This work presents new method, retrieved results and validation for complex and frequency dependent permittivity and permeability parameter extraction of two composite, homogeneous and isotropic magnetically loaded microwave absorbers. Permittivities and permeabilities are extracted from free space transmission measurements for frequencies from 22 up to 140 GHz. For validation of the results reflection measurements (samples with and without metal backing) are performed and are compared with simulations that use extracted models. The proposed new method solves some shortcomings of the popular methods: extracts both permittivity and permeability only from transmission parameter measurements, gives good results even with noisy data, does not need initial guesses of unknown model parameters.

This study presents a design of a compact stub-type bandpass filter with capacitively loaded stubs and a fold-back structure. This paper employed the fabrication process of low-temperature co-fired ceramic (LTCC) for filter realization of a multi-layer structure. The proposed filter structure required adding end capacitors to stubs to extend their electrical length, while achieving a length reduction of 30%. This study provided design curves to determine the dimensions of the end capacitor for reaching maximum electrical length extension. In addition, a fold-back configuration was applied to halve the filter size. An experimental filter operating at 5.8 GHz was fabricated and measured to validate the design concept, achieving a highly compact size of 14.3×8.2×0.76 mm³.

In this paper, several configurations of a rotary magnetic refrigerator are proposed and investigated using three dimensional finite element method simulations. Their electromagnetic performance is analyzed considering the magnetic flux density, the forces and the torque. The rotor is a single permanent magnet while the stator is made of four refrigerant beds and a magnetic yoke. Multipole stators or rotors with 4, 6 and 8 refrigerant beds have been tested. The beds can be fitted or set at the inner surface of the yoke. The yoke can have smooth or salient poles. To minimize the magnetic torque, an original structure is proposed and tested. It is composed of two half-systems assembled with a 45^o angle shift between rotors or stators. Because of the large amount of data, a suitable procedure to achieve an effective comparison between all configurations is established.

An analytical solution for the scattering of an electromagnetic plane wave from a perfect electromagnetic conducting (PEMC) circular cylinder coated with chiral material is derived. The PEMC cylinder as well as coating layer is of infinite length (2-D problem). Parallel polarization of the plane wave is considered for the analysis. The response of the chiral coated geometry has been observed for DPS-chiral, DNG-chiral and chiral-nihility coating layers. Also the behavior of the monostatic echo width for DPS-chiral and DNG-chiral layers has been studied against the admittance parameter. Results of bistatic echo width for the PEMC, PEC and PMC core have been presented. Under special conditions our results are in a very good agreement with the published literature.

In this paper, several simple antenna designs based on the use of an active dipole placed above a ground plane with an array of parasitic dipoles are presented. The parasitic dipoles are used to modify the pattern of the active dipole yielding a pencil beam of moderate gain. The use of one active element provides a very simple feeding network that reduces the complexity of the antenna. The proposed technique optimizes the geometry and configuration of both active and parasitic elements. It is shown that the performance of the designed antennas is considerably better than that of a similar antenna without parasitic elements.

This paper formulates a simple vector integral expression for electromagnetic waves received after scattering from a surface. The derived expression is an alternative to the Stratton-Chu equation frequently used for polarimetric surface scattering. It is intended for use in polarimetric Global Navigation Satellite System (GNSS) ocean remote sensing, or any type of polarimetric remote sensing from surfaces, when the surface roughness pattern is known from simulation or data. This paper is intended to present a complete accounting of the steps leading to the simpler vector integral expression. It therefore starts with the scalar case, using Maxwell's equations and Green's theorem. It principally treats the case of a transmitter within the integration volume, but discusses how the formalism changes if the transmitter is outside of the integration volume, as with plane waves. It then shows how the scalar expression can be extended to a vector expression for the component of the electric field in an arbitrary receive-polarization direction due to scattering from a rough surface of an incident wave with an arbitrary transmit polarization. It uses the Kirchhoff, or tangent-plane, approximation in which each facet on the ocean is considered to specularly reflect the incoming signal. The derived vector expression is very similar to that for a scalar wave, but it includes all vector properties of the scattering. Equivalence is demonstrated between the Stratton-Chu equation and the derived, simpler expression, which is operationally easier to code than the Stratton-Chu equation in many modeling applications.

In this paper, a novel design of open slot antenna for bandwidth enhancement is proposed and investigated. The bandwidth enhancement of the proposed antenna is achieved by simply attaching a rectangular stub to the circular radiating patch. Experimental results indicate that the bandwidth of the antenna can achieve an operating bandwidth of about 139% over a wideband frequency range from 2.57 to 14.23 GHz. This antenna has a small size of dimensions 20×35 mm² and is suitable for wideband applications in various wireless communication systems.

An improved CPW-fed configurations with dual-mode double-square-ring resonators (DMDSRR) for tri-band application is proposed in this paper. The resonant frequency equations related to DMDSRR geometry are introduced for simply designing tri-band bandpass filter (BPF). Resonant frequencies and transmission zeroes can be controlled by tuning the perimeter ratio of the square rings. To obtain lower insertion loss, higher out-of-band rejection level and wider bandwidth of tri-band, the improved coplanar waveguide (CPW) fed and the step impedance resonator (SIR) and meander line dual-mode perturbations are designed. The effective design procedure is provided. The proposed filter is successfully simulated and measured. It can be applied to WLAN (2.45, 5.20 and 5.80 GHz) and WiMAX (3.50 GHz) systems.

Nyquist folding receiver (NYFR) is a new kind of interception architecture, which can simultaneously intercept wideband signals in multi-Nyquist zones with one or two analog-to-digital converters (ADCs). A parameter estimation algorithm of the linear frequency modulated (LFM) signal intercepted by an improved NYFR is presented. Firstly, the NYFR is improved by introducing a synchronous mechanism, and we denote this structure as a synchronous NYFR (SNYFR). Secondly, taking LFM as an example, the input and output noise distributions of an SNYFR are discussed. Then, a fast parameter estimation algorithm is derived from the frequency spectrum of the output signal, and an advice for the design of local oscillator signal is given. Simulations show that the parameter estimation accuracy is close to the maximum likelihood when the signal to noise ratio (SNR) is above -3 dB.

In this paper, a high-efficiency wireless energy transmission via magnetic resonance is experimentally implemented in a resonator with the various sizes of transmitting and receiving coils and the receiving coil having two shapes of rectangular and circular types. The transmission efficiency is analyzed by varying the transmission distance. The resonance between the transmitting and receiving coils is achieved with lumped capacitors terminating the coils. The transmission efficiency of the resonator consisting of a circular transmitting coil with a diameter of 60 cm and rectangular receiving coil with a one side length of 10 cm is about 80% at the transmission distance of 20 cm. The transmission efficiencies of the wireless energy transmission resonator consisting of a receiving coil with the size of iPhone4 are about 75% and 40% at the transmission distances of 20 cm and 50 cm.

Circular synthetic aperture radar (CSAR) is different from other usual SAR modes, e.g., Stripmap SAR or Spotlight SAR, which takes a circular path rather than a straight path. It can provide not only two-dimensional (2-D) high resolution images but also three-dimensional (3-D) information about the target. In this paper, 2-D CSAR imaging containing 3-D information about the target is discussed. Considering the limited bandwidth of radar system and the limited angular persistence of the reflector's scattering characteristic in a real scene, we combine the data extrapolation technique based on the autoregressive (AR) model with the non-coherent combination of the sub-aperture images based on the approximate Generalized Likelihood Ratio Test (GLRT) technique to get a 2-D CSAR image with resolution improved and with aspect-dependent reflectivity characteristics kept. The GTRI T-72 tank dataset is processed to test the algorithm.

The potential field generated by two charged cylindrical perfect electrical conductors sandwiching a dielectric plane of finite thickness, and the influence of the dielectric plane on the field, is analysed. In particular, the field profile is examined when the cylinders are (i) rotating at some constant angular velocities, and (ii) surrounded, respectively, by uniform dielectric tubes of finite thickness.

Systems that employ stimulating and implantable monitoring devices utilize inductive links, such as external and implanted coils. The calculation of the mutual inductance and the magnetic force between these coils is important for optimizing power transfer. This paper deals with an efficient and new approach for determining the mutual inductance and the magnetic force between two coaxial coils in air. The setup is comprised of a thick circular coil of the rectangular cross section and a thin wall solenoid. We use an integro-differential approach to calculate these electrical parameters. The mutual inductance and the magnetic force are obtained using the complete elliptic integrals of the first and second kind, Heuman's Lambda function and one term that has to be solved numerically. All possible regular and singular cases were solved. The results of the presented work have been verified with the filament method and previously published data. The advantage of these proposed formulas for mutual inductance or for the magnetic force is that they give the solution in the analytical and the semi-analytical form either for regular cases or singular cases. It is not case with already known methods in which it is necessary to take particular care of these cases of consideration.

Power microwave was adopted to heat asphalt mixes with carbonyl iron powder (CIP) by its microwave absorbing characteristics. The Arch reflectivity system was employed for reflectivity tests in the frequency range of 2.0~4.0 GHz, and road properties of the asphalt mixes with different heating techniques were studied. The results indicate that 30 mm thickness of the asphalt mixes with the ratio of CIP absorber to asphalt 0.1 : 1.5, can effectively absorb microwave with a -19.1 dB absorbing peak at 2.45 GHz frequency. Microwave heating rate for asphalt mixes with CIP is 16 times higher than that for ordinary asphalt mixes. Microwave heating can enhance road properties of the asphalt mixes, such as Marshall stability, flow value, dynamic stability and splitting strength at low temperature to a certain extant when the ratio of CIP absorber to asphalt is from 0.1 : 1.5 to 0.3 : 1.5.

The performance of complementary ESD/Lightning protection devices being exposed to EMP was studied. We studied protection devices such as GDT (Gas Discharge Tube), TVS (Transient Voltage suppressor), and Varistor. The EMP signal has a very fast rise time of 100 psec and the maximum peak voltage of 2 kV. The GDT could not protect the EMP signal. The varistor showed about 35% of protection ability, and the TVS showed about 50% of protection ability. Thus the GDT is not a proper device to protect EMP. However, all of the protection devices did not show their nonlinear property.

The electromagnetic scattering of the synthesized three-dimensional (3-D) breaking wave crests which are formed by azimuthally aligning the individual 2-D breaking wave profiles has been numerically studied at the low-grazing angles (LGA) by using the multilevel fast multipole algorithm (MLFMA) with adaptive higher order hierarchical Legendre basis functions. Different from the specular (or quasi-specular) reflection and Bragg scattering, the ``sea-spike'' phenomenon which is characterized by that horizontally polarization (HH) signals greatly exceed vertically polarization (VV) signals has been demonstrated by analyzing both the backscattering of 3-D LONGTANK series and a plunging breaker. For the time-dependent evolution of the plunging breaker, the Doppler shifts and Doppler splitting effects are investigated by applying the fast Fourier transform (FFT) with a moving Hamming window. The spectrum of HH scattering has the feature of concentration, while the spectrum of VV scattering shows the Doppler splitting effects.

Existing focusing techniques for Ground Penetrating Radar (GPR) rely on migration of 2D or 3D images to remove clutter originating from objects laterally offset from the antenna. In applications requiring real-time focusing, a method operating on 1D trace data is required. This paper presents a new algorithm for focusing GPR images, the Vertical Offset Filter (VOF), using simulated and real GPR data.

It is well-known that the choice of the auxiliary surface and the arrangement of radiation centers play a decisive role for ensuring accuracy and stability of the method of auxiliary sources (MAS). Using level set technique, a numerical scheme is proposed to determine the optimal location and amplitudes of the auxiliary sources for three-dimensional scattering problems.

A low-loss passive metamaterial exhibiting negative refractive index or ``double negative'' electromagnetic properties at microwave frequencies is proposed. The metamaterial is a lattice of spherical particles made up of multiple dielectric materials in concentric layers. Because no magnetic constituents (that tend to have higher losses) are involved, the negative-index behavior is possible with very low values of attenuation. A negative-index metamaterial based on dielectric-coated metal spheres is also proposed, and is predicted to have lower attenuation than other structures based on metallic scatterers. Numerical results and design principles are given.

A dual-frequency cloak based on lumped LC-circuits is proposed. Multiple LC-resonant tanks are employed to satisfy the specific conditions for dual-frequency operations. In this way, the designed cloak features greatly reduce scattering cross sections at the two working frequencies simultaneously. Besides, explicit design equations are derived for the developed circuit systems. Based on these formulas, the range of the realizable frequency ratio of the presented cloak (the ratio between the two operating frequencies) is discussed. To verify the theoretical predictions, full-wave electromagnetic simulations are implemented. Good consistency between the numerical results and the design theories is achieved.