ECIT

In this paper, a scalable dispersion management approach for microstructured fibers (MSFs) is proposed and applied to the design of zero-dispersion fibers and ultrawideband dispersion-flattened fibers. The proposed method can predict the dispersion of MSFs accurately by taking secondary dispersion into account, this being the interactive contribution from both the material and the geometrical effects. The secondary dispersion is modeled as a function of the propagation index difference and wavelength, and the model can be exploited to predict the secondary dispersion of scaled structures. This method of predicting dispersion is then combined with the scalable property of the geometrical dispersion to form a scalable dispersion-tailoring approach. This new design approach is applied to the design of zero-dispersion MSFs working at 1.55 m and 1.3 m, respectively. It is then shown that the method can be used for the design of ultrawideband zero-dispersion fibers. A MSF with predicted dispersion as low as 0.2 ps/(kmnm) over the range 1.3-1.6 m is described.

In this paper, a scalable dispersion management approach for microstructured fibers (MSFs) is proposed and applied to the design of zero-dispersion fibers and ultrawideband dispersion-flattened fibers. The proposed method can predict the dispersion of MSFs accurately by taking secondary dispersion into account, this being the interactive contribution from both the material and the geometrical effects. The secondary dispersion is modeled as a function of the propagation index difference and wavelength, and the model can be exploited to predict the secondary dispersion of scaled structures. This method of predicting dispersion is then combined with the scalable property of the geometrical dispersion to form a scalable dispersion-tailoring approach. This new design approach is applied to the design of zero-dispersion MSFs working at 1.55 m and 1.3 m, respectively. It is then shown that the method can be used for the design of ultrawideband zero-dispersion fibers. A MSF with predicted dispersion as low as 0.2 ps/(kmnm) over the range 1.3-1.6 m is described.

In this paper, a confinement loss diagram (CLD) is proposed as a novel design tool for Bragg fibers. The CLD is a 2-D pseudocolor diagram, which presents the loss properties of a Bragg fiber in a coordinate of normalized frequency and the effective refractive index (ωr, neff), to quantitatively characterize the Bragg cladding without the parameters of the core. The CLD is derived from a ray reflection model, which describes the propagation in Bragg fibers as reflection and ray trajectory. Confinement loss is first determined from the reflection process and then developed into a 2-D CLD. In this paper, the confinement loss calculation with the ray reflection model is first shown to be accurate for Bragg fibers with a core radius as small as 0.8 wavelength, both in the TE modes and the TM modes. Then, the CLD is exploited to characterize the level core Bragg fiber and the depressed core Bragg fiber. It is found that the level core fiber is suitable for wide band designs, while the depressed core fiber is good for narrow band designs. Lastly, the CLD is applied to characterize the loss properties of different order bandgaps, so that the propagation region can be located for optimum Bragg fiber design.

Fast algorithms for electrically large objects buried in layered media are mainly hindered by two time-consuming processes. One is the table filling of Green's function, and the other is the solving of the impedance matrix equation. For the first, to accelerate the evaluation of the time-consuming Sommerfeld integral in the dyadic Green's function (DGF), the discrete complex image method (DCIM) is introduced to get a closed-form DGF. To further accelerate the calculation of DGF for the volume electric field integral equation (EFIE), DGF is split before applying DCIM. For the second, the iterative solver stabilized biconjugate gradient fast Fourier transform (BCGS-FFT) is combined with DCIM for solving the matrix equations. Meanwhile, the closed-form DGF enables the "spherical-mean" Green's function, which eliminates the singularity of Green's function. Numerical results show that the weaker singularity results in a faster and steadier convergence rate for iterative solvers

This paper gives the first report of a planar phase plate structure based on frequency selective surface, FSS, technology for the generation of helical far-field radiation patterns with circular polarization properties. The unit cell of the structure comprises two orthogonal split ring resonators designed to ensure 180 degrees phase shift between orthogonal transmission coefficients. This property is exploited to obtain progressive rotational phase shift within the structure and thus synthesize 360 degrees spiral phase profile. Measured far-field radiation patterns demonstrate spiral phase front generation for 10 GHz circularly polarized waves transmitted through the structure

ABSTRACT Presented is a design methodology which permits the application of distributed coupled resonator bandpass filter principles to form wideband small-aperture evanescent-mode waveguide antenna designs. This approach permits matching of the complex antenna aperture admittance of an evanescent-mode open-ended waveguide to a real impedance generator, and thereby to a coaxial feed probe. A simulated reflection coefficient of < - 10 dB was obtained over a bandwidth of 20%, from 2.0- 2.45 GHz, in a 2.58 GHz cutoff waveguide. Dielectric-filled propagating waveguide and air-filled evanescent-mode waveguide sections are used to form the resonators/coupling elements of the antenna's coupled resonator matching sections. Simulated realised gain variation from 3.4-5.0 dBi is observed across the bandwidth. The antenna's maximum aperture dimension is < 0.47 Λ0 at the upper operating frequency and so it is suitable for use in a wide angle scanning phased array. © The Institution of Engineering and Technology 2013.

ABSTRACT A report is presented on a split ring slot frequency selective surface (FSS) reflector whose element design and distribution allows generation of far-field difference patterns. The reflector operates by converting linearly polarised plane wave fronts into two orthogonal polarisations each with a deep null in the centre of the radiation pattern. The far-field measurement presented is in good agreement with the simulation and demonstrates a null depth of -20dB in the centre of the radiation pattern. © The Institution of Engineering and Technology 2013.

This paper presents the results of experimental study of passive intermodulation (PIM) generation in microstrip lines with U-shaped and meandered strips, impedance tapers, and strips with the profiled edges. It is shown that the geometrical discontinuities in printed circuits may have a noticeable impact on distributed PIM generation even when their effect is indiscernible in the linear regime measurements. A