A novel multi-state RF MEMS switch for microstrip antenna applications is presented. The proposed switch exhibits seven different states of operation, has a very simple DC biasing mechanism and can be integrated with antenna structure. Based on these properties, this switch may find its usage in multifunction reconfigurable antennas. To exhibit this application, it is employed in the reconfiguration mechanism of a U-slotted antenna. In different states of the switch, the antenna resonates at different frequencies. All the standard frequency bands of the wireless communication services with some additional frequency bands is covered with this reconfigurable U-slotted antenna. Moreover, the proposed antenna structure is a cost-effective solution since it comprises a commonly used FR4 substrate. The switch is integrated with antenna structure on the same substrate. A prototype of the designed antenna was fabricated and tested for performance verification of the proposed switch and antenna.

The range profile (RP) of an automobile is derived by compressing the wideband radar signal, and it can be utilized for the classification and thus contribute to lane change and collision avoidance. However, the limited radar bandwidth due to the cost and the system complexity impedes the successful classification. This paper proposes an efficient method to construct an efficient feature vector of the automobile RP through combined use of the central moment, the information on the maximum-minimum and the peak information. Simulation results using the five automobile models composed of point scatterers and a simple nearest neighbor classifier prove that the proposed method improves the classification result, especially in the multi-aspect classification.

This paper proposes a coupling model of the Quasi-Continuous High Magnetic Field (QCHMF) systems that incorporates the electrical, thermal and mechanical dynamics of the magnet system and the power supply system. The design of QCHMF systems is formulated as a five-objective optimization problem and a scoring system based on preference of the designer is adopted to classify the Pareto points of the optimization problem. An optimized mono-coil 50 T/100 ms QCHMF system is designed with a 67.5 MW rectifier of the Wuhan National High Magnetic Field Center (WHMFC), which is taken as an example to verify the proposed model and optimization method. Detailed simulation models of the optimized QCHMF system are built in Matlab and Comsol and the results agree well with the designed technical specifications. The proposed model and optimization method are generic which can be applied to other QCHMF systems with minor modifications.

When using ultra-wide band (UWB) radar to detect targets in various conditions, identifying whether the target buried under building debris or in bad visibility conditions is a human or an animal is crucial. This paper presents the application of the wavelet entropy (WE) method to distinguish between humans and animal targets through brick wall and in free space at a certain distance. In the study, WE, WE change, and WE of the related range points were estimated for the echo signals from five humans and five dogs. Our findings indicate that the entropy or degree of disorder in the energy distribution of the human target was much lower than that of the dog, and the waveform of the human's entropy was smoother than that of the dog. In addition, the body micro motions of humans are much more ordered than those of dogs. WE can be employed as a quantitative measure for recognizing invisible targets and may be a useful tool in the UWB radar's practical applications.

This paper analyzes the azimuth spectrum folding problem which arises from the dependence of the Doppler centroid on range frequency in squinted spotlight synthetic aperture radar (SAR). Based on the analysis, a novel approach for squinted spotlight SAR is proposed in this paper. In this approach, an azimuth preprocessing step including a deramping operation and an operation of azimuth spectrum replicating and filtering is introduced to eliminate spectrum folding problem. Then, a modified Range Migration Algorithm (RMA) is adopted to process the preprocessed data. This approach extends the focusing capacity of traditional two-step processing approach from broadside spotlight SAR to squinted case. Moreover, this approach is e±cient due to a limited azimuth data extension to resolve the spectrum aliasing problem. Experimental results on simulated raw data validate the proposed approach.

A novel compact microstrip-fed planar monopole antenna with quad-notched bands is presented. The proposed antenna is based on one rectangular-stepped-patch. To achieve the higher resonance over the 12 GHz, one lateral L-shaped structure is embedded in the ground. By inserting four U-shaped slots in the radiation patch, quad band-notched properties in the WiMAX (3.3-3.6 GHz), INSAT(4.5-4.8 GHz), lower WLAN (5.15-5.35 GHz) and higher WLAN (5.725-5.825 GHz) are obtained. Experimental results indicate that the designed UWB antenna can obtain broadband matched impedance values, good frequency selectivity over the notched bands, relatively flat group delay and nearly omni-directional transmission characteristics across the UWB frequencies. More importantly, the quad-notched bands can be reconfigurable by shorting the corresponding U-shaped slots.

An analysis method for electromagnetic field coupling to microstrip line connected with nonlinear components is proposed in this paper. Different from the published work, not only the voltage and current response of the nonlinear component connected to the transmission line (TL) can be obtained, but also the power transmitted from this nonlinear component to the next one at both the fundamental frequency and harmonics can be predicted. The proposed method suitably combines the classical field-to-TL coupling theory and the nonlinear large-signal scattering parameters on the basis of a black box model in frequency-domain. Then this method is experimentally validated by a laboratory system including a microstrip line connected with a simple nonlinear component constituted by the anti-paralleled HSMS-282C Schottky diodes pair welded to a 50 Ω microstrip line. The calculated results using the proposed method show good agreement with the measured data.

Directional and switched-beam antennas in wireless sensor networks are becoming increasingly appealing due to the possibility to reduce transmission power and consequently extend sensor node lifetime. In this work a reconfigurable beam-steering antenna is proposed for Wireless Sensor Network applications in the ISM band (f=2.4-2.4835 GHz). The proposed radiating structure consists of a vertical half-wave dipole antenna and eight microstrip antennas composed of a rectangular two-element patch antenna array. These microstrip antennas have a directional radiation pattern in the azimuth plane with a HPBW of nearly 60 degrees. A control circuit consisting of a transmission line, RF-switches and a 4:16 multiplexer has been designed in order to dynamically switch among nine radiation patterns, eight directional and one omnidirectional. Simulations and experimental results, referred to a low-cost realization on a FR4 substrate with a thickness of 1.6 mm, demonstrate appreciable performance.

In this paper, a novel power divider integrated with substrate integrated waveguide (SIW) and defected ground structures (DGS) techniques is proposed to provide both power dividing and filtering functions. The SIW technique holds advantages of low profile, low-lost, mass-production, easy fabrication and fully integration with planar circuits. By integrating with defected ground structures (DGS) technique, the size and cost of system can be effectively reduced as the proposed power divider has a function of filtering which leads to reduction of one filter. In order to verify the design approach, the proposed power divider with equal power divisions at the center frequency of 8.625 GHz is fabricated and measured. The measured results demonstrate that the insertion loss is less than 1.2 dB and the input return loss less than 16 dB across the bandwidth of 1.4 GHz (FBW is 16%). Moreover, the imbalances of the amplitude and phase are less than 0.3 dB and 0.5 degree, respectively.

It has been known through some examples that parameters of an electromagnetic medium can be so dened that there is no dispersion equation (Fresnel equation) to restrict the choice of the wave vector of a plane wave in such a medium, i.e., that the dispersion equation is satised identically for any wave vector. In the present paper, a more systematic study to define classes of media with no dispersion equation is attempted. In addition to the previously known examples, a novel class of Case 1 media with no dispersion equation is seen to emerge through the analysis making use of coordinate-free four-dimensional formalism in terms of multivectors, multiforms and dyadics.

D′B′, DB′ and D′B boundary conditions are used to investigate the resulting field patterns inside a parallel plate waveguide. The D′B′ boundary conditions are accomodated by assigning the behavior of perfect magnetic conductor (PMC) for transverse electric mode (TE) and that of perfect electric conductor (PEC) for transverse magnetic (TM) mode, to the boundary, respectively. Likewise, DB′ boundary conditions are incorporated by assuming the behavior of boundary as PMC for both the TE mode and TM mode. Finally D′B boundary conditions are realized by assigning PEC characteristic to the boundary for both TE and TM modes. A general wave propagating inside the parallel plate waveguide is assumed and decomposed into TE and TM modes for the purpose of analysis. Fractional curl operator has been used to study the fractional parallel plate D′B′, DB′ and D′B waveguides for different values of fractional parameter α. Behavior of the field patterns in the waveguides are studied with respect to the fractional parameter α describing the order of the fractionalization.

This paper presents two novel designs of truncated rhombus-like slotted antenna (TRLSA) based on aperture-coupled feeding technique. In conventional antennas, different patch dimensions are required to accommodate different frequencies which normally result in bigger antenna structures. Therefore, this paper proposes a unique structure of `zig-zag' slot embedded on two different antennas to achieve two different resonant frequencies but of the same patch dimensions. An analysis on design transformation which includes comparative simulation results of two reference antennas and TRLSAs has also been presented to provide better understanding on the design concept. CST Microwave Studio software has been used for design simulations and optimizations. The simulation and measurement results of TRLSAs are also presented. The results confirm that the antennas can operate at two different frequencies, 5.3 GHz and 5.8 GHz with the same patch dimensions by integrating the "zig-zag" slot at two different orientations in x- and y-axis respectively. Hence, size reduction is achieved for lower frequency patch which gives a great advantage for future development of a frequency reconfigurable antenna in an array configuration.

In this paper, a miniaturized wideband bandpass filter utilizing a square ring resonator and loaded open-stubs is proposed. One pair of bent open-stubs characterized as perturbations is installed outside the diagonal corners of the ring, and another pair of loaded open-stubs is added inside the ring resonator. By stretching the perturbation stubs more than half-wavelength of the ring, three pairs of degenerated modes in a ring are split for wideband operation. The first two split modes form the dominant passband. Meanwhile, the loading effect introduced by the loaded open-stubs could move the third split mode into the dominant passband, at the same time, an additional transmission zero is generated by the loaded open-stub, which improves the skirt selectivity. Due to the applying of the perturbation stubs as long as more than half-wavelength, this kind of wideband microstrip ring resonator filter occupies a smaller size than those conventional ones that based on ring resonator. To verify the mechanism above, a wideband bandpass filter centered at 3.5 GHz is designed, implemented, and fabricated. Measured results of experimental circuit show good agreement with simulated responses.

We systematically study the Cherenkov optical emission by a nonrelativistic modulated source crossing 3D dispersive metamaterial. It is found that the interference of the field produced by the modulated source with the periodic plasmonic-polariton excitations in a metamaterial leads to the specific interaction in the frequency range where the dispersive refractive index of a metamaterial is negative and the reversed Cherenkov emission is generated. Such resonance considerably modifies the spatial structure of the Cherenkov field. In our study parameters of a metamaterial and modulated source are fixed while the frequency spectrum of the plasmonic excitations is formed due to the fields interplay in the frequency domain.

A novel inductively loaded monopole for current and future ultra-wide-band (UWB) applications is presented. The antenna is compact and of small size (16 mm×20 mm×0.8 mm), and offer a very simple geometry suitable for low cost fabrication and straightforward printed circuit board integration. More specifically, the impedance matching of the classic printed loop loaded monopole is improved by employment of the tapered microstrip feed line between K-connector and the printed monopole. By using this technique, impedance bandwidth (S₁₁ < -10 dB) from 3.03 GHz to over 40 GHz is obtained. Measured and simulated return losses curves are provided along with radiation patterns and gain, as a function of frequency. Compared to the recently reported UWB antennas, the presented antenna have smallest size, widest bandwidth, and simple configuration to realize the application in current and future UWB communication systems. Furthermore, a symmetric radiation patterns and satisfactory gain make the presented antenna a suitable candidate for practical UWB applications.

We study the current distribution and input impedance of a circular loop antenna in the form of an infinitesimally thin, perfectly conducting narrow strip coiled into a ring. The antenna is located on the surface of an axially magnetized plasma column surrounded by a homogeneous isotropic medium. The current in the antenna is excited by a time-harmonic voltage creating an electric field with the azimuthal component in a gap of small angular opening on the strip surface. The emphasis is placed on the solution of the integral equations for the azimuthal harmonics of the antenna current in the case where the magnetoplasma inside the column is nonresonant. The properties of the kernels of the integral equations are discussed and the current distribution in the antenna is obtained. It is shown that the presence of a magnetized plasma column can significantly influence the electrodynamic characteristics of the antenna compared with the case where it is located in the surrounding medium or a homogeneous plasma medium the parameters of which coincide with those inside the column.

Eggs are one of the most nutritious foods available in nature. This rich nutritive environment attracts microbes to invade, feed and multiply. Salmonella enteritidis is one such microbe that is highly pathogenic and is the causative agent for the disease salmonellosis. To ensure safety of eggs, processing them without affecting their unique physical properties is essential. In this study, the impact of radiofrequency (RF) heating on the dielectric properties (dielectric constant and dielectric loss factor) of the egg at varying temperatures (5°C-56°C) and frequency (10 MHz-3 GHz) is evaluated. This study on the dielectric parameters is essential to devise a better heating paradigm wherein there is minimal detrimental effect to the egg components. Based on the dielectric study, the heating process parameters were determined. The effect of such heat treatment on the physical properties viz. Viscosity, foam density, foam stability and turbidity of the egg white were also studied. This study was conducted to provide sufficient literature and experimental background for employing RF in pasteurization of in-shell eggs. This study showed that if careful process parameter optimization and meticulous equipment design is done, RF heating can be successfully employed to pasteurize in-shell eggs.

Three hexagonal patch antennas are designed for circular polarization and experimentally validated. These antennas are labeled; simple hexagonal patch, hexagonal patch with slotted ground and hexagonal patch with parasitic element. The measured impedance bandwidths of the three antennas are 2% for the simple patch, 5.2% for the patch with slotted ground and 6.35% for the antenna with parasitic element. The axial ratio (measured) obtained is 4.73% for the patch with slotted ground and 3.33% for the hexagonal patch antenna with parasitic element. The measured radiation patterns of these antennas are found to be in good agreement with the simulated radiation patterns. The average gain of all the three antennas is also evaluated. A frequency selective surface (FSS) is proposed with dimensions smaller than that of a conventional FSS structure. The measured gain improvement with the proposed FSS is around 3 dB in the operating band.

In this paper we present designs of fibersμ having non-zero positive, non-zero negative and near-zero ultra-flattened dispersion with small dispersion slope and ultra-large effective area over a wide spectral range. The designs consist of a concentric multilayer segmented core followed by a trench assisted cladding and a thin secondary core. The central segmented core helps in maintaining desired dispersion over a wide range of wavelength. The second core of the fiber helps in achieving ultra-large effective area and trench assisted cladding reduces the bending loss. The designs of the fiber have been analyzed by using the transfer matrix method. For positive non-zero dispersion flattened fiber we have optimized dispersion near +4.5 ps/km/nm in the wavelength range 1.46-1.65 μm. Maximum value of dispersion slope of the fiber in above mentioned wavelength range is 0.026 ps/km/nm². In the design of negative non-zero dispersion flattened fiber, dispersion has been achieved near -6 ps/km/nm in the spectral range of 1.33-1.56 μm and maximum value of dispersion slope is 0.048 ps/km/nm². Dispersion and dispersion slope of near zero dispersion flattened fiber lie in the range [0.0039-0.520] ps/km/nm and [(0.0004)-(0.0365)] ps/km/nm² respectively in the spectral range of 1.460-1.625 μm. The near zero dispersion flattened fiber has an ultra-high effective area ranging from 114 μm² to 325.95 μm² in the aforementioned wavelength range, which covers the entire S+C+L-band. These values of mode area are noticeably higher than those reported in literature for flattened dispersion fibers with large mode area. Designed fiber show very small bending loss. We report breakthrough in the mode area of the single mode optical fiber with ultra flattened dispersion and low dispersion slope.

Electrical equipments usually radiate unintended emission which carries characteristic information when running, such as emanation from computers monitors, keyboards and other components, this emanation can be possibly used to reconstruct the source information. Most of the experiments related to this area are carried out inside a semi-anechoic chamber, and measurement out of it may not be considered to be optimal, because the data captured are usually not sufficient. Yet in this study, we take LCD monitors as typical examples and find that characteristics significantly differ between products, parameters such as the magnitude and spectrum were measured under normal environment. We take the PCB traces as antennas and acquire the raw signal directly near the antenna and extract the parameters to use as input to support vector machine (SVM) which was trained to identify the emanating source(LCD monitors). In this study, the method was tested using the emission captured from one Samsung (SyncMaster E1920) and two LG (L1753s) monitors, and a laptop(ACER Aspire 5542). The SVM was able to classify the source of signals with 98.9510% accuracy while using emission that captured from the running monitors.