mutual coupling in antenna arrays 2011

Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2012, Article ID 715138, 2 pagesdoi:10.1155/2012/715138

Editorial

Mutual Coupling in Antenna Arrays 2011

Hoi Shun Lui,1 Hon Tat Hui,2 and Marek Bialkowski3

1Department of Signals and Systems, Chalmers University of Technology, 412 96 Gothenburg, Sweden2Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 1175763 School of Information Technology and Electrical Engineering, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia

Correspondence should be addressed to Hoi Shun Lui, [email protected]

Received 16 February 2012; Accepted 16 February 2012

Copyright 2012 Hoi Shun Lui et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Mutual coupling in antenna arrays is a topic of continuousinterest to the researchers and application engineers in thefield. Since the application of antenna arrays has been ex-tended to many areas in modern days, the study of themutual coupling phenomenon has become a popular andimportant topic of research. We have seen many newmethods to analyse compensate for the mutual couplingeect in the last few years. In 2009, we have coordinated thefirst special issue on Mutual Coupling in Antenna Arrays.We have received 16 submissions and 9 of them have beenrecommended for publication. In this second special issue,we have received 29 manuscripts, out of which 17 have beenrecommended for publication by dedicated reviewers. Allthe accepted papers in both special issues have been subjectto a strict peer-reviewing process. On one hand, we greatlyacknowledge the reviewers for their professional reviews ofthe manuscripts, while, on the other hand, we are pleased tosee that a much larger attention has been paid by the authorsto this second special issue. The 17 accepted manuscriptscan be grouped into five categories: the implication ofmutual coupling problem in antenna array design, mutualcoupling in MIMO system antenna arrays, mutual couplingin direction finding problems, mutual coupling in widebandantenna arrays, and calibration methods for the mutualcoupling eect. A quick reference to these papers is givenbelow to introduce them to the interested readers.

In the first category, the paper An optimal design ofmultiple antenna positions on mobile devices based on mutualcoupling analysis by P. Uthansakul et al. introduces amethodof using the genetic algorithm (GA) to find the optimalantenna positions on a mobile device in order to achievean optimum operation under the influence of the mutualcoupling eect. In the paper, Synthesis of antenna arrays

and parasitic antenna arrays with mutual couplings by M.Thevenot et al., the authors present a synthesis methodfor various types of moderate-size antenna arrays togetherwith their feeding networks with an aim to optimize thearray performance in the presence of mutual couplingeect. The paper A Compact low-permittivity dual-layer ebgstructure for mutual coupling reduction by A. Azarbar andJ. Ghalibafan proposes a dual layer electromagnetic bandgap(EBG) structure, which has a lower resonant frequency thana single-layer one, to reduce the mutual coupling betweenan E-plane-coupled microstrip antenna array, resulting ina significant 19 dB mutual coupling reduction. The paperMutual coupling eects analysis in a cross-rhombic antennaarray by J. Sosa-Pedroza et al. presents a full-wave simula-tion analysis of the mutual coupling eect in a conformalarray consisted of cross-rhombic antennas. Results have beenobtained on the radiation patterns and the S11 parameters ofthe array. The paper A novel design of microstrip arrays forrelay-based wireless network by I. Petropoulos et al. reportsa design of relay-station antenna arrays based on reducingthe mutual coupling between the access link array and thebackhaul link array, achieving a coupling typically less than40 dB. In the last paper of this category, Optimization ofa 12.5 GHz microstrip antenna array using Taguchis methodby M. Spasos, et al., the authors present an optimizationdesign of a simple planar 5 5microstrip antenna array withinterconnected elements to achieve a good input matching(with S11 < 10 dB) without using any matching network.They used the Taguchis optimization method in the designwhich shows low interelement mutual coupling as well asgood self-impedance matching.

In the second category, the paper Investigation into theimpact of mutual coupling on the performance of a multiuser

2 International Journal of Antennas and Propagation

mimo system employing generalized channel inversion tech-nique by F. Wang et al. reports an investigation into theperformance of a multiuser MIMO system employing gener-alized channel inversion scheme. The investigation speciallyconsiders the eects of spatial correlation and antennamutual coupling which are significant in compact arrayantennas. In the paper An envelope correlation formulafor (N,N) MIMO antenna arrays using input scatteringparameters, and including power losses by Y. A. S. Dama etal., the authors present a method to derive a closed-formexpression for the correlation coecient in terms of thescattering parameters of an antenna array. This expressiontakes into account the antenna mutual coupling as well aspossible antenna losses into account. The paper Optimalantenna selection designs for coupled MIMO systems by P.S. Taluja and B. L. Hughes reports that the presence ofinactive antennas in a coupledMIMO system can profoundlyalter the system performance when the antennas are stronglycoupled. A new antenna selection technique that seeks toexploit mutual coupling to improve the system performanceis proposed. In the last paper in this category, The noise per-formance of a multiple-input-port and multiple-output-portlow-noise amplifier connected to an array of coupled antennasby F. Broyde and E. Clavelier, the authors investigated a noisecharacterization method for low-noise amplifiers connectedto a mutually coupled antenna arrays. The noise figures ofthe low-noise amplifiers were defined and determined.

In the third category, the paper Spatial correlation fordoa characterization using von mises, cosine, and gaussiandistributions by W. J. L. Queiroz et al. presents mathematicalexpressions for the spatial correlation between elements oflinear and circular antenna arrays, considering cosine, Gaus-sian, and Von Mises distributions for the direction-of-arrival(DoA) of the electromagnetic waves at the receiver antenna.The expressions obtained for the Von Mises distributioncan include or exclude the mutual coupling eect and aresimpler than those obtained for the cosine and the Gaussiandistributions of the angle of arrival. In the paper Eects ofground constituent parameters on array mutual coupling forDOA estimation by I. Ahmed et al., the authors suggestedthe use of an imperfect ground plane to reduce the mutualcoupling eect of a monopole antenna array mountedover the imperfect ground plane. A factor of 4 in thedecrease in both the real and imaginary parts of the mutualcoupling eect is reported. In the paper A Subspace-basedcompensation method for the mutual coupling in concentriccircular ring arrays for near-field source localisation byM. J. Abedin and A. S. Mohan, the authors proposed atechnique for compensating the eect of mutual couplingon parameter estimation that is suitable with any subspace-based superresolution algorithms. The method has beendemonstrated on a concentric circular-ring array formed bythin-dipole antennas in the receiving mode for near-fieldsource localization.

In the fourth category, there are two papers. The firstpaper Wideband analysis of mutual coupling compensationmethods by S. Henault and Y. M. M. Antar compares theperformance of various mutual coupling estimation andcompensation methods for wideband antenna arrays. The

main limitations and the required procedures to estimatethe coupling matrix are outlined. This paper found thatonly the full-wave method is accurate at all frequencies. Inthe second paper Mutual coupling eect on ultrawidebandantenna array performance by O. Ahmed and A. R. Sebak,the mutual coupling eect between array elements of two-and four-element ultrawideband (UWB) linear arrays on theperformances of these arrays is investigated. This study foundthat an array bandwidth improvement is achieved for botharray types when mutual coupling is strong enough. It alsofound that mutual coupling enhances the array realizablegain, especially in the mid-frequency band (58.5GHz)while it deteriorates the gain outside this frequency range.

In the last category, the first paper Ameasurement systemfor the position and phase errors of the elements in an antennaarray subject to mutual coupling by T. Lindgren and J. Borgdiscusses a method of estimating the position and phase ofeach individual antenna element in an array in the presenceof mutual coupling. The method uses both the measuredscattering matrix and the measured electric field with fourprobes located in the near-field of the array. The secondpaper An external calibration method for compensating forthe mutual coupling eect in large interferometric aperturesynthesis radiometers by J. Dong deals with the antennamutual coupling eect in interferometric aperture synthesisradiometers (IASRs) which degrades the radiometric systemperformance. First, the conventional mutual impedancemethod is adopted to analyze the mutual coupling eect inthe performance of IASR and a practical model of thecoupled visibilities is developed. Based on the model, anexternal calibration method is proposed to compensate forthe mutual coupling eect.

The papers in this second special issue came from varioustypes of studies. These papers reported the handling of themutual coupling problem in antenna arrays for various ap-plications. Through the collection of these papers, we hopeto bring out the state-of-the-art research on mutual couplingin antenna arrays such that more ideas and research on thistopic can be encouraged to come out in the future.

Hoi Shun LuiHon Tat Hui

Marek Bialkowski

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mutual coupling in antenna arrays 2011

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