The performance of a wearable antenna under bending conditions Designed on a Used Jeans for the ISM band

HaldiaInstit u Int.J.HIT.T R     *Correspond i   ORIGINA The p Desig n Subhras h 1* V.S.M. M Midnapore, Email Id: s u ABSTRA C In recent Area Net w track the b are collec t is placed e for transf e designed o lossy, da y dielectric tangent o f GHz. The indoor o p performa n KEY W O 1. INT R The use o sector is i track pat i and devi c to meas u pressure, pulse rate transmitt e connectio n wirelessl y mobile c o wearable u teofTechnology R ANSC:ECCN. V i ngAddress: subh r L CONTRIB U erforma n n ed on a U h il Nanda 1* , M anikpara, Jharg r 721102, India u bhrashilnanda7 C T days, an inc r w ork (WBA N b lood pressu r t ed and trans m e ither on the c e rring data to o n low-loss e y -to-day used probe kit u s f jeans are ta n gain obtain e p eration. Th e n ce of the ant e O RDS:Weara b R ODUCTI O o f electronic i ncreasing d a i ents’ health c es that are i n u re and trac k temperature, , etc., form t h e d to the out e n between y . 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Th a re designed c h also incre a h ave used hig e sign wearab l c e wearable r able garm e fort of the f iguration i s c ific absorp o rtant role h e n ationalJournalo f 0973‐6875 C CN Pag e bending 2 , India, 3 Vidya s p ortance of t h a round the b o t c. WBAN e n d ual. A wear a nnect the W B o rted wearab l d a wearable m arket. It is c h e dielectric a is designed h e gain obtai n u s, the ben d p timal perfor m N ), ISM Ban d l e things is s u e wearable a n on engineer e a ses the cost hly lossy, da y l e antennas. antennas a r e nts withou t individual, a s suitable f tion rate ( e re. The ba c f HITTransaction o e | 40 conditi o s agar Universit y h e Wearable o dy to measu r n sures that th a ble antenna, w B AN with th e l e antennas t h antenna on h c haracterized constant an d to resonate a n ed is suffici e d ing effect o m ance. d u itable to es t n tennas repo r e d low-loss f [3-6]. In our y -to-day use d r e integrated t hamperin g a planar str u f or the pu ( SAR) pla y c k radiation o o nECCN  o ns y , Body r e and e data w hich e LAN h at are h ighly in the d loss a t 2.45 e nt for o n the t ablish r ted so f abric, work, d jeans with g the u cture rpose. y s an o f the Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|41 patch antenna is very poor because of the presence of the Ground plane, thereby reducing the SAR value [7-10]. Bin Hu et. al. have designed two dipole antennas on a low-loss felt fabric for wearable applications [3]. B. Mandalet. al. have reported a circular-shaped monopole printed antenna on low-loss cotton fabric [4]. A rectangular-shaped patch antenna designed on low-loss jeans substrate for the 2.45GHz ISM band is reported by SweetyPurohit and FalguniRaval [6]. A wearable antenna may deform and bend while being worn on the body. It affects the resonant frequency and antenna performance. Lingnan Song and YahyaRahmat-Samii have studied the bending effect on a patch antenna [11]. In another study by Ivo Locher et al., a purely textile wearable antenna was designed to resonate at 2.4GHz and studied the bending effect [12]. In our work, we have used day-to-day jeans as the substrate to design the wearable antenna. The jeans is collected from a local market and is characterized using Open Open-Ended Coaxial Probe (OECP) technique. The dielectric constant of the material is 1.7976, and the loss tangent is 0.1125. The thickness of the single-layer jeans is 0.425mm. The jeans fabric is highly lossy compared to an engineered wearable material [13]. The highly lossy material poses a challenge to designing antennas as it results in poor gain and efficiency. In our previous work, we have designed and reported a wearable antenna using a single layer of the same lossy jeans. The antenna has a gain of -9.26 dBi and a radiation efficiency of 1.83% at 2.4GHz [13]. The poor gain and radiation efficiency are due to the high loss of the material. In our present work, the antenna height is optimized to improve the gain and efficiency. The antenna is designed on five layers of jeans; thereby, the height of the substrate is increased to 2.125mm. A wearable antenna is integrated with cloth, which might bend and tends to take a curvature depending on the shape of the body parts, like biceps, thighs, belly, back, etc. The radius of curvature depends on the location of the body where the antenna is integrated. We have studied the bending effect on the resonant frequency, radiation efficiency, and radiation pattern. The performance is studied for different radii of curvature. It is found that the resonant frequency shift is negligible, but the 2.45 GHz ISM band remains unchanged. The gain remains greater than 1.5 dBi, and the radiation efficiency is greater than 19 % for all radii of curvature. The designed antenna may be used for health monitoring, tracking, and management systems, fitness trackers, for health care data transmission, and the Internet of Things, etc. The antenna has been designed, and the performances are studied in the Finite Element Method (FEM) based simulator CST Microwave Studio. 2. ANTENNA DESIGN AND RESULTS The geometry of the proposed antenna is shown in Fig. 1.The width of the patch (W), the effective dielectric constant 󰇛𝜖󰇜, and the length (L) are calculated using equations (1), (2), and (3)[14]. 𝑊 𝑐 2𝑓𝜖1 2 󰇛1󰇜 Where fr = Resonant frequency, C = Speed of light. 𝜖𝜖1 2𝜖1 21 12ℎ 𝑤  󰇛2󰇜 𝐿 𝐶 2𝑓𝜖2 △ 𝐿 󰇛3󰇜 Where, ΔL is the increased length of the patch due to fringing effect, and it is calculated using equation (4) [14]. Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|42 The calculated length (L) and Width(W) of the patch are 44.22 mm and 51.73mm, respectively. Here inset feeding technique is used. The antenna is simulated using calculated dimensions on FEM based CST Microwave Studio [15] at different bending conditions. △𝐿 0.412ℎ𝜖0.3󰇡 0.264󰇢 𝜖0.258󰇡 0.8󰇢 󰇛4󰇜 2.1 OPTIMIZED DIMENSIONS OF THE ANTENNA The optimized dimensions of the antenna under flat conditions are tabulated in Table 1. Table 1: Optimized dimensions of the antenna Variables Optimized values Dielectric constant (𝜖r) 1.7976 Loss tangent (tan δ) 0.1152 Substrate height (h) 2.125 mm Patch length (L) 42 mm Patch width (W) 67 mm Ground Length (LG) 120 mm Ground Width (WG) 120 mm Inset Depth (ID) 4.8 mm Inset Spacing (IS) 4.9 mm Feed Length (LF) 20 mm Feed Width (WF) 1.8 mm Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|43 Figure 1: Geometry of the antenna The geometry and dimensions of the antenna are shown in Fig. 1. The antenna is simulated under different bending conditions, but the dimensions are kept unchanged. The pictures of the antenna at different radii of curvature are shown in Fig. 2. Simulated S11 plots under different bending conditions are shown in Fig. 3.Simulated Gain vs frequency plots under different bending conditions are shown in Fig. 4. Simulated Radiation efficiency vs frequency plots under different bending conditions are shown in Fig. 5. Simulated Co and Cross-Pole Radiation patterns at 2.45GHz under different bending conditions are shown in Fig. 6. Simulated 3D Radiation patterns at 2.45 GHz under different Bending Conditions are shown in Fig. 7.  ISSN:0973 Figure 2: 300mm, ( C . ‐6875 The pictur e C ) Bending w Fi g F S  e s of the ant e w ith Radius o g ure 3: Sim u F ig. 3. Simul a S ubhrashil Na n e nna at (A) W f Curvature 6 u lated S 11 Plo t a ted S 11 Plot s n da et. al. / In t W ithout Ben d 6 00mm, (D) B t s under diff e s under differ e t .J.HIT.TRAN S d ing, (B) Be n B ending with e rent bending e nt bending c S C:ECCN. Vol 1 n ding with R a Radius of C u conditions. c onditions. 1 2: Issue 1A(2 0 Pag e a dius of Cur v u rvature 900 m 0 25) e |44 v ature m m.  ISSN:0973 Figu r ‐6875 Figure 4: r e 5: Simula t S  Simulated G t ed Radiatio n S ubhrashil Na n G ain vs freque n Efficiency v n da et. al. / In t ncy plots un d s frequency p t .J.HIT.TRAN S d er different b p lots under di S C:ECCN. Vol 1 b ending cond i fferent bendi n 1 2: Issue 1A(2 0 Pag e i tions. n g condition s 0 25) e |45 s . Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|46 Figure 6: Simulated Co-Pole and Cross-Pole radiation patterns for (A) Without Bending, (B) Bending with Radius of Curvature 300mm, (C) Bending with Radius of Curvature 600mm, (D) Bending with Radius of Curvature 900mm. Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|47 Figure 7: Simulated 3D Radiation patterns at 2.45 GHz for (A) Without Bending, (B) bending with a Radius of Curvature 300mm, (C) bending with a Radius of Curvature 600mm, (D) bending with a Radius of Curvature 900mm. 3. CONCLUSION In this research work, a wearable antenna is designed to resonate at the 2.45 GHz ISM band on highly lossy day-to-day used jeans, and the antenna dimensions are optimized for different bending situations to get optimum performance, keeping the resonant frequency unchanged. The antenna is designed on day-to-day jeans, which reduces the cost and technical complexity, and also, the antenna performance is good enough to use in WBAN for short-distance communication. Subhrashil Nanda et. al. / Int.J.HIT.TRANSC:ECCN. Vol12: Issue 1A(2025)  ISSN:0973‐6875  Page|48 The antenna fabrication and experimental verification are in progress. The designed antenna may be used for health monitoring, tracking, and management systems, fitness trackers, various health care data transmission, Internet of Things, etc. References: [1]. 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