FR4-Based Microstrip Radiators: Balancing Fabrication Simplicity and On-Body Resonant Stability

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 13 Issue: 04 | Apr 2026 www.irjet.net p-ISSN: 2395-0072

FR4-Based Microstrip Radiators: Balancing Fabrication Simplicity and On-Body Resonant Stability

K. Vanitha1 , S. Jeevanantham2 , S. Sakthi Shri3 , T. Sathya4

1Professor, Dept. of Medical Electronics Engineering, Velalar College of Engineering and Technology, Tamil Nadu, India.

2Student, Dept. of Medical Electronics Engineering, Velalar College of Engineering and Technology, Tamil Nadu, India.

3Student, Dept. of Medical Electronics Engineering, Velalar College of Engineering and Technology, Tamil Nadu, India

4Student, Dept. of Medical Electronics Engineering, Velalar College of Engineering and Technology, Tamil Nadu, India.

Abstract - Wearable antennas play a vital role in bodycentriccommunicationsystems,particularlyinWirelessBody Area Networks used for healthcare monitoring, sports applications, and Internet of Things devices. However, designing antennas that maintain stable performance when placed close to the human body remains a significant challenge due to detuning effects, energy absorption, and mechanicaldeformation.Thispaperpresentsthedesignand analysisofacompactmicrostrippatchantennafabricatedon an FR4 substrate, operating in the 2.4 GHz Industrial, Scientific, and Medical band. The proposed antenna is developed with a focus on fabrication simplicity, cost effectiveness, and stable on-body performance. The design incorporates an optimized patch geometry and feeding structure to achieve proper impedance matching and acceptable radiation characteristics. Simulation and experimental analysis are conducted under free-space, bending, and on-body conditions to evaluate performance reliability. The results demonstrate consistent return loss, moderategain,andquasi-omnidirectionalradiationsuitable forshort-rangecommunication.Theantennamaintainsstable operation despite mechanical deformation and proximity to humantissue.Comparedtoflexibletextile-baseddesigns,the FR4-basedapproachoffersimprovedstructuralreliabilityand easeoffabricationwhilemaintainingacceptableperformance. This work highlights a practical balance between performance, cost, and manufacturability, making the proposed antenna suitable for integration into wearable communication systems. The study contributes to the development of efficient and low-cost wearable antenna solutions for next-generation body-centric wireless applications.

Key Words: Microstrip Patch Antenna, FR4 Substrate, Body-Centric Communication, Wireless Body Area Network, SAR Reduction.

1. INTRODUCTION

Wearablewirelesscommunicationsystemshaveemergedas akeytechnologyinmodernapplicationssuchashealthcare

monitoring, sports tracking, military communication, and Internet of Things devices. These systems rely heavily on efficient and compact antennas to enable reliable data transmissionbetweenbody-mounteddevicesandexternal networks.Wearableantennasareessentialcomponentsof Wireless Body Area Networks, where consistent performance,lowpowerconsumption,andcompactdesign arecriticalrequirements.

However,unlikeconventionalantennas,wearableantennas operate in close proximity to the human body, which significantly affects their performance. The interaction betweenelectromagneticwavesandhumantissuesleadsto challenges such as frequency detuning, reduced radiation efficiency, impedance mismatch, and increased Specific Absorption Rate. In addition, mechanical factors such as bending,stretching,andbodymovementfurthercomplicate thedesign.Therefore,developingawearableantennathat maintainsstableperformanceunderbothfree-spaceandonbodyconditionsisamajorresearchchallenge.

This paper presents the design and analysis of a compact microstrippatchantennaoperatinginthe2.4GHzIndustrial, Scientific, and Medical band using an FR4 substrate. The proposed design focuses on achieving a balance between fabricationsimplicity,costeffectiveness,andstableon-body performance. The antenna is analyzed under different conditions to ensure its suitability for wearable communicationapplications

1.1 Need for a Cost-Effective Wearable Antenna Solution

The increasing demand for wearable communication devices has created a need for antennas that are not only efficientbutalsoaffordableandeasytomanufacture.Many existing wearable antenna designs use specialized textile materialsorcomplexfabricationtechniques,whichincrease cost and limit large-scale deployment. This creates a gap between advanced research designs and practical implementation.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 13 Issue: 04 | Apr 2026 www.irjet.net p-ISSN: 2395-0072

A cost-effective solution using commonly available materialssuchasFR4substrateoffersapracticalalternative. FR4-basedantennasprovideeaseoffabrication,structural reliability,andconsistentelectricalproperties,makingthem suitable for prototyping and real-world applications. By focusing on simple design and accessible materials, the proposed antenna aims to make wearable communication technologymorescalableandwidelyusable.

1.2 Antennas in Body-Centric Communication

Antennas play a crucial role in body-centric communication systems, where devices are placed on or nearthehumanbodytoenablecontinuousdataexchange. Thesesystemsarewidelyusedinapplicationssuchashealth monitoring, fitness tracking, and smart wearable devices. Reliablecommunicationinsuchsystemsrequiresantennas that can operate efficiently despite the presence of the humanbody.

However, the human body introduces significant challenges due to its lossy and heterogeneous nature. It absorbselectromagneticenergy,whichcandegradeantenna performance and alter radiation patterns. Additionally, movement and varying body positions can affect signal stability.Therefore,wearableantennasmustbedesignedto provideconsistentperformance,adequategain,andreliable radiationcharacteristicsunderdynamicconditions.

2. PROPOSED METHODOLOGY

Theproposedsystemfocusesonthedesignandperformance evaluationofawearablemicrostrippatchantennaoperating at2.4GHzforbody-centriccommunicationapplications.The methodology involves antenna design, simulation, fabrication,andperformanceanalysisunderfree-spaceand on-body conditions. The system aims to achieve stable impedancematching,efficientradiationcharacteristics,and reliableoperationdespitetheinfluenceofthehumanbody andmechanicaldeformation

2.1 System Overview

The proposed antenna system consists of a microstrip patchstructurefabricatedonanFR4substrate,alongwitha conductive radiating patch, ground plane, and feeding mechanism.Theantennaisdesignedusingelectromagnetic simulation software to achieve resonance at the desired frequency of 2.4 GHz. Initially, the antenna dimensions, includingpatchlength,width,andsubstrateproperties,are calculated and optimized. The design is then simulated to analyzekeyparameterssuchasreturnloss,gain,bandwidth, and radiation pattern. After simulation, the antenna is fabricatedusingstandardprintedcircuitboardtechniques. Thefabricatedantennaistestedunderdifferentconditions, includingfree-space,bending,andon-bodyplacement.These evaluationshelpinunderstandingthepracticalperformance andstabilityoftheantennawhenintegratedintowearable applications.

2.2 Performance Analysis and Optimization

The performance of the proposedantenna is evaluated basedonparameterssuchasreturnloss,radiationpattern, gain, and bandwidth. A return loss value below -10 dB is consideredacceptableforproperimpedancematchingwithin theoperatingfrequencyband. Whentheantenna isplaced nearthehumanbody,performancedegradationmayoccur duetoelectromagneticabsorptionanddetuningeffects.To addressthesechallenges,theantennadesignisoptimizedby adjusting parameters such as feed position, ground plane configuration, and patch dimensions. Additionally, the antennaisanalyzedunderbendingconditionstoevaluateits robustness in real-world wearable scenarios. The optimization ensures that the antenna maintains stable performancewithminimalvariationinresonantfrequency andradiationcharacteristics.

Fig - 1:Design

2.3On-Body

Evaluation and Radiation Characteristics

Theproposedantennaistestedforon-bodyperformance to analyze its suitability for wearable communication systems. When placed on the human body, the antenna’s radiation characteristics, including gain and pattern distribution,arecarefullyobserved.Theresultsshowthatthe antennaexhibitsaquasi-omnidirectionalradiationpattern, which is suitable for body-centric communication where signal transmission is required in multiple directions. The gain achieved is moderate and sufficient for short-range wirelesscommunicationinthe2.4GHzband.Furthermore, the antenna demonstrates stable operation under bending and body-loading conditions, indicating its reliability for practical applications. Thecompactandlow-profile design ensures easy integration into wearable devices, making it suitable forapplicationssuch ashealth monitoring, fitness tracking,andIoT-basedsystems.

3. CONCLUSIONS

The proposed wearable microstrip patch antenna demonstrates an effective and cost-efficient solution for body-centric wireless communication applications. The antennaissuccessfullydesignedandfabricatedusinganFR4 substratetooperateinthe2.4GHzIndustrial,Scientific,and

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 13 Issue: 04 | Apr 2026 www.irjet.net p-ISSN: 2395-0072

Medical band. The system achieves stable impedance matching, acceptable return loss, and reliable radiation characteristics,makingitsuitableforshort-rangewireless communication. Experimental and simulation results confirmthattheantennamaintainsconsistentperformance under free-space, bending, and on-body conditions. The observed results indicate that the antenna provides moderategainandquasi-omnidirectionalradiation,which are essential for reliable communication in wearable environments. Despite the challenges introduced by the proximityofthehumanbody,suchasdetuningandenergy absorption, the proposed design effectively minimizes performance degradation. The antenna offers a compact, low-profile, and easy-to-fabricate structure, making it practical for integration into wearable devices. The use of readily available materials and simple design techniques ensureslowcostandscalabilityforreal-worldapplications.

Overall, this work presents a balanced approach between performance,cost,andmanufacturability.Itdemonstrates thefeasibilityofimplementingreliablewearableantennas using conventional materials, paving the way for future developmentsinwearablecommunicationsystems,Internet ofThingsdevices,andhealthcaremonitoringapplications.

REFERENCES

[1] M.Agiwal,A.Roy,andN.Saxena,‘‘Nextgeneration5G wireless net works: A comprehensive survey,’’ IEEE Commun.SurveysTuts.,vol.18,no.3, pp.1617–1655, 3rdQuart.,2016.

[2] N. H. M. Rais, P. J. Soh, F. Malek, S. Ahmad, N. B. M. Hashim,andP.S.Hall,‘‘Areviewofwearableantenna,’’ in Proc. Loughborough Anten nas Propag. Conf., Nov. 2009,pp.225–228.

[3] M. A. Shahzad, K. N. Paracha, S. Naseer, S. Ahmad, M. Malik,M.Farhan,A.Ghaffar,M.Hussien,andA.B.Sharif, ‘‘An artificial magnetic conductorbacked compact wearable antenna for smartwatch IoT applications,’’ Electronics,vol.10,no.23,p.2908,Nov.2021.

[4] H.Zu,B.Wu,P.Yang,W.Li,andJ.Liu,‘‘Widebandand high-gain wear able antenna array with specific absorption rate suppression,’’ Electronics, vol. 10, no. 17,p.2056,Aug.2021.

[5] B.Yeboah-Akowuah,E.T.Tchao,M.Ur-Rehman,M.M. Khan, and S. Ahmad, ‘‘Study of a printed splitring monopolefordual-spectrumcommunications,’’Heliyon, vol.7,no.9,2021,Art.no.07928.

[6] R. Singh, P. Kumari, S. Rawat, P. Singh, and K. Ray, ‘‘Design and performance analysis of low profile miniaturized MSPAs for body centric wireless communication in ISM band,’’ Int. J. Comput. Inf. Syst. Ind.Manage.Appl.,vol.9,pp.153–161,Jul.2017.

[7] H.I.Azeez,H.C.Yang,andS.W.Chen,‘‘Wearabletriband E-shaped dipole antenna with low SAR for IoT applications,’’Electronics,vol.8,no.6,p.665,2019.

[8] S.Seneviratne,Y.Hu,T.Nguyen,G.Lan,andS.Khalifa, ‘‘A survey of wearable devices and challenges,’’ IEEE Commun.SurveysTuts.,vol.19,no.4,pp.2573–2620, 4thQuart.,2017.

[9] G.Christina,‘‘Reviewonwearableantennasand their applications,’’IROJ.Sustain.WirelessSyst.,vol.3,no.4, pp.259–265,2022.

[10] T.Tuovinen,M.Berg,K.Y. Yazdandoost,andJ. Iinatti, ‘‘Ultrawidebandloopantennaoncontactwith human bodytissues,’’IETMicrow.,AntennasPropag.,vol.7,no. 7,pp.588–596,May2013.