A compact planar ultra-wideband (UWB) antenna with triple band notch characteristics is proposed in this paper. The antenna consists of a rectangular radiating patch and a modified partial ground plane, and has an overall dimension of 24 mm × 22 mm. Three resonant elements are placed above the ground plane to generate three notch frequency bands separately in the WiMAX, the lower WLAN and the upper WLAN frequency bands. The proposed antenna successfully simulate, prototyped and measured. Effects of the key deign parameters on band notch characteristics are also investigated. The realized antenna achieved an operating bandwidth (VSWR ≤ 2) ranges from 2.9 to more than 11 GHz with triple notched bands of 3.26-3.71 (12.9%), 5.15-5.37 (8.5%), and 5.78-5.95 (2.9%) GHz. Measured flat transfer function and constant group delay within the operating band except at notched bands makes the proposed antenna suitable for being used in practical UWB applications.

With the development of China's Compass Navigation Satellite System (CNSS), the demand for terminal antennas is quite urgent. In CNSS system, dual-band antennas are more attractive, because they can provide both the navigation and communication functions. In addition, since the `BEIDOU' antennas operate at low frequencies, they are not easy to be installed due to their usually large volumes, limiting their practical application. In this paper, we present a dual-band miniaturized CNSS microstrip antenna based on high-permittivity ceramic substrate. This antenna works at S Band (2492 MHz±5 MHz, right-handed circular polarization, RHCP) and L Band (1616±5 MHz, left-handed circular polarization, LHCP). Numerical results show that the impedance bandwidth (S₁₁<-10 dB), 3 dB axial ratio bandwidth and antenna gain at L Band are about 26 MHz, 6.5 MHz and 3.22 dB, respectively. While the impedance bandwidth (S₁₁<-10 dB), 3 dB axial ratio bandwidth and antenna gain at S Band are about 127 MHz, 28 MHz and 4.72 dB, respectively. An experiment was carried out to verify our design and the measured results agree well with the simulation ones. In addition, by using high-permittivity ceramic (ε_r=16) as the substrate, the antenna keeps its performances with a reduced size by 80% comparing with the conventional ones using low-permittivity substrates. This makes it suitable for practical applications.

A compact quad-band rectangular wide-slot antenna is developed for GPS L1 band, 2.5/3.5/5.5 GHz WiMAX and 2.4/5.2/5.8 GHz WLAN applications. The planar antenna consists of an L-shaped microstrip feed line and three stubs extending from the wide-slot on the ground plane. The performance of the antenna is enhanced by etching meander line on the top of the wide-slot. The proposed antenna has a size of 36*42*1 mm³ which is more compact than the previously reported antennas for the same application. The antenna has been simulated, fabricated and measured successfully. The measured results show that the antenna has the impedance bandwidths of 160 MHz (1.54-1.7 GHz), 380 MHz (2.38-2.76 GHz), 570 MHz (3.2-3.77 GHz) and 1130 MHz (5.12-6.25 GHz) for S₁₁ ≤ -10 dB. In addition, good radiation characteristics and stable antenna gains over the operating bands are obtained.

In this paper, dielectric characteristics of female breast tissues were measured. Breast Tissues were mainly composed of fat, fibro-glandular and tumor. Measured tissues were directly extracted from mice and a rat just before the measurements to maintain the tissues as fresh as living ones before degeneration. This makes the measured results more accurate. Because the extracted tissues were very thin, they were measured by two methods using HP probe and a newly designed two-port sample holder. Numerical results for the two-port sample holder were obtained for both the forward and inverse problems. Dielectric properties of breast tissues were measured in the frequency range between 50 MHz and 5 GHz. We calculated the electrical constant with the measured data from the two-port sample holder. As a result of the measurement, the dispersion characteristics of the female breast tissues were fitted into the first Cole-Cole model.

In bistatic synthetic aperture radar (SAR) with one stationary station, two-dimensional spatial variance is a major problem which should be handled. In this paper, an Inverse Scaled Fourier Transform (ISFT) imaging algorithm to deal with this problem is proposed. The approach linearizes the two-dimensional spatiallyvariant point target reference spectrum to derive the reflectivity pattern's spectrum. Based on this spectrum, an ISFT along range direction and a frequency shift along azimuth direction are used to achieve the two-dimensional spatial variance correction. This method is efficient as it only uses phase multiplication and FFTs. Numerical simulations verified the effectiveness of the method.

In this paper, we have investigated the marginal moment generating function (MMGF) for the correlated Nakagami-m fading channel by using maximal-ratio combining (MRC) diversity scheme at receiver for the computation of the channel capacity for various adaptive transmission schemes such as: 1) optimal simultaneous power and rate adaptation, 2) optimal rate adaptation with constant transmit power, 3) channel inversion with fixed rate, and 4) truncated channel inversion with fixed rate. The effects of diversity receiver as well as correlation coefficients on all these transmission schemes are discussed and the channel capacity obtained by this proposed approach for all schemes is compared with reported literature.

An analysis for circularly-polarized (CP) ring slot antennas fed by a coupling strip with resistive loading is presented. By treating the antenna as a two-port circuit, the amplitudes and phases of two orthogonal modes excited from the slot antenna can be found and expressed in terms of the S parameters of the circuit. The axial ratio calculated through the S parameters has a good agreement with that obtained from the pattern simulation of IE3D. The effects of varying key parameters of the coupling strip on the amplitudes and phases of the dual orthogonal modes are investigated in detail.

Wideband Circularly polarized antenna receive much attention in the wireless communication applications such as Global positioning system (GPS) and Personal communication system (PCS). In this paper, a microstrip square patch, truncated in opposite corners, suspended above the ground plane is proposed. The geometry incorporates the capacitive feed strip which is fed by a coaxial probe. The proposed structure is designed, simulated and fabricated to cover the entire frequency of GPS, i.e., L₁ (1.575 GHz), L₂ (1.227 GHz), and L₅ (1.176 GHz), covering from (1.15 GHz-1.6 GHz). The parameters such as return loss, VSWR, impedance, radiation efficiency axial ratio and radiation pattern are used for analyzing the performance of the antenna. Both simulated and experimental results are presented and they exhibit broadband characteristics, covering the desired frequency bands.

A new multilayer power divider with Substrate Integrated Waveguide (SIW) technology is proposed. In this work, two-way and four-way power dividers realizations by two-layer and three-layer SIW, respectively, are presented. Considering the small size of the structure, extension of this method to n-way power dividers and antenna feed networks are possible, and it has the potential for integration of compact multi-layer SIW circuits. Due to the lack of a multiport counterpart of the two-port thru-reflect-line (TRL) calibration, scattering matrix of an n-way power divider must be reconstructed from measured data. A method is introduced for reconstruction of S-parameters of the n-port noncoaxial device with a two-port vector network analyzer (VNA). The two-way power divider is designed for 8.7-10.5 GHz band. Transmission coefficient about -3.5 dB and return loss below -10 dB has been measured for this two-way power divider. For four-way power divider, transmission about -7 dB in the 9.5-10.5 GHz has been achieved.

A dielectric resonator loaded patch antenna excited by a coaxial cable is proposed in this paper. The results from measurement show a wide impedance bandwidth of 57.1% from 3.75 GHz to 6.75 GHz and a peak gain of 11.5 dB at the center of frequency band with an average gain improvement of 3 dB over the frequency band in comparison with the common dielectric resonator antennas. These results are in good agreement with those obtained by the computer simulations. A simple study of the antenna shows that the aperture size increase is the cause of gain enhancement. A theoretical model based on the simulated gain results of reference antenna and its equivalent aperture is presented for the proposed antenna structure with good agreement with simulation and measurement results. The advantages of the proposed antenna are high gain with broad bandwidth, and low fabrication cost in comparison to other types of high gain DRAs having narrow bandwidths and complex structures.

It has been demonstrated in previously published results that large fourth Stokes parameter may be generated from a rough surface over multi-layered media, where only the top interface is rough while the others are all flat boundaries. In this paper, we consider the four Stokes parameters in microwave emission from a two-layer rough surface. In this case, there are two rough boundaries. The rough surfaces vary in one horizontal direction so that the azimuthal asymmetry exists in the 3-D problem. Periodic boundary conditions were assumed. The results are compared with the previously published results from a rough surface over multi-layered media. It is shown that the ``two-layer'' periodic rough surfaces can reduce the vertical and horizontal brightness temperatures remarkably; the interactions between the two rough surfaces also enhance the third and fourth Stokes parameters, which disappear in new structure for the large dips in the vertical and horizontal brightness temperatures presented in the former Sastrugi structure. In particular, the fourth Stokes parameter can be larger than that in previous layered structure. In addition, for the case of sinusoidal rough surface without large slope with snow's permittivities, the top boundary rough only layered structure cannot support the large third and fourth Stokes parameters any longer while the two-layer rough surface structure can do still up to -34 K and 15 K, respectively. It is also found that the reason resulting in the large fourth Stokes parameter is caused by relative magnitude of permittivities of the two layers, all cases with large fourth Stokes parameter should satisfy the upper layer's permittivity larger than the lower one due to total internal reflection from the lower layer.

Uncertainties in an electromagnetic observable, that arise from uncertainties in geometric and electromagnetic parameters of an interaction configuration, are here characterized by combining computable higher-order moments of the observable with higher-order Chebychev inequalities. This allows for the estimation of the range of the observable by rigorous confidence intervals. The estimated range is then combined with the maximum-entropy principle to arrive at an efficient and reliable estimation of the probability density function of the observable. The procedure is demonstrated for the case of the induced voltage of a thin-wire frame that has a random geometry, is connected to a random load, and is illuminated by a random incident field.

ΛOptical bistability (OB) behavior of a Kobrak-Rice 5-level quantum system is investigated. It is demonstrated that the OB of the system can be controlled by either the intensity or relative phase of driving fields. We have also shown that by applying an incoherent pumping field, the OB behavior of the system changes and the considerable output is obtained for zero input in the gain region induced by incoherent pumping field.

Low speed flux-modulated permanent magnet machines (FMPMs) which are based on `magnetic-gearing effect' have attracted increasing attention due to their high torque capability and simple structure. In order to assess the potentials of FMPMs in the application of low-speed direct-drive, two flux-modulated interior PM machines with distributed windings and concentrated windings are quantitatively compared by using finite element method. The results demonstrate that the machine with distributed windings can offer higher peak electromagnetic torques and lower torque ripples. Moreover, the machine with distributed windings also present stronger flux-weakening capability and lower power losses. The results also indicates that the magnetic saturation problem should be paid full attention when design flux-modulated interior PM machine with concentrated windings. If this problem can be well solved, the performance of machine with concentrated windings may be improved.

Two novel compact magic-T configurations designed as a two layer structure are proposed in this paper. They consist of a microstrip tee-junction and resonance circuit composed of a microstrip line combined with rectangular or radial stubs. These microstrip circuits are respectively printed at the top and bottom layers of the structure, and coupled via a slot located in the common ground plane. The microstrip patch and slot are placed parallel to each other forming novel microstrip-slotline transitions, which provide broadband operation of the magic-Ts. Transmission line equivalent circuits are used to explain the performance of the proposed hybrids. It is shown that magic-T with a radial stub demonstrates wider operation bandwidth and better performance than the structure with a rectangular stub. In order to validate their performance, the prototypes of both configurations were manufactured and measured. Experimental and simulation results show that the resulting magic-T using a radial resonator has a fractional bandwidth of over 40% for 0.2\,dB amplitude and 1° phase imbalance. The experimental results are in good agreement well with equivalent circuit and full-wave simulations.

In the paper, the analysis of electromagnetic wave scattering from frequency selective surface is presented. The surface is composed of periodically arranged posts. The multimodal scattering matrix of such structure is derived and the transmission and reflection characteristic for the structure with arbitrary plane wave illumination are calculated. The exact full-wave theory based on the mode-matching method is applied to develop an efficient theory to analyze such structures. The validity and accuracy of the approach are verified by comparing the results with those obtained from alternative methods.

Spatial beam compression of an electromagnetic wave is one of the fundamental techniques employed in microwaves and optics. As there are many ways to achieve this task using the combination of prisms and lenses, recent research suggests the parabolic gradient index photonic crystals (GRIN PC) for the design of spatial beam compressor owing to its functionalities. However, the fabrication of a graded media with the parabolic profile is a difficult challenge in practical realization. To an alternative, present work attempts this problem with respect to the triangular gradient index profile. The performance and aspects of the beam compression are investigated experimentally using the pillar type GRIN PC at the microwave length-scales. The utility of the device for an effective beam injection to the photonic-waveguide component is further demonstrated experimentally.

We calculate the optical force exerted on the nanoparticle close proximity to the surface of fishnet metamaterials based on metal/dielectric/metal films when irradiated at near infrared wavelength. These forces show the resonant frequencies similar to the magnetic resonant frequencies in the double negative index fishnet metamaterial. We also present that the optical force can be enhanced by optimizing the geometry of the fishnet to provide a stronger magnetic resonant dipole. In contrast to the other plasmonic nanostructure always obtaining trapping force using electrical resonant dipole, our presented structure utilizes the magnetic resonance to provide a gradient force, which is suitable for the optical trapping of the nanoscale particles at illumination intensities of just 1 mW/μm², the optical force is sufficient to overcome the Earth's gravitational pull.

This paper presents a practical direction finding receiver based on six-port networks. To expand beam direction angles, improve measurement accuracy, and avoid phase ambiguity, we introduce a dual-baseline architecture into the direction finding receiver. We also propose a calibration technique based on support vector regression (SVR) for the following reasons: The nonlinearity of diode detectors and the asymmetry of six-port junctions can cause measurement phase errors. Moreover, the transmission parameters of two microwave channels differ with changes in received power. Results show that the SVR model can achieve a direction finding accuracy of 0.2932°.

Preparing the 3D-geometry models to perform electromagnetic compatibility (EMC) numerical simulations can be tedious and time consuming. Furthermore, the need to include the test setup in the models, in order to validate the software, by comparing the numerical results with the measured data, may lead to unwieldy simulation models with often unaordable computational costs. In this paper, we provide strategies for optimizing and simplifying the modeling process, together with guidelines for achieving the most unfavorable case in the simulation of EMC problems, as required for a certication process. A test case from the European FP7 HIRF-SE project is analyzed in this paper as an example of how to identify the unnecessary elements for the simulation, while retaining the essential physics of the problem.