The Characterization of Conductive Textile Materials Intended for Radio Frequency Applications

Shaw, Ravi; Long, B.R.; Werner, Douglas H.; Gavrin, Arthur J.

doi:10.1109/map.2007.4293934

Cited by 57 publications

(41 citation statements)

References 14 publications

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“…Another conductivity value of Zelt fabric shown in [11] is 1.749 x 10 5 S/m which is close to the result obtained by the proposed method. The conductivity value of the silver-coated e-textile is reported as 1.8 x 10 5 S/m [12], which presents relatively large difference to our measurement result, (3.47 x 10 5 S/m). This may be caused by the structural difference of the samples.…”

Section: Copper Aluminum Foil Zelt Fabriccontrasting

confidence: 93%

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Conductivity Measurement of E-textiles using a Microstrip Ring Resonator

Nguyen¹,

Chung²

2017

IJET

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Abstract-A conductivity measurement technique applicable for highly conductive textile materials is presented in this work. We employ a microstrip ring resonator as a test fixture to ease sample preparation and to increase measurement sensitivity. With this, the conductivity of a thin textile can be measured up to 10 6 S/m at 2 GHz. The conductivity value is extracted by comparing the measured and simulated transmission coefficients in an active learning iterative solver based on the surrogate-based optimization. The conductive textiles under test were Zelt and silver-coated e-textile, and the resulted conductivities are 2.29x10 5 and 3.47x10 5 S/m, respectively. These values are close to the DC conductivity given by the manufacturers.Keyword-Conductivity, e-textile, microwave, ring resonator, surrogate-based optimization. . They are highly flexible, durable and restorable, allowing direct integration onto clothing by ordinary sewing or embroidering techniques. They also offer low sheet resistance suitable for efficient current transmission without significant ohmic loss. I. INTRODUCTIONThe usual sheet resistance (R s ) of conductive textiles in the market ranges from 0.04~0.4 Ω/sq [3]. In other words, the conductivity (s) is 1.4x10 5 -1.3 x 10 6 S/m based on the formula  = 1/(R s t), where t is the thickness of the textile. These values are measured at DC using the well-known four-point-probe or Van der pauw method.For a wearable antenna application, however, it is necessary to acquire  or R s in the microwave regime to promote accurate antenna modeling. In contrast to copious measurement techniques for the permittivity of dielectrics, there is considerably less reported for the conductivity measurement of highly conductive materials ( > 10 5 S/m) at microwave frequencies (> 1 GHz) [3]- [4]. In these methods, resonators are mainly used as a test fixture to capture a slight variation in the quality factor (Q-factor) of low conductive loss materials. Furthermore, the resonators are often in a planar form to ease the measurement of thin foil or textile samples. The material's  is obtained by detecting the perturbation of Q-factor represented in a closed-form equation under the assumption that the radiation loss is trivial. However, in practice, the radiation loss of the half-opened planar resonator may mislead the extracted  and should not be overlooked.As an alternative, full-wave simulation data can be used instead of the approximate closed-form equation to estimate . In a full-wave simulation tool, a resonator identical to the measurement is modeled, and then the simulation data is collected by varying the material property (e.g., ) of a sample under test. Subsequently, the measured and simulation data are compared in an optimization algorithm to find the best fit. Recent reports have verified the effectiveness of this method for the measurement of the dielectric constant ( r ) and loss tangent (tan) of an antenna substrate [5]- [6].In this letter, we propose a conductivity measurement method employing...

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Section: Copper Aluminum Foil Zelt Fabriccontrasting

confidence: 93%

“…This may be caused by the structural difference of the samples. For example, the measured sample in [12] is a sparsely sewed straight line, otherwise the ring here is woven with more density. …”

Section: Copper Aluminum Foil Zelt Fabricmentioning

confidence: 99%

Conductivity Measurement of E-textiles using a Microstrip Ring Resonator

Nguyen¹,

Chung²

2017

IJET

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“…Concerning the material properties of electrotextiles, it is important to note that, due to surface roughness of the fabric, the sheet resistivity at VHF/UHF is significantly higher than at DC [23], [32]. Similar to non-conductive fabrics, the knitting or weave pattern will result in different conductivities with respect to the constituent yarns [24] [30].…”

Section: Electrotextile Patch Antennamentioning

confidence: 99%

“…Similar to non-conductive fabrics, the knitting or weave pattern will result in different conductivities with respect to the constituent yarns [24] [30]. Again, the characterization process may be performed by means of a resonant cavity [24] as well as by non-resonant microstrip transmission lines [23][25] [29] and antennas [17] techniques. Special attention must be devoted to a dedicated deembedding procedure that isolates the electrotextile's conductivity from all other effects.…”

Section: Electrotextile Patch Antennamentioning

confidence: 99%

Wearable Antennas for Off-Body Radio Links at VHF and UHF Bands: Challenges, the state of the art, and future trends below 1 GHz

Nepa

Rogier

2015

IEEE Antennas Propag. Mag.

106

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Abstract-An in-depth survey of wearable antennas for offbody radio links in the VHF and UHF frequency bands (below 1 GHz) is presented. The review encompasses distinctive specifications, design criteria and challenges, material characterization procedures, antenna topologies and technologies, multi-antenna systems, dedicated testing procedures, applications and future trends.Index Terms-Wearable antennas, body-worn antennas, textile antennas, embroidered antennas, VHF antennas, UHF antennas, antennas for body-centric communications, antennas for body area networks, antennas for personal area networks, antennas for off-body wireless communications. I. INTRODUCTIONhere are several existing and forthcoming wireless applications that either require or can benefit from one or more antennas that are directly stitched on a piece of clothing or a garment, or integrated into a personal accessory (such as shoes, glasses, buttons, helmets). These antennas are usually referred to as body-worn antennas, textile antennas, BAN (Body Area Network) antennas, antennas for body-centric communications, wearable antennas. The last term is the one that is going to be used in this paper, as it denotes any antenna that is small and light enough to be worn or carried on one's body.In the last decades, hundreds of scientific papers on wearable antennas have been published in the open literature [1]- [8]. Therefore, for the sake of completeness and clarity, a valuable analysis of the state-of-the-art on wearable antennas should be limited to antennas for a specific application, a given frequency range, or a chosen antenna technology. In this context, the present review focuses on wearable antennas operating in the VHF band and part of the UHF frequency band (below 1 GHz). Choosing 1 GHz as an upper boundary for this review is highly relevant, as the operating frequency is usually the main parameter to discriminate among available antenna topologies, technologies and characterization techniques. Moreover, we limit our discussion on antennas for off-body radio links, also excluding antennas integrated into mobile terminals/cases and operating close to the body. Specifically, only wearable antennas that can be used separately from the radio unit are of interest here.VHF/UHF wearable antennas are mostly used in professional mobile radio communications for soldiers, emergency operators and law-enforcement personnel. VHF As far as VHF/UHF wearable antennas are concerned, many of their distinctive features are related to the fact that the corresponding free-space wavelength (with 30cm<<10m when 30MHz

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“…The RF characteristics of the conductive textiles have been discussed by several authors [12][13][14]. Our research on textile transmission lines investigated that RF performance of conductive fabric made components were impacted by a number of parameters including the stitch direction, stitch material, spacing between the two stitches [11].…”

mentioning

confidence: 99%