International Journal of Antennas and Propagation https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Research on Spatial Channel Model for Vehicle-to-Vehicle Communication Channel in Roadside Scattering Environment Sun, 22 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/3098198/ In this paper, an extension of spatial channel model (SCM) for vehicle-to-vehicle (V2V) communication channel in roadside scattering environment is investigated for the first time theoretically and by simulations. Subsequently, to efficiently describe the roadside scattering environment and reflect the nonstationary properties of V2V channels, the proposed SCM V2V model divides the scattering objects into three categories of clusters according to the location of effective scatterers by introducing critical distance. We derive general expressions for the most important statistical properties of V2V channels, such as channel impulse response, power spectral density, angular power density, autocorrelation function, and Doppler spread of the proposed model. The impact of vehicle speed, traffic density, and angle of departure, angle of arrival, and other statistical performances on the V2V channel model is thoroughly discussed. Numerical simulation results are presented to validate the accuracy and effectiveness of the proposed model. Xin Chen, Yong Fang, Weidong Xiang, and Liang Zhou Copyright © 2017 Xin Chen et al. All rights reserved. A Compact Triple-Band Negative Permittivity Metamaterial for C, X-Band Applications Wed, 18 Oct 2017 09:08:45 +0000 http://www.hindawi.com/journals/ijap/2017/7515264/ We report a new design of triple-band electric metamaterial resonator (TBEMR) based on integration of open delta loops within square ring resonator. This metamaterial resonator has three distinct -negative regions (ENG) over C, X frequency bands. The transmission and reflection response of the proposed subwavelength resonator is analyzed using full-wave electromagnetic solver Ansys HFSS to demonstrate the presence of electrical resonances within frequencies 4–12 GHz. Effective medium parameters permittivity and permeability are extracted from simulated complex scattering parameters to verify existence of ENG regions. The investigations are also carried out regarding dependence of resonant frequencies on design parameters of the TBEMR unit cell. The effective medium ratio for proposed subwavelength resonator is compared with various other metamaterial resonators to indicate its compact nature. Dushyant Marathe and Kishore Kulat Copyright © 2017 Dushyant Marathe and Kishore Kulat. All rights reserved. A Design of Vertical Polarized Conformal Antenna and Its Array Based on UAV Structure Tue, 17 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/9769815/ The designs of conformal antenna and its array usually need to combine with different carrier structures. As for cone or cylindrical carrier, through using of invasive weed optimization (IWO), the conformal array should be the optimized design as the antenna installation space requirements of cylindrical carrier; through adopting the antenna unit miniaturization method, it designs out a conformal antenna and makes it easier to be installed and the omnidirectional circular polarized beam is also realized. As for unmanned aircraft carrier, it designs out the low profile of conformal vertical polarization antenna unit; through using the electric field integral equation (EFIE) and electric/magnetic current combined-field integral equation (JMCFIE) and multilevel fast multipole algorithm (MLFMA), it analyzes the two different characteristics of unmanned aircraft carrier on the influence of antenna performance. The results obtained through experiments and JMCFIE analysis are in good agreement; according to unmanned aircraft carrier, it also designed out the antenna in X/K-band spectrum; through IWO, the antenna array is optimized; the test results show that the array scanning angle can reach the corresponding beam direction. Zhang Wei and Yang Junfeng Copyright © 2017 Zhang Wei and Yang Junfeng. All rights reserved. Scattering of Electric Field from Leaky Coaxial Cable in Confined Area Mon, 16 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/2894397/ The new radiation model for the electric field scattering of single leaky coaxial cable (LCX) being a transmitting antenna in the rectangular blind zone at 1.8 GHz is reported. The effect of varying the receiving antenna distance from the LCX on the fluctuation of radiated field using Ray-Tracing Method is examined. The line of sight and reflected paths between the LCX and receiving antenna for both horizontal and vertical polarizations are considered. Furthermore, it is inferred that the selection of appropriate period of slots and distance of the receiver reduce the fluctuations of electric field. The theory and procedures used in this paper can be extrapolated in different slot patterns of the LCX and zones which have many valuable applications for mobile communication in underground mines, tunnels, and railways. Asad Saleem, Min Wang, and Guoxin Zheng Copyright © 2017 Asad Saleem et al. All rights reserved. Recent Advances in RF Propagation Modeling for 5G Systems Sun, 15 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4701208/ Mihajlo Stefanovic, Stefan R. Panic, Rausley A. A. de Souza, and Juan Reig Copyright © 2017 Mihajlo Stefanovic et al. All rights reserved. Transmission Control of Electromagnetic Waves by Using Quarter-Wave Plate and Half-Wave Plate All-Dielectric Metasurfaces Based on Elliptic Dielectric Resonators Tue, 10 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/8215291/ We present the design of all-dielectric Quarter-Wave Plate (QWP) and Half-Wave Plate (HWP) metasurfaces based on elliptic dielectric resonators (EDRs) for the transmission control of electromagnetic waves over the frequency band 20–30 GHz. First, an extensive numerical analysis was realized by studying the effect of the resonators geometry (thickness and ellipticity) on the transmission of both - and -polarized waves. Then, based on the numerical analysis, we have realized and characterized experimentally both QWP and HWP all-dielectric metasurfaces. Ali Yahyaoui, Hatem Rmili, Karim Achouri, Muntasir Sheikh, Abdullah Dobaie, Adnan Affandi, and Taoufik Aguili Copyright © 2017 Ali Yahyaoui et al. All rights reserved. Study on Selfish Node Incentive Mechanism with a Forward Game Node in Wireless Sensor Networks Sun, 08 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/8591206/ In a wireless sensor network, some nodes may act selfishly and noncooperatively, such as not forwarding packets, in response to their own limited resources. If most of the nodes in a network exhibit this selfish behavior, the entire network will be paralyzed, and it will not be able to provide normal service. This paper considers implementing the idea of evolutionary game theory into the nodes of wireless sensor networks to effectively improve the reliability and stability of the networks. We present a new model for the selfish node incentive mechanism with a forward game node for wireless sensor networks, and we discuss applications of the replicator dynamics mechanism to analyze evolutionary trends of trust relationships among nodes. We analyzed our approach theoretically and conducted simulations based on the idea of evolutionary game theory. The results of the simulation indicated that a wireless sensor network that uses the incentive mechanism can forward packets well while resisting any slight variations. Thus, the stability and reliability of wireless sensor networks are improved. We conducted numerical experiments, and the results verified our conclusions based on the theoretical analysis. Mohammed Ahmed Ahmed Al-Jaoufi, Yun Liu, Zhen-jiang Zhang, and Lorna Uden Copyright © 2017 Mohammed Ahmed Ahmed Al-Jaoufi et al. All rights reserved. A Printed LPDA Antenna Fed by a Microstrip Line to Double Sided Parallel Strip Line from Backside Sun, 08 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/6259682/ A novel planar printed log-periodic dipole array (LPDA) antenna fed by tapered microstrip line (MSL) to double sided parallel strip line (DSPSL) is proposed in this paper. The proposed antenna adopts MSL feeding approach from backside. Using this feeding technique makes the printed LPDA antenna easier to be integrated into radio frequency (RF) circuits. In this paper, four layers are used to construct the antenna. The four layers of the printed LPDA antenna are printed on three thin dielectric substrates which are integrated together. To validate this approach, a printed LPDA antenna is simulated and fabricated for operating in the S and C bands (2.5–6 GHz). The antenna showed a good result over the whole frequency range with 2 : 1 VSWR, an average gain of 6.5 dB, and stable radiation patterns. The measured results are in very good agreement with simulations. Zhou Yang, Huang Jingjian, Wu Weiwei, and Yuan Naichang Copyright © 2017 Zhou Yang et al. All rights reserved. Adaptive Antenna Null Broadening Beamforming against Array Calibration Error Based on Adaptive Variable Diagonal Loading Sun, 08 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/3265236/ An approach for null broadening beamforming is proposed based on adaptive variable diagonal loading (VDL) and combined with the covariance matrix taper (CMT) approach, aiming at improving the robustness of adaptive antenna null broadening beamforming when array calibration error exists. Hence, it is named VDL-CMT. In this novel approach, the signal-to-noise ratio in the tapered sample covariance matrix is estimated and the VDL factor can be obtained adaptively. Then, the covariance matrix of the CMT approach is loaded with the obtained VDL factor. According to simulation results, in the case of array calibration error, robustness of the VDL-CMT is significantly improved and its performance is better than that of the existing adaptive antenna null broadening beamforming approaches. Wenxing Li, Yu Zhao, Qiubo Ye, and Bin Yang Copyright © 2017 Wenxing Li et al. All rights reserved. DOA Estimation of Noncircular Signals Using Quaternions Sun, 08 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/9848169/ The two-dimensional (2D) direction-of-arrival (DOA) estimation problem for noncircular signals using quaternions is considered in this paper. In the framework of quaternions, we reconstruct the conjugate augmented output vector which reduces the dimension of covariance matrix. Compared with existing methods, the proposed one has two main advantages. Firstly, the estimation accuracy is higher since quaternions have stronger orthogonality. Secondly, the dimension of covariance matrix is reduced by half which decreases the computational complexity. Simulation results are presented verifying the efficacy of the algorithm. Tianzhen Meng, Minjie Wu, and Naichang Yuan Copyright © 2017 Tianzhen Meng et al. All rights reserved. Calculation Algorithm for Diffraction Losses of Multiple Obstacles Based on Epstein–Peterson Approach Tue, 03 Oct 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/3932487/ Applying propagation models with good accuracy is an essential issue for increasing the capacity and improving the coverage of cellular communication systems. This work presents an algorithm to calculate total diffraction losses for multiple obstacles objects using Epstein–Peterson approach. The proposed algorithmic procedure to model the diffracting can be integrated with other propagation mechanisms in ray-tracing for the prediction of received signal level in non-line-of-sight environments. This algorithm can be interpreted into software application to scan large areas with a reasonable simulation time. Ahmad S. Abdulrasool, Jabir S. Aziz, and Sadiq J. Abou-Loukh Copyright © 2017 Ahmad S. Abdulrasool et al. All rights reserved. A Novel Scheme with FG-FFT for Analysis of Electromagnetic Scattering from Large Objects Thu, 28 Sep 2017 12:30:59 +0000 http://www.hindawi.com/journals/ijap/2017/2939702/ The replacement values to the singularity of fitting Green’s function are intensively researched in Fitting Green’s function Fast Fourier Transformation (FG-FFT). As is shown in the research, the accuracy of fitting Green’s function of near element is affected by different replacement values. The experiments show that an appropriate replacement value can improve the accuracy of fitting Green’s function of near element, and it is called the optimal replacement value in this paper. In the case of application of the proposed scheme to FG-FFT, the number of the near correction elements is significantly reduced. Therefore, the optimal replacement scheme can dramatically reduce the memory requirement and computing time in FG-FFT. The experiments show that, compared with traditional random replacement schemes, the optimal replacement scheme can reduce the number of the near correction elements by about 55%60% and greatly improve the computational efficiency of FG-FFT. Jia-Ye Xie, Guang Yu, Li-Li Pang, Wei-Bin Kong, and Zhi-Xiang Huang Copyright © 2017 Jia-Ye Xie et al. All rights reserved. Anisotropic Scattering Characteristics of a Radially Multilayered Gyrotropic Sphere Thu, 28 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/3205198/ We present a new closed-form solution to the scattering of a monochromatic plane wave by a radially multilayered gyrotropic sphere using the -matrix method. This approach can be utilized to investigate the interactions of a plane wave and a gyrotropic spherical scatterer of multiple layers with each layer characterized by both permittivity and permeability tensors. Based on the completeness and noncoplanar properties of vector spherical wave functions (VSWFs), analytical expressions of the electromagnetic fields in each gyrotropic layer are first derived. The boundary conditions are then applied on each discontinuous interface to obtain the scattering coefficients. Validations are made by first comparing the radar cross section (RCS) values of a 2-layered gyrotropic sphere with that computed from the full-wave finite element method (FEM) simulation and then reducing the general case to uniaxial case to compare the RCS values with the published results computed by Fourier transform combined with VSWFs method; in both cases good agreements are observed. Several specific cases are fully explored to investigate how the RCS are influenced by the parameters of the multilayered spherical structure. The results show that when both electric and magnetic gyrotropy tensors are considered, the RCS of the multilayered spherical scatterer can be suppressed or enhanced, depending on proper configurations of the material parameters. Lei Cao, Yongpin Chen, and Kai Kang Copyright © 2017 Lei Cao et al. All rights reserved. Combination of the Improved Diffraction Nonlocal Boundary Condition and Three-Dimensional Wide-Angle Parabolic Equation Decomposition Model for Predicting Radio Wave Propagation Thu, 28 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/2728380/ Diffraction nonlocal boundary condition (BC) is one kind of the transparent boundary condition which is used in the finite-difference (FD) parabolic equation (PE). The greatest advantage of the diffraction nonlocal boundary condition is that it can absorb the wave completely by using one layer of grid. However, the speed of computation is low because of the time-consuming spatial convolution integrals. To solve this problem, we introduce the recursive convolution (RC) with vector fitting (VF) method to accelerate the computational speed. Through combining the diffraction nonlocal boundary with RC, we achieve the improved diffraction nonlocal BC. Then we propose a wide-angle three-dimensional parabolic equation (WA-3DPE) decomposition algorithm in which the improved diffraction nonlocal BC is applied and we utilize it to predict the wave propagation problems in the complex environment. Numeric computation and measurement results demonstrate the computational accuracy and speed of the WA-3DPE decomposition model with the improved diffraction nonlocal BC. Ruidong Wang, Guizhen Lu, Rongshu Zhang, and Weizhang Xu Copyright © 2017 Ruidong Wang et al. All rights reserved. A Compact Frequency Reconfigurable Hybrid DRA for LTE/Wimax Applications Mon, 25 Sep 2017 09:43:21 +0000 http://www.hindawi.com/journals/ijap/2017/3607195/ A compact hybrid antenna structure with frequency reconfiguration capabilities is presented in this article. The proposed design employs a combination of a rectangular DR element and a coupling slot on the structure’s ground plane (GP). The slot shifts the fundamental DRA mode by introducing a slow wave effect and its resonant behavior helps to achieve an omnidirectional pattern at low frequencies. The slot is loaded with a series of PIN diode switches whose ON/OFF combinations alter the effective slot length. Slot loading with PIN diodes results in frequency reconfiguration of the proposed structure with a large tuning range of 76.2% (between 1.73 and 3.86 GHz). A parametric analysis was performed to investigate the effects of slot length, width, and position on the reflection coefficients of the proposed structure. A prototype of the proposed design was fabricated and results were measured. The measured results show a close agreement with the simulated ones. The proposed design is suitable for DCS 1800 MHz, PCS 1900 MHZ, UMTS, LTE 2500–2700 MHz, and Wimax 3.5 GHz. Sajid Aqeel, M. R. Kamarudin, Aftab Ahmad Khan, Jawad Saleem, Jamal Nasir, Jalil-ur-Rehman Kazim, and Owais Owais Copyright © 2017 Sajid Aqeel et al. All rights reserved. Minimized Low-Profile Wideband Antennas Using High Impedance Surface Tue, 19 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/2563927/ This paper proposes minimized low-profile wideband antenna by employing high impedance surface (HIS), for wireless application scenarios at radio frequency, microwave, and even terahertz. To validate this concept with low cost and easy measurement, two prototypes at radio frequency are fabricated and tested. Firstly, antenna with dielectric-substrate reflector is proposed and analyzed and 4 × 6 HIS array is employed to minimize the antenna size to , while maintaining antenna performances such as bandwidth, gain, and directive radiation. Secondly, a substrate-less HIS is proposed to improve the antenna bandwidth from 36% to 52% and also reduces the antenna weight by 72%. Yizhu Shen Copyright © 2017 Yizhu Shen. All rights reserved. Assessment Method of Multipath Mitigation Performance for GNSS Antenna with Receiver Algorithms Mon, 18 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/1957572/ Multipath is one of the most important sources of positioning error in GNSS. Well-designed antennas can mitigate multipath signals and enhance the performance of GNSS receivers. This paper concentrates on methods to assess multipath mitigation performance for GNSS antennas. We propose a model to describe multipath environment in GNSS ground stations. The model analyzes effects caused by inclined reflective surfaces and multipath mitigating algorithms in receivers. A method to assess multipath mitigation performance is put forward by analyzing pseudorange code phase errors caused by multipath signals after signal processing. Based on the model and method, principles in site selection for GNSS antenna are introduced to minimize effects caused by multipath. Muzi Yuan, Du Li, Baiyu Li, Huaming Chen, and Gang Ou Copyright © 2017 Muzi Yuan et al. All rights reserved. Metamaterials, Metasurfaces, and Artificial Dielectrics: Theory and Applications to the Next-Generation Telecommunication Platforms Mon, 11 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4312542/ Davide Ramaccia, Ariel Epstein, Mirko Barbuto, and Scott Rudolph Copyright © 2017 Davide Ramaccia et al. All rights reserved. Robust Centered Element Concentric Circular Antenna Array with Low Side Lobe Using Variable Loading and Tapering Windows in the Presence of Array Imperfections Sun, 10 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/1408183/ This paper presents centered element concentric circular antenna array (CECCAA) using variable diagonal loading (VDL) technique and different filtering windows. The different filtering windows are modified to apply in the CECCAA system. The modified novel technique not only is able to reduce the side lobe level (SLL) but also has the ability to detect and highly attenuate the directional interferences. However, the performance of CECCAA system is degraded in the presence of array imperfections. This performance degradation problem due to array imperfections can be improved by using robust techniques. The proposed technique is also robust against array imperfections and improves the performance. Moreover, the performance of the proposed structure is better than a concentric circular antenna array (CCAA). Several examples are presented to analyze the performance of proposed beamformer by using different tapering windows. M. F. Reza, M. S. Hossain, and M. M. Rashid Copyright © 2017 M. F. Reza et al. All rights reserved. Millimeter-Wave Single-Layer Dual-Frequency Reflectarray Antenna Wed, 06 Sep 2017 08:07:40 +0000 http://www.hindawi.com/journals/ijap/2017/6170863/ To fulfill the dual-frequency requirements, elements are needed to resonate at two different, independently adjustably frequencies. A low weight, low cost, and easy to fabricate single-layer dual-frequency reflectarray is designed, fabricated, and measured, with gain values of 27 and 29.2 dBi at 20 and 30 GHz, respectively. Jinjing Ren and Wolfgang Menzel Copyright © 2017 Jinjing Ren and Wolfgang Menzel. All rights reserved. An Efficient Hybrid Method for 3D Scattering from Inhomogeneous Object Buried beneath a Dielectric Randomly Rough Surface Mon, 28 Aug 2017 10:02:06 +0000 http://www.hindawi.com/journals/ijap/2017/2847094/ An efficient iterative analytical-numerical method is proposed for three-dimensional (3D) electromagnetic scattering from an inhomogeneous object buried beneath a two-dimensional (2D) randomly dielectric rough surface. In the hybrid method, the electric and magnetic currents on the dielectric rough surface are obtained by current-based Kirchhoff approximation (KA), while the scattering from the inhomogeneous object is rigorously studied by finite element method (FEM) combined with the boundary integral method (BIM). The multiple interactions between the buried object and rough surface are taken into account by updating the electric and magnetic current densities on them. Several numerical simulations are considered to demonstrate the algorithm’s ability to deal with the scattering from the inhomogeneous target buried beneath a dielectric rough surface, and the effectiveness of our proposed method is also illustrated. Hong-jie He, Li-xin Guo, and Wei Liu Copyright © 2017 Hong-jie He et al. All rights reserved. Radio Frequency Fingerprint Extraction Based on Multidimension Permutation Entropy Mon, 28 Aug 2017 06:56:36 +0000 http://www.hindawi.com/journals/ijap/2017/1538728/ Radio frequency fingerprint (RF fingerprint) extraction is a technology that can identify the unique radio transmitter at the physical level, using only external feature measurements to match the feature library. RF fingerprint is the reflection of differences between hardware components of transmitters, and it contains rich nonlinear characteristics of internal components within transmitter. RF fingerprint technique has been widely applied to enhance the security of radio frequency communication. In this paper, we propose a new RF fingerprint method based on multidimension permutation entropy. We analyze the generation mechanism of RF fingerprint according to physical structure of radio transmitter. A signal acquisition system is designed to capture the signals to evaluate our method, where signals are generated from the same three Anykey AKDS700 radios. The proposed method can achieve higher classification accuracy than that of the other two steady-state methods, and its performance under different SNR is evaluated from experimental data. The results demonstrate the effectiveness of the proposal. Shouyun Deng, Zhitao Huang, Xiang Wang, and Guangquan Huang Copyright © 2017 Shouyun Deng et al. All rights reserved. Advances in DOA Estimation and Source Localization Sun, 27 Aug 2017 10:30:47 +0000 http://www.hindawi.com/journals/ijap/2017/1352598/ Elias Aboutanios, Aboulnasr Hassanien, Amr El-Keyi, Youssef Nasser, and Sergiy A. Vorobyov Copyright © 2017 Elias Aboutanios et al. All rights reserved. Application of Genetic Algorithm to Estimation of Function Parameters in Lightning Currents Approximations Sun, 27 Aug 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4937943/ Genetic algorithm (GA) is applied for the estimation of two-peaked analytically extended function (2P-AEF) parameters in this paper. 2P-AEF is used for approximation of measured and typical lightning discharge currents. Lightning discharge channel is often modeled as thin-wire vertical antenna at perfectly conducting ground. Engineering lightning stroke models assume that the current along that channel is related to the channel-base current which may be measured at the instrumented tall towers and in triggered lightning experiments. Mathematical modeling of lightning currents is important in verification of lightning strokes models based on simultaneously measured electromagnetic fields at various distances, so as in lightning protection studies, computation of lightning induced effects and simulation of overvoltages in power systems. Typical lightning discharge currents of the first positive, first negative, and subsequent negative strokes are defined by IEC 62305 Standard based on comprehensive measurements. Parameters of 2P-AEF’s approximation of the typical negative first stroke current are determined by GA and compared to approximations obtained by other functions. Measured currents at Monte San Salvatore in Switzerland, at Morro de Cachimbo Station in Brazil, and in rocket-triggered lightning experiments at Camp Blanding in Florida are approximated by 2P-AEFs, and good agreement with experimentally measured waveshapes is obtained. V. Javor, K. Lundengård, M. Rančić, and S. Silvestrov Copyright © 2017 V. Javor et al. All rights reserved. An X-Band Dual-Polarized Vivaldi Antenna with High Isolation Thu, 24 Aug 2017 08:22:41 +0000 http://www.hindawi.com/journals/ijap/2017/3281095/ An X-band dual-polarized Vivaldi antenna with high isolation is proposed. The procedure of this antenna design includes the conventional Vivaldi antenna with regular slot edge (RSE), the dual-polarized Vivaldi antenna with two Vivaldi antennas which have different feeding point positions in a cross-shaped form, and the two Vivaldi antennas with a galvanic contact in soldering point. By applying the RSE, it reduced the dimensions of the Vivaldi antenna and improved its radiation performance. The modified antenna is fabricated and measured. The measured results show that  dB at the entire X-band for the two Vivaldi antennas. The isolation () between the two feeding ports, which has been improved by applying the different feeding point positions and the galvanic contact in soldering point, is better than 34 dB at X-band. In addition, the cross-polarized discrimination is better than 21 dB for the two Vivaldi antennas, and the measured results also include the gain of two Vivaldi antennas. Denghui Huang, Hu Yang, Yuqing Wu, and Fei Zhao Copyright © 2017 Denghui Huang et al. All rights reserved. Analysis on Human Blockage Path Loss and Shadow Fading in Millimeter-Wave Band Sun, 20 Aug 2017 07:55:56 +0000 http://www.hindawi.com/journals/ijap/2017/7540202/ Millimeter-wave (Mm-w) is the trend of communication development in the future; users who carry mobile communication equipment could be blocked by others in a crowded population environment. Based on Shooting and Bouncing Ray (SBR) method and setting up different orientation receivers (RX), population density, and people fabric property at 28 GHz and 38 GHz, simulating experimental scene similar to station square by Wireless Insite software, we use least square method to do linear-regression analysis for path loss and build path loss model. The result shows that the path loss index has a certain change in the different frequency, orientation receivers, population density, and people fabric. The path loss index of RouteC1 and RouteA2 has an obvious change in the central transmitter (TX). Each route shadow fading obeys Gaussian distribution whose mean is 0. This paper’s result has a theoretical guiding for designing the communication system in a crowded population environment. Hongmei Zhao, Qian Wang, and Kunfeng Shi Copyright © 2017 Hongmei Zhao et al. All rights reserved. The Complex α-μ Fading Channel with OFDM Application Thu, 17 Aug 2017 08:54:02 +0000 http://www.hindawi.com/journals/ijap/2017/2143541/ The aims of this paper are threefold: (i) to present a model for the complex - fading channel; (ii) to propose an efficient, simple, and general method to generate complex - samples; (iii) to make use of this channel in order to assess the bit error rate performance of an OFDM system. An analytical framework is then used, whose output is validated through Monte Carlo simulation. Several important conclusions concerning the system performance as a function of the channel parameters, namely, nonlinearity, clustering, and power imbalance of in-phase and quadrature components, are drawn. Wander H. M. Freitas, Roberto C. D. V. Bomfin, Rausley A. A. de Souza, and Michel Daoud Yacoub Copyright © 2017 Wander H. M. Freitas et al. All rights reserved. A Low Profile Ultrawide Band Monopole Antenna for Wearable Applications Thu, 17 Aug 2017 06:18:37 +0000 http://www.hindawi.com/journals/ijap/2017/7362431/ A low profile pentagonal shaped monopole antenna is designed and presented for wearable applications. The main objective of this paper is to design a miniaturized ultrawide band monopole planar antenna which can work efficiently in free space but also on the surface of the human body. The impact of human tissues on antenna performance is explained using the proposed pentagonal monopole antenna. The antenna is designed with a pentagonal radiator and a matched feed line of 50 ohm and square slots are integrated on defected ground of FR4 substrate with a size of 15 mm × 25 mm to achieve ultrawide band (UWB) performance in free space and human proximity. This overall design will enhance the antenna performance with wide bandwidth ranging from 2.9 GHz to 11 GHz. Specific absorption rate (SAR) of the proposed antenna on dispersive phantom model is also measured to observe the exposure of electromagnetic energy on human tissues. The simulated and measured results of the proposed antenna exhibit wide bandwidth and radiation characteristics in both free space and human proximity. Srinivas Doddipalli, Ashwin Kothari, and Paritosh Peshwe Copyright © 2017 Srinivas Doddipalli et al. All rights reserved. Reconstructed Target Range Profile via Unitary ESPRIT Superresolution Algorithm Tue, 15 Aug 2017 09:47:57 +0000 http://www.hindawi.com/journals/ijap/2017/8127150/ We propose an efficient technique for target classification using one-dimensional high resolution range profile (HRRP). The proposed technique utilizes the unitary estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm to extract scattering centers and then reconstruct superresolution range profiles. Moreover, we employ the central moments to provide translation invariant and scale invariant feature vectors. Finally, the proposed unitary ESPRIT (U-ESPRIT) based range profile reconstruction method is applied to the simulated annealing resilient backpropagation (SARPROP) classification algorithm to evaluate the recognition performances. Recognition results using four different aircraft models are presented to assess the effectiveness of the proposed technique, and they are compared with those of the conventional range profiles obtained by fast Fourier transform (FFT). Comparison results on simulated data show that the HRRP reconstruction method is better than directly using HRRP in targets classification. Rui Zhang, Min Zhang, Xin Wang, and Zhaohui Cai Copyright © 2017 Rui Zhang et al. All rights reserved. High-Resolution ISAR Imaging with Wideband V-FM Waveforms Mon, 14 Aug 2017 09:34:44 +0000 http://www.hindawi.com/journals/ijap/2017/1908204/ V-FM waveforms, composed of two chirp signals with the opposite slopes, can also achieve high range resolution with wide bandwidth via intrapulse frequency modulation. In this paper, a framework for inverse synthetic aperture radar (ISAR) imaging of moving targets with V-FM waveforms is investigated, where the range compression of the received signals is achieved by the dual-channel dechirping and the azimuth compression is done via the traditional Fourier transform (FT). The two corresponding reconstructed temporary high-resolution range profiles (HRRPs) from the double channels are synthesized for the HRRPs of the target, in which one is flipped from left to right and added to the other. Then the final HRRPs are arranged into a two-dimensional (2D) array and the azimuth compression is done via FT to achieve the ISAR imaging after the motion compensation. Simulated trials, adopting the scattering center modeling of the Yak-42 plane, are used to validate the correctness of the analyses and the finally well-focused images greatly support the effectiveness of V-FM waveforms in ISAR imaging. Dejun Feng, Xiaoyi Pan, and Guoyu Wang Copyright © 2017 Dejun Feng et al. All rights reserved.