We report an analytical exciton emission model based on Green function for simulating the radiation characteristics of near-infrared Quantum Dot-light emitting devices (QD-LEDs). In this model the internally emitted light can be classified into the following modes: substrate, indium tin oxide (ITO)/organic waveguided, surface plasmonic modes, and external emitted mode. We investigate the influence of the thickness of different layers and the distance between the emitting center and the cathode metal on the emitted power distribution among these modes. In addition, we study the angular radiation profile for the externally emitted radiation and substrate waveguided mode in comparison with lambartian radiation profile. We show the change of the thickness of the different layers, and the positions of the emitting centers are critical to the optical performance of the device. The optimization of optical performance through device geometry increases the outcoupling efficiency more than five times.

This paper outlines typical issues in the design and fabrication of microstrip Wilkinson power dividers. As a practical solution, a modified Wilkinson divider configuration is proposed and designed for millimeter-wave antenna feeding networks. In this design, all microstrip branches and the resistive strip exhibit the same characteristic impedance. Probe measurements of Sparameters underline good matching, transmission and isolation characteristics of the proposed divider.

In order to reduce the monostatic signature of the junction between a radome and the metallic structure to which it is attached, a tapered resistive sheet can be used. In this paper, we describe an easy method to realize this tapering using geometric variations on a subwavelength scale, with a significant reduction of the number of processing steps as a result.

A novel, short-circuited, flat-plate dipole antenna for WLAN operation in the 2.4 GHz band is presented. The dipole antenna is narrow (5 mm in width) and structured to be of an L shape to fit in corners of possible wireless communications devices. The open ends of the two dipole arms are folded and face each other, so as to achieve a compact structure, and short-circuited via a short-circuiting strip, making it possible for the antenna to be cost-effectively fabricated by stamping one single metal plate only. The antenna when unbent into a flat, rectangular structure has dimensions 5 mm×47 mm and can be is easily fed by using a 50-Ω mini-coaxial cable. Details of a design prototype are described and discussed.

Considering microwaves as a viable alternative for the pasteurization of In-shell eggs, preliminary trials performed had confirmed that microwave at 2450 MHz can be successfully used to raise the temperature of in-shell eggs to the required pasteurization temperatures in a few minutes. Based on these trials a finite difference time domain (FDTD) model was developed using C language and MATLAB to simulate the E field and power distribution in lossy dielectric media like that of the egg components (egg white and yolk) taking into consideration the complex shape, dielectric properties and heterogeneous composition of the in-shell egg. This can be used to assist in the design and development of an industrial microwave in-shell eggs pasteurization unit.

In this paper the stability condition of the Runge-Kutta m-order multiresolution time-domain (RKm-MRTD) scheme has been studied. By analyzing the amplification factors, we derive the numerical dispersion relation of the RK-MRTD scheme. The numerical dispersive and dissipative errors are investigated. Finally, the theoretical predictions of the numerical errors are calculated through the numerical simulations.

Ultra wideband (UWB) Microwave imaging is one of the most promising emerging imaging technologies for breast cancer detection, and is based on the dielectric contrast between normal and cancerous tissues at microwave frequencies. UWB radar imaging involves illuminating the breast with a microwave pulse and reflected signals are used to determine the presence and location of significant dielectric scatterers, which may be representative of cancerous tissue within the breast. Beamformers are used to spatially focus the reflected signals and to compensate for path dependent attenuation and phase effects. While these beamforming algorithms have often been evaluated in isolation, variations in experimental conditions and metrics prompts the assessment of the beamformers on common anatomically and dielectrically representative breast models in order to effectively compare the performance of each. This paper seeks to investigate the following beamforming algorithms: Monostatic and Multistatic Delay-And-Sum (DAS), Delay-Multiply-And-Sum (DMAS) and Improved Delay-And-Sum (IDAS). The performance of each beamformer is evaluated across a range of appropriate metrics.

The concept of partially coherent four-petal Gaussian (PCFPG) beam is introduced and described in analytical forms. Based on the Huygens-Fresnel integral formula, average intensity and beam spreading in turbulent atmosphere are derived in analytical expressions. Effects of beam parameters and atmospheric structure constant on intensity distributions and effective beam sizes are investigated in detail, respectively. Results show that PCFPG beams carrying larger coherence lengths or higher beam orders would be less affected by turbulence. It is also indicated that, when the propagation distance increases, the PCFPG beam would convert into the Gauss-like profile sooner or later, but this degradation can be reduced by modulating beam parameters. Results in this paper may provide potential applications in free-space optical communications.

A novel wideband rectangular dielectric resonator antenna (DRA) is proposed in this paper. A hybrid structure with an isolated dielectric resonator (DR) and an equivalent air-dielectric DR is introduced by lifting the resonator from the ground plane. The hybrid structure is excited by a slot-fed mechanism to obtain a smooth transition between each resonant mode. The resonant modes of the isolated DR and the equivalent DR are merged together to form a wideband impedance bandwidth. It is found that the bandwidth of the proposed antenna can be greatly enhanced by using the hybrid DRA structure instead of the case mounted on the ground plane. A detailed parametric study is carried out to analyze the characteristics of the proposed antenna. Measured results show that the proposed DRA has a 10 dB impedance bandwidth of 61% from 2.4 GHz to 4.5 GHz and the radiation pattern is stable through the operating frequency.

A new quasi-lumped suspended-substrate stripline structure admitting implementation of miniature highly selective narrowband filters is studied. Appreciable improvement of the device selectivity is achieved with supplementary strip conductors introduced between the resonators, which induce attenuation poles near both passband edges. Furthermore, these supplementary conductors reducing the coupling between the resona-tors allow diminishing the inter-resonator spacing and the total size. A four-resonator filter is synthesized using the intelligence optimization method. Experimental results of the manufactured filter are presented.

This paper suggests a new solution for enhancing the immunity against the influence of size variation in ground on a boardintegrated GPS antenna. The original GPS antenna considered has the advantages of a simple design, low cost, and being directly integrated with the associated circuit board. Nevertheless, its performance depends on the ground of the circuit board. Without any special solution, the original antenna can withstand a ground size enlarged up to 122%, with respect to the minimal size required, for meeting the GPS specification. By using the suggested solution, the antenna can allow a ground size enlarged up to 269%. Thus, the improved antenna is more suitable for practical employment. In this investigation, various prototype antennas, with the suggested solution, were created and examined. Both simulated and measured results obtained demonstrate its promising performance stated above.

Electromagnetic wave scattering by many small particles is studied. An integral equation is derived for the self-consistent field E in a medium, obtained by embedding many small particles into a given region D. The derivation of this integral equation uses a lemma about convergence of certain sums. These sums are similar to Riemannian sums for the integral equation for E. Convergence of these sums is essentially equivalent to convergence of a collocation method for solving this integral equation. By choosing the distribution law for embedding the small particles and their physical properties one can create a medium with a desired refraction coefficient. This coefficient can be a tensor. It may have a desired absorption properties.

This paper presents a reconstruction approach which exploits the field detected by a holographic radar in order to localize and geometrically qualify a set of scattering objects. In particular, thanks to the adoption of the Kirchhoff Approximation, the problem is formulated as a linear inverse one wherein the unknown function is the characteristic function accounting for the support (location and geometry) of the target(s). The reconstruction performances of the approach have been investigated through an accurate numerical analysis, and an experimental validation has also been performed with the aim of testing the effectiveness and the practical relevance of the proposed method.

This paper uses the accurate and computationally efficient complex image technique (CIT) to find the electric field and SAR distributions inside a human head illuminated by a finite-length dipole. The human head model used consists of 3 planar layers of lossy dielectrics. The accuracy of the results is verified by comparison with HFSS software. It was found that the CIT requires about 1 minute and 16 MB of RAM, while HFSS requires about 2 hours and 1.5 GB of RAM to find the SAR distribution using a 2.19 GHz Core 2 Due PC. The CIT method can also efficiently solve other types of antennas on other planar head models.

This paper presents the design and results of a compact Ultra-wideband (UWB) monopole antenna with a dual band-notched characteristic. The antenna consists of a semi-elliptical radiator with two meandered slots on it to produce a deep notch at 3.5 GHz (the center of WiMax band) and another notch at 5.25 GHz (the center of the lower WLAN band). The antenna is fabricated and measured, and the measured impedance bandwidth defined by VSWR<2 is 8.5 GHz (2.5--11 GHz), with the dual notched bands of 3.3--3.7 GHz and 5.12--5.37 GHz are obtained. The computer simulation results of the radiation pattern and peak gain of the antenna also agree well with measurements.

In this paper, a novel nine elements array dielectric resonator antenna (DRA) is presented. The DRA was excited by a microstrip feeder with a rectangular aperture coupled slots. The slot positions were determined based on the characteristic of standing wave ratio over a short ended microstrip. The measured gain of the array DRA operating at 5.84 GHz was about 10 dBi having impedance bandwidth of 60 MHz. The proposed DRA exhibits an enhancement of the gain in comparison with a single pellet DRA. The size of the whole antenna structure is about 60 mm × 40 mm and potentially can be used in wireless systems.

It is a current need of research to extensively use the freely available satellite images. The most commonly available satellite images are Moderate Resolution Imaging Spectroradiometer (MODIS) and The Advanced Very High Resolution Radiometer (AVHRR). The problems with these images are their poor spatial resolution that restricts their use in various applications. This restriction may be minimized by application of the fusion techniques where high resolution image will be used to fuse with low resolution images. Another important aspect of fusion of different sensors data as optical and radar images (where both can provide the complimentary information), and the resultant fused image after fusion may give enhanced and useful information that may be beneficial for various application. Therefore, in this paper an attempt has been made to fuse the full polarimetric Phased Arraytype L-band SAR(PALSAR) image with MODIS image and assess the quality of fused image. PALSAR image has a advantage of availability of data in four different channels. These four channels are HH (Transmitted horizontal polarization and received also in horizontal polarization), HV (Transmitted horizontal polarization and received vertical polarization), VH (Transmitted vertical polarization and received horizontal polarization) and VV (Transmitted vertical polarization and received vertical polarization), which provides various landcover information. The curvelet based fusion technique has been applied to MODIS band 1 and 2 and PALSAR HH (HV and VV bands for assessing the effect of fusion in land cover distinction). The three major land covers agriculture, urban and water are considered for evaluation of fusion of these images for the Roorkee area of India. The results are quite encouraging, and in near future it may provide a better platform for maximize the use of MODIS images.

This research uses innovative approaches for characterizing spring probes, a final-test bottleneck applied to microwave packaging. The modeling method depends on conventional microwave on-wafer measurement. This paper compares the novel microwave 3D direct calibration and measurement to observe the issues of spring probe reliability. We makes the key component of a novel approach to 3D calibration and measurement, the double-sided thru calibration element with delay time delivers from 3D EM simulation. The current study compares the modeling method and 3D direct measurement to prove the capability of the latter and presents the reliability about compressing distance of spring probes.

The development of compact antennas plays an important role in the rapidly growing mobile communication market. This paper presents a novel design technique of the quad-band small internal antenna covering GSM-900/DCS-1800/PCS-1900/IMT-2000 bands. The innovative quad-band built-in handset antenna is developed within the limit of a 44×25×4 mm³ volume. The following document describes a new idea of increasing operational bandwidth for the compact planar inverted F antenna (PIFA). The proposed compact antenna introduces the open-end slots in the ground plane almost all under the radiating patch. The size reduction method is attractive for practical antenna implementations. In addition, the end user's hand handling effects on the performances of the proposed antenna are studied.

A 54-66 GHz sub-harmonic monolithic passive mixer using the standard 0.15 μm pHEMT process is demonstrated. The proposed mixer is composed of a hairpin diplexer, an open stub, and a low-pass filter. The mixer also utilizes a pair of anti-parallel diodes to achieve a subharmonic mixing mechanism. The hairpin diplexer formed with two parallel-coupled line band-pass filters is used to improve the isolation between the radio frequency (RF) and local oscillation (LO) ports. The low-pass filter supports an intermediate frequency (IF) ranging from dc to 1 GHz. This proposed configuration leads to a die size of less than 1.5 mm². With a conversion loss of 15.2--18.3 dB, the 2LO-to-RF isolation is found to be better than 27.5 dB. A high LO-to-RF isolation of 23.5--45 dB over 54--66 GHz RF bandwidth, as well as 1 dB compression power of 8 dBm, can be achieved.