Design and simulation of flexible jute antenna with performance validation on bending and soaking conditions

Abstract

Recently, there has been an abrupt increase in the integration of community antenna to flexible, textile and wearable applications. The proposed work introduces the design of a flexible wearable patch antenna using a jute fiber substrate for better performance. The antenna has been designed and simulated with jute substrate at the operating frequency of 3.23 GHz. The antenna has been fabricated and tested under normal, wet, on-hand and bending conditions using a vector network analyzer. The various parameters such as reflection coefficient parameter and voltage standing wave ratio of the fabricated antenna are measured and compared with the simulation results. The tested results show that the performance of the antenna under normal, wet, on-hand and bending conditions is almost approximately equal. Due to better performance in soaking and bending conditions as well as low cost and adequate availability of jute material, the proposed antenna can be used in various applications such as biomedical, military, radio location, ground radar, search and rescue applications, and more.

Keywords

jute wearable antenna soaking wet condition flexible

Recent researches show that communication equipment has been becoming upgraded day by day in terms of full efficiency. Conventional antennas have been improved in all fields, but they also possess some limitations when they are applied to wearable applications. Due to the use of rigid flame resistant level 4 substrates and other fiberglass/ceramic materials, these antennas may perform less efficiently or they may even risk breakage under bending conditions.^1–3 The previously mentioned limitations can be easily overcome by using effectively bendable antenna, which means antenna with flexible substrate materials. With the compatibility trend, antenna engineers have some restrictions with miniaturization and low profile. This can be done by selecting a flexible material with a low cost and with highly effective and highly efficient functions.

Recently, substrate made up of textile materials such as cotton,⁴ jeans,⁵ cellulose (paper based),⁶ pulp fibers⁷ and flannel fabric⁸ and synthetic materials such as polyester,⁴ polymer,⁴ foam⁹ and rubber¹⁰ have been used to structure antennas. These materials enable the antenna to be more adjustable and suitable for all environments. Of these two materials, textile materials are more often readily available and easy to deploy.

The combination of communication devices with textiles¹¹ has been rapidly increasing in commercial as well as military applications. Rapid improvements in computer networks such as personal area network, body area network and local area network have enabled more expeditious and more precise data transfer as well as analysis to be carried out. Technologies such as radio and television broadcasting, cellular communication (Bluetooth, 3G/4G), location tracking system,¹² wireless fidelity (Wi-Fi), worldwide interoperability for microwave access (WiMAX)¹³ and radio frequency identification¹⁴ have been integrated as a single system called a communication and network system. Many studies have been carried out on flexible textile antenna. The following are some of the works focused on flexible antenna using textile material as a substrate.

Indumathi and Bhavithra have designed an antenna with jeans fabric as the substrate for patient monitoring applications.⁵ Four types of antennas have been designed, fabricated and compared by the researchers. There is a reduction of –29 dB return loss with higher substrate dimensions.

Khan et al.⁷ have structured an antenna using pulp fibers (ligno-cellulose fibril sheet) as a substrate for dual band operation of 2.4–2.5 and 5.725–5.875 GHz. The pulp-based antenna has operated with measured return loss values of –15 dB at 2.7 GHz and –28 dB at 5.6 GHz, respectively. Although the antenna shows better results with respect to the reflection coefficient (–28 dB), there is no proof about its bending and wet performance and the substrate dimensions are higher.

Osman et al. have designed a wearable ultra-wideband antenna with the dimensions of 60 mm × 60 mm using a flannel fabric substrate⁸ whose dielectric constant is 1.7 and loss tangent about 0.025 with the shielding and copper conducting sheets. The designed antenna has been tested under flat, wet and bending conditions. The results show that the return loss of antenna when inside the water and immediately in wet condition is higher compared with other conditions.

Dubey et al. have framed a trophy-shaped flexible wearable antenna using a foam substrate material⁹ whose dielectric constant is approximately equal to unity. Three different shapes of antenna using the foam substrate have been designed, simulated and compared. The return loss has been observed to be around –30 dB. However, there is a major shift in the operating frequency between the measured and simulated antennas.

Dar et al. have designed a flexible wearable antenna using a rubber substrate.¹⁰ In their work, bandwidth decreases with the addition of content in rubber material. Impedance matching shifts the operating frequency abruptly as the antenna undergoes bending and wet conditions.

Ferreira et al. have designed and simulated a 2.4 GHz rectangular patch antenna.¹⁵ Denim material has been used as the antenna substrate and copper and nickel-plated polyester fabric have been used as the conducting layers. When applying the antenna to a bending curvature around its width, there is an offset downward in the frequency. On the other hand, an offset upward in the frequency has been observed for bending around the antenna length dimension.

Vejasegaran et al. have structured and simulated an embroidered textile antenna which dually operates at industrial, scientific and medical band frequencies.¹⁶ Nylon material patted in silver and cotton are used as conductive and non-conductive goods. The simulated results show that there is a shift in resonant frequency during bending.

Sanchez-Montero et al. have designed a textile antenna¹⁷ using felt fabric. The antenna dimensions are 70 mm × 85 mm and the antenna is subjected to bending and introduction of water drops. It performs better under various bending conditions with minimal effects. However, there is an abrupt shift in the operating frequency when subjected to humidity conditions.

Recently, nano cellulose¹⁸ has been a promising material, and has become a hot area of research for the advancement of the next generation of flexible “green” electronics due to its biodegradability, light weight and durability. Nevertheless, there are still considerable challenges that need to be addressed before nano cellulose paper can be widely used in electronic devices as it possesses the following issues: the cost of pure nano cellulose is high, due to the hydrophilic properties of nano cellulose,¹⁹ and the shape, humidity stability and shelf life of transparent nanopaper²⁰ are unsatisfactory. These problems should be resolved in order to minimize them. Thus, all flexible substrate materials have their own characteristics such as disability to absorb moisture, high cost, unavailability and bending effects, and consequently these characteristics affect the overall performance of the antenna.

Recently, it has been exhibited that jute fiber²¹ can act as a substrate material for the microstrip antennas. Jute fiber is a biodegradable, reliable, durable, non-toxic and inexpensive fiber^22–26 and it is compatible, possesses higher thermal stability and is easily dryable after washing. Unlike nano cellulose,¹⁸ jute does not require any chemical treatment or coating to act as a substrate. Jute is widely cultivated all over the world. Due to its environmentally friendly properties and reusability,^27,28 jute is an ideal material as a dielectric substrate for the fabrication of antennas. The proposed work is an initial attempt to display the utilization of jute fiber as a new substrate for flexible antennas and its performance has been analyzed under various conditions which will be discussed in detail.

The main contributions of the proposed work include:

Primary approach to using jute fabric as a substrate for the flexible antenna.

Antenna miniaturization with reduced return loss and better voltage standing wave ratio (VSWR).

Good antenna performance in flat, on-hand and bending conditions, even when placed inside water, makes it suitable for use in wearable applications.

Proposed methodology

The process of the design and fabrication of the prototype involves five stages. The complete flow chart of the proposed work has been schematically illustrated in Figure 1. The first stage deals with the selection of substrate material.

Figure 1.

Flowchart of the proposed work.

By properly applying the dielectric constant value of the substrate, the proposed antenna has been designed. The second stage deals with the patch antenna design using computer simulation technology (CST) software. The third stage involves the comparison of antenna parameters for different thickness values of the substrate after a series of simulations for optimization. In the fourth stage, the designed antenna has been fabricated with proper probe feeding. The final stage deals with the measurement of antenna using a vector network analyzer under flat, on-hand bend and wet conditions. The parameter values such as return loss and VSWR are tabulated, plotted and analyzed.

Substrate material

The substrate material chosen for the proposed work is jute material. The sample of jute material is shown in Figure 2.

Figure 2.

Sample of woven jute material.

Jute is one of the most affordable natural fibers and second to cotton in quantity.²⁴ This type of fiber comprises plant materials, cellulose and lignin.²⁵ The various parameters of jute fiber, taken from the literature, are given in Table 1.^21–28

Table 1.

Properties of jute fiber

Parameter	Value
Relative permittivity	1.87
Loss tangent	0.052
Electrical conductivity	0.0132538 S/m
Magnetic conductivity	1005.91 1/Sm
Thermal conductivity	0.4273 W/K/m
Heat capacity	1.36 kJ/K/kg
Material density	0.0015 kg/m³
Young's modulus	28.43 GPa

Even though jute is a notable fabric,²⁶ its utilization in microwave antennas has been restricted, and its execution in that field has not been validated. There have been several reviews on jute.²⁸ But often they have been centered on mechanical,^29–34 thermal and dielectric properties. Jute is also a suitable substrate for an antenna, since its dielectric properties do not change with water absorption.²⁸ Jute has the advantage that it does not easily wrinkle and wear off as cotton. Besides, it also keeps the environment free from pollution.

Antenna design considerations and simulations

Microstrip patch antenna^35,36 has been chosen for the antenna design, since it has many benefits over typical microwave antenna in the ways of simple design, lower dimension, low profile and simple fabrication

For designing the microstrip patch, the resonant frequency, thickness and dielectric constant values of the substrate material should be chosen; the width of the patch (W) is then calculated using equation (1)^11,37

W = \frac{1}{2 f_{r} \sqrt{μ_{0} ɛ_{0}}} \sqrt{\frac{2}{ɛ_{r} + 1}}

(1)

where

fr

denotes the resonant frequency (GHz).

μ_{0}

denotes the permeability in free space, 1.257 × 10 ⁻⁶ Henry per meter (H/m);

ɛ_{0}

denotes the permittivity in free space, 8.85 × 10^-12 Farad per meter (F/m); and

ɛ_{r}

denotes the relative permittivity.

The effective dielectric constant ( $ɛ_{reff}$ ) has been defined as a function of the ratio of the width to the height of a microstrip line (W/h), as well as the dielectric constant of the substrate material. It can be calculated as

ɛ_{reff} = \frac{ɛ_{r} + 1}{2} + \frac{ɛ_{r} - 1}{2} [1 + 12 \frac{h}{W}]^{- 1 / 2}

(2)

where h denotes the height of the dielectric substrate material.

The effective dielectric constant has been calculated as 1.05 by substituting the height of the substrate as 44 mm, width of the patch as 22 mm and relative permittivity of the substrate as 1.87.²⁸

The effective length of the patch (L_eff) is the sum of the actual length of the antenna and its extension or the fringe effects. It is calculated as

L_{eff} = \frac{c}{2 f_{r} \sqrt{ɛ_{reff}}}

(3)

where c denotes the velocity of light in air, 3×10⁸ m/s.

The effective length of the patch is calculated as 41.76 mm.

The length extension (ΔL) can be calculated from

Δ L = 0.412 h \frac{(ɛ_{reff} + 0.3) (\frac{W}{h} + 0.264)}{(ɛ_{reff} - 0.258) (\frac{W}{h} + 0.8)}

(4)

The length extension has been calculated as 1.815 mm.

The actual length (L) of the patch is obtained by using equation (5) as

L = L_{eff} - 2 Δ L

(5)

Finally, the length of the patch is calculated as 38 mm.

The antenna has been designed and simulated in CST Studio Suite® 2019 version software as shown in Figure 3 with the thickness of substrate 1.0 mm.

Figure 3.

Rectangular patch antenna designed using CST Studio Suite®.

CST Studio Suite® is a more advanced version of 3D electromagnetic analysis software package³⁸ for the purpose of designing, analyzing and optimizing the microwave devices and components. CST Studio Suite® functions by digitizing Maxwell's equation using the finite integration technique. Hence, it is user friendly for researchers to deal with. It has been utilized in driving innovation and building organizations around the globe. Due to its user-friendly interface, CST Studio Suite® easily designs an antenna compared with ANSYS HFSS software, and its time domain solver is fast and accurate.

The structure comprises jute substrate 44 mm long and 35 mm wide embedded on the ground plane made of copper sheet of 0.03 mm thickness whose dimension is the same as that of the substrate. Above the substrate, the copper sheet of the patch with 0.03 mm thickness has been excited from port 1 by means of a 50-Ω coaxial probe transmission line. The patch antenna has –17.38 dB return loss as shown in Figure 4 with VSWR of 1.31. The radiation pattern is shown in Figure 5.

Figure 4.

S-parameter for the designed patch antenna.

Figure 5.

Radiation pattern of the designed patch antenna.

To enhance the performance of the antenna, the shape of the antenna has been optimized. After many series of optimizations, the layout of the designed antenna is finalized as shown in Figures 6 and 7. The final values of the antenna parameters are validated and listed in Table 2. The use of the slot decreases the quality factor of the patch because of less energy stored beneath the patch and greater radiation.

Figure 6.

Proposed antenna layout.

Figure 7.

Proposed antenna using CST Studio Suite® model.

Table 2.

Antenna dimensions

Parameter	Dimension (mm)
Width of the patch W	22
Width W1	18
Width W2	2
Width W3	4.5
Width W4	3
Length of the patch L	38
Length L1	15
Strip line length	14
Right leg length	10
Left leg length	5

Compared with a rectangular patch, this design has the advantage of smaller space and smaller area. The top side of the patch is bound with an inverted U-shaped slot of 1 mm gap, 18 mm wide and 4 mm high. The use of the slot in the design enables the antenna to perform better. Thus, the proposed antenna is a simple microstrip patch antenna with an inverted U-shaped slot. Since it has a microstrip feed, it couples electromagnetic waves through the slot above and radiates them.

The simulated results of return loss, radiation pattern and directivity are shown in Figures 8, 9 and 10, respectively. The results show a better return loss (–30.22 dB) value with directivity of 6.801 dB having –10 dB return loss bandwidth of 50 MHz.

Figure 8.

Return loss: simulated result.

Figure 9.

Radiation pattern: simulated result.

Figure 10.

Directivity: simulated result.

The antenna has been bent and placed in the hand model for specific absorption rate (SAR) calculation as shown in Figure 11. The hand model has been designed using biomaterials available in CST software which uses the methodology of IEC/IEEE 62704-1, an international standard for computing maximum SAR³⁹ for the operating frequency range of 30 MHz to 6 GHz. The hand structure consists of bone (relative permittivity=15.3 and conductivity=0.06 S/m) with thickness of 15 mm, surrounded by fat material (relative permittivity = 5.28 and conductivity=0.10 S/m) with thickness of 5 mm, followed by muscle (relative permittivity = 52.7 and conductivity=1.73 S/m) with thickness of 5 mm, then blood (relative permittivity=76.8 and conductivity=1.23 S/m) with thickness of 5 mm and finally skin (relative permittivity=38 and conductivity=1.46 S/m) with thickness of 4 mm. For wearable applications, it is essential to test the antenna under on-body conditions. For such applications, SAR is necessary to study the amount of radiation absorbed by the body and its unit is watts per kilogram. The Federal Communications Commission limit for public exposure from cellular telephones is an SAR level of 1.6 W/kg.⁴⁰ The calculated SAR value for 10 g of tissue of the proposed antenna is 0.53 W/kg, as shown in Figure 12.

Figure 11.

Antenna bent on the on-hand model.

Figure 12.

Specific absorption ratio calculation for the proposed antenna.

Antenna fabrication

In order to validate the simulated results, an experimental prototype of the proposed antenna has been fabricated as shown in Figures 13 and 14. The 50-Ω sub miniature version A (SMA) connector is used where the inner terminal of the connector is welded to the strip antenna line and the outer terminal is welded to the ground plane. The benefits of using the SMA connector are easy fabrication, ease of matching and low spurious radiation. The antenna has been tested with the vector network analyzer Model N9912A from Agilent Technologies.⁴¹

Figure 13.

Fabricated antenna with front view.

Figure 14.

Fabricated antenna with back view.

The antenna is easily bendable as shown in Figure 15. Figures 16 to 20 show the measurements of the antenna under flat, bending, on-hand, and soaking (wet) conditions, respectively. The antenna is tested in water under partially immersed and fully immersed states. The antenna is easily bent and tested with a 70-mm diameter plastic cylinder. Thus, the bending of the antenna with a 70-mm diameter cylinder, which is equivalent to 30′ from the flat condition, does not affect the patch and the effectiveness of the antenna.

Figure 15.

Bending of antenna.

Figure 16.

Fabricated antenna: flat condition.

Figure 17.

Fabricated antenna: bending condition.

Figure 18.

Fabricated antenna: on-hand condition.

Figure 19.

Fabricated antenna: soaking condition with partially immersed state.

Figure 20.

Fabricated antenna: soaking condition with fully immersed state.

Results and discussion

The antenna has been partially immersed in water and then fully immersed. When it is measured during both these conditions, the reflection coefficients are the same (=–28.2 dB). After wetting, the antenna is fully dried and examined with the same vector network analyzer. The reflection coefficient values are the same as the previous values. This meant that the antenna will be reusable, sustainable and ready to be used in all types of conditions. The proposed design has been tested under several conditions to examine its robustness and sustainability in an acceptable operating frequency. Figures 21 and 22 show the comparison of return loss and VSWR measurements of the simulated and measured antennas under various conditions and the values are also tabulated in Table 3. The mean and standard deviation values for the antenna parameters of frequency, return loss and VSWR are calculated and tabulated in Table 4. It is clear that the standard deviation is very low for frequency (0.064576) and VSWR (0.115117). It means that the values are close to the mean value. For return loss, the standard deviation is 4.000021 which can be acceptable.

Figure 21.

Comparison of return loss measurement.

Figure 22.

Comparison of voltage standing wave ratio measurement.

Table 3.

Various parameter values of simulated and measured antennas

Antenna condition	Frequency (GHz)	Return loss or reflection coefficient (dB)	Voltage standing wave ratio	Bandwidth (MHz)
Normal condition (simulated)	3.23	−30.22	1.06	50
Normal condition (measurement)	3.20	−28.54	1.04	100
Wet condition (measurement)	3.07	−28.2	1.14	100
On-hand condition (measurement)	3.22	−20.67	1.328	200
Bending condition (measurement)	3.17	−23.41	1.182	130

Table 4.

Mean and standard deviation for antenna parameters

Antenna parameters	Mean	Standard deviation
Frequency (GHz)	3.178	0.064576
Return loss or reflection coefficient (dB)	−26.208	4.000021
Voltage standing wave ratio	1.15	0.115117

Under the flat/normal condition, the antenna performs well with a return loss of −28.54 dB and a VSWR of 1.04 at an operating frequency of 3.2 GHz. For the wet condition, the antenna is dipped into the water in a container and measured. The main factor to be considered for any type of fiber substrate material is the ability to absorb moisture. Water has a much higher and constant relative permittivity than any type of flexible textile material.¹¹ Thus, when the water content is absorbed by the textile fiber, it modifies the properties of the textile fabric by increasing its dielectric property and loss tangent.^17,42

Likewise, the water absorbed by the textile substrate minimizes and shifts the operating frequency. The operating frequency is slightly shifted to 3.07 GHz but this is not a major shift. The performance of the antenna is good. The antenna provides a better return loss (−28.2 dB) and a low VSWR (1.14) compared with the work of Osman et al.⁸ which achieved a return loss below −8 dB.

Under on-hand and bending conditions, the antenna also performs well with a reasonable return loss (−20.67 dB and −23.41 dB) and a low VSWR (1.32 and 1.182) at the operating frequencies of 3.22 and 3.17 GHz, respectively. It is evident from these measurements that the antenna is applicable for wearable applications.

From the results obtained, it is clear that the operating frequency shifts slightly for the measured antenna under all conditions. Jute fabric has some air gaps, due to the weaving process. These air gaps will cause changes in the operating frequency. However, it can be seen that there are no major differences between the values of return loss and VSWR for the simulated and measured values. The objective of any antenna is to achieve less than −10 dB return loss that is more than 90% of power transmitted and less than 10% of power reflected. This is easily achieved from the results obtained from the measurements.

Compared with the work of Sanchez-Montero et al.¹⁷ which indicates an abrupt shift in the operating frequency (from 2.45 GHz to 3.5 GHz) and an increase in return loss (from −20 dB to greater than −10 dB) when subjected to water drops on the patch, this present work shows no abrupt shift in operating frequency or increase in return loss. The thickness of the substrate material used (felt) is 2 mm which is greater than the thickness of the jute substrate (1 mm) of the proposed antenna. For flexible applications, the thickness of the substrate should be low. Also Sanchez-Montero et al. do not test their antenna fully immersed in water. Instead the water content is dropped onto the antenna for absorption.

Thus, the previously mentioned results indicate that the modest change in antenna performance with the consideration of water and moisture application suggests that the proposed antenna is optimal for any environment. Reducing the size becomes a big challenge for wireless body area network (WBAN) antenna design. The proposed antenna justifies its stand as an antenna suitable for WBAN in terms of reduced size (44 mm × 35 mm) and low SAR value (0.53 W/kg). The antenna can also be placed anywhere on the human body due to its versatility in bending.

Conclusion and future works

A comprehensive study on flexible antenna made from a new substrate has been presented. The prototype has been well made and its performances have also been investigated. The primary approach for the proposed antenna is to use jute fabric as the flexible substrate. The results show that jute fabric can act as a reasonable substrate material for flexible applications. Due to its light weight, long durability, low cost and low environmental concerns, it is possible to substitute rigid substrate materials. Since this antenna performs well with regard to water absorption and moist conditions (return loss −28.2 dB) and is resistant to wear and tear, different types of special antenna can be designed for even search and rescue applications. In addition, the performance of the antenna with human tissue and bending condition has been examined. The results for various parameters (return loss −20.67 dB and −23.41 dB, respectively) are found to be adequate for wearable applications. Thus, the antenna can be used for various applications such as biomedical, military radio location and especially in ground radar (3.1−3.4 GHz). However, air gaps in the substrate material, long-term behavior, reduced bandwidth and repeated washability need to be addressed in future investigations.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

M Pandimadevi

References

Khaleel HR. Novel metamaterial based antennas for flexible wireless systems. PhD Thesis, University of Arkansas at Little Rock, USA, 2012.

Al-Fayyadh

Alsabbagh

Al-Rizzo

. Design a flexible antenna integrated with artificial magnetic conductor. Adv Comput Tech Electromagn 2017; 2017: 1–15.

Mohamadzade

Hashmi

Simorangkir

RBVB

, et al. Recent advances in fabrication methods for flexible antennas in wearable devices: state of the art. Sensors 2019; 19: 2312.

Sankaralingam

Gupta

. Development of textile antennas for body wearable applications and investigations on their performance under bent conditions. Prog Electromagn Res B 2010; 22: 53–71.

Indumathi

Bhavithra

. Design of wearable textile antenna for patient monitoring. Int J Pure Appl Math 2018; 119: 1179–1184.

Poggiani

Mezzanotte

Mariotti

, et al. 24-GHz patch antenna array on cellulose-based materials for green wireless internet applications. IET Sci Meas Technol 2014; 8: 342–349.

Khan

Razaq

Ali

, et al. Antenna miniaturization using pulp fibers as a substrate for dual band operation. Microw Opt Technol Lett 2016; 58: 2146–2148.

Osman

MAR

Rahim

MKA

Samsuri

, et al. Textile UWB antenna bending and wet performances. Int J Antenn Propag 2012; 2012. Article ID 251682.

Dubey

Singh

Bhoi

, et al. Realization of trophy based flexible wearable antenna based on foam substrate. Int J Eng Sci Technol 2018; 7: 222–224.

10.

Dar

Ahmed

Raees

. Characterizations of flexible wearable antenna based on rubber substrate. Int J Adv Comput Sci Appl 2016, pp. 7.

11.

Salvado

Loss

Gonçalves

, et al. Textile materials for the design of wearable antennas: a survey. Sensors 2012; 12: 15841–15857.

12.

Ismail

Gaydecki

Barton

. A flexible wearable antenna for location tracking applications. Int J Commun Antenn Propag 2018; 8: 494.

13.

Osklang

Phongcharoenpanich

Akkaraekthalin

. Triband compact printed antenna for 2.4/3.5/5 GHz WLAN/WiMAX applications. Int J Antenn Propag 2019; 2019. Article ID 8094908.

14.

Huang

Sim

CYD

Liang

, et al. Low-profile flexible UHF RFID tag design for wristbands applications. Wirel Commun Mob Comp 2018; 2018. Article ID 9482919.

15.

Ferreira

Pires

Rodrigues

, et al. Wearable textile antennas: examining the effect of bending on their performance. IEEE Antenn Propag M 2017; 59: 54–59.

16.

Vejasegaran

Jusoh

Kamarudin

, et al. Embroidered dual band textile antenna for ISM band application on bending performance. J Eng Appl Sci 2016; 11: 6204–6209.

17.

Sanchez-Montero

Lopez-Espi

Alen-Cordero

, et al. Bend and moisture effects on the performance of a U-shaped slotted wearable antenna for off-body communications in an industrial scientific medical (ISM) 2.4 GHz band. Sensors 2019; 19: 1804.

18.

Lee

. Development and applications of transparent conductive nanocellulose paper. Sci Technol Adv Mater 2017; 18: 620–633.

19.

Kalia

Dufresne

Cherian

, et al. Cellulose-based bio- and nanocomposites: a review. Int J Polym Sci 2011; 2011. Article ID 837875.

20.

Inui T, Koga H, Nogi M, et al. High-dielectric paper composite consisting of cellulose nanofiber and silver nanowire. In: 14th IEEE international conference on nanotechnology, Toronto, ON, Canada, 18–21 August 2014.

21.

Zeouga

Osman

Gharsallah

, et al. Truncated patch antenna on jute textile for wireless power transmission at 2.45 GHz. Int J Adv Comput Sci Appl 2018, pp. 9.

22.

Shahinur

Hasan

Ahsan

, et al. Characterization on the properties of jute fiber at different portions. Int J Polym Sci 2015; 2015. Article ID 262348.

23.

Basu

Roy

. Blending of jute with different natural fibers. J Nat Fibers 2007; 4: 13–29. .

24.

Pradeep

Baludu

Basha

, et al. Fabrication and characterization of jute/glass fiber reinforced epoxy hybrid composites. Int Res J Eng Technol 2019; 6: 5138–5142.

25.

Islam

Shahida

, et al. Mechanical and interfacial characterization of jute fabrics reinforced unsaturated polyester resin composites. Nano Hybrids Composites 2019; 25: 22–31.

26.

https://www.testextextile.com/physical-properties-of-jute-fiber-with-chemical-composition/ .

27.

Rawal

Paharia

Kumar

. Enhancing the mechanical properties of virgin and damaged jute/polypropylene hybrid nonwoven geotextiles via mild alkali treatment of jute fibers. Text Res J 2018; 88: 2132–2140.

28.

Jabbar

Militký

Wiener

, et al. Static and dynamic mechanical properties of novel treated jute/green epoxy composites. Text Res J 2016; 86: 960–974.

29.

Fraga

Frullloni

de la Osa

, et al. Relationship between water absorption and dielectric behavior of natural fiber composite materials. Polym Test 2006; 25: 181–187.

30.

De Llorens

. Fabric structures in architecture, Woodhead Publishing, 2015.

31.

Kłosowski

Zagubień

. Analysis of material properties of technical fabric for hanging roofs and pneumatic shells. Arch Civ Eng 2003; XLIX: 277–294.

32.

Chatterjee

Singh

. Studies on wicking behavior of polyester fabric. J Text 2014; 2014. Article ID 379731.

33.

Lee

Obendorf

. Statistical modeling of water vapor transport through woven fabrics. Text Res J 2012; 82: 211–219.

34.

Bassett

Postle

Pan

. Experimental methods for measuring fabric mechanical properties: a review and analysis. Text Res J 1999; 69: 866–875.

35.

Singh

Tripathi

. Micro strip patch antenna and its applications: a survey. Int J Comput Tech Appl 2011; 2: 1595–1599.

36.

Pandimadevi

Tamilselvi

. Comparative study of microstrip patch antenna using different flexible substrate materials. Int J Pure Appl Math 2018; 118: 751–766.

37.

Pranathi

GVP

Rani

Satyanarayana

, et al. Patch antenna parameters variation with ground plane dimensions. Int J Adv Res Electric Electronics Instr Eng 2015; 4: 2320–3765.

38.

https://www.3ds.com/products-services/simulia/products/cst-studio-suite/ .

39.

https://standards.ieee.org/standard/62704-1-2017.html .

40.

Varshney

Malhotra

Sharma

, et al. Specific absorption rate (SAR) value of mobile phones: an awareness study among mobile users. Indian J Community Health 2018; 30: 156–162.

41.

http://literature.cdn.keysight.com/litweb/pdf/N9912-90001.pdf .

42.

Toba

Kitagawa

. Wireless moisture sensor using a microstrip antenna. J Sensors 2011; 2011. Article ID 827969.