High frequency field expressions are derived at the focal points of a paraboloidal reflector placed in a homogenous and reciprocal chiral medium. Firstly Geometrical Optics (GO) field expressions are derived for the paraboloidal reflector placed in chiral medium. As the GO fails at the focal points, so Maslov's method has been used to find the field expressions which are also valid around the focal point. By using hybrid space, Maslov's method combine the simplicity of ray theory and the generality of Fourier Transform method. Some numerical results including contour plots and line plots around the focal region of paraboloidal reflector placed in chiral medium are obtained using the derived expressions.

This paper presents a generalized approach to design an electromagnetically coupled microstrip ring antenna for dual-band operation. By widening two opposite sides of a square ring antenna, its fractional bandwidth at the primary resonance mode can be increased significantly so that it may be used for practical applications. By attaching a stub to the inner edge of the side opposite to the feed arm, some of the losses in electrical length caused by widening can be regained. More importantly, this addition also alters the current distribution on the antenna and directs radiations at the second resonant frequency towards boresight. It has also been observed that for the dual frequency configurations studied, the ratio of the resonant frequencies (f_r2/f_rr) can range between 1.55 and 2.01. This shows flexibility in designing dual frequency antennas with a desired pair of resonant frequencies.

An innovative preconditioner has been developed in this work. It significantly improves the convergence of the iterative solvers applied to electromagnetic radiation problems by a renormalization of the matrix equation. The preconditioner balances the disparities in terms of magnitude and units caused by the strong self-coupling of the antennas, the non-uniformity of the meshes and also by the coexistence of wire and surface basis functions. It can be easily integrated into different electromagnetic solvers with a negligible impact on the computational cost on account of its simple implementation.

In this paper, a complementary meander line split-ring resonator (C-MLSRR) model is proposed and its equivalent circuit model is given. Prototypes of microstrip lines loaded with C-MLSRR with and without series capacitive gaps are designed, which exhibit a negative permittivity behavior (without series capacitive gaps) and a left-handed behavior (with series capacitive gaps), respectively, at two different frequencies. The application of the C-MLSRRs in compact dual band (i.e., 2.52 GHz and 5.35 GHz) notch filter for wideband application is presented to highlight the unique features of the C-MLSRRs.

A repeaterless hybrid CATV/16-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) transport system employing half-split-band and remote light injection techniques is proposed and demonstrated. Over an 80-km SMF transmission without optical amplification, good performances of carrier-to-noise ratio (CNR), composite second order (CSO), and composite triple beat (CTB) were obtained for CATV band; simultaneous high CNR and low bit error rate (BER) values were achieved for 16-QAM OFDM band. This architecture presents a feasible way to transmit both analog and digital video signals.

The improved high-frequency method for solving the bistatic scattering from electrically large conductive targets is presented in this paper. Since the previous physical optical methods overlooked the current impact of shadow zone and led to the increasing problems of the large angle bistatic calculation, the improved method is deduced by introducing the current marching technique into the conventional physical optical method. Combined with the graphical-electromagnetic computing method that extracted the illuminated and shadow facet in accordance with the direction of the incident sort iteration, one may calculate the bistatic radar cross-section of a conductive targets object. The numerical results show that this method is efficient and accurate.

Phase modulation is critical due to its applicability in varied RF devices such as phased array antennas, radars to name a few. In this paper, we report experimental data on phase modulation in the X-band frequency using tunable metamaterials such as a planar design of stacked dual split ring resonators (DSRRs) of 3mm thickness at 8.5 GHz. Modulation was brought about by switching between the open and closed states of the rings causing a net change in the effective refractive index and thereby producing a phase variation. One and two dimensional free-space scanning experiments were carried out where a phase modulation of 62 degrees was demonstrated. The measured data matched well with the numerically simulated results.

The non reciprocal effect of such devices as microstrip and coplanar isolators can be based on the field displacement phenomenon induced by a magnetized ferrite material. The structure under study is made from a ferrite thin-film deposited on a alumina substrate. A non symmetrical coplanar line is put on the ferrite film and the absorber is made from either a graphite film or a Tantalum Nitride film or a copper slab. In order to work in millimeter wave range the barium ferrite was selected. Moreover, the size of the component could be less than the circulator one. The small size and simple shape are the principal advantages of a coplanar isolator structure.

A 6:1 unequal Wilkinson power divider that combines the advantages of a coplanar waveguide with an electromagnetic bandgap (EBG CPW) and microstrip line structures suitable for a PCB circuit design is proposed. The highly characteristic impedance transmission line (TL) is realized by employing the proposed EBG CPW structure, which is difficultly achieved using the conventional microstrip line or CPW due to printed circuit board (PCB) process limitations. The proposed EBG structure enables the CPW line to have a very high characteristic impedance of over 207 Ω. The fabricated 6:1 power divider delivers excellent matching and isolation performances with more than 34 dB at 1.5 GHz. It also has exact dividing ratios of 8.46 dB and 0.7 dB at two output ports, respectively.

Brillouin fiber laser (BFL) is demonstrated using a piece of photonic crystal fiber (PCF) in conjunction with a Bismuth-based erbium-doped fiber (Bi-EDF) as the gain media with a simple ring resonator. The proposed BFL operates at wavelength of 1574.08 nm, which is 0.08 nm shifted from the Brillouin pump wavelength with a maximum peak power of 8 dBm. The BFL has a side mode suppression ratio and 3 dB bandwidth of approximately 23 dB and 0.02 nm respectively limited by the optical spectrum analyzer resolution. The BFL is also stable at room temperature and compact due to the use of only 20 m long of PCF and 215 cm long of Bi-EDF.

In a dual-plane compact electromagnetic band-gap (CEBG) microstrip structure, patches are etched periodically in the ground plane to prohibit the propagation of electromagnetic waves in certain frequency bands so as to provide filtering functionality. However, the existence of the etched patches in the ground plane becomes a natural concern for the reason that these structures might be more prone to electromagnetic interference from nearby radiating components as compare to a microstrip filter with a perfect ground plane. In this paper, an investigation into the electromagnetic susceptibility of a C-EBG filter structure is presented. This study examines the effects of the the interference source on the performance of a C-EBG structure in terms of the relative frequency, power level, position, and polarization. From the study, useful guidelines are drawn for the applications of EBG microstrip structures in an environment rich in electromagnetic interference.

This paper presents an efficient and simple approach of implementing the Landau-Lifshitz-Gilbert (LLG) equation of magnetisation motion within the Finite-Difference Time-Domain (FDTD) method. This combined electromagneticmicromagnetic simulation technique is particularly important for modeling electromagnetic interaction with lossy magnetic material in the presence of current and magnetic sources, particularly at very high frequencies. The efficient implementation involves simple two-point spatial interpolations that are applicable to two and three-dimensional FDTD grids, and uses a stable iterative algorithm for the time integration of the LLG equation. A ferromagnetic resonance numerical experiment on a rectangular Permalloy prism excited through its cross-section by a non-uniform pulse field from a transmission line was carried out for the purpose of verifying the combined FDTD-LLG computations. The numerical results were in good agreement with linearised analytical solutions of the LLG equation for uniform and non-uniform precession modes. This paper also presents a brief investigation on the use of non-staggered FDTD grid schemes to model magnetic material using the LLG equation, and indicates that the classical FDTD staggered scheme offers simplicity in implementation and more accuracy for modeling wave interaction with lossy magnetic material than the non-staggered schemes based on Maxwell's equations formulation.

The unified theory of near-field-far-field transformation techniques with spiral scannings for quasi-spherical antennas is extended in this paper to the case of nonspherical ones, i.e., antennas with two dimensions very different from the third one. To this end, such a kind of antennas is no longer considered as enclosed in a sphere, but in a proper convex domain bounded by a rotational surface. The extension, heuristically derived by paralleling the rigorous procedure valid when adopting the spherical source modelling, allows the overcoming of its main and serious drawbacks. In fact, the corresponding near-field-far-field transformations with spiral scannings for nonspherical antennas make use of a reduced number of near-field measurements and, above all, allow one to consider measurement surfaces at a distance smaller than one half the antenna maximum size, thus remarkably reducing the error related to the truncation of the scanning zone. These are very important features, which make the spiral scannings more and more appealing from the practical viewpoint. Some examples of the application of this theory to spirals wrapping the conventional scanning surfaces employed in the near-field-far-field transformations are reported for various source modellings, and the accuracy and robustness of the far-field reconstructions are assessed.

A perfect electric conductor placed in chiral nihility medium and excited by a uniform plane wave has been considered as an original problem. Using fractional operators, solutions to Maxwell equations which may be regarded as intermediate step between the original solution and dual to the original solution are determined. Each fractional operator is composed of fractional curl operator. As more than one dual to original solution exists, so in each case, corresponding impedance of the fractional dual reflector has been determined.

The conventional perfectly matched layer (PML) absorbing boundary condition is shown to be unstable when it is extended to truncate the boundary of the double negative (DNG) medium. It is a consequence of the reverse directions of the Poynting and phase-velocity vectors of plane waves propagating in such material. In this paper, a modified uniaxial PML (UPML), which is stable for the DNG medium, is derived. The auxiliary differential equation technique is introduced to derive the discrete field-update equations of DNG-UPML. Numerical results demonstrate the effectiveness and stability of the new UPML for the DNG medium.

A new subspace method based on spatial-temporal structure is presented for estimation of directions-of-arrival (DOA's) and ranges of multiple near-field sources impinging on an array of sensors. The arrival angle and range parameters are directly given by the eigenvalues of a set of constructed matrices and the computational complexity of the proposed method is lower than those of several available methods which do not require search operation. Simulation results show that the proposed method outperforms an ESPRIT-like method.

This paper presents an approach of a shaped reflector antenna synthesis using a steepest decent method (SDM). It first discretizes the reflector surface into small patches and then uses grid nodes as variables in the synthesis procedure. Even though the number of variables can be very large for a large reflector antenna, the advantage of providing closed-form solutions for the derivatives of a cost function potentially makes this approach very efficient. The large number of variables also assists this procedure to reach a more global optimum as usually met in ordinary SDM. Numerical examples are presented to validate this approach.

The aim of this paper is to present a method to carry out the synthesis of large phased arrays when they are affected by complex environments which can influence the radiation pattern. The synthesis is performed with the help of the Multilevel Characteristic Basis Function Method to calculate a matrix relating input voltages and the far field pattern samples. The method is illustrated with the synthesis of a Secondary Surveillance Radar antenna on a turret containing multiple obstacles.

This paper proposes a methodology for numerically synthesizing element values of coupled resonator filters. These element values are compatible in retrieving coupling matrix of a cross-coupled quadruplet structure (also known as the folded structure). Differed from direct synthesis by matrix rotation, numerical solution has been adopted here to its equivalent coupling model. For varied specified return loss, numerical solutions of these element values have been derived and their accuracy is verified with their analytical counterparts to be extended for stringent design requirement. In addition, multiple sets of data are tabulated and categorized for efficient filter synthesis design under different specified pass-band return loss. In the end, an example quadruplet filter is designed, fabricated and measured for validation of the presented synthesis design methodology.

The properties of composite electromagnetic scattering from a square conducting plate target above a one-dimensional sea surface are discussed with the diffraction of plate edge taken into account. The characteristics of electromagnetic scattering from the sea surface are investigated based on the Kirchhoff Approximation (KA). The backscattering field of a plate target is calculated with the method of higher equivalent edge currents. Besides, the method of equivalent edge currents (MEC), Physical Optics (PO) approximation and the reciprocity theorem method are combined to calculate the composite scattering field from the conducting plate target above a sea surface. The effect of the plate size, inclination, edge diffraction and the frequency of incident wave on the composite scattering field is analyzed.