We address the performance analysis of the natural frequency-based radar target detection in this paper. We show how to calculate the detection performance recursively by making a polynomial approximation of the probability density function (PDF) of the standard normal distribution. Why we make a polynomial approximation of the PDF of the standard normal distribution is that the PDF of the standard normal distribution is not analytically integrable but that the polynomial is definitely analytically integrable, which makes it possible to calculate the detection performance without look-up table. The Taylor polynomial is used for an approximation of the PDF of the standard normal distribution. We derive the error of the approximation, the bound of the error of approximation, and the optimal polynomial approximation in the sense that the bound of the error of the approximation is minimized. We validate the derived expressions via numerical simulation.

A time domain chipless RFID tag based on cascaded microstrip coupled transmission line sections (C-sections), which can operate in multi-frequency bands is presented. The group delay characteristics of the C-sections are exploited to generate the tag Identification (ID). The tag comprises cascaded commensurate group of C-sections and two cross-polarized ultra wide-band (UWB) antennas. Since the proposed tag can operate in multi-frequency, this paper proves the possibility of increasing the coding capacity compared to the existing time domain designs. A tag operating at ISM (Industrial Scientific and Medical) bands at 2.45 GHz and 5.8 GHz together with conformance of frequency and power regulations is discussed elaborately. The proposed device is designed, prototyped and experimentally verified. The time domain characteristic of the tag is also validated experimentally by interrogating with a short pulse. Furthermore, measurement results obtained using a commercial UWB (Ultra Wide Band) radar which can be used a chipless RFID reader is also incorporated. The obtained results confirm the concept and the possibility of using temporal multi-frequency in chipless RFID.

A 1 x 3 element linear array using cylindrical dielectric resonator antennas (CDRAs) is designed and presented for 802.11a WLAN system applications. The top and bottom elements of CDRA array are excited through the rectangular coupling slots etched on the ground plane, while the slots themselves are excited through the microstrip transmission line. The third element (i.e., central CDRA) is excited through the mutual coupling of two radiating elements by its sides. This mechanism enhances the bandwidth (96.1%) and gain (14.3%) as compared to aperture coupled technique. It is also observed that the side lobe levels are reduced over the designed frequency band. Using CST microwave studio, directivity of 10.5 dBi has been achieved for operating frequency of 5.6 GHz. Designed antenna array is fabricated and tested. Simulated and measured results are in good agreement. The equivalent lumped element circuit is also designed and presented using Advanced design system (ADS) for this proposed array.

In this article, a novel wideband planar monopole antenna for applications in 2.4 GHz Bluetooth and UWB bands is presented and investigated. The low-profile antenna comprises an approximate rectangle patch for covering the UWB band (3.1~10.6 GHz). A lower pass band, 2.4 GHz Bluetooth band (2.4~2.484 GHz), can be realized by adding a pair of U-shaped parasitic strips bilaterally beside the feed line without affecting its UWB behavior. The proposed antenna is designed and built on a FR-4 substrate, with overall size of 18 mm×32 mm. The simulated and measured results are presented and show that the proposed compact antenna has a stable and good radiation patterns across all the relevant bands.

A simple structure for achieving low mutual coupling between two inverted-F antennas is presented. A low coupling between the antennas can be achieved by using two slits on the ground plane. The interval between the antennas can be closer than λ/8. Furthermore, this technique can be combined with other techniques. This is good for designing small handsets which need shorter intervals between antennas. In this paper, the authors present an slitted ground structure and report analysys on the mechanism the structure, where a mutual coupling of -35 dB can be achieved using the slitted ground.

The reflectivity of three layer and four layer optical fiber based surface plasmon resonance sensors having silica material substrate and chalcogenide material substrate is plotted and studied. Using the transfer matrix method, the reflection coefficient for p-polarized incident lights at various wavelengths is obtained. It is observed that the sensitivity, detection accuracy and quality parameters of the sensor having silica substrates are much larger than the chalcogenide substrates. These parameters can also be increased by introducing an additional thin layer of silica/chalcogenide material on the metallic surface. Also, these sensor parameters are highly affected by the thickness of the additional thin layer.

In this paper, a novel circularly polarized Spidron fractal slot antenna array developed for broadband satellite communication in the Ku-band is discussed. A Spidron fractal slot configuration was utilized as a single radiating element to achieve circularly polarized radiation. The effects of altering the feeding position on the resonance behavior and the radiative characteristics were assessed. As a consequence, the design was expanded from a single element to a 2×2 subarray and further to a 4×4 array in order to enhance the bandwidth performance of the antenna when integrated with a sequential feeding network. Two prototype arrays were fabricated and tested, and measurements revealed that the 2×2 subarray has a 10-dB reflection coefficient bandwidth between 10 and 14.28 GHz, 3 dB axial ratio bands between 10.15 and 11.15 GHz and between 11.75 and 13.92 GHz, and a maximum gain of 11.4 dB at 13 GHz. The results for the 4×4 array indicated that both the 10-dB reflection coefficient and 3 dB axial ratio bandwidths cover the entire operating frequency from 10 to 15 GHz in the Ku-band. The maximum gain for the 4×4 array was 15.63 dB at 12.6 GHz.

In multidimensional numerical simulations of optoelectronic devices the rigorous Maxwell equations are solved in different ways. However, numerically efficient incoherent propagation of light inside the layers has not been resolved yet. In this paper we present two time- and resource-efficient approaches for optical simulations of incoherent layers embedded in multilayer structures: (a) phase matching and (b) phase elimination approach. The approaches for simulating the incoherent propagation of light in thick layers are derived from Maxwell equations. Both approaches can be applied to any layer in the structure regardless of the position inside the structure and the number of incoherent layers. In rigorous simulations, for low absorbing thick layers scaling down the thickness and increasing extinction coefficient of the layer proportionally is implemented to shorten computational time. The simulation results are verified with the experiment on two types of structures: a bare glass incoherent layer and an amorphous silicon solar cell.

An analytical technique referred to as the propagator matrix method (PMM) is presented to study the problem of electromagnetic (EM) waves interacting with the nonuniform magnetized plasma. In this method, the state vector is proposed to describe the characteristics of eigen waves in anisotropic medium, and state vectors at two different locations are related with each other by the propagator matrix. This method can be used to deal with the phenomenon of the transformation of EM wave polarization induced by anisotropic magnetized plasma, besides the conventional propagation characteristics through plasma slab, which overcomes the drawback of other analytical methods introduced in former studies. The EM problem model considered in this work is a steady-state, two-dimensional, nonuniform magnetized plasma slab with arbitrary magnetic declination angle, which is composed of a number of subslabs. Each subslab has a fixed electron density, and the overall density profile across the whole slab follows any practical distribution function. Based on PMM, a significant feature of strong transformation of EM wave polarization is addressed when an incident wave normally projects on the slab, which leads to the reflected or transmitted waves containing two kinds of waves, i.e., the co-polarized wave and the cross-polarized wave. The effects of varying the plasma parameters on the reflected and transmitted powers of co-polarization and cross-polarization, as well as the absorptive power for the typical bi-exponential density profile are investigatedin in detail, which provides a certain reference to various plasma technologies such as plasma stealth and communications through re-entry plasma sheath.

Magnetic angle sensors detect the angular position of a permanent magnet attached to a rotating shaft. The magnet is polarized diametrically to the rotation axis. No soft magnetic flux guides are present. The semiconductor die is placed on and orthogonal to the rotation axis. There are two kinds of systems: (i) perpendicular systems detect the field components perpendicular to the rotation axis, and (ii) axial systems detect the component parallel to the rotation axis. The former use magneto-resistive sensors or vertical Hall effect devices; the latter use Hall plates. This paper focuses on axial systems, derives their conceptual limitations, and compares them with perpendicular systems. An optimized system and optimum shapes of magnets are reported. Angle errors due to assembly tolerances of magnet and sensor versus shaft are explained. It is proven that assembly tolerances of optimized axial systems give three times larger errors than perpendicular systems.

Absolute adaptive current statistical (AACS) model and modified strong tracking unscented filter (MSTUF) are proposed for maneuvering target tracking (MTT) under nonlinear measurement in this paper. The key point of the AACS model is to associate the instantaneous acceleration variance with some elements of state covariance matrix by constructing acceleration increment models of the acceleration limit and acceleration mean in the CS model, while the maneuvering frequency can adjust itself according to the change of the measurement residual. MSTUF is proposed for high maneuver tracking under nonlinear measurement by incorporating the modified strong tracking filter (STF) into the unscented filter (UF). Since the state covariance, process noise covariance and maneuvering frequency can adjust themselves jointly according to the residual, the proposed algorithm, called the AACS-MSTUF, has a good performance on both maneuver and non-maneuver. Simulation results indicate that the overall performance of the proposed algorithm is better than the interacting multiple-model unscented filter (IMM-UF), UF and original strong tracking unscented filter (STUF) based on the CS model (CS-STUF) when considering tracking accuracy, stability, convergence and computational complexity.

We propose a compact passive device as a super-concentrator to obtain an extremely high uniform static magnetic field over 50 T in a large two-dimensional free space in the presence of a uniform weak background magnetic field. Our design is based on transformation optics and metamaterials for static magnetic fields. Finite element method (FEM) is utilized to verify the performance of the proposed device.

A novel design of a CPW fed printed monopole antenna for dual polarization applications is proposed in this paper. The monopole is formed of a rectangular patch embedded with a hour-glass shaped slot. In a modified version of the antenna, an additional spiral shaped slot is incorporated in the ground plane. The overall dimensions of the antenna are kept at 40 x 40 mm. The impedance bandwidth achieved by the first antenna is 123% from 2.5 GHz to 10.5 GHz which is further increased to 145.5% at the center frequency of 11 GHz with the second antenna. A low polarization ratio (< 10 dB) arising from increased cross-polarization is obtained in the frequency band of 4 GHz to 10 GHz making the antenna useful for dual-polarization applications in this band.

Magnetic Resonance Imaging (MRI) technique is one of the most useful diagnostic tools for human soft tissue analysis. Moreover, the brain anatomy features and internal tissue architecture of brain tumor are a complex task in case of 3-D anatomy. The additional spatial relationship in transverse, longitudinal planes and the coronal plane information has been proved to be helpful for clinical applications. This study extends the computation of gray level co-occurrence matrix (GLCM) and Run length matrix (RLM) to a three-dimensional form for feature extraction. The sub-selection of rich optimal bank of features to model a classifier is achieved with custom Genetic Algorithm design. An improved Extreme Learning Machine (ELM) classifier algorithm is explored, for training single hidden layer artificial neural network, integrating an enhanced swarm-based method in optimization of the best parameters (input-weights, bias, norm and hidden neurons), enhancing generalization and conditioning of the algorithm. The method is modeled for automatic brain tissue and pathological tumor classification and segmentation of 3D MRI tumor images. The method proposed demonstrates good generalization capability from the best individuals obtained in the learning phase to handle sparse image data on publically available benchmark dataset and real time data sets.

The detailed analysis of localized elongated photonic nanojets generated by a graded-index microellipsoid is reported. Using high resolution finite-difference time-domain simulation, we have studied the distribution of the electric energy density within and in the vicinity outside a dielectric core-shell microellipsoid. Here we consider dielectric composite microellipsoid consisting of a core and several concentric shells having different types of index grading. It becomes possible to elongate the nanojet abnormally. The latitudinal and longitudinal sizes of a nanojet and its peak intensity depending on the optical contrast variation of shells are numerically investigated. The results may provide a new ultra-microscopy technique for optical detection of natural or artificially introduced nanostructures deeply embedded within biological cells.

A recently developed technique to design and model an isolated Defected Ground Structure (DGS) has been employed to successfully design and characterize a DGS to be used in between two microstrip patches to reduce their mutual coupling. This is the only technique that can handle isolated DGS and as such has been explored for microstrip antennas in this paper for the firt time. An X-band design has been examined. A prototype is used to obtain measured data which are employed to verify the technique experimentally for microstrip array.

Wireless capsule endoscopy (WCE) was developed as a painless diagnostic tool for endoscopic examination of the gastrointestinal (GI) tract, but, to date, the low operating power of the capsule and the high data rate of the RF telemetry system are still key concerns. Innovative, novel solutions must be developed to address these concerns before WCE can be used extensively in clinical applications. In this paper, we propose a novel RF transmitter for WCE applications that only requires 1.5 V to transmit the required data as opposed to using a DC power supply. Our proposed, direct-conversion transmitter system consists of a current reuse oscillator, an envelope filter, and an L-section matching network. The oscillator is powered by the transmitting data which keep the oscillator in turned on and off for the transmitting 1 and 0 bit respectively and results in the on-off keying (OOK) of the modulated signal at the output of the oscillator. The rate of data transmission at the modulated signal is limited by the transient period of the oscillator start-up. When the start-up time of the oscillator is optimized, an OOK modulation rate of 100 Mb/s can be attained. In order to eliminate the oscillator decay noise, we used an envelope filter connected in series with the oscillator to filter out the decay part of the oscillation. Finally, the output impedance of the envelope filter is matched to the 50-Ω antenna with an L-section, low-pass, matching network to ensure maximum power transmission. The entire transmitter system was simulated in a 0.18-μm Complementary metal-oxide-semiconductor (CMOS) process.

This paper presents a new type of a negative coupling structure for designing elliptic-response filters with cross-coupling. The proposed coupling structure consists of short-circuited coupled transmission lines. Using the fact that insertion phase of the coupled line structure is different from that of an inductive iris, it is shown that the proposed coupling structure can be used as the negative coupling structure. In order to verify the proposed coupling structure, we designed a 4th-order cross-coupled elliptic-response bandpass filter with substrate integrated waveguide resonators. A pair of transmission zeros in measurement and simulation results validates that the proposed structure can be used as the negative coupling structure.

In this paper, we reformulate the quasi-static spectral domain analysis (SDA) applicable to a lossy anisotropic multilayer asymmetric coplanar waveguide (ACPW). The SDA formulation also incorporates two-layer model of a conductor thickness and the concept of effective permeability to account for the low frequency dispersion due to the magnetic field penetration in an imperfect conductor. The paper further presents the single layer reduction (SLR) formulation and circuit model to compute frequency dependent line parameters of a lossy anisotropic multilayer ACPW. The accuracy of formulation is comparable to that of the HFSS and CST, without using complex and time consuming full-wave methods. The results of CST for ε_eff, Z₀, α_d, α_c of multilayer ACPW, in the frequency range 1 GHz-100 GHz, deviate from results of HFSS up to 0.49%, 1.53%, 2.06% and 10.73% respectively; whereas corresponding deviations of the present SDA and SLR combined formulation are up to 1.38%, 2.09%, 3.57% and 8.87%.

In the present paper a novel mathematical model of physical processes of transient electromagnetic waves excitation and propagation in a biconical transmission line with radially inhomogeneous magneto-dielectric filling is proposed. The model is based on time domain mode expansions over spherical waves. The basis functions of the mode expansions are calculated analytically. The mode expansion coefficients are governed by Klein-Gordon-Fock equation with coefficients depending on a radial spatial coordinate. The explicit finite difference time domain computational scheme is derived to calculate the mode expansion coefficients. Dependences of cutoff frequencies of higher modes of TE and TM waves on the line geometry and dielectric filling are studied. In order to calculate electromagnetic field in the line with higher accuracy, just finite number of terms in the mode expansions is required. Electromagnetic field excited by the transient electric ring current is calculated in both homogeneous and radially inhomogeneous biconical transmission line. It is shown that there is a possibility to increase the bandwidth of the line via introduction of partial dielectric filling without changing the line geometrical size.