This paper presents a method for extracting the coupling matrix and the unloaded Q from the measured (or electromagnetic simulated) S-parameters of a narrow band cross-coupled resonator bandpass filter with losses. The Cauchy method is applied to determine the characteristic polynomials of the S-parameters of a filter in the normalized low-pass frequency domain. A five-parameter optimization method is proposed to obtain the unloaded Q and remove the phase shift of the measured S-parameters, which is caused by the phase loading and the transmission lines at the input/output ports of a filter. Once the characteristic polynomials of the S-parameters with the phase shift removed have been determined, the coupling matrix of a filter with a given topology can be extracted using well established techniques. Two application examples are given to illustrate the validity of the proposed method.

This paper introduces a novel technique for efficiently combining implicit space mapping (ISM) with method of moments (MoM) for the synthesis of antenna arrays and explores several example applications of the ISM approach. The antenna arrays geometric parameters are extracted to be optimized by ISM, and a fitness function is evaluated by MoM simulations to represent the performance of each candidate design. A coarse-mesh MoM and a fine-mesh MoM solver are used for the coarse and the fine models, respectively. To achieve the parameter extraction, the auxiliary parameter is selected and the approximation between the two models is accomplished by particle swarm optimization (PSO). The results show that the running time of the ISM algorithm is 2~3 times faster than that of other optimization algorithms (e.g. PSO).

In this paper we develop an empirical approach to the design of Ultra Wideband (UWB) antennas employing the Inverse Parabolic Step Sequence (IPSS). The relationships developed can be used to miniaturize the antenna and achieve a good impedance match over the UWB bandwidth. The overall aim of this process is to give a good starting point for detailed numerical optimizations. We will illustrate the use of these formulae in three different designs of IPSS-based antennas. A low loss duroid substrate of loss tangent, tan δ, 0.0009, relative permittivity 2.2 and thickness 1.575 mm is used to simulate these planar monopole antennas in Ansoft High Frequency Structure Simulator (HFSS).

A new four-parameter modified refractivity profile (M-profile) model for the evaporation duct is introduced in this paper. In the estimation of radio refractivity structure from sea clutters, a parametric M-profile model is normally employed. The conventional M-profile model for evaporation ducts is the one-parameter log linear model, which has some potential disadvantages in describing the observed M-profiles which would result in rough results of evaporation duct estimation. Based on this model, three new parameters are introduced and a four-parameter M-profile model is proposed here. This model has the ability to (a) more accurately match real-world M-profiles, (b) well replicate the observed clutter field, and (c) show clutter power or path loss sensitivity to each model parameter. All these abilities are necessary for robust refractivity estimations. The performance of this model is tested and validated through the estimation for two truly measured M-profiles.

Bandwidth enhancement technique of circularly polarized square slot antenna is presented in this paper. A square slot antenna with the components of L-probe separated could achieve an axial ratio (AR) bandwidth of 33.84%. Placing Stubs in the slot by studying the electric field behaviour could enhance the AR bandwidth by around 10%. Creating an L-shaped slot on the ground plane, where the electric field rotates in the desired clockwise direction, can further enhance the bandwidth by 7%. A < -10 dB S₁₁ bandwidth of 46.15% and < 3 dB AR bandwidth of 50.35% could be achieved with the present design. Unidirectional patters are obtained by having a cavity at the wide slot of the antenna and shows a measured bandwidth of 41.79% in S₁₁ and 44.97% in AR. Both antennas show a cross polarization discrimination of more than 15 dB on a wide azimuth range. The measured results well comply with the simulated results.

Reflection of electromagnetic plane wave from a planar chiral nihility-chiral nihility interface is calculated as a special case of two different chiral media by assuming that permittivities and perme-abilities of the both media approach to zero. That is, ε_i→0, μ_i→0, and chiralities κ_i≠0, i=1, 2. These results are used to find the geometrical optics reflected fields of a cylindrical chiral nihility-chiral nihility interface, when it is excited by a plane wave. Using the Maslov's method, field expression which yields finite values around the focus of cylindrical interface is also determined.

We investigate numerically the collision of nonlinear envelope pulses in composite right- and left-handed transmission lines with regularly spaced Schottky varactors. Because of the nonlinearity caused by the Schottky varactors, the dispersive distortion of envelope pulses is well compensated. We find that when two nonlinear envelope pulses traveling in the opposite directions collide, two envelope pulses are newly developed. The carrier wave frequency of the newly developed pulse is the harmonic of the colliding pulses that satisfies the phase-matching condition.

The design and measured results of a compact, low cost, low conversion loss microstrip single balanced Schottky diodes mixer is proposed. This mixer is designed for Ka-band satellite transponder simulator to convert the 30 GHz radio-frequency (RF) signal down to the 20 GHz intermediate-frequency (IF) signal with 9.8 GHz local oscillator (LO) frequency. This design takes full advantage of the frequency relationship of the RF, IF and LO, which is 3 : 2 : 1. A microstrip rat-race ring is designed at the LO frequency, which also functions as a 180-degree hybrid coupler at the RF frequency by its intrinsic multi-band characteristic. The amplitude and phase balance at both LO and RF frequency are analyzed, which guarantee the state-of-art performance of this single balanced mixer. The multi-function open/short stubs and a lowpass filter (LPF) with bonding wires across the rat-race ring are optimized to realize this low conversion loss mixer. The measured results show that the conversion loss is less than 9 dB at the IF frequency from 20.0 to 21.6 GHz, and the power of the second harmonic of LO is -45dBm with +6.5dBm LO drive power. The 3rd order inter-modulation products (IMD3) could be lower than -50 dBc with LO power higher than +7.8dBm at the input RF power of -15 dBm.

A set of characteristic basis functions of the energy radiation pattern for a true-time-delay array of equi-spaced elements radiating a pulsed/transient wave-field was derived. This set is determined by the array layout and by the set of excitation waveforms that can be used to expand the actual excitation pulse. It is established that the characteristic basis function set spans the mapping of the square amplitudes of the discrete Fourier transform of the excitation coefficients to the energy radiation pattern. This mapping is further used to analyze array performance and re-examine the term array sparsity. Additional use of this set can be found in synthesizing an array radiation pattern to meet prescribed requirements.

The propagation characteristics of electromagnetic waves at the interface between an isotropic regular medium and an anisotropic metamaterial for arbitrary orientation of principal axis are investigated. In terms of the different sign combinations of the tensor components along principal axes, the anisotropic media are divided into four classes. The existence conditions of negative refraction are discussed in different cases, indicating that the conditions for the existence of negative refraction are closely dependent on the principal components and the rotation angle. Furthermore, the influence of the rotation of the principal axes on the incident angle region is analyzed for each case, and the optimal material parameters are attained for the maximum area of the incident angle region of negative refraction occurrence.

The asymptotics of induced current of forward and backward waves on a strongly elongated spheroid is constructed by matching the asymptotic representations to exact solution valid in a vicinity of the rear tip of the spheroid. These asymptotic results are compared with numerical computations.

This work demonstrates that the well-known box configuration comprising four inverter-coupled resonators is capable of realizing a dual-band filter characteristic. A dual-band filter is designed at 1 GHz and subsequently implemented as a Combline microstrip filter exhibiting measured frequency characteristics which closely matched the simulations.

We have derived simple analytical expressions for the frequency-dependent effective permittivity tensor of a one-dimensional metal-dielectric photonic crystal in the long wavelength limit. Our results describe the transition between the regime described by Rytov's formulas and that predicted by Xu et al [5], where the effective plasma frequency is independent of the metallic-layer parameters. The derived expressions can be useful for determining the frequency intervals where such an anisotropic system can exhibit metamaterial behavior.

Electrothermal effects in various through silicon via (TSV) arrays are investigated in this paper. An equivalent lumped-element circuit model of a TSV pair is derived. The temperature-dependent TSV capacitance, silicon substrate capacitance and conductance are examined for low-, medium-, and high-resistivity silicon substrates, respectively. The partial-element equivalent-circuit (PEEC) method is employed for calculating per-unit-length (p.u.l.) resistance, inductance, insertion loss and characteristic impedances of copper and polycrystalline silicon (poly-Si) TSV arrays, and their frequency- and temperature-dependent characteristics are treated rigorously. The modified time-domain finite-element method (TD-FEM), in the presence of a set of periodic differential-mode voltage pulses, is also employed for studying transient electrothermal responses of 4- and 5-TSV arrays made of different materials, with their maximum temperatures and thermal crosstalk characterized thoroughly.

The principal aim of this article is the presentation of EpsiMu, a tool for dielectric properties measurement. This general tool can be used to characterize all types of materials, but in this article we apply it to porous or granular materials. The tool consists of a coaxial cell and dedicated software that allow us to reconstruct the permittivity in almost real-time by a de-embedding process. Dielectric permittivity of soils sample was measured using this microwave tool. So, we can then determine the relationship between the dielectric properties and volumetric water content θ of Fontainebleau sand (center of France) and Dune of Pilat sand (Arcachon Bay area, France). The clay effect on Fontainebleau sand is also studied. We discuss the usefulness of several models that link the permittivity to volumetric water content of soil. It is shown that the soil permittivity model is not directly applicable to Fontainebleau sand and Dune of Pilat sand. We find a good match between our results representing the relative permittivity ε'_r veversus the volumetric water content θ and the Complex Refractive Index model (CRIM) between 600 MHz and 1 GHz. Alternative regression formulae are proposed. The implication of the determination of volumetric water content, θ, is discussed. A linear relation between the dielectric loss tangent and volumetric water content θ of soils is established.

Throughout the performance of a RF immunity test according IEC 61000-4-3 there are several factors that should be taken into account to ensure the quality and to estimate the uncertainty associated to the results. One phenomenon that should be considered to calculate uncertainty is the disturbing effect produced by the EUT over the electric field generated within the calibrated uniform field area; nevertheless the mentioned effect is not easily quantifiable because the measuring process using additional antennas or field probes inside the semianechoic chamber could also alter the electric field distribution. An experimental method for quantifying the mentioned uncertainty contribution is presented. The method is based upon the fact that antenna-EUT coupling and reflection effects could be measured through changes in the input impedance of the field generation antenna. A validation procedure for the proposed method is also described. Hence, a relationship between the reflection coefficient at the antenna input port and the electric field strength is derived. The uncertainty contribution is calculated through the maximum relative change in the E-field intensity magnitude for the frequency range of 80-1000 MHz, considering the worst case for several EUT positions.

An investigation on the possibility of obtaining a negative refractive index behavior in split ring resonators (SRRs) through magneto-electric coupling is presented. We have performed rigorous electromagnetic simulations using a full-wave 3D simulator, and the obtained results have been verified by our experimental realizations and measurements. The results confirm that the increase of magnetoelectric gyrotropic activity inside a bi-anistropic medium can lead to the establishment of backward-wave propagation.

A three sections circular waveguide aperture antenna with conical beam is presented. By using two waveguide steps, the aperture distribution of the antenna can be controlled to realize the requirements on the radiation pattern with conical beam including the flare angle, gain and the side lobe level. Through optimized design, the impedance bandwidth of 550MHz with -10 dB return loss, the gain of 8.1 dB and a flare angle of 50 degrees have been achieved at the central frequency 35 GHz. Good agreement has been observed between simulated results and measured ones. The proposed antenna is easy to be fabricated and suitable for many applications.

An open L-slot antenna with triple-band operation for WLAN and WiMAX applications has been designed and implemented with a slit and a strip, which can be used to generate two band-rejected characteristics. Both the strip and the slit play a very important role in suppressing the dispensable bands. By adjusting the dimensions of the slit and strip, the proposed antenna shows three separated operation frequencies with a bandwidth of 14% from 2.24 to 2.58 GHz, a bandwidth of 19% from 3.02 to 3.66 GHz, and a bandwidth of 10% from 5.62 to 6.21 GHz, respectively. Detailed designs and experimental results are reported in this paper.

A fundamental relation between the cross sectional confinement of an arbitrary mode of a general waveguide and its propagation length is found. It is shown that due to material loss of the waveguide, the propagation length shrinks as the confinement of the mode increases. Normalized second central moment of magnetic energy density in the cross section plane of the waveguide is used as a measure of mode size and it is found that for a given mode size, there is a limit for the waveguide propagation length. This limit depends solely on permittivity of the waveguide material and its surrounding medium. As an application, this result provides a lower bound for propagation loss in subwavelength optical confinement in plasmonic waveguides which are of special interest for their nano-meter mode dimensions.