A reconfigurable stacked patch antenna is introduced for wireless power reception and data telemetry application in sensors. The proposed antenna operates at 5.8 GHz with 9.4 dBi gain and 7.6% bandwidth. At a lower frequency 2.45 GHz the antenna operates as a planar inverted-F antenna (PIFA) with 3.3 dBi gain and 2% bandwidth. Switching between the two regimes of operation is achieved using PIN diodes. It is proposed that the antenna can be used for wireless power reception in sensors at 5.8 GHz and for data telemetry in between a sensor and a control station at 2.45 GHz. The wireless power reception ability of this antenna was tested and verified by developing a high efficiency schottky diode rectifying circuit. The RF-to-DC conversion efficiency was 85% for an input power density level of 1 mW/cm².

In this paper, we introduce a new technique for an electronic beam scanning/directivity reconfigurable which can be carried out by using a joint array of Metallic Electromagnetic Band Gap (M-EBG) sectoral antennas. This study opens new avenues of research on M-EBG sectoral antennas by combining multiple radiating elements in an array. Usually M-EBG structures are designed in passive configurations to radiate fixed/shaped beams thanks to a specific radiating aperture at the surface of the M-EBG antenna. However by opting this new technique, we are able to control the radiating aperture, and therefore provide a tunable directivity/beam pattern. The objective of the paper is to propose a solution for M-EBG antennas in order to achieve Beam Scanning and Directivity reconfigurability. The main advantage of the proposed technique is that the array have negligible mutual coupling between the radiating elements, simplifying therefore the conception of the beam-forming network and the problems of constrained beam scanning. Another objective of the paper is to be able to achieve wide angle beam scanning -/+58 degrees. This method makes it possible to obtain in a simple way an agile M-EBG antenna without the need of the expensive active electronic components. Several results show the effectiveness and the capabilities of the proposed technique.

A low frequency (50 Hz) dielectric barrier discharge (DBD) system with a single dielectric cover on copper coil anode is designed to generate and sustain the microdischarge plasma which is very practical for material processing applications. The DBD system is powered by a high tension ac source consisting of a conventional step up transformer and variac. The dielectric barriers (quartz and glass) between the conducting electrodes appreciably influences the discharge plasma characterized by optical emission spectroscopy technique. Using intensity ratio method, the electron temperature and electron number density are determined from recorded spectra as function of ac input voltage, type and thickness of dielectric barrier and inter-electrode gap. It is observed that both the electron temperature and electron number density increase with the increase in ac input voltage and ε_r/d ratio, while a decreasing trend is observed with increase in inter-electrode gap.

The 35GHz and 96GHz electromagnetic wave propagation characteristics in plasma are studied theoretically and experimentally in this paper. The variations of the incident electromagnetic wave attenuation along with the plasma density, collision frequency and electromagnetic wave frequency are acquired based on the physical model. The electromagnetic wave propagation properties in plasma are studied experimentally with the shock tube, and the experimental results match well with the theoretical ones. The theoretical and experimental results show that increasing the electromagnetic wave frequency is an alternative and effective method to solve the reentry blackout problems.

Network fade countermeasures for link budget can be better implemented based on the knowledge of seasonal variability of rainfall attenuation in a locality. Therefore, in this study, a seasonal approach is applied to estimate the effects of spatial rainfall attenuation in Durban (29^o52'S, 30^o58'E), South Africa using two-year rainfall data obtained from the RD-80 Joss-Waldvogel (J-W) distrometer. An analysis is undertaken for different seasons to obtain the rainfall rate exceedences at 0.001%, 0.01%, 0.1% and 1% of time. Consequently, rainfall drop-size distribution (DSD) models are developed for the control site at different seasons for the same period. The probability density analysis for each model indicates that the lognormal distribution best fits the summer and autumn season with percentage root-mean-square errors (RMS) of 30% and 26% respectively; gamma distribution fits winter season with RMS error of 16% and Weibull distribution fits spring season with RMS error of 26%. The results from the rainfall rate and rainfall DSD are combined to estimate the rainfall specific attenuation, by applying spherical droplet assumption for Mie scattering techniques, between 2 GHz and 1000 GHz. With this, the seasonal k and α coefficients for specific attenuation are derived from the best rainfall DSD models, using regression technique at 2.5 GHz, 25 GHz, 40 GHz and 100 GHz. At these frequencies, the results show that the predicted specific attenuation coefficients for all seasonal rainfall rates at the control site are lower, when compared to those from ITU-R models. It is concluded that specific attenuation levels may be similar and more intense in summer and autumn seasons, while, lower and less intense in autumn and winter seasons at similar rainfall rates.

This investigation is one of the first steps towards the realization of low-cost, mass producible, miniaturized antenna solutions utilizing screen printed magnetic thick films of cobalt nanoparticle ink. The ink has a curing temperature lower than 125°C, feasible printing characteristics and metal loading higher than 85 wt.%. The properties are achieved by using an oxidatively polymerising natural fatty acid, linoleic acid, both as a surfactant and a binder. DSC-TGA-MS-analysis, TEM and SEM microscopies were utilized to investigate ink composition, nanoparticle coating and print quality. The resonant frequency of a microstrip patch antenna was tuned by screen printing of cobalt nanoparticle ink with different layer thicknesses on top of the antenna element. The influence of magnetic layers on resonance frequency, return loss, total efficiency and radiation pattern was measured and compared with a reference antenna without the magnetic films. For example, five layers of magnetic film (52 μm total thickness) tuned the resonance frequency (2.49 GHz) of the patch antenna by 68 MHz. The radiation efficiency of the patch antenna was increased from 39% to 43% by the loading of a 52 μm thick magnetic film compared to the reference antenna. The radiation patterns remained essentially unchanged, despite the presence of the magnetic thick films.

The time-domain studies of the modal fields in a lossy waveguide are executed. The waveguide has a perfectly conducting surface. Its cross section domain is bounded by a singly-connected contour of rather arbitrary but enough smooth form. Possible waveguide losses are modeled by a conductive medium which fills the waveguide volume. Standard formulation of the boundary-value problem for the system of Maxwell's equations with time derivative is given and rearranged to the transverse-longitudinal decompositions. Hilbert space of the real-valued functions of coordinates and time is chosen as a space of solutions. Complete set of the TE-time-domain modal waves is established and studied in detail. A continuity equation for the conserved energetic quantities for the time-domain modal waves propagating in the lossy waveguide is established. Instant velocity of transportation of the modal flux energy is found out as a function of time for any waveguide cross section. Fundamental solution to the problem is obtained in accordance with the causality principle. Exact explicit solutions are obtained and illustrated by graphical examples.

The reflection and transmission of electromagnetic waves obliquely incident on a uniaxial chiral slab with the optical axis perpendicular to the interface have been investigated. Firstly, the formulas of the reflection and transmission are derived. Then numerical results for four cases of the uniaxial chiral media are presented and different chiral parameters are considered. Finally, the Brewster's angles and total transmission are discussed.

A novel extremely wide band dipole antenna with omni-directional radiation patterns is investigated experimentally and numerically. The proposed antenna comprises two groups of crossing semicircular discs. The shape of each disc is modified to broaden the working bandwidth. Measured results demonstrate that the novel antenna possesses good impedance match from 0.45 to 38.9 GHz for S₁₁ lower than -10 dB, in good agreement with simulated results. Omni-directional radiation patterns keep stable within the operating band. The proposed antenna is highly suitable for various wide band systems.

Traditional optimization methods are not well suited for thinning large arrays to obtain a low sidelobe level (SLL). The chaotic binary particle swarm optimization (CBPSO) algorithm is presented as a useful alternative in the synthesis of thinned arrays. The proposed algorithm is improved by nonlinear inertia weight with chaotic mutation to increase the diversity of particles. Two examples have been proposed and solved. Simulation results compared with published results illustrate the effectiveness of the proposed method for both linear and planar arrays.

Although a Coherent Transponder (CT) is widely utilized in the field of Synthetic Aperture Radar (SAR), its Digital Elevation Model (DEM) has yet not been well studied for Interferometry SAR (InSAR). Based on the fact that the interferometry phase is a constant for CT with single transmit antenna, this paper mainly focuses on InSAR DEM induced by CT. The decorrelation effect in the intersection region of CT and nature terrain is researched in detail to support the analysis of CT's phase-unwrapping. The most important property, which makes DEM of CT being unique, is found to be the "slope" effect. The incline angel of "main slope" of DEM is verified to be determined only by the depression angle of InSAR system, whereas the incline angles of the "subordinate slopes" are affected by all the geometric parameters of InSAR baseline. Finally, all the incline angels are independent of CT' s waveform modulations, since the modulations have no contribution to the interferometry phase.

Multiple signal classification (MUSIC) algorithm has been applied to localize small scatterers for super-resolution imaging. A problem associated with this application is the estimation of the number of scatterers in presence of noise and multiple scattering between targets. In this paper, we show that the mathematical model behind the scattering from the small objects is well compatible with the minimum description length (MDL) model. This leads us to use the MDL so as to estimate the number of scatterers before application of the MUSIC algorithm. As the MDL assumes the sources are independent, the nearby wave sources are grouped together to improve the independency criterion. The application of MDL to synthetic and experimental data verifies accurate estimation of the target number with low complexity, even if the data embodies significant noise and multiple scattering.

A high performance balun bandpass filter (BPF) with very simple structure is proposed in this letter, this structure realizes superior performance in bandpass filtering meanwhile with good differential performance of the balun. The proper balanced outputs and BPF characteristic by the symmetric feeding and skew-symmetric feeding have been obtained, and the theory of this simple structure for unbalanced input to balanced outputs has been studied. The center frequency of the fabricated balun-BPF was operated at 2.4 GHz with 5.8% fractional bandwidth (FBW), and this frequency is used for Bluetooth and some other communication systems. The differences between the two outputs are 180° ± 5° in phase and within 0.39 dB in magnitude. At f₀, the amplitude imbalanced and phase difference are within 0.37 dB and 179.2°, respectively. The measured frequency responses agree well with the simulated ones. With the theoretical analyses and practical results, it is shown that the proposed one has the advantages of simple structure, convenient analysis and good performance of both BPF and balun.

An array of conformal antenna structures mounted on a bending surface exhibits a substantial shift in main beam direction. This paper demonstrates a method to compensate for the induced beam shift by using the change in length of the surface produced by the bend. This change in length modifies the capacitance in a composite right/left-handed transmission (CRLHTL) line, causing a phase shift in the line. A potential implementation is proposed that can correct an 18º beam shift with only an induced change in length of 0.144%. The paper establishes that this passive compensation concept is feasible and provides significant benefits over active compensation systems in terms of weight reduction, cost, simplification and the ability to operate in radio silence.

A coplanar rectangular slot antenna operating in the very wide frequency band from 0.27 to 3.1 GHz (bandwidth over 166%) has been designed for GPR applications. The antenna, which is supposed to be positioned on the soil surface, appears particularly compact (34 x 29 cm²) and exhibits a low cross-polarization in the E-plane. 3D FDTD simulations have allowed to make a detailed parametric study associated with the antenna dimensional parameters in order to optimize the radiating performances. The slot antenna has also been studied with a shield to be further integrated in a bistatic subsurface radar positioned on the soil surface. Simulated results of the link in the presence of a homogeneous soil then including buried objects met in civil engineering structures are presented and discussed. First experimental results on a sandy soil have been compared to numerical ones.

We report the transmission response of generalized Fibonacci photonic crystal F_l(m,n) in microwave domain for normal incidence, where l is the generation number, and m and n are parameters of the Fibonacci distribution. The transmission spectra are calculated through the transfer matrix method and studied by varying the Fibonacci parameters. The structure is exploited to design a microwave mirror with large photonic band gap and polychromatic stop band filters. Therefore, other structure configurations based on the generalized Fibonacci system are proposed. A juxtaposition of p multilayer systems built according to Fibonacci distribution [F_l(m,n)]^p makes possible to have switches like property (off-on-off-on-off-on-…). Then, an hybrid structure which is obtained by sandwiching p stacks of generalized Fibonacci photonic crystal between two periodic photonic crystals is proposed to enlarge the photonic band gap in microwave domain.

A compact ultrawideband (UWB) monopole antenna with two U-shaped slots for WLAN and WiMAX dual band-notched functions is proposed and experimentally studied. The proposed antenna with the size of 28 mm×24 mm×1.6 mm is excited by a 50Ω microstrip feed line. The band-notch functions are realized by loading two approximate half-wavelength U-shaped slots which change the current distribution on the Y-shaped patch. The obtained results show that the designed antenna has an impedance bandwidth of 2.95 GHz-12 GHz for S₁₁ ≤ -10 dB, except two frequency stop-bands of 3.32 GHz-3.98 GHz for WiMAX and 4.81 GHz-6.68 GHz for WLAN. The antenna has successfully fabricated and measured. The return loss, band-notched characteristic, radiation patterns and peak gains are presented.

A family of miniaturized substrate integrated waveguide (SIW) dual-mode filters with a series of cross-slot structures etched on the waveguide surface are investigated and presented. By introducing the series of cross-slot structures: pure cross-slot, T-shaped loaded cross-slot and H shaped loaded cross-slot in original dual-mode SIW filters, size reductions of 22.15%, 30.56% and 56.25% are achieved, respectively. Moreover, the proposed family of SIW dual-mode filters can produce two controllable transmission zeros. Compared with SIW dual-mode filters in references and original filter, proposed filters exhibit compact size while retain good performance of bandwidth and minimum insertion loss. To verify the presented design, three SIW dual-mode filters are fabricated on the standard printed circuit board process. The measured results are in good agreement with the simulation.

This paper presents a novel 377 Ω rectangular stepped patch antenna with partial ground plane at downlink radio frequency range of GSM-900 band. Two steps are incorporated into the patch antenna, and bandwidth expansion was investigated by the currents flowing through the patch antenna. The antenna simulation was carried out in the ADS 2009 environment. The fabricated antenna on FR4 substrate indicates an impedance bandwidth of 32.7% (310 MHz) at 947 MHz centre frequency with return loss of -28.12 dB. The simulated, test and field results of the antenna design are discussed.

The authors discuss and demonstrate the feasibility of using ultra wide band microwave radar to detect and identify small arms fire. Detection and tracking is by standard radar techniques, but identification is carried out by exciting the projectiles Complex Natural Resonances and using this aspect independent information to assign a caliber to the incoming projectiles. The typical sizes of small arms projectiles (calibers 5.56 mm through to 13 mm) imply that ultra wide band illumination in the microwave region of the spectrum between 1.5-5.5 GHz is required to excite these object's fundamental resonances. The authors give a discussion of the effects of motion on the quality of the complex natural resonance data obtainable and present both simulated and laboratory data for the radar cross section of three different caliber projectiles (5.56 mm, 7.62 mm and 13 mm).