This paper considers the localization of an emitter where the transmitted signal is unknown for receivers. To improve the localization accuracy, we propose an efficient method to estimate the emitter position by reconstructing the transmitted signal jointly. Simulation results show that the localization performance of the proposed method is much better than the existing algorithms.

A compact coplanar waveguide (CPW) fed close ring resonator (CRR) loaded four-element metamaterial (MTM) array antenna for wireless application is designed and discussed in this article. The array is designed with corporate feeding network, arranged in a manner to offer 3 dB power at its each element. The proposed 1×4 MTM array antenna offers a fractional bandwidth of 10.18% with respect to the resonance frequency of f_r = 2.26 GHz. At the resonance frequency of 2.26 GHz, the proposed 1×4 MTM array antenna offers a gain of 5.10 dBi in the direction of broadside radiation. Each element of the proposed array antenna consists of CRR, which removes the requirement of via and allows the design of a uniplanar MTM array. The overall electrical size of the single element antenna shows compactness of 0.255λ₀ × 0.155λ₀ × 0.012λ₀, where λ₀ is the free space wavelength at its resonance frequency of f_r = 2.3 GHz. The proposed MTM array antenna is designed, and simulated on ANSYS HFSS 14.0 and simulated results are verified with the fabricated proto-type.

Transformation optics is a convenient method to control paths of electromagnetic waves and radiation characteristics of antennas. In this paper, we try to increase the gain of Balanced Antipodal Vivaldi Antenna (BAVA) over 8-16 GHz frequency band using an optical conformal transformation. The proposed antenna can be implemented by ordinary dielectric materials and graded photonic crystals (GPCs). In this designed BAVA, better side lobe level (SLL) and cross-polarization are achieved compared to a conventional BAVA. Simulation results validate the performance of the design approach.

This paper presents a Ka-band 4-bit BiCMOS digital step attenuator with maximum attenuation of 7.5 dB (16 states). The proposed attenuator design is based on switched T-bridge network including phase correction network and is fabricated in 0.13 μm SiGe BiCMOS technology. Attenuator with phase correction structure shows root mean square (RMS) amplitude errors <0.8 dB at 31 to 33 GHz and the RMS insertion phase varying from 2.8° to 5.8° over 31-33 GHz. The measured insertion loss is 19 dB and total chip size including pad is 1.92×0.4 mm².

In this paper, we propose a novel interconnection technique for a flip-chip quad flat no-lead (FC QFN) package which can decrease the amount of the transmission line (TL) phase shift. The RF die inputs and outputs (I/O) are connected to the package lead fingers by a small size, 1000 μm length, microstrip line having a gap capacitor consisting of staked plates (fingers) where the space in between is filled by a ceramic material of 10.2 dielectric constant value. This technique can reduce the effect of transmission line inductance and makes the novel package interconnection behaving as a composite left right handed (CLRH) TL; hence, one can set the TL phase shift to zero degree at the desired operating frequency band (i.e. S-band) by just tuning geometrical and/or physical interconnection structure parameters.

The accuracy of wave propagation prediction is very important in telecommunication network planning. The parabolic equation model has an advantage in computation efficiency and accuracy for wave propagation prediction. The recursive convolution nonlocal boundary condition has an advantage in improving the computational efficiency. In this paper, the recursive convolution nonlocal boundary conditions are extended to deal with the issue of horizontal diffraction loss in multiple obstacles. The validation is performed with experiments and the results show a good agreement.

The scheme of energy and data wireless transmission with the same carrier based on M-ary Differentially-Encoded Amplitude and Phase Shift Keying (MDAPSK) technology is an effective method to implement energy supply and data communication for implantable medical devices. In this paper, based on a large number of finite-difference time-domain simulation analyses, combined with knowledge of the clinical demand for implantable medical devices, the 13.56-402 MHz band is selected as the biological channel frequency band, and attenuation characteristic analysis and mathematical modeling are carried out. Based on massive amounts of simulation data, the Levenberg-Marquardt and general global optimization methods are adopted to build a homogeneous and heterogeneous biological channel model in the aforementioned frequency band. In order to verify the reliability and versatility of the mathematical model, an adult male rabbit is employed for a living implantation experiment. Using a vector network analyzer, different frequency electromagnetic wave receiving efficiencies in different biological channels are measured. The measured data are highly consistent with the simulation data, which fully verifies the rationality of the proposed biological channel model. This work provides a theoretical basis and model reference for the clinical application of an implantable medical device wireless transmission system.

By introducing the Wilkinson divider and dual L-shaped strips as a feeding network, broadband design of planar circularly polarized (CP) annual-ring antenna for ultra-high frequency (UHF) RFID system is proposed and experimentally studied. The proposed broadband CP antenna can provide the impedance bandwidth (RL≥10 dB) of about 246 MHz (25.0% @ 985 MHz) and the 3 dB axial-ratio (AR) bandwidth of about 180 MHz (19.5% @ 925 MHz) to meet the worldwide UHF RFID band (860~960 MHz). Meanwhile, with unidirectional pattern in the XZ- and YZ-planes, the measured peak gain and radiation efficiency are about 7.7 dBic and 70% across the operating band, respectively.

A technique for converting a wide-band coplanar waveguide fed antenna to UWB by positioning slots in the modified ground plane (MGP) adjacent to the feed is proposed in this paper. The slots can be symmetrically or asymmetrically positioned for optimum performance. One slot pair is initially positioned through parametric analysis in the modified ground plane at an equal distance from the feed end for the maximum achievable impedance bandwidth. The second slot pair is similarly positioned, optimising the antenna for ultra wideband operation. Two CPW fed antenna geometries are experimented using the technique, one unique and the other, a generic circular monopole. Both antennas have MGP and are fabricated on an FR4 substrate. The analysis and simulation have been done in FEM based High Frequency Structure Simulator (HFSS). The performance of the two antennas is measured with a Vector Network Analyzer ‘Agilent PNAE8362B'. The impedance bandwidth and radiation pattern validate the performance of the antennas for ultra wideband applications. The experimentally obtained bandwidth precisely covers UWB, and principal patterns are uniform throughout the band.

One of the faults in medium voltage (MV) overhead power line is a high impedance fault (HIF) owing to low-current discharge to a tree (THIF). This type of fault generates signals in wide frequency bandwidth which may lead to electromagnetic interference (EMI) with neighboring devices and consequently results in degradation in the performance of nearby systems. This problem becomes more critical when MV power lines path is located in a wooded area in which there will be frequent transient conflicts between trees and power lines especially in the windy conditions. Given the importance of this issue, the ability of THIF to generate EMI is first demonstrated in this paper. Thereafter, a hybrid technique based on combination of quantile regression (QR) and empirical mode decomposition (EMD) is proposed to perform a feature extraction from THIF signals. By comparing the QR results of different samples of THIF signal with other similar signals, the validation of proposed method is depicted. In summary, the original contributions of current research include 1) assessing EMI due to THIFs, 2) using EMD in pre-processing of THIFs signals and extracting their main components, 3) recommending QR for the feature definition of THIF.

Nonlinear characteristics of semiconductor devices play a key role in the performances of circuits, but their modelling is still a big challenge in circuit simulations nowadays. This paper explores modelling nonlinear characteristics of circuits containing semiconductor devices by presenting a modified physically based simulation method. A p-i-n diode microstrip circuit is taken as a sample, and its nonlinear characteristics, such as the power limiting, bistability, and forward recovery characteristics, are simulated and analysed. The applied method demonstrates its good capability and accuracy of modelling the nonlinear characteristics in the simulation, and moreover clarifies the underlying physical mechanisms. In contrast, the Advanced Design System (ADS) software, a popular circuit simulation program based on the equivalent circuit model, fails to reveal some of those nonlinear characteristics.

The currents flowing through a transmission line produce a rotating magnetic field of vertical and horizontal components which are orthogonal in space and vary with time. Buried and aerial metallic pipelines that run parallel to or are placed in the vicinity of overhead AC high voltage transmission lines are affected by this field resulting in an induced voltage on the pipelines. Several related studies and safety standards dealing with this problem have been published. Nevertheless on a multi-circuit line, the issue of current phase shift variation has not been fully covered yet. This paper provides a detailed analysis of the effect of current phase shifts on the magnetic field distribution and polarization pattern around power lines using analytical approach from electromagnetic field theory. In this study, not only the variation of the filed distribution with phase arrangements and phase shifts is further established, but also the characteristic nature of the variation of the field distributions for six phase arrangements is examined in more detail. The results show that the magnetic field distribution at the ground level and the spatial distribution of the magnetic field polarization ratio vary significantly with the phase sequence arrangement as well as the current phase shifts between the two circuits. The field polarization differs at different locations. The information from the results can be useful for consideration in designing an effective AC mitigation technique and in placing pipelines in the utility corridor with power lines. Pipelines should be placed in a region of minimum field intensity within the right-of-way of the line, in order to have minimal induction on the pipeline in normal operating conditions of the line.

Point target detection in space-based infrared (IR) imaging system is an important task in many applications such as IR searching and tracking and remote sensing. Although it has attracted great interest and tremendous efforts during last decades, it remains a challenging problem due to the uncertain heterogeneous background and the limited processing resources on the onboard platform. Aiming at this problem, a novel background suppression method based on multi-direction filtering fusion is proposed in this paper. The process of background prediction for each pixel by this method can be divided into two steps. Firstly, eight predicted values are obtained by using linear filtering methods along eight different directions respectively. Then, Gaussian weighted sum of the eight predicted values is computed to generate the final result. We conduct several groups of experiments on different categories scenes with simulated targets, and the final experimental results demonstrate that our methods can not only obtain state-of-the-art performance on background suppression (especially for heterogeneous backgrounds), but also detect targets accurately with low false alarm rate and high speed in IR point target detection tasks.

In this paper, a CPW-fed circular patch UWB-extended bandwidth antenna is proposed which is fabricated and characterized on silicon. The proposed antenna covers fractional bandwidth of 132.08% with high rejection triple band-notch characteristics [WiMAX(3.30 GHz-3.80 GHz)/WLAN(IEEE802.11a/h/j/n 5.15 GHz-5.35 GHz, 5.25 GHz-5.35 GHz, 5.47 GHz-5.725 GHz, 5.725 GHz-5.825 GHz)/X-band downlink satellite communication system (7.25 GHz-7.75 GHz)]. Gain and efficiency of the proposed antenna in the entire bandwidth vary between 3.96 dBi-10.98 dBi and 84%-95%, respectively. Also, group delay in the entire operating band is ≤ 1.0 ns. Furthermore, the proposed antenna exhibits good dipole like radiation pattern in E-plane and omnidirectional pattern in H-plane with small dimension of 20×20×0.5 mm³.

Aimed at solving the problems of high initial cutoff frequency, small stopband range and poor inhibition in the current electromagnetic band gap (EBG) structure, an electromagnetic band gap structure designed on the basis of periodic Z-bridge EBG inserted by a double complementary slit ring resonator (DBCSRR) cell is proposed. Compared with the traditional EBG structure, the proposed EBG structure can achieve 270 MHz-20 GHz bandwidth in a reference of -30 dB, which is wide in range. The measured and simulated results indicate the wideband of noise suppression. In addition, the lower and upper cutoff frequencies are estimated by using equivalent circuit models, respectively. Moreover, the IR-Drop and dc resistance is accurately investigated through 3-D simulations. Finally, the transfer characteristics of single signal line are studied.

Based on metamaterials and compressive sensing theory, we design a single pixel millimeter-wave fast imaging system by a 1D aperture array. The aperture array is realized by a column of complementary electric-lc (cELC) units etched on amicrostrip transmission line. Each cELC unit resonates at a different frequency, where the energy is coupled from the aperture to free space. A sequence of random field patterns can be obtained by controlling geometric parameters of each cELCunit. We use the frequency as the index of measurement matrix which well satisfies the restricted isometry property (RIP) and is well suited for compressive sensing (CS). A prototype of CS imaging system operatingatKa-band (27-40 GHz) is fabricated which can detect a 5 cm * 5 cm object precisely at a distance of 50 cm.

An extremely wideband photonic crystal antenna is proposed with a very compact size of 16.6 x 26.6 x 0.9mm³. The double-layer materials of silicon and glass are selected as the antenna substrate. The band gap performance of photonic crystals can decrease electromagnetic wave absorption of silicon substrate, restrain surface wave loss of antenna, and increase electromagnetic wave space radiation. Hence the periodical photonic crystal with square lattices is applied in upper silicon substrate. The glass substrate not only decreases effective dielectric constant of antenna, but also supports silicon substrate with photonic crystal. MEMS processes are used to realize photonic crystal antenna with plenty tiny through-holes. The simulated and measured results demonstrate that photonic crystal can effectively expand the working bandwidth of base antenna.

This paper analyzes rectangular and circular patch antennas fabricated from meshed conductors and backed with solid ground planes. Because of the meshing, the antennas are rendered optically transparent, where the transparency is determined by the mesh geometry. It is found that although there is a compromise between the antenna's efficiency and the optical transparency of the meshed patch, it is possible to optimize the antenna by refining mesh lines to certain extent. The limiting factors for refining mesh lines include material handling and fabrication process as well as the increased line impedance when being refined, which accordingly causes loss in antenna's efficiency. A refined mesh with thin linewidth increases both antenna performance and transparency. Additionally, it is found that the reduction of certain mesh lines increases the optical transparency with minimal hindrance to the antenna's efficiency, leading to further enhancement to the see-through percentage. Although it is possible to refine mesh lines to improve the antenna's efficiency or gain, it is seen that there is a limit for such an optimization method. This limit is closer to the efficiency of a solid patch for a lower transparency, whereas it is lower for increased transparency. Cross polarization level was also examined, and there was no signifficant efft on such a parameter due to meshing.

This paper aims at designing a wideband planar inverted F antenna (PIFA). The design of a PIFA begins with an elementary step such as the etching of antenna element pattern in a metal trace. After the etching adherence is developed by incorporating bonding between it and a printed circuit board which is primarily an insulating dielectric substrate. A ground plane is developed by a prolonging metallic layer which is adhered to the opposite side of the substrate. The simulation is done using ANSYS HFSS full wave 3D simulation software. The proposed PIFA is very compact and also provides a gain of 2.86 dB. As a consequence of the exemplary feature like an omnidirectional radiation pattern, there is an exceptional improvement in coverage. Moreover, the frequency bands covered by the PIFA are for applications including USPCS, UMTS, ISM/Bluetooth and WLAN at (1.85 to 1.99) GHz, (1.90 to 2.20) GHz, (2.4 to 2.485) GHz and (5.1 to 5.90) GHz, respectively.

In this correspondence, the two-dimensional (2-D) direction-of-arrival (DOA) estimation problem for partially polarized (PP) signals is considered. In particular, we focus on an array geometry containing three identical uniform linear arrays (ULAs). Compared with existing methods, the proposed one has three main advantages. Firstly, the estimation accuracy is higher since it exploits the polarization information. Secondly, it can work effectively under the coexistence of both noncircular and circular signals. Finally, pair matching for 2-D DOA is not required which reduces the computational complexity. Simulation results are presented verifying the efficacy of the algorithm.