Antenna Design for 4x4 MIMO 5G Communication

Antenna Design for 4x4 MIMO 5G Communication

1Student, Dept. of Electronics and Telecommunication Engineering, Goa Engineering college, Goa, India.

2Assistant Professor, Dept. of Electronics and Telecommunication Engineering, Goa Engineering college, Goa, India. ***

Abstract - The design presented in the paper for the 5G application (5G NR N78 Band) at the operating frequency 3.5GHz of a patch antenna with Ushapedslotwasinvestigated to realise a structured 4x4 MIMO antenna. To widen the bandwidth U-shaped slot was cut out on the microstrip patch antenna that was coaxially fed. FR4 material was used as the dielectric substrate in designing with relative permittivity 4.4 with a height of 1.6mm and loss tangent 0.02. The antenna model was designed and analyzed using HFSS software to obtain a bandwidth of 250 MHz with good performance parameters like VSWR, Gain, Reflection coefficient and Impedance. The parameters and analysis have been added in this paper.

Key Words: Microstrip, 5G NR N78 Band, U-Slot, MIMO, HFSS.

1. INTRODUCTION

ThetechnologyofMIMO(Multiple-inputmultiple-output), oneofthekeycomponentsplayingsubstantialroleinthe5G system of communication can greatly boost spectral efficiency without using additional power. 3GPP (3rd GenerationPartnershipProject)recognizedmanylicensed and also unlicensed bands which form a wide bandwidth from 3.3GHz to 5GHz as the combination of 5G NR bands N77(3.3–4.2GHz),N78(3.3–3.8GHz)andN79(4.4–5GHz) [2]. The 5G sub-6 GHz spectrum has NR bands N77/N78/N79 its key constituents. The main method for improvingallfacetsofwirelesscommunicationsisMIMO.It hasa significantimpacton 5Gtechnologyand ischanging how everyday people engage with these technologies. By implementing 5G New Radio (NR), data can reach more usersandbeaccessedbymorepeopleatthesamefrequency andtimerates.Alight-weightandsmallersizedantennais probablyrecommendedtoenablethehighmobilityrequired for a wireless equipment to communicate. Microstrip antennasthatcompactenoughareamongthebesttoolsfor thisjob.Duetotheirlow costandplanarform,microstrip antennas have been extensively well used in modern systems. Cutting a U-shaped slot in the patch of the rectangularpatchantennathatiscoaxiallyfedisonewayto increase the bandwidth. The finite ground plane and Ushapedslotareemployedtoproduceexcellentimpedance matchingandexpandthebandwidth[4].Dueofitsbenefits, ourdesigntakesintoaccountaU-shapedslotonthepatch antenna's rectangular shape. For our design, we took into accountthecoaxialprobefeedapproachbecauseitissimple

and adaptable because it may be positioned wherever is necessary to meet impedance. In this paper a single basic structure of Microstrip patch antenna was considered for designing. The design of a 2x2 and finally 4x4 antenna systemwithmultiplesingleelementantennaswereplaced compactlyinaMIMOconfiguration.

2. DESIGN OF THE ANTENNA

In-depth study has recently been conducted to improve bandwidth, gain, and offer size utilizing a variety of strategies.Thesemethodsincludetheuseofsubstrateswith reduced dielectric permittivity, air-filled dielectric media, thickersubstrates,andslotantennaarchitecture.

Gain can be gained by loading a certain slot on the patch element of the antenna that conducts, which results in a smallerantennaandincreasedbandwidth.Whenslotsare introduced onto a conducting patch element, the excited patchsurfacecurrentchannelsmightmeander,whichlowers theresonantfrequencyandresultsinasmallerantennathan a traditional microstrip patch antenna at the intended frequency.

Antennaimpedance,bandwidth,gain,andsizepropertiesare improvedbyloadingslotsontheconductingpatchelement with a thick air dielectric material and igniting it with a singlecoaxfeedsetup.

Inthegivenfrequencyrange,thecoaxialfeedingtechnique hasadvantagesoverthemicrostriplinefeedingtechnique forantennacharacteristics.Overall,coaxialfeedingproduces superior outcomes. compared to micro strip line feeding, ignoringgain,forallantennaparameters.

In Fig. 1, Fig. 2 and Fig.3 the rectangular U-slot patch antenna'sgeometrywhichisproposedaboveisshown.

ThetwosingleUslotantennawhicharecoaxiallyfedare placedoppositetoeachotherinasymmetricalmanner andtheresultsareobtained.

3. DESIGN CONSIDERATIONS

The center frequency (fo) is taken as 3.5 GHz with lower bound frequency (flow) as 3.3 GHz and upper bound frequency(fhigh)as3.8GHz.Theantennawasdesignedfor the application of 5G for the 5G NR N78 band. Dielectric material FR4withdielectric constant4.4andloss tangent 0.02wasused.Substrateheightwastakenas1.6mm.

DESIGNEQUATIONS

PatchDimensions:

1) Width

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2) Effectivedielectricconstant

����������=����+12+����−12√[1+12��/��]

Lengthextension

ⅆ��=0.412��(����������+0.3)(��/��+0.2)/((����������− 0.258)(��/��+0.8))

3) Length

��������=(��0/2��0√����������)−2ⅆ��

Grounddimensions:

1) Widthoftheground

����=��+6��

Finally,the4x4MIMOantennaconfigurationisachieved afterplacingmultipleantennascompactlyinthetotalarea andachievingthefeedlocationafteriteratingforthebest impedancematch.

Fig.4. shows the detailed dimensions of the single patch antennawhereLgisthegroundplanelengthandWgasthe width and the patch length and width are L and W respectively.ThepatchconsistsofaU-slotwiththefollowing dimensions:Dfortheslotwidth,Cfortheslotheight,Hfor theslotheightfromthepatchbase,andEandFfortheslot widthbetweentheupperandlowerlayersoftheU-slot.

2) Lengthoftheground

����=��+6��

The most popular method of feeding Microstrip patch antennasisemployedi.e.coaxial-probefeeding.Thistypeof feedingtechniquehasthe keybenefitthatthefeedcan be placedanywhereitisneededinsidethepatchtomatchthe inputimpedance[8].Afterseveraliterations,itspositionon the patch determined the impedance match that were estimatedtomeeta50ohmimpedance.

Thevariousdesignparametersthatwerecalculatedforthe single element of the MIMO antenna configuration are providedbelowinTable1.

Table -1: Design

4. SIMULATION & RESULT

HFSSsoftwarewasusedtocreateandsimulatethisantenna model. The feed point location (13.04, 17.84) yielded the best impedance matching, with a measured impedance of 50.5. The VSWR and Reflection coefficient were also determined to be minimal at this feed point. The performance characteristics of the antenna are shown in Table2

Ideally,VSWRmustlieintherangeof1-2whichisachieved inourdesign.Thevswrvalueobtainedisbetween1to1.5 whichagoodefficiency.

The above graphs show the plots of several performance parameters.Theantennawasdiscoveredtohaveagainof 13.8 dBi and be resonating at 3.42GHz. The Reflection coefficient and VSWR values are modest and sufficiently closetooptimumvalues.Inthecontextofpatchantennas, thebandwidthof250MHzisagoodfigure.

Itcanbeseeninfigurethattheoptimizedmodelafterproper impedancematchingcancoverthebandwidthfrom3.35to 3.6GHz with return loss less than -10 dB. The feed point location is determined using the formulae to produce the impedancematching,andtherightplacementpointisthen foundfollowingnumerousiterationstoreachthevalue50.

Theisolationbetweenapairoftheantennaelementsismore than20dB.

ThesimulationwiththeHFSSsoftwareshowstheresultsof radiation in different direction using 3D radiation pattern wherethemaximumgainthatcanbeseenis13dBiandthe radiation pattern is almost isotropic in nature, which is desiredourapplication.

5. CONCLUSIONS

Theperformancecriteriafortheantennacreatedspecifically for the use, 5G application (5G NR N78 Band) at the operating frequency 3.5GHz with the incorporation of Ushaped slot single antenna that was coaxially fed and designed using FR4 substrate material with the height of 1.6mm to realize a 4x4 MIMO antenna are reliable. Furthermore,agoodbandwidthisachievedwiththeleast amountofreturnlossandVSWR.

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