggest that the frequency response of the filter is strongly related to that of the spiral slots. But a series gap on the center conductor of the CPW changes the overall response of the device For validation of these concepts, a bandpass filter operating at about 3.5 GHz has been designed, fabricated and tested. Experimental results show good agreement with electromagnetic simulations. The design for a microwave laminate shown here requires an area of approximately 0.1λ₀ x 0.1λ₀.

The Laser Doppler Vibrometer (LDV)-based Acoustic to Seismic (A/S) landmine detection system is one of the reliable and powerful landmine detection techniques. The interpretation of LDV-based A/S data is performed off-line, manually, depending heavily on the skills, experience, alertness and consistency of a trained operator. This takes a long time. The manually obtained results suffer from errors, particularly when dealing with large volumes of data. This paper proposes some techniques for the automatic detection of objects from the acoustic images which are obtained from the LDV-based A/S landmine detection system. These techniques are based on color image transformations, morphological image processing and the wavelet transform. The results obtained are optimized to select the best image type and the best morphological operation used in terms of the higher probability of detection, the lower false alarm rate, the accuracy and the processing speed.

Peak to Average Power Ratio (PAPR) is one of the serious problems in any wireless communication systems using multi carrier modulation technique like OFDM, which reduces the efficiency of transmit high power amplifier. In this paper, proposed scheme will be introduced that combines interleaving technique and companding technique to reduce PAPR. This scheme will be compared with the system that uses other technique for reduction which is the clipping method. By using proposed scheme, the PAPR of OFDM signal can be reduced by 6.3 dB over the original system, i.e., without PAPR reduction. Also, SNR decreases by more than 5 dB for Bit Error Rate(BER) of 10^-3 over the original system. Moreover, the proposed method gives improvement more than 4.5 dB for BER of 10^-3 over the system that uses clipping. All these systems will be evaluated in the presence of nonlinear power amplifier.

The diffraction by a semi-infinite parallel-plate waveguide with sinusoidal wall corrugation is analyzed for the E-polarized plane wave incidence using the Wiener-Hopf technique together with the perturbation method. The problem is formulated in terms of the simultaneous Wiener-Hopf equations by introducing the Fourier transform for the unknown scattered field and applying approximate boundary conditions in the transform domain. Employing the factorization and decomposition procedure together with a perturbation series expansion, the zero- and first-order solutions of the Wiener-Hopf equations are obtained. Explicit expressions of the scattered field inside and outside the waveguide are derived analytically by taking the inverse Fourier transform and applying the saddle point method. Far field scattering characteristics of the waveguide are discussed in detail via representative numerical examples.

A novel TEM horn antenna placed in a solid dielectric medium is proposed for microwave imaging of the breast. The major design requirement is that the antenna couples the microwave energy into the tissue without being immersed itself in a coupling medium. The antenna achieves this requirement by: 1) directing all radiated power through its front aperture,and 2) blocking external electromagnetic interference by a carefully designed enclosure consisting of copper sheets and power absorbing sheets. In the whole ultra-wide band the antenna features: 1) good impedance match, 2) uniform field distribution at the antenna aperture, and 3) good coupling efficiency.

In this paper, we study a class of modified incomplete Cholesky factorization preconditioners LL^T with two control parameters including dropping rules. Before computing preconditioners, the modified incomplete Cholesky factorization algorithm allows to decide the sparsity of incomplete factorization preconditioners by two fillin control parameters: (1) p, the number of the largest number p of nonzero entries in each row; (2) dropping tolerance. With RCM reordering scheme as a crucial operation for incomplete factorization preconditioners, our numerical results show that both the number of PCOCG and PCG iterations and the total computing time are reduced evidently for appropriate fill-in control parameters. Numerical tests on harmonic analysis for 2D and 3D scattering problems show the efficiency of our method.

In this paper, design of the RII triple-clad structure as a dispersion flattened optical fiber including small pulse broadening factor as well as small dispersion and its slope applicable in broadband and fast communication is considered. The proposed optimization technique is based on the Genetic Algorithms (GA) consisting suitable fitness function for each application. The putting forward design method introduces the pulse broadening factor (?/?₀) about 1.0016 after 200 Km propagation at the zero dispersion wavelength that is so excellent compared to the structure (1.2794) reported in [2] recently. Meanwhile, the proposed structure provides high bit rate (more than 197.8 Gb/Sec at 100 km), large dispersion length (larger than 17400 km), uniform dispersion slope ([0.04,-0.08] ps/km/nm²) and broad bandwidths as well as small and uniform dispersion (smaller than 2.02 ps/km/nm) at [1.55-1.7] μm wavelength interval even for core diameter larger than 4.62 μm. Another important thing discussed in this paper is a proposal for optimization of the broadening factor on large wavelength duration, which is necessary for large bandwidth applications. The suggested technique is capable to minimize the pulse broadening factor over duration of wavelengths that is necessary for large bandwidth applications such as dense wavelength division multiplexing (DWDM) and optical time division multiplexing (OTDM). Our calculation for extracting optical properties of the proposed structure is evaluated analytically. For this purpose modal analysis of these fibers for obtaining possible wave vectors for given system parameters are done using Transfer Matrix Method (TMM) in cylindrical coordinate.

This paper presents the exact 3D calculation of the magnetic field produced by a tile permanent magnet whose polarization is both tangential and uniform. Such a calculation is useful for optimizing magnetic couplings or for calculating the magnetic field produced by alternate magnet structures. For example, our 3D expressions can be used for calculating the magnetic field produced by a Halbach structure. All our expressions are determined by using the coulombian model. This exact analytical approach has always proved its accuracy and its usefulness. As a consequence, the tile permanent magnet considered is represented by using the fictitious magnetic pole densities that are located on the faces of the magnet. In addition, no simplifying assumptions are taken into account for calculating the three magnetic field components. Moreover, it is emphasized that the magnetic field expressions are fully three-dimensional. Consequently, the expressions obtained are valid inside and outside of the tile permanent magnet, whatever its dimensions. Such an approach allows us to realize easily parametric studies.

A new design of feed for radial line slot antenna (RLSA) is presented. For better impedance match to the waveguide the effect of the various feed parameters is analyzed and their design sensitivity is studied. This paper emphasizes the advantages of using feed with a funnel below the connector entry and a conical segment over the entering probe.

A system level integration of simulation methods for high data-rate transmission circuit design applications is developed in this paper. While the elementary circuit theory was responsible for designing the circuits to meet the required performance specifications, three dimensional full-wave electromagnetic simulation technique was adopted to characterize the off-chip parasitic effects induce from the packages. The developed technique was applied for the design of optical Pick-Up Head (PUH) driver circuitry and a data transmission rate up to 640Mega bits per second (Mb/s) was achieved with standard 0.35 μm CMOS technology, showing the promising feature of applying such technique in successful design for high data-rate transmission circuits.

A novel set of boundary conditions requiring vanishing of the normal components of the D and B vectors at the boundary surface was introduced recently and labeled as the DB-boundary conditions. Basic properties of a resonator structure defined by the spherical DB boundary are studied in this paper. It is shown that the resonance modes polarized TE and TM with respect to the radial direction coincide with those of the respective PEC and PMC resonators. Modes in the DB resonator show higher degree of degeneracy than those of the PEC resonator which may find application in materials research.

In this work, we propose to use a type of periodic structures, the soft surfaces in their planar version, to reduce the back radiation of patch antennas. A key aspect of these surfaces when compared to other periodic structures is their anisotropy which provides different behaviour for different field polarization (horizontal or vertical). This make them especially convenient for this application, as the soft surfaces force the field intensity for any polarization to be zero on the surface for waves propagating along the surface. In this paper, a design example is presented and the back radiation reduction by using planar soft surfaces is demonstrated.