An efficient approach is utilized for extracting the modal parameters of high frequency structures and their sensitivities with respect to all the design parameters. Using one FDTD simulation, the modal parameters of all the guided and leaky modes are extracted over the frequency band of interest. An adapted version of the matrix pencil method is utilized for efficient extraction of the modal parameters. In addition, using no extra simulations, the sensitivities of the propagation constants with respect to all the design parameters of the structure are extracted regardless of their number. The computational time is a small fraction of the cost of similar approaches.

Electromagnetic fields in a cavity filled with double negative dispersive medium and bounded by a closed perfectly conducting surface is studied in the Time Domain. The sought electromagnetic fields are found in a closed form by using decomposition over cavity modes and solving in TD the differential equations for the time varying mode amplitudes. Some features of frequency response of such an electromagnetic system are presented. Waveforms of electromagnetic fields excited by a wideband pulse are considered.

There are three approaches for the solution of the diffraction problem of plane waves by an impedance half-plane in the literature. The diffracted field expressions, obtained by the related methods, are compared numerically. The examination of the scattered field shows that the most reliable solution is the field representation of Raman and Krishnan. Since the diffracted fields of Senior and Maliuzhinets do not compensate the discontinuities of the geometrical optics waves at the transition regions.

We combine the analytic eigen mode expansion method with the finite-difference, frequency-domain (FD-FD) method to study two-dimensional (2-D) optical waveguide devices for both TE and TM polarizations. For this we develop a layer-mode based transparent boundary condition (LM-TBC) to assist launching of an arbitrary incident wave field and to direct the reflected and the transmitted scattered wave fields back and forward to the analytical regions. LM-TBC is capable of transmitting all modes including guiding modes, cladding modes and even evanescent waves leaving the FD domain. Both TE and TM results are compared and verified with exact free space Green's function and a semi-analytical solution.

After a report on strange electromagnetic resonances emerging in an isotropic paraelectric Menger sponge (MS) now known as a photonic fractal, vigorous studies began to reveal their properties. However, the mechanics of how the resonances occur is still unknown. This report focuses on the findings that the resonances can be perturbation-theoretically identified as those originally occurring in an isolated dielectric cube, and that they arise within band gaps and uncouple with Bloch modes for a certain multiperiodic lattice. This interpretation is justified by the fact that the MS can be considered as a cube embedded in the lattice rather than the outcome of conventional recursive fractal structuring operations. An experimental formula for resonance conditions already reported can be derived from this interpretation.

A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study on laboratory animals was designed and implemented. The system is based on a reverberation chamber. An input power up to 5 W can be sent to an indoor transmitting antenna and an electric field strength (E) more than 90 V/m can be reached inside the chamber. The system was characterized at different input powers measuring E in different points by means of a miniature sensor. Then, boxes with 300 cc of physiological liquid inside were realized as simple phantoms simulating laboratory animals (rats) and E inside the liquid was measured, performing several simulations by moving the phantoms (1,2) in the chamber and/or putting them still in different positions. On the basis of these measurements, the SAR (Specific Absorption Rate) and the Pe (power efficiency = SAR/input power) were determined at different powers. The actual system is characterized by a low power efficiency with respect to the "in vivo" exposition systems based on transversal electromagnetic (TEM) cells. Its advantage is to have inside the chamber a habitat similar to the usual one for the laboratory animals.

A single-stage ultra-wideband (UWB) CMOS low noise amplifier (LNA) employing interstage matching inductor on conventional cascode inductive source degeneration structure is presented in this paper. The proposed LNA is implemented in 0.18 μm CMOS technology for a 3 to 5 GHz ultra-wideband system. By careful optimization, an interstage inductor can increase the overall broadband gain while maintaining a low level of noise figure of an amplifier. The fabricated prototype has a measured power gain of +12.7 dB, input return loss of 18 dB, output return loss of 3 dB, reverse isolation of 35 dB, noise figure of 4.5 dB and input IP3 of -1 dBm at 4 GHz, while consuming 17 mW of DC dissipation at a 1.8 V supply voltage.

A reconfigurable patch antenna consisting of a square patch with two cross-shaped diagonal slots is presented. The proposed design approach is based on the use of two pairs of switches in order to obtain both frequency and polarization reconfigurability. Specifically, three different polarization states have been obtained: A Right-Hand Circular Polarization, a Left-Hand Circular Polarization and a Linear Polarization. Experimental results, referred to a realization on a FR4 substrate of the layouts corresponding to the useful switch configurations, are reported.

In this paper, a compact, wide fractional bandwidth bandpass filter using a new open slot split ring resonator (OSSRR) defected ground structure and compact microstrip resonating cell (CMRC) is presented. OSSRR is the modified and dual version of the open split ring resonator (OSRR). The band pass filter (BPF) is constructed by cascading lowpass and highpass sections designed using CMRCs and OSSRR respectively. The designed BPF has wide fractional bandwidth of 74%, sharp passband to stopband transition and low passband insertion loss of less than 1 dB. The simulated results are well validated by the experimental results.

A novel compact strip-line fed UWB antenna with band-notched characteristic is proposed. By employing a balanced antipodal structure and strip-line feed, the size of this antenna has been reduced to only 23 mm×27.5 mm with the dielectric substrate of relative permittivity 2.65. Meanwhile, a slot is added onto the radiating patch of the mid metalisation layer to realize the band-notched function, by tuning the length of which suitable rejected frequency band can be obtained. According to the measured results, the proposed antenna has a large bandwidth totally satisfying the requirement of UWB applications (3.1~10.6 GHz) with good stable omnidirectional radiation patterns and gains except in the rejected frequency band (4.9~6.2 GHz). Details of this antenna are described, and the experimental results of the constructed prototype are given, too.

Novel configurations of complementary split ring resonator (CSRR) with dual mesh-shaped couplings and defected ground structures (DGS) are introduced to design the high performance of wide pass-band and stop-band band pass filters (BPF). This paper presents a low insertion loss (-0.82 dB), symmetry and sharper transmission zero level (-51.88 dB), using effective DGS and alternative coupling for CSRR. The filter with center frequency at 1.92 GHz, pass-band from 1.21 GHz to 3.05 GHz (BW = 95.8%) and wider stop-band (extended to 4.2f₀ below -20 dB rejection level) is designed and fabricated. Simulation and measured results including surface current distributions and frequency responses are presented and discussed.

In this paper, a hybrid algorithm combined method of moments (MoM) with particle swarm optimization (PSO) is used to realize low radar cross section (RCS) array synthesis. Both the scattering factor and the radiation factor are involved in the proposed objective function to achieve the promising dipole array with a reduced RCS and satisfied radiation performance. To improve the optimization efficiency, radiation constraint conditions are adopted to avoid unnecessary scattering calculation. The symmetric matrix and block treatment are also used to fill the MoM impedance matrix. The optimization results show that the proposed algorithm is able to achieve RCS reduction of 5.5 dB for dipole array.

A 77 GHz microstrip antenna array with a small surface providing high side and grating lobe suppression is presented. This may serve as a starting point for 77 GHz automotive radar applications. Multiple Wilkinson dividers guarantee both impedance matching at the input port (TX) as well as low return loss for the incoming (RX) signal. Phase shifting is done by adjusting the level of the Wilkinson dividers or by meandered sections of transmission line. The influence of the radiation caused by the feeding network is analyzed and the absolute degradation in side lobe suppression is derived in this paper.

A compact dual-band high-impedance-surface EBG structure is employed as a reflector for a dual-band annular-slot antenna. The reflector comprises an array of miniaturized EBG cells which utilizes square patches augmented by four S-shaped corrugated arms to reduce the resonant frequency of the proposed EBG structure. In order to broaden the bandwidth and adjust the frequency ratio for the dualband EBG structure, a log-periodic spacing between the S-shaped strips is introduced. The combination of microstrip-fed annular slot and EBG reflector provides directional properties for both frequency bands with reduced size and low-profile.

A completely analytical computation of the electromagnetic field produced by an optical fiber helix is presented for the first time. The analysis utilizes the transformation of radially traveling cylindrical waves between two skew cylindrical coordinates systems, that has been previously derived by the author, in order to express the waves radiated by each infinitesimal part of the helix in terms of cylindrical waves around the helix axis and be able to integrate the contributions analytically. Under certain realistic geometrical assumptions, an unperturbed propagation of a single fiber mode is assumed to account for the infinite fiber length, leading to elegant final series expressions in terms of mixed angular-axial Hartree space harmonics, which show clearly the effect of the helical geometry on the field distribution. Analytical formulas are obtained for the field inside and outside the helix cylinder and an interesting two-term decomposition of the outward radiated field is concluded.

A new design technique of microstrip patch antenna is presented in this paper. The proposed antenna design consists of inverted patch structure with air-filled dielectric, direct coaxial probe feed technique and the novel slotted shaped patch. The composite effect of integrating these techniques and by introducing the new multi-slotted patch, offer a low profile, high gain, broadband, and compact antenna element. A wide impedance bandwidth of 27.62% at -10 dB return loss is achieved. The maximum achievable gain is 9.41 dBi. The achievable experimental 3-dB beamwidth (HPBW) in the azimuth and elevation are 60.880 and 390 respectively at centre frequency.

A dual-band enhanced-bandwidth microstrip antenna is presented with a frequency separation of f2/f1=1.33. In order to achieve the dual-frequency operation, a rectangular patch is loaded with a stub at one of its radiating edges. To improve bandwidth at each band, two parasitic patches are coupled to the driven element.

We investigate the electromagnetic properties of three-dimensional (3D) arbitrarily-shaped invisible cloaks based on the analytical field transformation theory instead of the complicated numerical simulations. Very simple closed-form expressions for fields and energy flows have been derived for arbitrarily-shaped 3D cloak, which could help us to investigate the electromagnetic properties of the 3D cloaks rapidly and efficiently. The difference between 2D and 3D cloaks have been compared in detail. Distributions of the fields, power flows and wave polarizations for the 3D case have been discussed inside the cloak. Numerical results have been presented at the cutplanes of cloaks to valid the theoretical analysis, which shows clearly how the incident waves are bent at the inner boundary. In order to further reveal the physical essence of the cloaks, both 3D spherical and ellipsoidal cloaks have been considered based on the analytical method. The common features and the differences for the two structures have been also illustrated in this paper.

This paper proposes a hybrid classifier for polarimetric SAR images. The feature sets consist of span image, the H/A/α decomposition, and the gray-level co-occurrence matrix (GLCM) based texture features. Then, the features are reduced by principle component analysis (PCA). A 3-layer neural network (NN) is constructed, trained by resilient back-propagation (RPROP) method to fasten the training and early stop (ES) method to prevent the overfitting. The results of San Francisco and Flevoland site compared to Wishart Maximum Likelihood and wavelet-based method demonstrate the validness of our method in terms of confusion matrix and overall accuracy. In addition, NNs with and without PCA are compared. Results show the NN with PCA is more accurate and faster.