A novel procedure for estimating the Fresnel reflection coefficient of a transversally homogeneous half-space medium is introduced. GPR multistatic measurements are exploited as data whereas the Fresnel coefficient (as a function of the incidence angle) is retrieved by inverting a linear integral equation. Having estimated the reflection coefficient it can be exploited to determine the medium electromagnetic parameters. Numerical examples are used to show procedure effectiveness for different types of homogeneous half-space media within a two-dimensional scalar geometry. The case of a layered half-space is also discussed.

In this paper, novel uniplanar tunable and switchable bandpass filters are designed by using the centrally-loaded slot-line resonator. From the voltage-wave distribution along the resonator, the appropriate location for the loading element is determined to be the center of the slot-line resonator, where the voltages of the fundamental signal and second harmonic are maximum and zero, respectively. As a result, the fundamental frequency can be tuned while the second harmonic remains almost unchanged. For the first time, the properties of the centrally-loaded slot-line resonator are analyzed by using the even- and odd-mode method, and their respective resonant frequencies are derived. The demonstrated tunable bandpass filter can give a 30.9% frequency tuning range with acceptable insertion loss when a varactor is used as the loading element. By replacing the loading varactors with PIN diodes, a switchable bandpass filter is realized in which the attenuation in the fundamental passband can be controlled. In experiments, the switchable bandpass filter exhibits a 2.13 dB insertion loss in the fundamental passband when the PIN diodes are off and more than 49 dB isolation across the passband when the PIN diodes are on.

Using a building block approach which combines a transverse resonance method with a mode-matching technique, a rigorous analysis of a lossless bi-isotropic H-guide is presented. First, the modal equation of a parallel-plate waveguide containing the inner medium of the H-guide is obtained. Then, a mode matching technique is used to develop a full-wave analysis of the H-guide. The influence of nonreciprocity on the guidance properties of the structure is discussed.

A non-resonant microwave method has been proposed for complex permittivity determination of low-loss materials with no prior information of sample thickness. The method uses two measurement data of maximum/minimum value of the magnitude of transmission properties of the sample. An explicit expression for sample thickness and two expressions for inversion of the complex permittivity of the sample are derived. The method has been validated by transmission measurements at X-band (8.2--12.4 GHz) of a low-loss sample located into a waveguide sample holder.

In this paper propagation losses of body implanted antennas are studied at the ISM bands of 433 MHz, 915 MHz, 2450 MHz and 5800 MHz. Two body models are used, one based on a single equivalent layer and the other based on a three layer structure, showing the advantages and limitations of each one. Firstly, the antenna pair gain at different implanted antenna depths is analyzed. Next, we show the effects of the thickness of the different body tissue layers. Finally, we discuss the consequences of using a coating layer to isolate the antenna from the harsh environment of the human body.

This paper presents a new unequally spaced and excited resonant slotted-waveguide antenna array. It is realized by employing an improved resonant-slot coupled cavity chain composite right/left-handed (CRLH) waveguide. As the CRLH waveguide works at the infinite wavelength frequency, all the slot elements along the waveguide wall are excited in-phase. Thus both the element spacings and excitation amplitudes are introduced into the synthesis to realize a resonant slotted-waveguide antenna array. A seven-element unequally spaced and excited antenna array which generates pencil beam is synthesized, simulated and fabricated. The results show, with comparison to the equally spaced but unequally excited resonant slotted-waveguide antenna array, the proposed unequally spaced and excited array produces a lower peak sidelobe level (PSLL).

A canonical problem is used to investigate the effects of various radar parameters on the performance of both steppedfrequency and short-pulse through-barrier radar imaging systems. For simplicity, a two-dimensional problem is considered, consisting of a perfectly conducting strip located behind a lossy dielectric slab of infinite extent illuminated by line sources. To assess the impact of the parameters on system performance, images of the target are created using the reflected field computed at several positions in front of the barrier and adjacent to the sources. Specific parameters considered include sample rate, A/D bit length, pulse width, and SNR for a time-domain system. For a stepped-frequency system, A/D bit length, bandwidth, and SNR are considered.

Charges and fields in a rotating non-magnetic conducting sphere under stationary conditions are investigated by using Minkowski's electrodynamics of moving media and the Lorentz force equation, taking into account the electric permittivity of the sphere. Starting from the assumption that the magnetic field inside the sphere is constant, exact solutions of the corresponding field equations are obtained in a first-order theory. However, it is found that there is a range of values of the sphere's net charge for which the physical interpretation of the results is difficult within a continuum model. Outside that range, our solution to the classic electromagnetostatic problem appears plausible.

A novel class of electromagnetic media called that of SQ-media is defined in terms of compact four-dimensional differential-form formalism. The medium class lies between two known classes, that of Q-media and SD-media (also called self-dual media). Eigenfields for the defined medium dyadic are derived and shown to be uncoupled in a homogeneous medium. However, energy transport requires their interaction. The medium shares the nonbirefringence property of the Q-media (not shared by the SD media) and the eigenfield decomposition property of the SD media (not shared by the Q-media). Comparison of the three medium classes is made in terms of their three-dimensional medium dyadics.

In recent years, through the wall imaging has become a topic of intense research due to its promising applications in police, fire and rescue or emergency relief operations. In this paper, we propose to use the DORT method (French acronym for Decomposition of the Time Reversal Operator) to detect and localize a moving target behind a wall. One of the DORT method major strengths is that detection remains possible through a distorting medium. In this paper, the DORT method is successfully applied to detect and track moving human beings behind a thick concrete wall. The smallest detectable displacement is also investigated.

Evaluation of electric and magnetic fields due to lightning discharge is important in determination of lightning induced voltage and power system protection especially to the distribution system. In this paper, by using dipole method, Maxwell equations and second order finite-difference time domain (later referred as a 2nd FDTD method) on two realistic return stroke currents, an algorithm for evaluation of electric fields is proposed, which is based on numerical methods in the time domain. Besides proving greater accuracy, it also allows the evaluation of electric and magnetic fields away from lightning channel. In addition, the comparison between simulation results and measured fields' wave shape showed that the proposed algorithm is in good agreement for evaluation of electric and magnetic fields due to lightning channel.

In this paper, a modified square slot antenna with modified radiating patch, for UWB applications is proposed. The proposed antenna consists of a square radiating patch with a double fed structure and a ground plane with a pair of L-shaped slots which provides a wide usable fractional bandwidth of more than 140% (3--18 GHz). By optimizing the L-shaped slots dimensions and rectangular slot width, the total bandwidth of the antenna is greatly improved. The designed antenna has a small size of 35×35 mm².

We use both FEM (finite element method) and FDTD (finite difference time domain method) to simulate the field distribution in Maxwell's fish eye lens with one or more passive drains around the image point. We use the same Maxwell's fish eye lens structure as the one used in recent microwave experiment [arXiv:1007.2530]: Maxwell's fish eye lens bounded by PEC (perfect electric conductor) is inserted between two parallel PEC plates (as a waveguide structure). Our simulation results indicate that if one uses an active coaxial cable as the object and set an array of passive drains around the image region, what one obtains is not an image of the object but only multiple spots resembling the array of passive drains. The resolution of Maxwell's fish eye is finite even with such passive drains at the image locations. We also found that the subwavelength spot around the passive drain is due to the local field enhancement of the metal tip of the drain rather than the fish eye medium or the ability of the drain in extracting waves.

In this paper the microwave images of two-dimensional section of multiple objects are formed by using the wideband range profiles of the target. Scattered electric field is obtained by the designed two-dimensional imaging system and Fourier transformed into the highly-resolved range profiles while the target rotates. A filtered back-projection (FBP) algorithm is implemented to form the image from the space domain range profiles. Images of multiple cylindrical rods from both numerically simulated and measured data indicate that the approached imaging scheme can achieve high dynamic range and can be potentially implemented for biomedical imaging detections.

The research in the paper puts forward a novel method for synthesizing conformal arrays and optimizing low cross-polarizations including the effects of element mutual coupling and mounted platform. Starting from the far-field superposition principle, an efficient approach with active element pattern technique is proposed to calculate the far-field patterns. Coordinate transform is used to create polarization quantities, and a general process for the element polarized pattern transformation is proposed. The two numerical examples are proposed, and the desired sidelobe levels and low cross-polarizations are optimized. Numerical results denote the proposed method is valid.

The reflection of linearly polarized light from an ultrathin biaxially anisotropic dielectric film on an isotropic transparent material is investigated in the long-wavelength limit. The approximate expressions for the reflection characteristics of s- and p-polarized electromagnetic plane waves are obtained. The analytical approach developed in this paper not only provides insight into the nature of reflection problem for biaxially anisotropic ultrathin films but also furnishes the methods for resolving the inverse problem for such anisotropic layers. It is shown that a key capability of the developed analytical method is to decouple the usual correlations in the index and the thickness of ultrathin films.

A modified UWB power divider formed by installing one delta stub on each branch is proposed. Delta stub is used as a substitution of radial stub that can present wideband characteristic. The proposed structure makes branch line shorter and stub's size smaller than those of similar works based on UWB power divider using radial stub. It also achieves a compact size of 18 mm by 13 mm. The simulation and measurement results of the developed divider are presented and shown good agreement in the UWB range.

In the present paper a dual frequency resonance antenna is achieved by introducing half U-shaped slot in semicircular disk. It is analysed by using circuit theory concept. The resonance frequency is found to be 1.50 GHz and 2.32 GHz, and the bandwidth of the proposed antenna for lower and upper resonance frequency is found to be 5.96% and 11.08% respectively. It is found that the resonance frequency depends inversely on the slot length and feed point, while it increases with increasing the slot width and coaxial probe feed radius. The frequency ratio is found to be 1.54. The theoretical results are compared with IE3D simulation as well as reported experimental results, and they are in good agreement.

The objective of this paper is to establish the properties of the electromagnetic wave propagation in a diversity of situations in material media with magnetic monopoles and even in the situations of entities simultaneously containing electric and magnetic charges. This analysis requires the knowledge and solutions of the ``Maxwell" equations in material media compatible with the existence of magnetic monopoles and the extended concepts of linear responses (conductivity, split-charge susceptibility, kinetic susceptibility, permittivity and magnetic permeability) in the case of presence of electric and magnetic charges. This analysis can facilitate insights and suggestions for electrical and optical experiments according a better knowledge of the materials whose behaviour can be analyzed under the consideration of the existence of entities with equivalent properties of the magnetic monopoles.

This work proposes a substrate integrated waveguide (SIW) power divider employing the Wilkinson configuration for improving the isolation performance of conventional T-junction SIW power dividers. Measurement results at 15 GHz show that the isolation (S₂₃, S₃₂) between output ports is about 17 dB and the output return losses (S₂₂, S₃₃) are about 14.5 dB, respectively. The Wilkinson-type performance has been greatly improved from those (7.0 dB~8.0 dB) of conventional T-junction SIW power dividers. The measured input return loss (23 dB) and average insertion loss (3.9 dB) are also improved from those of conventional ones. The proposed Wilkinson SIW divider will play an important role in high performance SIW circuits involving power divisions.