International Journal of Antennas and Propagation The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Towards Washable Electrotextile UHF RFID Tags: Reliability Study of Epoxy-Coated Copper Fabric Antennas Tue, 24 Nov 2015 07:00:46 +0000 We investigate the impact of washing on the performance of passive UHF RFID tags based on dipole antennas fabricated from copper fabric and coated with protective epoxy coating. Initially, the tags achieved read ranges of about 8 meters, under the European RFID emission regulation. To assess the impact of washing on the performance of the tags, they were washed repeatedly in a washing machine and measured after every washing cycle. Despite the reliability challenges related to mechanical stress, the used epoxy coating was found to be a promising coating for electrotextile tags in moist conditions. Shiqi Wang, Ngai Lok Chong, Johanna Virkki, Toni Björninen, Lauri Sydänheimo, and Leena Ukkonen Copyright © 2015 Shiqi Wang et al. All rights reserved. A Compact Two-Level Sequentially Rotated Circularly Polarized Antenna Array for C-Band Applications Mon, 23 Nov 2015 12:54:07 +0000 A compact circular polarized antenna array with a convenient gain/bandwidth/dimension trade-off is proposed for applications in the C-band. The design is based on the recursive application of the sequential phase architecture, resulting in a 4 × 4 array of closely packed identical antennas. The 16 antenna elements are disc-based patches operating in modal degeneration, tuned to exhibit a broad while imperfect polarization. Exploiting the compact dimension of the patches and a space-filling design for the feeding network, the entire array is designed to minimize the occupied area. A prototype of the proposed array is fabricated with standard photoetching procedure in a single-layer via less printed board of overall area 80 × 80 mm2. Adequate left-hand polarization is observed over a wide bandwidth, demonstrating a convenient trade-off between bandwidth and axial ratio. Satisfying experimental results validate the proposed design, with a peak gain of 12.6 dB at 6.7 GHz maintained within 3 dB for 1 GHz, a very wide 10 dB return loss bandwidth of 3 GHz, and a 4 dB axial ratio bandwidth of 1.82 GHz, meaning 31% of fractional bandwidth. Stefano Maddio Copyright © 2015 Stefano Maddio. All rights reserved. Slot Parameter Optimization for Multiband Antenna Performance Improvement Using Intelligent Systems Thu, 19 Nov 2015 09:31:58 +0000 This paper discusses bandwidth enhancement for multiband microstrip patch antennas (MMPAs) using symmetrical rectangular/square slots etched on the patch and the substrate properties. The slot parameters on MMPA are modeled using soft computing technique of artificial neural networks (ANN). To achieve the best ANN performance, Particle Swarm Optimization (PSO) and Differential Evolution (DE) are applied with ANN’s conventional training algorithm in optimization of the modeling performance. In this study, the slot parameters are assumed as slot distance to the radiating patch edge, slot width, and length. Bandwidth enhancement is applied to a formerly designed MMPA fed by a microstrip transmission line attached to the center pin of 50 ohm SMA connecter. The simulated antennas are fabricated and measured. Measurement results are utilized for training the artificial intelligence models. The ANN provides 98% model accuracy for rectangular slots and 97% for square slots; however, ANFIS offer 90% accuracy with lack of resonance frequency tracking. Erdem Demircioglu, Ahmet Fazil Yagli, Senol Gulgonul, Haydar Ankishan, Emre Oner Tartan, Murat H. Sazli, and Taha Imeci Copyright © 2015 Erdem Demircioglu et al. All rights reserved. Comparing Two Approaches for Point-Like Scatterer Detection Thu, 19 Nov 2015 09:13:09 +0000 Many inverse scattering problems concern the detection and localisation of point-like scatterers which are sparsely enclosed within a prescribed investigation domain. Therefore, it looks like a good option to tackle the problem by applying reconstruction methods that are properly tailored for such a type of scatterers or that naturally enforce sparsity in the reconstructions. Accordingly, in this paper we compare the time reversal-MUSIC and the compressed sensing. The study develops through numerical examples and focuses on the role of noise in data and mutual coupling between the scatterers. Angela Dell’Aversano, Giovanni Leone, and Raffaele Solimene Copyright © 2015 Angela Dell’Aversano et al. All rights reserved. Miniaturized Circularly Polarized Stacked Patch Antenna on Reactive Impedance Surface for Dual-Band ISM and WiMAX Applications Thu, 19 Nov 2015 07:13:20 +0000 This paper proposes a compact microstrip patch antenna for operating in 2.4 GHz ISM and 3.5 GHz WiMAX bands with circularly polarized (CP) radiation. The CP radiation in dual-bands is a result of two multilayered truncated corner stacked square patches, while the reactive impedance surface (RIS) is used for antenna size miniaturization for the lower operating frequency band. Since the overall lateral antenna dimensions are controlled by the lower frequency band (higher wavelength), reducing the electrical size of the antenna for lower band results in overall smaller antenna dimensions. The measured 3-dB axial ratio bandwidths of the in-house fabricated antenna prototype are 6.1% (2.40–2.55 GHz) for the lower band and 5.7% (3.40–3.60 GHz) for the upper band, while the 10-dB bandwidths for the two bands are 8.1% (2.39–2.59 GHz) and 6.9% (3.38–3.62 GHz), respectively. The maximum gain at boresight for the lower band is 2.93 dBic at 2.5 GHz, while the gain for the upper band is 6.26 dBic at 3.52 GHz. The overall volume of the proposed antenna is 0.292λo × 0.292λo × 0.044λo, where λo is the corresponding free-space wavelength at 2.5 GHz. Kush Agarwal and Saugata Dutta Copyright © 2015 Kush Agarwal and Saugata Dutta. All rights reserved. A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna Wed, 11 Nov 2015 06:23:21 +0000 A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characteristics of the broadband station antenna, and bandwidth is also guaranteed. The measured results show that the antenna can obtain 45% relative bandwidth, and 30 dB isolation degree also can be got, and the radiation performance is also good. Measurement results confirmed that the antenna gain can be guaranteed among 48% relative bandwidth, 15 dB of gain is got among bandwidth of 1.69–2.78 GHz, the isolation degree of different polarization method can reach 30 dB, and the measurement gain of two polarization methods of antenna both can reach 8.5 dBi. Jianming Zhou Copyright © 2015 Jianming Zhou. All rights reserved. Effects of Medium Characteristics on Laser RCS of Airplane with E-Wave Polarization Tue, 10 Nov 2015 14:24:54 +0000 Plane wave incidence should be postulated to have an authentic target detection. Practically, the plane wave is incapable usually of keeping its power in the far field especially when propagating through an inhomogeneous medium. Consequently, we assume an incident beam wave with a finite width around the target. In this work, we calculate numerically a laser radar cross section (LRCS) of conducting targets having smooth cross sections with inflection points such as airplane in random media. Effects of fluctuations intensity of random media on the LRCS performance are studied in this paper. E-wave polarization (E-wave incidence) is considered while the mean target size is approximately twice the wavelength. Hosam El-Ocla Copyright © 2015 Hosam El-Ocla. All rights reserved. Sub-Millimeter-Wave 10 dB Directional Coupler Based on Micromachining Technique Tue, 10 Nov 2015 12:05:25 +0000 A waveguide 10 dB directional coupler operating from 325 GHz to 400 GHz is designed based on the short-slot Riblet-type coupling configuration and fabricated using the deep reactive ion etching (DRIE) silicon micromachining technique. The skin depth and the conductivity of the gold film with the roughness of 0.2 μm are investigated at 300~1000 GHz frequency band for the higher accuracy. In order to measure the small-size four-port coupler using the two-port VNA with big-size flanges, three testing topologies are designed, in which the terahertz (THz) wedged-type absorbing material terminals are adopted as the waveguide matching loads. The measured average insertion loss is 0.5 dB after deducting the intrinsic loss and the measured average isolation is better than 25 dB, which are in good agreement with simulations. The analysis and the design are verified to be accurate and valuable for the high-performance sub-millimeter-wave waveguide components. Shuang Liu, Jiang Hu, Yong Zhang, Yupeng Liu, Tianhao Ren, Ruimin Xu, and Quan Xue Copyright © 2015 Shuang Liu et al. All rights reserved. Optimized Method for Generating and Acquiring GPS Gold Codes Tue, 10 Nov 2015 09:41:47 +0000 We propose a simpler and faster Gold codes generator, which can be efficiently initialized to any desired code, with a minimum delay. Its principle consists of generating only one sequence (code number 1) from which we can produce all the other different signal codes. This is realized by simply shifting this sequence by different delays that are judiciously determined by using the bicorrelation function characteristics. This is in contrast to the classical Linear Feedback Shift Register (LFSR) based Gold codes generator that requires, in addition to the shift process, a significant number of logic XOR gates and a phase selector to change the code. The presence of all these logic XOR gates in classical LFSR based Gold codes generator provokes the consumption of an additional time in the generation and acquisition processes. In addition to its simplicity and its rapidity, the proposed architecture, due to the total absence of XOR gates, has fewer resources than the conventional Gold generator and can thus be produced at lower cost. The Digital Signal Processing (DSP) implementations have shown that the proposed architecture presents a solution for acquiring Global Positioning System (GPS) satellites signals optimally and in a parallel way. Khaled Rouabah, Salim Attia, Rachid Harba, Philippe Ravier, and Sabrina Boukerma Copyright © 2015 Khaled Rouabah et al. All rights reserved. A Directional Antenna in a Matching Liquid for Microwave Radar Imaging Tue, 10 Nov 2015 09:05:28 +0000 The detailed design equations and antenna parameters for a directional antenna for breast imaging are presented in this paper. The antenna was designed so that it could be immersed in canola oil to achieve efficient coupling of the electromagnetic energy to the breast tissue. Ridges were used in the horn antenna to increase the operating bandwidth. The antenna has an exponentially tapered section for impedance matching. The double-ridged horn antenna has a wideband performance from 1.5 GHz to 5 GHz (3.75 GHz or 110% of impedance bandwidth), which is suitable for breast microwave radar imaging. The fabricated antenna was tested and compared with simulated results, and similar bandwidths were obtained. Experiments were conducted on breast phantoms using these antennas, to detect a simulated breast lesion. The reconstructed image from the experiments shows distinguishable tumor responses indicating promising results for successful breast cancer detection. Saeed I. Latif, Daniel Flores Tapia, Diego Rodriguez Herrera, Mario Solis Nepote, Stephen Pistorius, and Lotfollah Shafai Copyright © 2015 Saeed I. Latif et al. All rights reserved. Simple, Compact, and Multiband Frequency Selective Surfaces Using Dissimilar Sierpinski Fractal Elements Sun, 08 Nov 2015 12:30:27 +0000 This paper presents a design methodology for frequency selective surfaces (FSSs) using metallic patches with dissimilar Sierpinski fractal elements. The transmission properties of the spatial filters are investigated for FSS structures composed of two alternately integrated dissimilar Sierpinski fractal elements, corresponding to fractal levels , 2, and 3. Two FSS prototypes are fabricated and measured in the range from 2 to 12 GHz to validate the proposed fractal designs. The FSSs with dissimilar Sierpinski fractal patch elements are printed on RT/Duroid 6202 high frequency laminate. The experimental characterization of the FSS prototypes is accomplished through two different measurement setups composed of commercial horns and elliptical monopole microstrip antennas. The obtained results confirm the compactness and multiband performance of the proposed FSS geometries, caused by the integration of dissimilar fractal element. In addition, the proposed FSSs exhibited frequency tuning ability on the multiband frequency responses. Agreement between simulated and measured results is reported. Clarissa de Lucena Nóbrega, Marcelo Ribeiro da Silva, Paulo Henrique da Fonseca Silva, Adaildo Gomes D’Assunção, and Gláucio Lima Siqueira Copyright © 2015 Clarissa de Lucena Nóbrega et al. All rights reserved. Target Detection in Low Grazing Angle with Adaptive OFDM Radar Sun, 08 Nov 2015 11:45:32 +0000 Multipath effect is the main factor of deteriorating target detection performance in low grazing angle scenario, which results from reflections on the ground/sea surface. Amplitudes of the received signals fluctuate acutely due to the random phase variations of reflected signals along different paths; thereby the performances of target detection and tracking are heavily influenced. This paper deals with target detection in low grazing angle scenario with orthogonal frequency division multiplexing (OFDM) radar. Realistic physical and statistical effects are incorporated into the multipath propagation model. By taking advantage of multipath propagation that provides spatial diversity of radar system and frequency diversity of OFDM waveform, we derive a detection method based on generalized likelihood ratio test (GLRT). Then, we propose an algorithm to optimally design the transmitted subcarrier weights to improve the detection performance. Simulation results show that the detection performance can be improved due to the multipath effect and adaptive OFDM waveform design. Yang Xia, Zhiyong Song, Zaiqi Lu, Hao Wu, and Qiang Fu Copyright © 2015 Yang Xia et al. All rights reserved. Electromagnetic Interference between Cranes and Broadcasting Antennas Thu, 05 Nov 2015 13:32:46 +0000 An interesting phenomenon was noticed in some cases by workers operating with cranes in electromagnetic field of broadcasting antennas. They experienced electrical shock or burning pain at distances of kilometers away from powerful transmitters because cranes act as unintentional receiving antennas. The solution to this problem depends on dimensions and positioning of the crane structure, electromagnetic field strength at the site, frequency, and directional characteristic of the transmitting antenna. Electromagnetic interference between such structures is analyzed in this paper. Computational results for the induced currents and voltages in crane, treated as wire antenna problem, are determined using integrodifferential equations for the current along conductive structure, satisfying boundary condition for the electric field. Point matching method as the Method of Moments (MoM) is applied for solving these equations and polynomial approximation of the current is used. Results are presented for different crane structures and possible solutions to this problem are given. V. Javor Copyright © 2015 V. Javor. All rights reserved. Design of Joint Spatial and Power Domain Multiplexing Scheme for Massive MIMO Systems Wed, 04 Nov 2015 11:45:14 +0000 Massive Multiple-Input Multiple-Output (MIMO) is one of the key techniques in 5th generation wireless systems (5G) due to its potential ability to improve spectral efficiency. Most of the existing works on massive MIMO only consider Time Division Duplex (TDD) operation that relies on channel reciprocity between uplink and downlink channels. For Frequency Division Duplex (FDD) systems, with continued efforts, some downlink multiuser MIMO scheme was recently proposed in order to enable “massive MIMO” gains and simplified system operations with limited number of radio frequency (RF) chains in FDD system. However these schemes, such as Joint Spatial Division and Multiplexing (JSDM) scheme and hybrid precoding scheme, only focus on multiuser transmission in spatial domain. Different from most of the existing works, this paper proposes Joint Spatial and Power Multiplexing (JSPM) scheme in FDD systems. It extends existing FDD schemes from spatial division and multiplexing to joint spatial and power domain to achieve more multiplexing gain. The user grouping and scheduling scheme of JSPM is studied and the asymptotic expression for the sum capacity is derived as well. Finally, simulations are conducted to illustrate the effectiveness of the proposed scheme. Zheng Jiang, Bin Han, Peng Chen, Fengyi Yang, and Qi Bi Copyright © 2015 Zheng Jiang et al. All rights reserved. Transmission Scheme with Limited Channel State Information Feedback for 3D MIMO System Wed, 04 Nov 2015 11:18:03 +0000 Three-dimensional (3D) multiple-input multiple-output (MIMO) system can exploit the spatial degree of freedom in vertical dimension and can significantly improve system performance compared with 2D transmission scheme. However, in the actual frequency division duplex (FDD) transmission mode, the large overhead of the reference signal and channel state information (CSI) feedback would become a barrier for performance improvement of 3D MIMO system with the significantly increased number of transmit antennas. To deal with these problems, this paper proposes a new transmission scheme of the channel state information-reference signal (CSI-RS), where the CSI-RS is precoded with 3D beamforming vectors and composed of two components: long-term CSI-RS and short-term CSI-RS. For the purpose of conducting efficient transmission in widely used FDD system, we also propose a corresponding limited channel state information feedback scheme. Moreover, multiuser pairing and scheduling criteria based on the design of the CSI-RS are proposed to realize the multiuser transmission. We have investigated multiple options for 3D MIMO codebook scheme and finally adopt the Kronecker product-based codebook (KPC) for precoding operation at the base station (BS). Simulation results demonstrate that our proposed scheme for the 3D MIMO system achieves a better tradeoff between resource overhead and throughput performance. Xing Li, Hui Zhao, Long Zhao, Wenxiu Zhao, and Senyao Zheng Copyright © 2015 Xing Li et al. All rights reserved. A Simplified Multiband Sampling and Detection Method Based on MWC Structure for Mm Wave Communications in 5G Wireless Networks Wed, 04 Nov 2015 07:20:46 +0000 The millimeter wave (mm wave) communications have been proposed to be an important part of the 5G mobile communication networks, and it will bring more difficulties to signal processing, especially signal sampling, and also cause more pressures on hardware devices. In this paper, we present a simplified sampling and detection method based on MWC structure by using the idea of blind source separation for mm wave communications, which can avoid the challenges of signal sampling brought by high frequencies and wide bandwidth for mm wave systems. This proposed method takes full advantage of the beneficial spectrum aliasing to achieve signal sampling at sub-Nyquist rate. Compared with the traditional MWC system, it provides the exact quantity of sampling channels which is far lower than that of MWC. In the reconstruction stage, the proposed method simplifies the computational complexity by exploiting simple linear operations instead of CS recovery algorithms and provides more stable performance of signal recovery. Moreover, MWC structure has the ability to apply to different bands used in mm wave communications by mixed processing, which is similar to spread spectrum technology. Min Jia, Xue Wang, Xuemai Gu, and Qing Guo Copyright © 2015 Min Jia et al. All rights reserved. Phase Errors Simulation Analysis for GNSS Antenna in Multipath Environment Wed, 04 Nov 2015 07:17:09 +0000 High-precision GNSS application requires the exact phase center calibration of antenna. Various methods are published to determine the locations of the phase center. In the outfield, when the phase errors that arose by multipath exceed the phase center variations (PCV) tolerance, the calibration values may be not useful. The objective of this paper is thus to evaluate the phase errors that arose by multipath signals. An improved model of antenna receiving signal is presented. The model consists of three main components: (1) an antenna model created by combination of right hand circular polarization (RHCP) and left hand circular polarization (LHCP), (2) a multipath signals model including amplitude, phase, and polarization, and (3) a ground reflection model applying to circular polarization signals. Based on the model, two kinds of novel up-to-down (U/D) ratios are presented. The performance of the model is assessed against the impact of up-to-down ratio of antenna on phase errors. Lixun Li, Baiyu Li, Huaming Chen, and Feixue Wang Copyright © 2015 Lixun Li et al. All rights reserved. Constrained Power Focusing in Inhomogeneous Media as a Polarization Optimization Thu, 29 Oct 2015 09:32:22 +0000 The problem of focusing a field into inhomogeneous media is a canonic open problem relevant in many engineering areas. Several approaches have been developed, for example, Time Reversal, Inverse Filter, and Eigenvalues approach, but they suffer from several drawbacks which are counteracted by Optimal Constrained Power Focusing (OCPF) technique. OCPF was first introduced to deal with scalar fields and, recently, it has been extended to tackle the problem of focusing vector fields. In particular, the proposed approach allows reducing the focusing problem, which is NP-hard in case of vector fields, to a series of convex programming (CP) ones. In this paper, an alternative OCPF formulation is presented, which consists in the research of the most suitable polarization of the field into the target point and relies on the convexity of the problem when fixing this polarization. Such a result allows the development of two different solution procedures: an enumerative one that can take advantage of parallel programming in order to explore all possible polarizations and hybrid one which relies on the exploitation of global search algorithm just to solve the nonconvex part of the problem at hand. Domenica Anna Maria Iero Copyright © 2015 Domenica Anna Maria Iero. All rights reserved. On the Surface Fields of a Small Circular Loop Antenna Placed on Plane Stratified Earth Wed, 28 Oct 2015 13:41:06 +0000 An analytical method is presented which makes it possible to derive exact explicit expressions for the time-harmonic surface fields excited by a small circular loop antenna placed on the top surface of plane layered earth. The developed procedure leads to casting the complete integral representations for the EM field components into forms suitable for application of Cauchy’s integral formula. As a result, the surface fields are expressed as sums of Hankel functions. Numerical simulations are performed to show the validity and accuracy of the proposed solution. Mauro Parise Copyright © 2015 Mauro Parise. All rights reserved. Small Size and Low Cost UHF RFID Tag Antenna Mountable on Metallic Objects Wed, 28 Oct 2015 10:03:15 +0000 Reducing tag size while maintaining good performance is one of the major challenges in radio-frequency identification applications (RFID), in particular when labeling metallic objects. In this contribution, a small size and low cost tag antenna for identifying metal objects in the European UHF band (865–868 MHz) is presented. The antenna consists of a transmission line mounted on an inexpensive thin dielectric which is proximity-coupled to a short-ended patch mounted on FR4 substrate. The overall dimensions of the tag are 33.5 × 30 × 3.1 mm. Experimental results show that, for an EIRP of 3.2 W (European regulations), such a small and cheap tag attains read ranges of about 5 m when attached to a metallic object. Sergio López-Soriano and Josep Parrón Copyright © 2015 Sergio López-Soriano and Josep Parrón. All rights reserved. Multiobjective Synthesis of Steerable UWB Circular Antenna Array considering Energy Patterns Wed, 28 Oct 2015 08:52:26 +0000 True-time delay antenna arrays have gained a prominent attention in ultrawideband (UWB) applications such as directional communications and radar. This paper presents the design of steerable UWB circular array by using a multiobjective time-domain synthesis of energy pattern for circular antenna arrays. By this way we avoid individual beamforming for each frequency in UWB spectrum if the problem was addressed from the frequency domain. In order to obtain an energy pattern with low side lobe level and a desired main beam, the synthesis presented is performed by optimizing the true-time delays and amplitude coefficients for the antenna elements in a circular geometry. The method of Differential Evolution for Multiobjective Optimization (DEMO) is used as the optimization algorithm in this work. This design of steerable UWB circular arrays considers the optimization of the true-time exciting delays and the amplitude coefficients across the antenna elements to operate with optimal performance in the whole azimuth plane (360°). A comparative analysis of the performance of the optimized design with the case of conventional progressive delay excitations is achieved. The provided results show a good performance for energy patterns and for their respective power patterns in the UWB spectrum. Leopoldo A. Garza, Marco A. Panduro, David H. Covarrubias, and Alberto Reyna Copyright © 2015 Leopoldo A. Garza et al. All rights reserved. A Multibeam Dual-Band Orthogonal Linearly Polarized Antenna Array for Satellite Communication on the Move Tue, 27 Oct 2015 09:08:35 +0000 The design and simulation of a 10 × 8 multibeam dual-band orthogonal linearly polarized antenna array operating at Ku-band are presented for transmit-receive applications. By using patches with different coupling methods as elements, both perpendicular polarization in 12.25–12.75 GHz band and horizontal polarization in 14.0–14.5 GHz band are realized in a shared antenna aperture. A microstrip Rotman lens is employed as the beamforming network with 7 input ports, which can generate a corresponding number of beams to cover −30°–30° with 5 dB beamwidth along one dimension. This type of multibeam orthogonal linearly polarized planar antenna is a good candidate for satellite communication (SatCom). Yi Liu, Hu Yang, Shaojun Mao, and Jiang Zhu Copyright © 2015 Yi Liu et al. All rights reserved. Electromagnetic Pulse of a Vertical Electric Dipole in the Presence of Three-Layered Region Wed, 21 Oct 2015 14:11:38 +0000 Approximate formulas are obtained for the electromagnetic pulses due to a delta-function current in a vertical electric dipole on the planar surface of a perfect conductor coated by a dielectric layer. The new approximated formulas for the electromagnetic field in time domain are retreated analytically and some new results are obtained. Computations and discussions are carried out for the time-domain field components radiated by a vertical electric dipole in the presence of three-layered region. It is shown that the trapped-surface-wave terms should be included in the total transient field when both the vertical electric dipole and the observation point are on or near the planar surface of the dielectric-coated earth. D. Cheng, T. T. Gu, P. Cao, T. He, and K. Li Copyright © 2015 D. Cheng et al. All rights reserved. Analysis and Design of Cavity-Backed Probe-Fed Hybrid Microstrip Antennas on FR4 Substrate Tue, 20 Oct 2015 12:04:18 +0000 A novel cavity-backed probe-fed linearly polarized microstrip antenna based on the concept of hybrid radiators is proposed and implemented. The resulting flush-mounted antenna exhibits symmetrical bandwidth, low cross-polarization radiation in the H-plane, due to its hybrid patch, and low cost, since it can be built on a FR4 laminate. Substrate integrated waveguide technology is used in the fabrication of the metallic cavity. The effect of mutual coupling is analyzed for two classical arrangements: the side-by-side and the collinear configurations. D. C. Nascimento, Prêntice C. Ribeiro Filho, Alexis F. Tinoco-S, and J. C. da S. Lacava Copyright © 2015 D. C. Nascimento et al. All rights reserved. Imaging Method Based on Time Reversal Channel Compensation Mon, 19 Oct 2015 07:54:52 +0000 The conventional time reversal imaging (TRI) method builds imaging function by using the maximal value of signal amplitude. In this circumstance, some remote targets are missed (near-far problem) or low resolution is obtained in lossy and/or dispersive media, and too many transceivers are employed to locate targets, which increases the complexity and cost of system. To solve these problems, a novel TRI algorithm is presented in this paper. In order to achieve a high resolution, the signal amplitude corresponding to focal time observed at target position is used to reconstruct the target image. For disposing near-far problem and suppressing spurious images, combining with cross-correlation property and amplitude compensation, channel compensation function (CCF) is introduced. Moreover, the complexity and cost of system are reduced by employing only five transceivers to detect four targets whose number is close to that of transceivers. For the sake of demonstrating the practicability of the proposed analytical framework, the numerical experiments are actualized in both nondispersive-lossless (NDL) media and dispersive-conductive (DPC) media. Results show that the performance of the proposed method is superior to that of conventional TRI algorithm even under few echo signals. Bing Li and Bin-Jie Hu Copyright © 2015 Bing Li and Bin-Jie Hu. All rights reserved. A Horizontally Polarized Omnidirectional Antenna Using Stacked Curve Dipoles for DTV Reception Mon, 19 Oct 2015 07:52:34 +0000 This paper presents an omnidirectional antenna using stacked curve dipoles radiating horizontal polarization for digital television (DTV) reception. The proposed antenna consists of stacked curve dipoles designed on brass sheet. The parametric study is carried out for various dimensions of curve dipoles to improve the impedance bandwidth. The results show good impedance matching for of less than −10 dB along the frequency range from 404 MHz to 871 MHz. The antenna gain is between −10 dBi and 0.67 dBi along the frequency range from 470 to 862 MHz. Chuwong Phongcharoenpanich, Weerayuth Polkaew, Bancha Luadang, and Prayoot Akkaraekthalin Copyright © 2015 Chuwong Phongcharoenpanich et al. All rights reserved. A Design of Dual Broadband Antenna in Mobile Communication System Mon, 19 Oct 2015 06:28:50 +0000 A design of dual broadband antenna is proposed in this paper; it consists of one low frequency unit and two high frequency units. The low frequency unit consists of a pair of printing vibrators; the high frequency unit consists of a pair of printing oscillators, which is bent at its end, and high frequency unit and low frequency unit are set on the same dielectric substrate. Through adding a parasitic unit on antenna, it can enhance frequency bandwidth without affecting the bandwidth. In the high frequency unit, it adopts gap-coupled microstrip line feeding method in order to get enough bandwidth. Through the test of dual broadband antenna, it can be found that, in the low frequency part, the antenna covers 20% bandwidth of the total bandwidth, and it covers the frequency from 800 MHz to 980 MHz. In the high frequency, the antenna covers 60% of total bandwidth and its frequency is from 1540 MHz to 2860 MHz, so the designed antenna can satisfy the frequency requirements of 2G/3G/LTE (4G) communication system. Jianming Zhou Copyright © 2015 Jianming Zhou. All rights reserved. Analysis and Design of a Novel Multiband Antenna for Mobile Terminals Tue, 13 Oct 2015 06:11:02 +0000 A multiband planar terminal antenna with a compact size of 40 mm × 24 mm is proposed in this paper. This antenna consists of a monopole patch with two slots on it and a meandering strip loaded on the top. Two parasitic stubs and a branch on the ground are used to adjust and widen the impedance bandwidth of the antenna. Simulations and measurements are carried out to study the antenna performances in terms of impedance matching, efficiency, gain, and radiation patterns. Both of simulation and measurement results are shown to illustrate the good performance of the proposed antenna. The antenna can operate at 450–474 MHz, 860–1040 MHz, 1705–2428 MHz, and 2500–2710 MHz. These operating bandwidths cover GSM900, DCS, PCS, UMTS, LTE2500, and LTE’s low frequency band (450–470 MHz). It is very suitable for multifunctional terminal applications in wireless communication systems. Yuan Yao, Wanzhong Chen, Xiaodong Chen, and Junsheng Yu Copyright © 2015 Yuan Yao et al. All rights reserved. Enhancing Image Denoising Performance of Bidimensional Empirical Mode Decomposition by Improving the Edge Effect Mon, 12 Oct 2015 11:15:04 +0000 Bidimensional empirical mode decomposition (BEMD) algorithm, with high adaptive ability, provides a suitable tool for the noisy image processing, and, however, the edge effect involved in its operation gives rise to a problem—how to obtain reliable decomposition results to effectively remove noises from the image. Accordingly, we propose an approach to deal with the edge effect caused by BEMD in the decomposition of an image signal and then to enhance its denoising performance. This approach includes two steps, in which the first one is an extrapolation operation through the regression model constructed by the support vector machine (SVM) method with high generalization ability, based on the information of the original signal, and the second is an expansion by the closed-end mirror expansion technique with respect to the extrema nearest to and beyond the edge of the data resulting from the first operation. Applications to remove the Gaussian white noise, salt and pepper noise, and random noise from the noisy images show that the edge effect of the BEMD can be improved effectively by the proposed approach to meet requirement of the reliable decomposition results. They also illustrate a good denoising effect of the BEMD by improving the edge effect on the basis of the proposed approach. Additionally, the denoised image preserves information details sufficiently and also enlarges the peak signal-to-noise ratio. Feng-Ping An, Da-Chao Lin, Xian-Wei Zhou, and Zhihui Sun Copyright © 2015 Feng-Ping An et al. All rights reserved. Frequency Diverse Array MIMO Radar Adaptive Beamforming with Range-Dependent Interference Suppression in Target Localization Sun, 11 Oct 2015 09:42:32 +0000 Conventional multiple-input and multiple-output (MIMO) radar is a flexible technique which enjoys the advantages of phased-array radar without sacrificing its main advantages. However, due to its range-independent directivity, MIMO radar cannot mitigate nondesirable range-dependent interferences. In this paper, we propose a range-dependent interference suppression approach via frequency diverse array (FDA) MIMO radar, which offers a beamforming-based solution to suppress range-dependent interferences and thus yields much better DOA estimation performance than conventional MIMO radar. More importantly, the interferences located at the same angle but different ranges can be effectively suppressed by the range-dependent beamforming, which cannot be achieved by conventional MIMO radar. The beamforming performance as compared to conventional MIMO radar is examined by analyzing the signal-to-interference-plus-noise ratio (SINR). The Cramér-Rao lower bound (CRLB) is also derived. Numerical results show that the proposed method can efficiently suppress range-dependent interferences and identify range-dependent targets. It is particularly useful in suppressing the undesired strong interferences with equal angle of the desired targets. Kuandong Gao, Huaizong Shao, Jingye Cai, Hui Chen, and Wen-Qin Wang Copyright © 2015 Kuandong Gao et al. All rights reserved.