Due to the difficulty in estimating the 2D image plane of the inverse synthetic aperture radar (ISAR) image, we recently proposed a new paradigm to construct the training database based on the flight scenario. However, because the flight condition for the training and the test data was identical, much more study is required for this method to be applied to the real ISAR scenario. This paper presents a study on the factor that can affect the applicability of scenario-based method to the real target ISAR recognition. Simulation results using five scatterer models show that accurate measurement of flight direction and aspect angle variation are required and enough bandwidth larger than 200 MHz should be guaranteed for the successful classification.

A novel 3D Frequency Selective Surface (FSS) architecture based on a circular ring unit element is presented. The circular ring was made 3D by creating a cylindrical element of a certain length, adding an extra degree of freedom into the structure. The length of the cylinder is shown through electromagnetic simulation to have a significant effect on the frequency characteristics of the FSS. Increasing the length of the cylinder can change the FSS from a band-stop to a band-pass filter response. The center frequency of both band pass and band stop responses can also be tuned with adjustment to the length. Dielectric materials are introduced in the center of the cylindrical unit cell elements to simultaneously obtain a stop and pass band with a sharp transition. For high dielectric filling materials, the 3D periodic structure exhibits negative refractive index metamaterial properties. A parametric analysis was conducted on these new cylindrical unit elements, and a prototype 3D FSS structure has been constructed and experimentally validated.

If sampling frequency is not high enough, the effect of adaptive memory polynomial predistortion linearizer is not very good for TWTA linearization. In order to keep the adaptive memory polynomial predistortion linearizer valid, usually the output power level of the TWTA must be reduced, which corresponds to a reduced efficiency of the TWTA. In this paper, we present a digital predistortion linearizer by combining LUT (Look-Up-Table) and memory-effect compensation technique, which may provide good linear performance with less reduction of the output power and relatively low sampling frequency. The results of simulations and experiments show that good linearity improvement can be reached for an X-band TWTA with this predistortion linearizer.

In this paper, we propose to study the variability of specific absorption rate (SAR) of a human head due to different materials in the vicinity of the handset. We include the effects of the human hand, handset chassis and additional conductive material particularly hand-ring jewelry. A finite-difference time-Domain (FDTD) method was used to analyze different positions of the conductive ring materials within the hand model. Furthermore, the impact of this material on the performance of an antenna was considered in this study. We found that including a hand model leads to a significant reduction in SAR. The hand influences not only SAR distribution but also antenna performance. Moreover, adding conductive materials to the hand results in increases in the local SAR values of the head model. The results suggest that the hand model is important in SAR evaluation and that having an additional conductive material on the hand may vary the amount of electromagnetic (EM) energy absorption depending on the position of the material.

A compact linear tapered slot antenna with wideband performance is proposed. The antenna consists of a microstrip to slotline transition and a linear tapered slot structure which is connected to the slotline. Due to the linear tapered slot, the antenna can realize unidirectional radiation in wideband band. The microstrip to slotline transition is implemented by using a tapered cross, which can easily obtain impedance transformation. Furthermore, this transition can be realized with a small size. The antenna is fabricated and optimized numerically. Both simulated and measured results validate the performance of the antenna in frequency and time domains. The results show that the antenna achieves a bandwidth up to 118% from 2.6 -10.1 GHz. The simulated time domain response of the antenna also shows its good performance in time-domain. The antenna can be well applied to ultra-wideband system.

An accurate and behavioral modeling method of symmetrical T-tree interconnect network is successfully investigated in this paper. The T-tree network topology understudy is consisted of elementary lumped L-cells formed by series impedance and parallel admittance. It is demonstrated how the input-output signal paths of this single input multiple output (SIMO) tree network can be reduced to single input single output (SISO) network composed of L-cells in cascade. The literal expressions of the currents, the input impedances and the voltage transfer function of the T-tree electrical interconnect via elementary transfer matrix products are determined. Thus, the exact expression of the multi-level behavioral T-tree transfer function is established. The routine algorithm developed was implemented in Matlab programs. As application of the developed modeling method, the analysis of T-tree topology comprised of different and identical RLC-cells is conducted. To demonstrate the relevance of the model established, lumped RLC T-tree networks with different levels for the microelectronic interconnect application are designed and simulated. The work flow illustrating the guideline for the application of the routine algorithm summarizing the modeling method is proposed. Then, 3D-microstrip T-tree interconnects with width 0.1 μm and length 3 mm printed on FR4-substrate were considered. As results, very good agreement between the results from the reduced behavioral model proposed and SPICE-computations is found both in frequency- and time-domains by considering arbitrary binary sequence ''01001100" with 2 Gsym/s rate. The model proposed in this paper presents significant benefits in terms of flexibility and very less computation times. It can be used during the design process of the PCB and the microelectronic circuits for the signal integrity prediction. In the continuation of this work, the modeling of clock T-tree interconnects for packaging systems composed of distributed elements using an analogue process is in progress.

This paper presents propagation measurements results using Integrated Services Digital Broadcast - Terrestrial (ISDB-T) to investigate the characteristics of 6 MHZ wideband Digital Terrestrial Television channel at 677 MHz for fixed and portable reception. Empirical measurements were done at predetermined measurement points consisting of 21 radials for a total of 92 locations extending to 20 kilometers around the National Broadcasting Network (NBN) digital transmitter. Characterizations were conducted using antenna heights of 9 m (fixed reception), 3 m (fixed reception), and 1.5 m (portable reception). Modulation Error Rate (MER), power received, field strength and delay profiles were captured to help characterize the channel in an urban area in and around Metro Manila at day time for temperatures ranging from 26°C to 32°C. Measured field strength was compared to NTC F (50, 90) curves. Polynomial fit using least square errors was used to plot the field strength coverage of NBN. For large-scale fading, it is observed that signal power conforms to Log Normal distribution. The study helped identify problem sites within the coverage. These are locations within the coverage area or at the outskirts of the coverage area where DTV signal is not received at all. A more accurate description of the DTT channel will lead to a better design of the parts of the Digital Television system from the network to transmitting system and receiving equipment. Path loss exponents computed for the three antenna heights can be helpful in developing empirical prediction models.

A compact dual band-notched Ultra-Wideband antenna with sharp band-notched characteristics and controllable notched bandwidths is presented. The antenna consists of a spade-shaped microstrip-fed Ultra-Wideband planar monopole antenna and two sets of band-notched structures. The band-notched structures are employed to generate the desired lower and upper rejection bands with good frequency selectivity and sufficient rejection bandwidths. Moreover, the bandwidth of the lower and upper rejection bands can be independently adjusted by changing the size of the band-notched structures. Finally, a UWB antenna is successfully designed with the dual notched bands for the lower WLAN band (5.15-5.35 GHz) and upper WLAN band (5.725-5.825 GHz). A good impedance match is obtained in 3.1-10.6 GHz frequency range (|S₁₁|<-10 dB), except the lower and upper WLAN band (|S₁₁| >-5 dB). The ratios of the notched bandwidths between -5 dB and -10 dB in the two stop bands are greater than 0.73.

An exact series solution for radiation and scattering of the dielectric-loaded multi-slotted cylinder with thickness is formulated by using radial mode matching technique. The radiated and guided fields are represented in terms of an infinite series of radial modes. By applying the appropriate boundary conditions, the coefficients of radiated and guided fields are obtained. The behaviors of resonance features are characterized for variation in frequencies, source positions, slot thickness, and dielectric coating properties.

Multi-refraction effects with one polarization in a two-dimensional triangular photonic crystal (PhC) were systematically studied by theoretical analysis and numerical simulation. The more complicated refraction behaviors can be excited in the higher band regions based on the intricate undulation of one band or the overlap of different bands. A novel non-handedness effect is proposed for the first time with group velocity perpendicular to phase velocity. Furthermore, triple refraction phenomena and special collimation effects of symmetrical positive-negative refraction with the loose incident conditions have been found in different band regions of this PhC. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical device.

This paper identifies an abstraction that is found in the equations that describe the 3D interaction between cuboidal permanent magnets and applies this to the magnetic design of a gravity compensator. It shows how the force between magnets and its position-sensitivity, important design parameters for magnetically levitated 6-DoF gravity compensators, may be translated into the magnetic domain and verifies this with 3D analytical models. With this information, a number of basic gravity compensator topologies is derived. These topologies are subsequently investigated in more detail, with specific focus on combining a high force with low position sensitivity.

This work studies the impact of estimating soil wave number in Underground Focused SAR imaging for tunnel detection applications. It is demonstrated that neglecting wave refraction at the ground surface results in poor underground imaging; however, by considering refraction with inexact, yet sufficiently high, estimates of soil dielectric constant, clear target images can be produced. In addition, using a wrong wave number for the soil incorrectly predicts the tunnel's depth, but gives positive identification of its transverse extent.

An integral equation formulation describing the scattered field from a distribution of optically small Rayleigh objects of arbitrary shape adsorbed onto a planar dielectric substrate is presented. When certain approximations are introduced concerning the scatterers' permittivity contrast and small size compared to the wavelength, simple closed-form expressions are obtained for the ellipticity ratio and reflectivity which can be readily related to the surface coverage and average height of the surface layer. The formulation is an alternative to thin-island film theory often used to describe electromagnetic scattering from such configurations. Results derived from the integral equation model are compared with previously published measurements of ellipticity ratio and reflectivity and are found to be in good agreement with observation.

In this paper, the properties of the omnidirectional photonic band gap (OBG) realized by one-dimensional (1D) Fibonacci quasi-periodic structure which is composed of superconductor and isotropic dielectric have been theoretically investigated by the transfer matrix method (TMM). From the numerical results, it has been shown that this OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG cease to change with increasing Fibonacci order, but vary with the ambient temperature of system, the thickness of the superconductor, and dielectric layer, respectively. The bandwidth of OBG can be notably enlarged with increasing the superconductor thickness. Moreover, the frequency range of OBG can be narrowed with increasing the thickness of dielectric layer and ambient temperature. The damping coefficient of superconductor layers has no effect on the frequency range of OBG under low-temperature conditions. It is shown that Fibonacci quasi-periodic 1D superconductor dielectric photonic crystals (SDPCs) have a superior feature in the enhancement frequency range of OBG. This kind of OBG has potential applications in filters, microcavities, and fibers, etc.

Boundary element discretizations of exterior Maxwell problems lead to dense complex non-Hermitian systems of linear equations that are difficult to solve from a linear algebra point of view. We show that the recently developed class of inverse-based multilevel incomplete LU factorization has very good potential to precondition these systems effectively. This family of algorithms can produce numerically stable factorizations and exploits efficiently the possible symmetry of the underlying integral formulation. The results are highlighted by calculating the radar-cross-section of a full aircraft, and by a numerical comparison against other standard preconditioners.

We successfully synthesized hollow AuAg alloyed triangular nanoboxes (TNBs) with localized surface plasmon resonances (LSPR) spectra position from visible to NIR region. We then study the surface plasmon properties of AuAg alloyed TNBs and explore their application in surface enhanced Raman scattering (SERS) imaging. We also investigated the laser induced near-field ablation of TNBs, which have the potentials of drug delivery for cancer treatment. Finite Difference Time Domain (FDTD) method is used to calculate electromagnetic fields induced by optical excitation of LSPR of AuAg alloyed TNBs for the first time. The calculated results are proved through in-vivo SERS imaging by three types of SERS tags based on TNBs. Furthermore, the unique hollow structure of TNBs may facilitate direct encapsulation of anticancer drugs, without any surface coatings. The femtosecond laser near-field ablation experiment is studied as one possible method to release the drug encapsulated inside the hollow structure. These studies show that the nanostructures are easy to break down and promising as a nanodevice model for controlled drug delivery.

In this paper we studied the effect of a chiral-substrate bianisotropy on the surface waves of the microstrip resonator. The effective technique used to formulate the characteristic equations of the surface waves in a medium equipped with a complex anisotropy is presented and detailed. The equations concerning an evaluation of the cut-off frequencies are given in more detailed forms. A simple approximate formula for estimating the wave number of the surface mode TM₀ and TE₁ are obtained. An estimated maximum value of chiral slab thickness without the excitation of surface waves is given. All of our original results are compared with those published in the literature.

Distance-based impedance matching networks for a tunable high frequency (HF) system are presented in this paper for the improved performance. The transmitting antenna for a HF system with an operating frequency of 13.56 MHz consists of a two-turn loop and three channel impedance matching networks corresponding to the distance of the receiving antenna. Each impedance matching network maximizes the system performance such as uniform power efficiency and reading range at specific distance between a transmitting and a receiving antenna. By controlling the distance-based matching networks, the power efficiency of the proposed antenna improves by up to 89% compared to the conventional antenna system with the fixed matching (FM) condition for distances, and the reliable reading range according to the impedance matching conditions is also increased. The proposed technique is applicable for near field communication (NFC), radio frequency identification (RFID), or wireless power transfer (WPT) devices.

In this paper, a compact planar monopole antenna with eight-band LTE/WWAN (LTE700/2300/2500/GSM850/900/1800/1900/UMTS) operation for laptop computer application is presented. This design structure comprises a bent driven strip and two coupled strips, which can contribute multiple resonance modes to combine two wide operating frequency bands covering 665-1023 MHz and 1612-2924 MHz. The proposed antenna fed by a 50-Ω coaxial cable occupies a small size of only 65(L)x11(W)x0.4(H) mm³, so it can be flexibly embedded inside the casing of the laptop computer as an internal antenna. A fabricated prototype of the antenna is tested and analyzed. Experimental results exhibit that nearly omnidirectional coverage and stable gain variation across the desirable LTE/WWAN bands can be obtained with the antenna.

In this paper, two different kinds of near-field measurement techniques are presented. The first one uses coaxial probes that do not give precise measurements on microelectronic devices. We saw in [1] that the spatial resolution of these probes reach 500 μm for monopole and is millimetric for dipole probe. The second one is based on the Pockels effect that converts an electromagnetic (EM) field into optical modulation. Our objective is to improve the Ex/Ey near-field measurement with this second technique. The performance of the electro-optic (EO) probe is compared with dipole probes of 2.5 and 5 mm with the use of simulations and measurements, on a wire above a ground plane and on coupled microstrip lines. At the end, a discussion about the technical limitations of the EO probe is made.