EditorialAntenna Systems for Internet of Things

Hassan Tariq Chattha ,1 Qammer H. Abbasi,2 Masood Ur-Rehman ,3

Akram Alomainy,4 and Farooq A. Tahir 5

1Department of Electrical Engineering, Faculty of Engineering, Islamic University of Madinah, Saudi Arabia2School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK3School of Computer Science & Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK4School of Electronic Engineering and Computer Science, Queen Mary, University of London, London, E1 4NS, UK5Research Institute for Microwave and Millimeter-Wave Studies, National University of Sciences and Technology (NUST),Islamabad, Pakistan

Correspondence should be addressed to Hassan Tariq Chattha; chattha43@hotmail.com

Received 2 September 2018; Accepted 2 September 2018; Published 17 September 2018

Copyright © 2018 Hassan Tariq Chattha et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Internet of Things (IoT) shall be imperative in incorporatingdifferent heterogeneous end systems including everythingfrom smart homes to the industrial Internet of Things withsmart agriculture, smart cities, and the smart grid. Apartfrom the sophisticated communication protocols, the choiceof an antenna system will be a critical component of allthese node end smart devices. Choosing the right antennafor an application imposes a key design challenge. As IoTmodules continue to shrink incorporating more wirelesstechnologies, making space for antennas is becoming anincreasingly significant challenge.Thus, IoT-module antennadesign faces the restrictions of ever-shrinking footprintswhile maintaining reasonable antenna performance undersevere conditions such as noise, fading, and the need for effi-ciency. Enhanced techniques for multiplexing, interferencemitigation, scheduling, and radio resource allocation workalongside the antenna design for the realization of efficientantenna systems for IoT.

The explosive growth of the Internet of Things and smartindustrial applications creates many scientific and engineer-ing challenges that are the main intentions of this specialissue for ingenious research efforts for the development ofefficient, cost-effective, scalable, and reliable antenna systemsfor IoT. The antenna designs for UWB and RFID tags in IoTenabled environment, MIMO antenna systems, transmissiontechniques of massive MIMO systems, and position toler-ance design method and effects of randomness in element

positions in antenna arrays are given particular emphasis inthe contributions included in this special issue.

Contributions. This special issue contains 6 scientific paperscovering a range of antenna designs, techniques, and systemsrelated to the Internet of Things.

In “A Novel Dual Ultrawideband Cpw-Fed PrintedAntenna for Internet of Things (Iot) Applications” by Q.Awais et al., the authors present a printed antenna with copla-nar waveguide (CPW) feeding having rectangular shapedblocks with dual-band characteristics. The antenna has com-pact dimensions of 35 mm × 25 mm with an FR4 used assubstrate. For increasing the impedance bandwidth and gainof the antenna, a technique of rounded corners is exploited.The two ultrawidebands covered by the proposed antennaare 1.1 GHz to 2.7 GHz and 3.15 GHz to 3.65 GHz, whichinclude 2.45 GHz Wi-Fi/Bluetooth, majority of the 3G, 4Gbands, and a lower 6 GHz 5G band of 3.4 GHz to 3.6 GHz.The simulated results are compared with the measured oneswhich are generally in good accordance with each other. Theantenna being low-profile is a suitable candidate for the 5GIoT portable applications.

In “Position ToleranceDesignMethod for Array Antennain Internet of Things” by C. Wang et al., the authors discussthe position error of array antenna which is a significantfactor of deteriorating the gain and sidelobe of the array,thus seriously affecting the performance of antenna array for

HindawiWireless Communications and Mobile ComputingVolume 2018, Article ID 8691612, 2 pageshttps://doi.org/10.1155/2018/8691612

2 Wireless Communications and Mobile Computing

the Internet of Things (IoT). Using the sensitivity analysistheory, the authors derive the sensitivity of the array radiationfield with respect to the position of the antenna element.The authors have also proposed a novel design method ofposition tolerance for array antenna and have applied it to a20 x 20 planar array and have compared it with the antennaarray designed by the traditional method. It is found thatthe gain loss of both of the antenna array is the same, i.e.,0.5 dB, whereas the peak side lobe level is lowered by 1.937dB (𝜙 = 0∘)/1.586 dB (𝜙 = 90∘). In addition, the uncertaintyanalysis is also performed which has proved that the newlydesigned array has higher probability to obtain the requiredperformance characteristics, which validates the new designmethod being innovative and effective.

In “On the Capacity and Transmission Techniques ofMassiveMIMO Systems,” the authorM. A. Haleem discussesthe Massive-MIMO wireless system which is a multiusersystem having base stations consisting of a large number ofantenna elements with respect to the number of user deviceswith each equipped with a single antenna. The potential ofthe massive MIMO system is its ability to realize multiuserchannels with near zero mutual coupling. In a high bit ratemassive MIMO system with m base station antennas and nusers, downlink capacity increases as log

2m bps/Hz and the

capacity per user decreases as log2n bps/Hz. This capacity

can be obtained by power sharing using signal weightingvectors aligned with respective 1 x m channels of the users.For a low bit-rate transmission, time sharing obtains thecapacity equivalent to that of power sharing. If the channelcoupling factor increases, the system capacity decreases.The probability distribution of channel coupling factor is aconvenient tool to predict the number of antennas needed toqualify a system as Massive MIMO.

In “Tunable Platform Tolerant Antenna Design for RFIDand IoTApplicationsUsingCharacteristicModeAnalysis” byA. Sharif et al., the authors highlight the significance of RadioFrequency Identification (RFID) as an emerging technologyfor sensing, identifying, tracking, and localizing differentgoods as being cost effective in tagging a large number ofgoods. The authors have proposed a platform tolerant RFIDtag antenna having tuning capabilities. The CharacteristicMode Analysis (CMA) is used to design and optimize theproposed tag antenna.Theproposed antenna contains a patchfolded around an FR4 substrate and a loop as feeder printedon a paper substrate. Feeding loop is stacked over the foldedpatch thus providing impedance matching with differentRFID chips. Having separate radiator and feeder, the pro-posed antenna exhibits the capability of getting its impedancematched with a variety of RFID chips. The frequency bandcovered by the proposed tag antenna is an American RFIDband of 902-928 MHz and has the capability of being able tobe tuned to the European RFID band of 865-868MHz) usingtunable strips. For the demonstration of platform tolerantoperation, the RFID tag is mounted on different materials tomeasure its maximum read range, which is found to be 4.5 min free space, on a dielectric, and a value of 6.5mwhen placedabove a 200 mm x 200 mmmetal plate.

In “Compact Ultra-Wide Band MIMO Antenna Systemfor Lower 5GBands” byH.Al-Saif et al., the authors propose a

planar antennawith ultrawideband characteristics forMIMOapplications. The presented antenna is simulated in the CSTmicrowave studio and is designed to cover lower 5G bandsfrom 2 to 12 GHz, thus covering the IEEE 802.11 a/b/g/n/acas well.The proposed antenna has compact andminiaturizeddimensions of 25 mm x 13 mm x 0.254 mm. The measuredand simulated results are presented having good accordancewith each other. The simulated and measured reflectioncoefficients S

11for the proposed design are below -10 dB

over the frequency band in interest. The mutual couplingfound between the two antennas is under -20 dB in desiredfrequency range.The 2D radiation patterns in E andH planesexhibit omnidirectional far fields with a peak measured gainof 4.8 dB. The fractional bandwidth of the proposed antennais found to be around 143%, thus showing its ultrawidebandcharacteristics.

In “Effect of Randomness in Element Position on Per-formance of Communication Array Antennas in Internet ofThings” by C. Wang et al., the authors discuss the activephased array antennas, being a critical component of wirelesscommunication, and face the restrictions of creating effectiveperformance with the effect of randomness in the position ofthe array element, which are inevitably produced in the man-ufacturing and operating processes of the antenna. A newmethod for efficiently and effectively evaluating the statisticperformance of the antenna is presented, with considerationof randomness in element position. A coupled structural-electromagnetic statistic model for array antenna is pro-posed from the viewpoint of electromechanical coupling.In addition, a 12 x 12 planar array is illustrated to evaluatethe performance of the antenna with the saddle-shapeddistortion and random position error. The results show thatthe presented model can obtain the antenna performancequickly and effectively, providing an advantageous guidancefor structural design and performance optimization for arrayantennas in a wireless application.

These contributions bring a good insight of the presentdevelopment activities and research happening related toantenna systems for the Internet of Things. The editorsare optimistic that this special issue will contribute to theknowledge base and benefit the scientific community.

Conflicts of Interest

Authors have no conflicts of interest.

Acknowledgments

The editors would like to commend the contributions of theauthors for making the special issue a success. Taking thisopportunity, the editors would like to appreciate the effortsof the reviewers as well for the rigorous review process, thusenhancing the quality of the manuscripts submitted.

Hassan Tariq ChatthaQammer H. AbbasiMasood Ur-Rehman

Akram AlomainyFarooq A. Tahir

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