The synthetic aperture radar (SAR) signatures of moving target are the basis of ground moving target detection and imaging (GMTI&Im). However, previous studies are mainly based on the 2-D separable SAR processing, and little work has been done to investigate the signatures of moving target after the application of a particular fine resolution SAR image formation algorithm. In this paper, the spectrum of moving target after polar format algorithm (PFA) processing is derived. Based on this spectrum, detailed analysis on the SAR signatures of moving target, including the geometric displacement, residual range migration, and the defocusing effect in both range and azimuth dimensions are performed. Simulation results validate the theoretical analysis.

The time-to-frequency-domain conversion is often required in many applications of the finite-difference time-domain (FDTD) method. This paper presents a new FDTD time-to-frequencydomain conversion algorithm based on the optimization of nonuniform fast Fourier transform (NUFFT) with several redundancy-reduction techniques. The proposed algorithm can perform the FDTD conversion at multiple desired frequencies without the limitation of uniformly spaced frequencies in the fast Fourier transform (FFT). In addition, with a very low storage cost, the algorithm can be much more efficient than other FDTD conversion techniques if a moderate number of frequencies or more are of interest. This algorithm is very useful for some FDTD applications.

The constitutive parameters measurement of thin solid and liquid materials by transmission-reflection methods generally suffers from a) the requirement of the transformation of measured scattering parameters from the reference plane to the end surfaces of the material (measurement plane) and b) inaccurate knowledge on the length of the material, if the material does not fill the entire measurement cell (a waveguide or coaxial-line section). In this research paper, a microwave waveguide method for constitutive parameters determination of these materials is proposed to simultaneously eliminate these problems. There are three main advantages of the proposed method as: a) it explicitly determines the constitutive parameters from measured S-parameters; b) it does not require the knowledge about sample length since it directly measures it as a byproduct of the method; and c) it offers a self-checking feature to trace the performance and accurateness of measurements. This feature does not depend on the constitutive parameters of the sample. We measured the complex permittivity of some thin solid and liquid test samples for validation of the method.

Coaxial magnetic gears are a new breed of magnetic devices, which utilize the interaction of permanent magnet fields to enable torque transmission. Apart from using a numerical approach for their magnetic field analysis, an analytical approach is highly desirable since it can provide an insightful knowledge for design and optimization. In this paper, a new analytical approach is proposed to calculate the magnetic field distribution in coaxial magnetic gears. A set of partial differential equations in terms of scalar magnetic potential is used to describe the field behavior, and the solution is determined by considering the boundary constraints. The accuracy of the proposed approach is verified by comparing the field distribution results with those obtained from the finite element method.

In this paper, we propose a generalized Wilkinson power divider operating at two arbitrary frequencies with unequal power dividing ratio. To achieve unequal power division and perfect matching at dual-frequency, a novel structure consisted of four dual-frequency transformers in two sections is proposed. For the compact power divider, the parallel and series RLC structures can be chosen to obtain effective isolation between the two outports according to different frequency ratios. Furthermore, the closed-form design equations of the unequal dual-frequency power divider are derived based on circuit theory and transmission line theory. Finally, simulation and experiment results of two examples including parallel and series RLC structures indicate that all the theoretical features of these unequal power dividers can be fulfilled at dual-frequency simultaneously.

This paper presents a simple feed-forward back-propagation Neural Network (NN) model to detect and locate early breast cancer/tumor efficiently through the investigation of Electromagnetic (EM) waves. A spherical tumor of radius 0.25 cm was created and placed at arbitrary locations in a breast model using an EM simulator. Directional antennas were used to transmit and receive Ultra-Wide Band (UWB) signals in 4 to 8 GHz frequency range. Small training and validation sets were constructed to train and test the NN. The received signals were fed into the trained NN model to find the presence and location of tumor. Very optimistic results (about 100% and 94.4% presence and location detection rate of tumor respectively) have been observed for early received signal components with the NN model. Hence, the proposed model is very potential for early tumor detection to save human lives in the future.

This paper presents a new concept to implement tunable lowpass filters by employing slot resonators etched in the ground plane. The tenability is achieved with the use of switches with varactor diodes attached across the slots on the ground. The concept is demonstrated by considering 10-slots lowpass and 4-slots low pass filters. The Microstrip lines with a folded slot etched in the ground plane structure are modelled in multilayered media. To analyze this type of structure an iterative method based on the concept of waves is developed and adapted to determine features of very high frequency's electronic circuits in a planar wave guide. The analysis takes into account eventual coupling parasites. Experimental measurements are performed to validate the computation. The approach involves the mixed magnetic and electric filed equation technique and the wave concept iterative process which involves S-parameters extraction technique. In this sense, a program in FORTRAN has been elaborated to determine different parameters S_ij characterizing the studied structure.

A uniform asymptotic expression is developed for calculating the fields scattered by a perfect electrically conducting plate illuminated by a vectorial gaussian beam. This expression has been obtained under the physical optics approximation using the saddle point method. Some numerical applications are presented and compared with some reference methods such as a MoM. A brief parameter study of this solution is presented.

We evaluate effective dielectric permittivity and electric conductivity for water-saturated rocks based on a realistic model of a representative cell of the pore space which has periodical structure. We have applied the method of two-scale homogenization of the Maxwell equations, which results in up-scaling coupled equations at the microscale to equations valid at the macroscale. We have analyzed the interfacial Maxwell-Wagner dispersion effect and the Archie law as well.

The amplitude modulation (AM) and frequency modulation (FM) signal transmission of time modulated linear arrays (TMLA) is studied in this paper. The signal with a certain bandwidth received by a TMLA is time modulated by RF switches, generating many sideband signals at multiples of the time modulation frequency and each of them has the same bandwidth as the original signal. The AM and FM signals received by the TMLA were analyzed, and the requirements of the time modulation frequency for the recovery of the original signal is presented. Simulation results show that the time modulation frequency of the TMLA should be equal to or greater than the bandwidth of the original signal and a band-pass filter (BPF) has to be used to recover the original signal.

The proposed work focuses on the experimental investigation of radiation characteristics of the discarded IC chips mounted on the dielectric substrate when fed trough one of the metal leg pins. Several sets of the experimental results are obtained using Vector Network Analyzer to obtain the return loss characteristics of the proposed structure. The return loss characteristics reveal that at some frequencies the ICs certainly show radiation mechanism. Feeding the same chip at different pin locations, changes the resonant frequency. The measured radiation pattern of the IC chip shows an omni-directional characteristic. This experimental study also reveals that the ICs can be easily interfered by the surrounding radiation prevalent in any wireless environment following the reciprocity principle of an antenna.

A bandpass filter (BPF) is presented for ultra-wideband (UWB) applications with a notched band to reject the unwanted signals from the wireless local area network (WLAN) systems. The proposed UWB BPF consists of two pairs of open-loop resonators on the top layer and one coupled resonator on the bottom layer. The rejection band is introduced by adding an asymmetric open-loop resonator to two outer arms of open-loop resonators. The bandpass filter is designed to be operated within full bandwidth of 3.1 to 10.6GHz and to eliminate the WLAN signals of 5.8GHz. The suppression at 5.8GHz is larger than 15dB. The proposed configuration is proved to be both simple and compact.

A circulator is needed in a C-band airborne synthetic aperture radar system which employs single antenna configuration. The circulator provides full-duplex capability to transmit high-power RF signal and receive the echo signal via the same antenna simultaneously. Commercially available circulators with moderate isolation are inadequate for this application. An innovative Cancellation Network (CN) has been designed to enhance the performance of the conventional circulator. This paper highlights the conceptual design and measurement results of the CN. An improvement of more than 27 dB has been achieved.

The present study was carried out to evaluate the information leakage of a computer display image that can be reconstructed using the conducted emission on its power leads. The reconstructed images can be generated from the relevant signal that was conducted-emitted by the switching of RGB (Red-Green-Blue) signals in the monitor. The relevant signal was then contained in the frequency region higher than 100 MHz in the conducted emission. From these findings, a measurement system was developed to measure the relevant signal in a conducted emission to 1000 MHz. The relevant signals of three PCs were then measured taking account of the signal-to-noise ratio. The measurement results revealed that the relevant signal level depended on the PC and receiving frequency. In addition, the qualities of the reconstructed images were checked using certain receiving frequencies. The reconstructed image quality and the measured relevant signal level were then compared for the same receiving frequency, and a correlation was found.

In this paper, a metal-clad planar optical waveguide biosensor with five layer structure is studied theoretically for the detection of Pseudomonas and Pseudomonas-like bacteria. Using a very simple boundary matching technique, we derive the mode equation and other necessary formulae for the proposed biosensor and analyse its performance under different conditions related to its constituents. The numerical results presented in this paper leads to a significant optimization of the important design parameters to sense micro-scale biological objects. Also, we compare our computed results with the results given for a biosensor with four layer structure. In addition, we discuss the importance and need of the inclusion of the thickness of an affinity layer as fifth layer in the four layer structure of the metal clad planar waveguide.

We study theoretically the propagation of electromagnetic waves in an infinite and homogenous medium with both temporal and spatial dispersion included. We derive a partial differential equation connecting temporal and spatial dispersion to achieve negative group velocity. Exact solutions of the equation are found and shown to lead to the possibility of exciting constant negative group velocity waves. We then investigate the effect of spatial dispersion on the power flow and derive the first-, second-, and third-order corrections of power flow due to the nonlocality in the medium. This derivation suggests a path beyond the group velocity concept.

The design of a novel Fractal planar inverted F antenna (F-PIFA) based on the self affinity property is presented in this paper. The procedure for designing a Fractal Planar Inverted F Antenna is explained and three different iterations are designed for use in cellular phones. The F-PIFA has a total dimension of 27 mm x 27 mm and has been optimized to be operational at GSM (Global System for Mobile Communication), UMTS (Universal Mobile Telecommunication System) and HiperLAN (High Performance Radio LAN) with the frequencies range from 1900 MHz to 2100 MHz, 1885 to 2200 MHz and 4800 MHz to 5800 MHz respectively. The antenna achieved -6 dB return loss at the required GSM, UMTS and HiperLan frequencies with and has almost omnidirectional radiation pattern. This antenna has been tested using realistic mobile phone model and has met the performance criteria for a mobile phone application. Simple semiempirical formulas of the operational frequency, numerical calculation and computational SAR of the antenna also has been presented and discussed.

The characteristics of guided modes in the planar waveguides which the core or cladding consists of chiral nihility meta-materials are studied theoretically. The dispersion curves, electromagnetic fields, energy flow distribution and the power of several low-order guided modes in the chiral nihility waveguides are presented. Some novel features such as anomalous dispersion curves, the power flows opposite to the wave vector propagation direction in the chiral nihility waveguides have been found.

Microwave methods require some sort of calibration before physical (thickness, flaw, etc.) and electrical (permittivity, permeability, etc.) measurements of materials. It is always attractive to devise a method which not only eliminates this necessity but also saves time before measurements. Microwave calibration-independent measurements can be utilized for this goal. However, in the literature, these measurements are only applied for electrical measurements of materials. In this research paper, we investigate the performance of microwave calibration-independent measurements for thickness evaluation of dielectric materials to increase the potential of available microwave techniques for thickness evaluation of dielectric materials. We derive an explicit expression for thickness estimation of dielectric materials from calibration-independent measurements for the adopted calibration-independent technique. We also propose a criterion for increasing the performance of measurements. We conducted thickness measurements of six dielectric specimens with different lengths to validate the derived expressions and the proposed criterion for thickness measurements.

This paper presents a diagnosis method for articular cartilage damage using polarization-sensitive optical coherence tomography (PS-OCT). Through signal analysis, the optical characteristics of intact cartilage and different types of mild lesions within cartilages can be quantified from measures such as the scattering coefficient (μ_s), effective anisotropy factor (g_eff), and birefringence coefficient (Δn). Our preliminary investigation using porcine articular cartilage indicated that both subsurface morphological changes and apparent variations in optical properties, which may be the early signs of cartilage degeneration, were found in three types of diseased cartilages.