Understanding the propagation of light in continuous inhomogeneous materials is important to design optical structures and devices. To have accurately numerical calculations Berreman's 4×4 propagation matrix method is generally used, and layer approximation, i.e., the whole one-dimensional continuous inhomogeneous material is divided into many small homogeneous layers, is assumed. However, this layer approximation is only correct up to the second-order of the layer thickness. To efficiently solve Berreman's first-order differential equation, a simple fourth-order symplectic integrator is presented. The efficiency of the fourth-order symplectic integrator was studied for a cholesteric liquid crystal. Numerical results of reflectance spectra show that the fourth-order symplectic integrator is highly efficient in contrast to the extensively used fast 4×4 propagation matrix.

In this paper, a compact and simple microstrip-fed slot antenna is proposed for ultra-wideband (UWB) applications, which consists of a circular patch and an open T-slot to realize the microstrip-line to slot transition well over a widened frequency range. The simulations and measurements show that this simple structure with the novel design generates a broadband impedance bandwidth of 10dB return loss from 2.5 to 12.5 GHz (BW=133.3%) adjustable by variation of its parameters. Details of the antenna design and experimental results of the constructed prototype are presented. In addition, a geometric parameters study of the proposed antenna is able to provide more useful information for antenna design.

A uniform asymptotic solution is presented for evaluating the field diffracted by the edge of a lossy double-negative metamaterial layer illuminated by a plane wave at skew incidence. It is given in terms of the Geometrical Optics response of the structure and the transition function of the Uniform Geometrical Theory of Diffraction, and results easy to handle. Its accuracy is well-assessed by numerical tests and comparisons with a commercial solver based on the Finite Element Method.

In this work, the introduction of Defected Microstrip Structures and Defected Ground Structures is presented to improve the performance of a traditional stepped-impedance microstrip lowpass filter. The attenuation in the stop-band is enhanced by more than 15 dB and selectivity is increased, without modifying the insertion loss in the pass band. A comparison of characteristics in filters is made when the combination of Defected Ground and Defected Microstrip Structures, as well as when only the first one are used. A model of the Defected Microstrip Structure and the corresponding equations to obtain the equivalent lumped and distributed element values are also given.

The modified finite-difference time-domain (M-FDTD) method is proposed to analysis electromagnetic bandgap of 1D layered anisotropic plasma photonic crystal(PPC) under the situa-tion of the EM wave oblique incidence. The presence of it avoids the usage of two-dimensional FDTD iterative and greatly improving the computational efficiency. By the algorithm, the reflec-tion coefficients of electromagnetic waves with different incidence angles are computed, and compare the results with the analytical solution. The results show that the method of the accuracy and effectiveness. Finally, the algorithm is applied to calculate electromagnetic bandgap charater-istics of PPC with the different incident angles, and their reflection coefficients under the condi-tion of the different incident angles are analyzed.

Confocal Microwave Imaging (CMI) for the early detection of breast cancer is based on several assumptions regarding the dielectric properties of normal and malignant breast tissue. One of these assumptions is that the breast is primarily dielectrically homogeneous, and that the propagation, attenuation and phase characteristics of normal breast tissue allows for the constructive addition of the UWB returns from dielectric scatterers within the breast. However, recent studies by Lazebnik et al. have highlighted a very signicant dielectric contrast between normal adipose and broglandular tissue within the breast. This dielectric heterogeneity presents a considerably more challenging imaging scenario, where constructive addition of the UWB returns, and therefore tumor detection, is much more dicult. In a dielectrically homogeneous breast, each additional beamformed backscattered signal adds coherently with existing signals, resulting in an improved image of any dielectric scatterers present. However, in a dielectrically heterogeneous breast, signals with a longer propagation distance are more likely to encounter heterogeneity and therefore are more prone to incoherent addition, reducing the overall quality of the breast image. In this paper, a novel beamforming algorithm is described, which gives extra weighting to signals with shorter propagation distances to create an improved image of the breast. The beamformer is shown to provide improved images of more dielectrically heterogeneous breasts than the traditional delay and sum beamformer from which it is derived.

The novel characteristics of wave transmission and reflection in one-dimensional semi-infinite chiral photonics have been investigated theoretically. Waves in each region have been formulated for both normal and oblique incidences. At a given incident angle, the transmission or reflection is found to be easily adjusted to be equal to 1 for the chiral photonics using chiral nihility media. The wave tunneling and rejection properties in chiral nihility photonics, as well as their parametric dependences on periodicity, chiral nihility and incident angles, have been explicitly presented theoretically and verified numerically.

A novel fractal antenna-array type is proposed. The design is based on the Sierpinski rectangular carpet concept. However, the generator is a circular ring area, filled with radiating elements, so the higher stages of the fractal development produce large arrays of circular rings which, besides the high directivity, have the advantage of the almost uniform azimuthal radiation pattern, attribute that many applications require. The introduced arrays can operate as direct radiating multi-beam phased arrays and meet the requirements of satellite communications links: high End of Coverage (EOC) directivity, low Side Lobe Level (SLL) and high Career to Interference ratio (C/I). These operational indices were further optimized by a synthesized multi-objective and multi-dimensional Genetic Algorithm (GA) which, additionally, gave arrays no more than 120 elements.

In this paper, an analytical method to characterize the frequency behaviour of Composite Right/Left Handed (CRLH) loaded printed dipole antenna is presented. One needs to determine the parameters of ungrounded reactive components realizing CRLH structures. Efficient resonant RLC circuit models based on Partial Elements Theory are presented to calculate inductance of meander line inductor and inter digital capacitor, while their capacitance is determined by Conformal Mapping Method. By using these circuit models and dispersion relation of balanced CRLH TL, negative resonance modes of antenna can be obtained. In addition, to validate the accuracy of the proposed analytical method, a prototype of the CRLH loaded printed dipole antenna is simulated, fabricated and measured.

In homeland security and law enforcement situations, it is often required to remotely detect human targets obscured by walls and barriers. In particular, we are specifically interested in scenarios that involve a human whose torso is stationary. We propose a technique to detect and characterize activity associated with a stationary human in through-the-wall scenarios using a Doppler radar system. The presence of stationary humans is identified by detecting Doppler signatures resulting from breathing, and movement of the human arm and wrist. The irregular, transient, non-uniform, and non-stationary nature of human activity presents a number of challenges in extracting and classifying Doppler signatures from the signal. These are addressed using bio-mechanical human arm movement models and the empirical mode decomposition (EMD) algorithm for Doppler feature extraction. Experimental results demonstrate the effectiveness of our approach to extract Doppler signatures corresponding to human activity through walls using a 750-MHz Doppler radar system.

We introduce a new slot resonator in the ground plane of a microstrip that is loaded with a parallel plate capacitor. The loaded slot has a 73% reduced length. Its unloaded Q-factor is 98 which is 91% higher than that of an ordinary slot. It is suitable to reject the narrow band unwanted signal. The proposed high Q-factor compact slot resonator also suppresses the undesired spurious high frequency response of the unloaded slot resonator. The structure is further used to determine the unknown dielectric constant of a sheet material with 0.04 variation in ε_r.

The Complete Complementary Sequence (CC-S) consists of several complementary orthogonal sequences and has optimal sidelobe level performance, which is satisfied with the requirement of the orthogonal Multiple Input Multiple Output (MIMO) radar signals. Aimed at the difficulty of high sidelobe level in Synthetic Aperture Radar (SAR) imaging processing in range dimension, an approach of depressing sidelobe level based on CC-S in MIMO SAR system was proposed. The transmitter model for orthogonal MIMO SAR system using CC-S and the corresponding matched filter (MF) were established in this paper. In addition, the MIMO SAR imaging results were simulated. The simulation results demonstrate that the performance of CC-S employed in orthogonal MIMO radar system is much better than that with traditional Linear Frequency Modulation (LFM) signal, by which the feasibility and validity of CC-S applied in orthogonal MIMO SAR system are justified.

Here we report a prism made of stacked quasi-selfcomplementary extraordinary transmission surfaces which allows simultaneously left- and right-handed propagation within the V-band for vertical and horizontal polarizations, respectively and righthanded propagation within the W-band for both polarizations. The numerical dispersion diagram of the infinite structure and effective indexes of refraction retrieved from S-parameters under normal incidence together with the finite integration time domain simulations predict single negative and double positive birefringence. The unusual type of birefringence single negative and regular double positive birefringence are afterwards demonstrated experimentally at the millimeter-waves (V- and W-bands) by the wedge experiment which lets us check, using a straightforward geometrical method, the refraction of each component. The effective index of refraction is retrieved via the Snell's law and compared to those obtained through the dispersion diagram and the retrieval method from S-parameters computed with the commercial software CST Microwave StudioTM^TM.

This paper describes in detail different formulations of the inverse-source problem, whereby equivalent sources and/or fields are to be computed on an arbitrary 3-D closed surface from the knowledge of complex vector electric field data at a specified (exterior) surface. The starting point is the analysis of the formulation in terms of the Equivalence Principle, of the possible choices for the internal fields, and of their practical impact. Love's (zero interior field) equivalence is the only equivalence form that yields currents directly related to the fields on the reconstruction surface; its enforcement results in a pair of coupled integral equations. Formulations resulting in a single integral equation are also analyzed. The first is the single-equation, two-current formulation which is most common in current literature, in which no interior field condition is enforced. The single-current (electric or magnetic) formulation deriving from continuity enforcement of one field is also introduced and analyzed. Single-equation formulations result in a simpler implementation and a lower computational load than the dual-equation formulation, but numerical tests with synthetic data support the benefits of the latter. The spectrum of the involved (discretized) operators clearly shows a relation with the theoretical Degrees of Freedom (DoF) of the measured field for the dual-equation formulation that guarantees extraction of these DoF; this is absent in the single-equation formulation. Examples confirm that single-equation formulations do not yield Love's currents, as observed both with comparison with reference data and via energetic considerations. The presentation is concluded with a test on measured data which shows the stability and usefulness of the dual-equation formulation in a situation of practical relevance.

A new antenna structure is formed by combining the concept of reconfigurable planar antenna array (RPAA) with the parasitic elements to produce beam steering patterns. The antenna has been integrated with the PIN diode switches that enable the beam to be steered in the desired direction. This has been done by changing the switch state to either on or off mode. In this work, a number of parasitic elements have been applied to the antenna, namely reflectors and directors. They are placed in between the driven elements, which is aimed to improve the beam steering angle. With such configuration, the main beam radiated by the array can be tilted due to the effect of mutual coupling between the driven elements and parasitic elements (reflectors and director). The unique property of this antenna design is that instead of fabricating all together in the same plane, the antenna's feeding network is separated from the antenna radiating elements (the patches) by an air gap distance. This allows reducing the spurious effects from the feeding line. The optimization results for the resonant frequencies of the antennas with variable air gap heights are also been studied. The antenna is made for 5.8 GHz. Good agreement is achieved between the simulation and measurement.

A new design approach based on wave analysis has been implemented in order to derive voltage gain, center frequency and bandwidth of millimeter wave amplifier using parameters of transmission lines (TL). The derived formula allows one to design high frequency amplifier with predetermined bandwidth and centner frequency. It has been shown that in the case of lossy TL or at high frequency, circuit theory cannot predict the amplifier gain behavior while presented wave theory can accurately predict the frequency response of the amplifier in both low and high frequency ranges.

A hybrid mode-matching/compact 2-D finite-difference frequency-domain (MM/compact 2-D FDFD) method is proposed for the analysis of rectangular ridged waveguide discontinuities. In order to apply MM technique, mode spectrum of the ridged waveguide is determined by an improved compact 2-D FDFD method with only two transverse field components at the cutoff frequencies which lead to two independent sets of real symmetric eigenvalue problems for TE and TM modes. Solving these two separate eigenvalue equations, cutoff wave numbers and discrete mode field functions can be obtained respectively from eigenvalues and eigenvectors. Finally, the generalized scattering matrix (GSM) of the rectangular-ridged waveguide step discontinuity can be easily calculated through the transverse field matching procedure. The method is demonstrated at the examples of two waveguide structures, and results are shown to be in excellent agreement with those by the commercial CAD software HFSS.

A novel broadband Van Atta array operating in a broadband with frequency offset characteristic is proposed. A single sideband mixer is introduced to achieve sideband choice without utilizing filters which make this array have excellent performance and wider applications than the conventional Van Atta array. The simulated results of the amplitude and phase of the array show that this antenna array can achieve retrodirectivity with frequency offset and good isolation in a broadband. The experimental performance of the array is observed within the frequency range from 2.8 GHz to 3.4 GHz.

An advanced aspheric and asymmetric large aperture dielectric lens antenna is proposed firstly here for high resolution at W-band frequency. Large aperture and aspheric lens provides minimum focusing error and high resolution in millimeter wave quasi-optics application. To the best of the authors' knowledge we design first time 500 mm large aperture lens for W-band quasi optics application. Near field radiation pattern, beam size and focal length of the lens are obtained theoretically and experimentally as well. Dielectric rod waveguide antenna is also designed and employed as a source antenna for the lens. The measured and simulated results of the DRW antenna also show very good performance at W-band frequency, and it has 15.3 dB gain with -22.5 dB sidelobe levels at 94 GHz.

Existence of backward electromagnetic surface waves at an interface separating a semi-infinite uniform left-handed metamaterial and a 1D photonic crystal composed of alternating layers of two kinds of single-negative (ε-negative and μ-negative) metamaterial is theoretically investigated. Dispersion characteristics of surface states are analyzed for two different cases of ENG-MNG and MNG-ENG layered periodic structures. It was demonstrated that in the presence of metamaterial, surface waves are sensitive to light polarization and there exist only backward TM-polarized (or TE-polarized) surface Tamm states depending on the ratio of the thicknesses of two periodic stacking layers.