International Journal of Antennas and Propagation https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Compact Broadband Dual ZOR Antenna for Multiband Smart Mobile Phone Applications Wed, 24 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4831650/ A compact broadband dual zeroth-order resonator (ZOR) antenna is proposed for multiband smart mobile phone applications. The theory of broadband zeroth-order mode and multimode technique is used to design the proposed antenna covering GSM850 (824–894 MHz), GSM900 (880–960 MHz), DCS1800 (1710–1880 MHz), PCS1900 (1850–1990 MHz), W2100 (1920–2170 MHz), LTE2300 (2300–2400 MHz), LTE2600 (2500–2690 MHz), and Wi-Fi (2400–2500 MHz) bands. In order to achieve broadband operations, the proposed antenna consists of a large ZOR and a small ZOR that can generate and merge resonant frequencies of the negative-order, zeroth-order, and positive-order modes. The overall size of the antenna is 40 mm × 6 mm × 3 mm. The performance of the antenna is verified by both full-wave simulations and experiments. The measured impedance bandwidths of 3 : 1 VSWR in the low and high bands are 210 MHz (0.81–1.02 GHz) and 1170 MHz (1.69–2.86 GHz), respectively. The antenna provides omnidirectional radiation patterns and measured radiation efficiencies exceeding 43.3% and 47.5% for low and high bands, respectively. The antenna performance applied to the commercial smart mobile phone device is also presented. The measured results show that it has the active performance of good total radiated power, total isotropic sensitivity, and specific absorption rate, which can meet the requirement of the smart mobile phone. Jeong Keun Ji Copyright © 2017 Jeong Keun Ji. All rights reserved. Synthesizing Asymmetric Side Lobe Pattern with Steered Nulling in Nonuniformly Excited Linear Arrays by Controlling Edge Elements Wed, 24 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/9293031/ In radar antennas, asymmetric side lobes are useful, where undesired signals such as noise and ground clutter should be minimized. Also, for practical implementation, the feeding network of such antennas should be efficiently designed. In this paper, a simple analytical method for synthesizing asymmetric side lobe pattern with a wide-angle steered null in the nonuniformly excited linear arrays is presented. In this method, the difference in the side lobe levels on both sides of the main beam is achieved by varying just the phase excitations of the two-edge elements. The major novelty of this paper lies in the fact that the required asymmetric side lobe pattern can be achieved by changing a single phase shifter resulting in a simple feeding network. Jafar Ramadhan Mohammed and Khalil H. Sayidmarie Copyright © 2017 Jafar Ramadhan Mohammed and Khalil H. Sayidmarie. All rights reserved. Dual Polarized Dual Fed Vivaldi Antenna for Cellular Base Station Operating at 1.7–2.7 GHz Tue, 23 May 2017 09:36:24 +0000 http://www.hindawi.com/journals/ijap/2017/1304359/ The paper presents a novel dual polarized dual fed Vivaldi antenna structure for 1.7–2.7 GHz cellular bands. The radiating element is designed for a base station antenna array with high antenna performance criteria. One radiating element contains two parallel dual fed Vivaldi antennas for one polarization with 65 mm separation. Both Vivaldi antennas for one polarization are excited symmetrically. This means that the amplitudes for both antennas are equal, and the phase difference is zero. The orthogonal polarization is implemented in the same way. The dual polarized dual fed Vivaldi is positioned 15 mm ahead from the reflector to improve directivity. The antenna is designed for 14 dB impedance bandwidth (1.7–2.7 GHz) with better than 25 dB isolation between the antenna ports. The measured total efficiency is better than 0.625 dB (87%) and the antenna presents a flat, approximately 8.5 dB, gain in the direction of boresight over the operating bandwidth whose characteristics promote it among the best antennas in the field. Additionally, the measured cross polarization discrimination (XPD) is between 15 and 30 dB and the 3 dB beamwidth varies between 68° and 75° depending on the studied frequency. Marko Sonkki, Sami Myllymäki, Jussi Putaala, Eero Heikkinen, Tomi Haapala, Harri Posti, and Heli Jantunen Copyright © 2017 Marko Sonkki et al. All rights reserved. Numerical Simulations of the Lunar Penetrating Radar and Investigations of the Geological Structures of the Lunar Regolith Layer at the Chang’E 3 Landing Site Tue, 23 May 2017 07:35:37 +0000 http://www.hindawi.com/journals/ijap/2017/3013249/ In the process of lunar exploration, and specifically when studying lunar surface structure and thickness, the established lunar regolith model is usually a uniform and ideal structural model, which is not well-suited to describe the real structure of the lunar regolith layer. The present study aims to explain the geological structural information contained in the channel 2 LPR (lunar penetrating radar) data. In this paper, the random medium theory and Apollo drilling core data are used to construct a modeling method based on discrete heterogeneous random media, and the simulation data are processed and collected by the electromagnetic numerical method FDTD (finite-difference time domain). When comparing the LPR data with the simulated data, the heterogeneous random medium model is more consistent with the actual distribution of the media in the lunar regolith layer. It is indicated that the interior structure of the lunar regolith layer at the landing site is not a pure lunar regolith medium but rather a regolith-rock mixture, with rocks of different sizes and shapes. Finally, several reasons are given to explain the formation of the geological structures of the lunar regolith layer at the Chang’E 3 landing site, as well as the possible geological stratification structure. Chunyu Ding, Yan Su, Shuguo Xing, Shun Dai, Yuan Xiao, Jianqing Feng, Danqing Liu, and Chunlai Li Copyright © 2017 Chunyu Ding et al. All rights reserved. A Wave Splitter with Simple Structure Based on Biaxial Anisotropic Medium Tue, 23 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/2741925/ A TE/TM wave splitter based on biaxial anisotropic slab is designed. According to the total reflection and total transmission of TE/TM waves incident from isotropic medium into biaxial anisotropic medium, we propose a wave splitter with simple structure and little limitation on both constitutive parameters and incident angle. All the results are verified by simulation. Chushun Zhang, Hui Huang, Luchen Huang, Yaru Dong, and Xiaoyu Liu Copyright © 2017 Chushun Zhang et al. All rights reserved. Improved Reflectarray Phase-Only Synthesis Using the Generalized Intersection Approach with Dielectric Frame and First Principle of Equivalence Tue, 23 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/3829390/ An improved reflectarray Phase-Only Synthesis technique which employs the generalized Intersection Approach (IA) algorithm is fully described. It is formulated with the First Principle of Equivalence and takes into account a dielectric frame which is usually present to screw the reflectarray breadboard to the supporting structure. The effects of the First Principle of Equivalence versus the Second Principle in the computation of the radiation patterns, as well as the dielectric frame, are assessed and taken into account in an efficient implementation of the generalized IA in order to obtain more accurate results. Different strategies to speed up the synthesis process are presented and to improve convergence. The technique is demonstrated through two examples for space and terrestrial applications: an isoflux pattern for global Earth coverage from a satellite and a Local Multipoint Distribution Service pattern for central stations of cellular systems, both with a working frequency of 25.5 GHz. In addition, experimental results validate the approach described in this work with a prototype with an isoflux pattern working at 30 GHz. Daniel R. Prado, Manuel Arrebola, Marcos R. Pino, and Fernando Las-Heras Copyright © 2017 Daniel R. Prado et al. All rights reserved. Adaptive Countering Technique for Angle Deception Based on Dual Polarization Radar Seeker Mon, 22 May 2017 08:11:56 +0000 http://www.hindawi.com/journals/ijap/2017/2345491/ Angle deception jamming makes the monopulse radar seeker track to itself but not the real target, which is catastrophic for the guidance radar. In this paper, an adaptive technique based on dual polarization radar is presented to counter it. How angle deception jamming acts on the monopulse tracking radar is first investigated. An angle estimation technique of the real target is then derived from the conventional monopulse method, although it is being interfered with by angle deception jamming. Meanwhile, the polarization ratio characteristic of the angle deception jamming could be adaptively estimated in current practical scene. Furthermore, the similar characteristic of Jones vectors is defined as the rule to judge whether the target is being interfered with by jamming. It can make the radar seeker select different techniques for angle estimation adaptively. Finally, two major factors of angle estimation accuracy are analyzed by simulation and the effectiveness of the proposed technique is proved through experiments. Qiang Zhang and Weijun Pan Copyright © 2017 Qiang Zhang and Weijun Pan. All rights reserved. A Low-Profile Reflector-Enhanced Drop-Shaped Printed Antenna for Wide-Band Wireless Communications Sun, 21 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/7196765/ An improved low-profile printed antipodal drop-shaped dipole antenna for wide-band wireless applications is presented. The proposed radiating structure is integrated with a planar metal reflector useful to enhance antenna gain up to 5.5 dBi and the front-to-back ratio up to 21 dB. The geometry of reflector, feeding line, and dipole arms is optimized in order to achieve a broad operating bandwidth useful to meet the requirements of modern wireless communication protocols. Furthermore, the particular shape of the metal reflector and the adoption of a thin low-permittivity dielectric substrate result in a low distortion of the radiated field and a limited back radiation which makes the antenna suitable for UWB applications as well. These features, together with the low profile and the limited occupation area, make the antenna well adapted to mobile terminals as well as radio base stations. A locally conformal FDTD numerical procedure has been adopted to design and analyse the radiating structure, while a SEM technique has been employed to highlight the field perturbation caused by the antenna reflector as well as to extract the characteristics underlying the transient behaviour of the antenna. The experimental measurements performed on an antenna prototype are found to be in good agreement with the numerical computations. Giovanni Cappelletti, Diego Caratelli, Renato Cicchetti, Claudio Gennarelli, Massimiliano Simeoni, and Orlandino Testa Copyright © 2017 Giovanni Cappelletti et al. All rights reserved. Analysis of Ship RCS Detected by Multifrequency HFGWR Thu, 18 May 2017 08:19:05 +0000 http://www.hindawi.com/journals/ijap/2017/4964267/ One of the important applications of high frequency-ground wave radar (HFGWR) is to detect offshore ships. A proper method should be used to obtain the ship radar cross section (RCS), which is a key parameter of the ship. This paper proposes a method based on an automatic information system (AIS). The relationship of the ship RCS versus bearing for different frequencies is analyzed by processing multifrequency HFGWR data. With this new method, bearing information is taken into consideration, which is not the case in traditional empirical formulas. The results provide prior knowledge for ship detection and tracking; therefore, the probability of detection is significantly improved. Ke Sun, Biyang Wen, and Ruokun Wang Copyright © 2017 Ke Sun et al. All rights reserved. The CFS-PML for 2D Auxiliary Differential Equation FDTD Method Using Associated Hermite Orthogonal Functions Thu, 18 May 2017 08:17:04 +0000 http://www.hindawi.com/journals/ijap/2017/5817380/ The complex frequency shifted (CFS) perfectly matched layer (PML) is proposed for the two-dimensional auxiliary differential equation (ADE) finite-difference time-domain (FDTD) method combined with Associated Hermite (AH) orthogonal functions. According to the property of constitutive parameters of CFS-PML (CPML) absorbing boundary conditions (ABCs), the auxiliary differential variables are introduced. And one relationship between field components and auxiliary differential variables is derived. Substituting auxiliary differential variables into CPML ABCs, the other relationship between field components and auxiliary differential variables is derived. Then the matrix equations are obtained, which can be unified with Berenger’s PML (BPML) and free space. The electric field expansion coefficients can thus be obtained, respectively. In order to validate the efficiency of the proposed method, one example of wave propagation in two-dimensional free space is calculated using BPML, UPML, and CPML. Moreover, the absorbing effectiveness of the BPML, UPML, and CPML is discussed in a two-dimensional (2D) case, and the numerical simulations verify the accuracy and efficiency of the proposed method. Feng Jiang, Xiao-Ping Miao, Feng Lu, Li-Yuan Su, and Yao Ma Copyright © 2017 Feng Jiang et al. All rights reserved. Topological Design of Planar Circularly Polarized Directional Antenna with Low Profile Using Particle Swarm Optimization Wed, 17 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4983724/ A topological method for the design and optimization of planar circularly polarized (CP) directional antenna with low profile was presented. By inserting two parasitic layers, generated by particle swarm optimization, between the equiangular spiral antenna and the ground, a low-profile wideband CP antenna with directional radiation pattern and high gain is achieved. The optimized antenna shows an impedance matching band () of 4–12 GHz with a whole-band stable directional pattern in 4–11.5 GHz, and the antenna gain peak is 8 dBi, which work well in the available band. Measured return loss, antenna gain, and far field patterns agree well with simulation results. Xiaonan Zhao, Junping Geng, Ronghong Jin, Yao Jin, Xiang Liu, and Wenyan Yin Copyright © 2017 Xiaonan Zhao et al. All rights reserved. A Review of Sensing Strategies for Microwave Sensors Based on Metamaterial-Inspired Resonators: Dielectric Characterization, Displacement, and Angular Velocity Measurements for Health Diagnosis, Telecommunication, and Space Applications Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/5619728/ Four sensing approaches for the implementation of microwave sensors based on transmission lines loaded with metamaterial-inspired resonators are considered in this review paper, and examples of applications are pointed out. In all the cases, sensing is based on the effects that the magnitude under measurement causes in the transmission properties of the resonator-loaded line. Such four strategies are (i) resonance frequency variation, (ii) coupling modulation through symmetry disruption (causing variation of the notch depth), (iii) frequency splitting (also exploiting symmetry properties), and (iv) amplitude modulation of a harmonic signal. Such sensors are useful in various scenarios, of interest in fields as diverse as characterization of dielectric materials for communication circuits, medical diagnosis and treatment with microwave technologies, and sensors for space applications, among others. Lijuan Su, Javier Mata-Contreras, Paris Vélez, and Ferran Martín Copyright © 2017 Lijuan Su et al. All rights reserved. Experimental Results of Network-Assisted Interference Suppression Scheme Using Adaptive Beam-Tilt Switching Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/2164038/ This paper introduces a network-assisted interference suppression scheme using beam-tilt switching per frame for wireless local area network systems and its effectiveness in an actual indoor environment. In the proposed scheme, two access points simultaneously transmit to their own desired station by adjusting angle of beam-tilt including transmit power assisted from network server for the improvement of system throughput. In the conventional researches, it is widely known that beam-tilt is effective for ICI suppression in the outdoor scenario. However, the indoor effectiveness of beam-tilt for ICI suppression has not yet been indicated from the experimental evaluation. Thus, this paper indicates the effectiveness of the proposed scheme by analyzing multiple-input multiple-output channel matrices from experimental measurements in an office environment. The experimental results clearly show that the proposed scheme offers higher system throughput than the conventional scheme using just transmit power control. Tomoki Murakami, Riichi Kudo, Koichi Ishihara, Masato Mizoguchi, and Naoki Honma Copyright © 2017 Tomoki Murakami et al. All rights reserved. A Wide-Band Test Fixture for Analyzing Parasitic Effects of RF Passive SMD Components Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/7852135/ A wide-band test fixture is designed for the measurement of parasitic effects of RF passive SMD (surface mounted devices) components. Two calibration methods, TRM (Thru-Reflect-Match) from 45 MHz to 2 GHz and TRL (Thru-Reflect-Line) from 2 GHz to 12 GHz, are used for error correction. The measurement standards and fixture are designed based on these two calibration methods. For experimental verification, the multilayered ceramic SMD capacitors of Johanson Technology are measured. The parasitic effects of the SMD capacitors are analyzed. The designed fixture is feasible and applicable for quick and accurate measurement of RF passive SMD components. Xin Cao and Zongxi Tang Copyright © 2017 Xin Cao and Zongxi Tang. All rights reserved. Statistical Analysis of High-Resolution Coherent Monopulse Radar Sea Clutter Thu, 11 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/7471918/ A statistical analysis that properly characterizes sea clutter processes is indispensable both for optimum detection algorithm design and for performance prediction problems in maritime surveillance applications. In this paper, we present the statistical analysis of experimental sea clutter data collected by a high-resolution coherent monopulse radar. First, we present the amplitude statistical analyses for these clutter data. The results show that the , Pareto, and CIG distributions can each provide good fits to the clutter data for three channels of monopulse radar. The analyses on the variations of the distribution parameters with range suggest that the scale parameter is closely associated with the clutter powers and that the shape parameter is influenced by the sea state. Then, we focus on the correlation properties. The averaged results suggest that the temporal and spatial correlation properties are similar for the clutter of all three channels. Moreover, the clutter between the sum and difference channels is almost completely correlated in elevation and is lowly correlated in azimuth. Finally, we perform a spectral analysis, highlighting the temporal and spatial variabilities of Doppler spectra. It is found that the individual Doppler spectra in all three channels can be represented by Gaussian-shaped power spectral densities, and their centroid and width can be modeled as two separate stage linear functions of spectrum intensity. Hong Zhu, Qingping Wang, Ning Tai, Jingjian Huang, and Naichang Yuan Copyright © 2017 Hong Zhu et al. All rights reserved. Localization of Near-Field Sources Based on Sparse Signal Reconstruction with Regularization Parameter Selection Thu, 11 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/1260601/ Source localization using sensor array in the near-field is a two-dimensional nonlinear parameter estimation problem which requires jointly estimating the two parameters: direction-of-arrival and range. In this paper, a new source localization method based on sparse signal reconstruction is proposed in the near-field. We first utilize -regularized weighted least-squares to find the bearings of sources. Here, the weight is designed by making use of the probability distribution of spatial correlations among symmetric sensors of the array. Meanwhile, a theoretical guidance for choosing a proper regularization parameter is also presented. Then one well-known -norm optimization solver is employed to estimate the ranges. The proposed method has a lower variance and higher resolution compared with other methods. Simulation results are given to demonstrate the superior performance of the proposed method. Shuang Li, Wei Liu, Daqing Zheng, Shunren Hu, and Wei He Copyright © 2017 Shuang Li et al. All rights reserved. Novel Method for 5G Systems NLOS Channels Parameter Estimation Thu, 11 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/5236246/ For the development of new 5G systems to operate in mm bands, there is a need for accurate radio propagation modelling at these bands. In this paper novel approach for NLOS channels parameter estimation will be presented. Estimation will be performed based on LCR performance measure, which will enable us to estimate propagation parameters in real time and to avoid weaknesses of ML and moment method estimation approaches. Vladeta Milenkovic, Stefan Panic, Dragan Denic, and Dragan Radenkovic Copyright © 2017 Vladeta Milenkovic et al. All rights reserved. A Broadband Left-Handed Metamaterial Microstrip Antenna with Double-Fractal Layers Sun, 07 May 2017 06:32:25 +0000 http://www.hindawi.com/journals/ijap/2017/6145865/ This paper proposes a microstrip patch antenna based on the left-handed metamaterial concept, using planar periodic geometry, which results in improved characteristics. This periodic geometry is derived from fractal shapes, which have been widely used in antenna engineering. The metamaterial property was obtained as a result of the double-fractal structure on both the upper and the bottom sides of the antenna. The final structure has been optimized to enhance bandwidth, gain, and radiation characteristics of the microstrip antenna. This combination significantly improved antenna performance; our design could support an ultrawide bandwidth ranging from 4.1 to 19.4 GHz, demonstrating higher gain with an average value of 6 dBi over the frequency range and a peak of 10.9 dBi and a radiation capability directed in the horizontal plane of the antenna. Roman Kubacki, Salim Lamari, Mirosław Czyżewski, and Dariusz Laskowski Copyright © 2017 Roman Kubacki et al. All rights reserved. Circularly Polarized Antenna Array Fed by Air-Bridge Free CPW-Slotline Network Thu, 04 May 2017 06:56:47 +0000 http://www.hindawi.com/journals/ijap/2017/5230142/ A novel design of and circularly polarized (CP) microstrip patch antenna arrays is presented in this paper. The two CP antenna arrays are fed by sequentially rotated coplanar waveguide (CPW) to slotline networks and are processed on 1 mm thick single-layer FR4 substrates. Both of the two arrays are low-profile and lightweight. An air-bridge free CPW-slotline power splitter is appropriately designed to form the feeding networks and realize the two CP antenna arrays. The mechanism of circular polarization in this design is explained. The simulated and measured impedance bandwidths as well as the 3 dB axial ratio bandwidths and the radiation patterns of the two proposed antenna arrays are presented. This proposed design can be easily extended to form a larger plane array with good performance owing to its simple structure. Yilin Liu, Kama Huang, and Xia Luo Copyright © 2017 Yilin Liu et al. All rights reserved. Bandwidth Extension of a Printed Square Monopole Antenna Loaded with Periodic Parallel-Plate Lines Wed, 03 May 2017 07:44:26 +0000 http://www.hindawi.com/journals/ijap/2017/4082780/ A novel wideband monopole antenna employing periodically loaded parallel-plate lines is presented in this paper. The proposed antenna consists of a main square patch, a rectangular ground plane, and a periodical structure which is printed on both sides of substrate. A strong electromagnetic coupling technique is used to design the element that enhances impedance bandwidth and decreases the side-lobe level throughout the effective bandwidth. The antenna achieves a wide impedance bandwidth of about 61.1% or ranging from 2.16 to 4.06 GHz, an omnidirectional far-field pattern, and a peak radiation gain of 2.37 dBi. Finally, the proposed antenna is analyzed and measured. The measured results show satisfactory performance and good agreement with the simulated results. Linglong Meng, Weimin Wang, Ming Su, Jinchun Gao, and Yuanan Liu Copyright © 2017 Linglong Meng et al. All rights reserved. High Isolation Dual-Polarized Patch Antenna with Hybrid Ring Feeding Wed, 03 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/6193102/ This paper presents a hybrid ring feeding dual-polarized patch antenna with high isolation in a wide working band. The proposed antenna consists of a circular radiating patch printed on the upper horizontal substrate, two pairs of shaped strips printed on two vertical substrates, and a hybrid ring feeding network printed on the lower two horizontal substrates. The proposed antenna adopts shape strips coupled feeding structure to achieve a wide operating band. Furthermore, a hybrid ring feeding structure with high isolation in a wide bandwidth, which is firstly proposed, is applied as feeding network. When one port is excited, the feeding network can realize twice the power cancellation. Thus, high ports isolation characteristics can be obtained. A prototype of the proposed antenna is fabricated and measured. Measured results show that the 10 dB reflection coefficient bandwidths of the two ports are both about 38.7%, with port isolation higher than 40 dB through most of the band, and the cross-polarizations are below −24 dB. Xian-Jing Lin, Ze-Ming Xie, and Pei-Sheng Zhang Copyright © 2017 Xian-Jing Lin et al. All rights reserved. Wideband RCS Reduction of Microstrip Array Antenna Based on Absorptive Frequency Selective Surface and Microstrip Resonators Tue, 02 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/1260973/ An approach for wideband radar cross section (RCS) reduction of a microstrip array antenna is presented and discussed. The scheme is based on the microstrip resonators and absorptive frequency selective surface (AFSS) with a wideband absorptive property over the low band 1.9–7.5 GHz and a transmission characteristic at high frequency 11.05 GHz. The AFSS is designed to realize the out-of-band RCS reduction and preserve the radiation performance simultaneously, and it is placed above the antenna with the operating frequency of 11.05 GHz. Moreover, the microstrip resonators are loaded to obtain the in-band RCS reduction. As a result, a significant RCS reduction from 1.5 GHz to 13 GHz for both types of polarization has been accomplished. Compared with the reference antenna, the simulated results exhibit that the monostatic RCS of the proposed array antenna in - and -polarization can be reduced as much as 17.6 dB and 21.5 dB, respectively. And the measured results agree well with the simulated ones. Jingjing Xue, Wen Jiang, and Shuxi Gong Copyright © 2017 Jingjing Xue et al. All rights reserved. Time to Frequency Domain Analysis of Narrow Band Antennas Sun, 30 Apr 2017 08:11:30 +0000 http://www.hindawi.com/journals/ijap/2017/7419179/ This paper presents system modeling of three different single band antennas using the singularity expansion method (SEM). To acquire the accurate physical complex poles and the corresponding residues of the narrow band antenna model, an enhanced Matrix Pencil (MP) method has been applied to the impulse response of the antennas. A delayed time parameter is introduced to enhance the performance of the MP method to extract the actual physical poles and eliminate the nonphysical poles caused by the early time response of the narrow band antennas. The poles extracted by the enhanced MP method are located precisely within the single operating band of each antenna. The one set of the developed parameters is used to accurately characterize narrow band antennas in both time and frequency domains. The far field impulse response of a fabricated single band microstrip antenna has been measured in the laboratory and then reconstructed precisely using the SEM based model with the proposed MP scheme. Sajjad Ur Rehman and Majeed A. S. Alkanhal Copyright © 2017 Sajjad Ur Rehman and Majeed A. S. Alkanhal. All rights reserved. A Review of Antennas for Picosatellite Applications Sun, 30 Apr 2017 07:03:51 +0000 http://www.hindawi.com/journals/ijap/2017/4940656/ Cube Satellite (CubeSat) technology is an attractive emerging alternative to conventional satellites in radio astronomy, earth observation, weather forecasting, space research, and communications. Its size, however, poses a more challenging restriction on the circuitry and components as they are expected to be closely spaced and very power efficient. One of the main components that will require careful design for CubeSats is their antennas, as they are needed to be lightweight, small in size, and compact or deployable for larger antennas. This paper presents a review of antennas suitable for picosatellite applications. An overview of the applications of picosatellites will first be explained, prior to a discussion on their antenna requirements. Material and antenna topologies which have been used will be subsequently discussed prior to the presentation of several deployable configurations. Finally, a perspective and future research work on CubeSat antennas will be discussed in the conclusion. Abdul Halim Lokman, Ping Jack Soh, Saidatul Norlyana Azemi, Herwansyah Lago, Symon K. Podilchak, Suramate Chalermwisutkul, Mohd Faizal Jamlos, Azremi Abdullah Al-Hadi, Prayoot Akkaraekthalin, and Steven Gao Copyright © 2017 Abdul Halim Lokman et al. All rights reserved. Efficient Design Methodology for a Complex DRA-SIW Filter-Antenna Subsystem Sun, 30 Apr 2017 05:35:03 +0000 http://www.hindawi.com/journals/ijap/2017/6401810/ This work reports on an efficient design methodology for realizing hybrid filter-antenna subsystems. Designing a filter-antenna subsystem in the case of complex multimode filter is not straightforward. The coupling of the antenna with a multimode filter depends upon several uncorrelated parameters. An efficient design methodology is proposed which can address these complex problems. The work focuses on the characterization of radiating and filtering elements and then proposes a reliable model, which is derived mathematically as well as from rigorous statistical analyses, which can then be used for designing hybrid filter-antenna structures such as a hybrid DRA codesigned with a SIW based multimode filter. A highly compact filter-antenna subsystem has been designed employing the proposed methodology, and the measured results validate the proposed design technique. Umair Naeem, Amjad Iqbal, Muhammad Farhan Shafique, and Stéphane Bila Copyright © 2017 Umair Naeem et al. All rights reserved. Novel Wideband Metallic Patch Antennas with Low Profile Sun, 30 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/6936097/ Two planar metallic patch (MP) antennas with low profiles are investigated and compared in this paper. The MP of each antenna consists of metallic patch cells and it is centrally fed by a rectangular slot. Two modes with close resonance frequencies are excited, providing a quite wide bandwidth. The antenna principle is explained clearly through a parametric study. Simulated and measured results show that the MP antennas with profile of 0.06 can obtain a 10 dB impedance bandwidth of ~32% and an average gain of ~10 dBi. Zhong-Xiang Zhang, Meng Kong, Shuo Wang, and Yong-Mei Pan Copyright © 2017 Zhong-Xiang Zhang et al. All rights reserved. Reconfigurable Antenna for Jamming Mitigation of Legacy GPS Receivers Sun, 30 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/4563571/ We propose a simple solution for jamming mitigation of L1 band GPS by electronically switching antenna beam for wide and narrow beamwidths. Assuming the jamming signal is directed from low elevation angles, antenna reception can be made significantly lower at these angles by electronically reconfiguring the antenna beamwidth. Four-element antenna array and one of the elements of the array are designated as antijam (array) mode and normal mode of the antenna. The antenna is placed on a degenerate-ground with symmetric slots in the ground. Front-end configuration for this antenna is also discussed. Simulations and measurements are performed to validate the proposed design. The antenna achieves more than 15 dB rejection in measurements and more than 20 dB cross-polarization improvement compared to standalone (normal mode) antenna. The system can easily be replaced with existing active antenna to improve antijam capability of the receiver. İsmail Şişman and Korkut Yeğin Copyright © 2017 İsmail Şişman and Korkut Yeğin. All rights reserved. A Miniaturized 4 : 1 Unequal Wilkinson Power Divider Using Artificial Transmission Lines and Double-Sided Parallel-Strip Lines Thu, 27 Apr 2017 08:21:05 +0000 http://www.hindawi.com/journals/ijap/2017/6751694/ A 4 : 1 unequal Wilkinson power divider using microstrip artificial transmission lines (ATLs) is proposed. For the ATL, a series of meandered-line inductors, parallel-plate capacitors, and interdigital capacitors are employed. The designed power divider is composed of three ATLs, and a method has been proposed using technology of ATLs and double-sided parallel-strip lines (DSPSLs) to design line of high characteristic impedance. Microstrip line with very high characteristic impedance of over 150 Ω has been achieved by this method, which cannot be easily achieved by conventional transmission lines because of comparably thin conductor width. The fabricated 4 : 1 unequal power divider has good operational performance and occupies  mm, which is only about 40% of area compared to a conventional one at 0.9 GHz. Wen Huang, Wei Ruan, and Fei Tan Copyright © 2017 Wen Huang et al. All rights reserved. Reconfigurable Antenna Arrays with Multiple Requirements: A Versatile 3D Approach Thu, 27 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/6752108/ This paper proposes a deterministic method for the 3D synthesis of antenna arrays that jointly accounts for far-field pattern reconfigurability, polarization setting, dynamic range ratio reduction, and near-field control. The conceived algorithm, which generalizes some existing solutions, relies on a weighted cost function, whose iterative minimization is accomplished by properly derived closed-form expressions. This feature, combined with the possibility of selecting the weighting parameters, provides a fast and versatile approach, whose capabilities are numerically checked by considering different synthesis problems and array structures in the presence of mutual coupling. Massimiliano Comisso, Giulia Buttazzoni, and Roberto Vescovo Copyright © 2017 Massimiliano Comisso et al. All rights reserved. Method for Estimating Optimum Free Resonant Frequencies in Overcoupled WPT System Thu, 27 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijap/2017/1830687/ In our previous work, we proposed the method to maximize the output power even in the overcoupled state of the wireless power transfer (WPT) system by controlling free resonant frequencies and derived closed-form expression for optimum free resonant frequencies of the primary and secondary resonators. In this paper, we propose the mutual coupling approach to derive the optimum free resonant frequencies and show the measured power transfer efficiency (PTE) using the transmission efficiency as well as the system energy efficiency. The results of the proposed approach exactly coincide with those of the previous work, and the fabricated prototype achieves the transmission efficiency of about 80% by tuning the free resonant frequencies to the optimum values in the overcoupled state. Dong-Wook Seo and Jae-Ho Lee Copyright © 2017 Dong-Wook Seo and Jae-Ho Lee. All rights reserved.