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The change rules of the shielding effectiveness (SE) of the sleeve has not been clarified, which leads to the lack of the basis for the design, manufacture and evaluation of the electromagnetic shielding (EMS) clothing.

According to a simplified analysis model, a series of sleeve samples with different fabrics and styles are designed and manufactured. The SE of the sleeve is tested with the proposed special test method in a semi-anechoic chamber to analyze the influence of different factors on the SE of the sleeve.

The SE is greatly reduced about 60–90% after the fabric is manufactured into the sleeve. The larger the sleeve length is, the higher the peak value of the SE is. When the sleeve length is low, the SE value is easy to appear negative. As the cuff circumference increases, the SE of the sleeve will change with the frequency band. The influence of the cuff style on the SE of the sleeve mainly depends on the cuff width and style. The larger the cuff width is, the lower the overall SE of the sleeve is. The more wrinkles there are at the cuff, the better the SE of the sleeve is.

Our results provide a reference for the design, production and evaluation of the sleeve and the whole EMS clothing.

The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However, until now, the three-dimensional arrangement structure has not been described because of the complex structure, which leads to many difficulties for the subsequent analysis of the electromagnetic characteristics. Therefore, the purpose of this paper is to propose a feature extraction method to describe the arrangement structure of the conductive fiber based on the three-dimensional calibration and image processing technology, providing a new idea for the above problem.

First, the three-dimensional positions of the conductive fibers in the EMSF are calibrated using the VHX-600 3D digital microscope and the MATLAB7.5 software. The arrangement characteristics of the conductive fibers are analyzed, and equivalent twist, cross-sectional content, and average angle of a single fiber are proposed to describe the arrangement characteristic of the conductive fiber. Then, a digital description model of the conductive fiber is constructed according to the feature parameters and its three-dimensional structures are reproduced using CATIA. Finally, the reliability of the model is verified by an FDTD example, and the significance and application of the model are given.

The proposed method can provide the feature extraction and description for the complex spatial three-dimensional arrangement structure of conductive fibers. The feature parameters can reflect different micro arrangement features of the conductive fiber. The proposed idea and method can provide a solid foundation for subsequent studies of the electromagnetic properties of the EMSF.

The study in this paper is of great significance and academic value. This paper provides a new three-dimensional calibration method and constructs multiple feature parameters to describe the complex three-dimensional arrangement structure, providing a new effective method to overcome the problem of the conductive fiber description. The proposed method provides an important basis for the shielding mechanism, transmission characteristics, electromagnetic calculation and product design, and woven technology of the EMSF.

Stainless-steel electromagnetic shielding (EMS) fabrics are widely applied as protective materials against electromagnetic interference (EMI). However, these fabrics primarily shield electromagnetic waves through reflection, which can lead to the formation of resonance effects that severely compromise their protective capabilities and potentially cause secondary electromagnetic pollution in the external environment.

In this paper, carbon nanotube fibers are added via spacing method to replace some stainless-steel fibers to impart absorbing properties to stainless-steel EMS fabric. The shielding effectiveness (SE) of the EMS fabrics across various polarization directions is analyzed. Additionally, a spacing arrangement for the carbon nanotube fibers is designed. The EMS fabric with carbon nanotube fibers is manufactured using a semi-automatic sample loom, and its SE is tested using a small window method test box in both vertical and horizontal polarization directions.

According to the experimental data and electromagnetic theory analysis, it is determined that when the spacing between the carbon nanotube fibers is less than a specific distance, the SE of the stainless-steel EMS fabric significantly improves. The fabric exhibits stable absorbing properties within the tested frequency range, effectively addressing the issue of secondary damage that arises from relying solely on reflective shielding. Conversely, as the spacing between the carbon nanotube fibers exceeds this distance, the SE diminishes. Notably, the SE in the vertical polarization direction is substantially higher than that in the horizontal polarization direction at the same frequency.

This study provides a new path for the development of high-performance EMS fabrics with good wave-absorption characteristics and SE.

The purpose of this paper is to explore the influence of hole on shielding effectiveness (SE) of electromagnetic shielding (EMS) fabric under incident polarization wave, and to propose a “Key Size” theory to explain the influence mechanism.

“Key Size” parameters describing hole shape are established, and a number of representative samples with rectangular and oval holes are made. SE of the samples are tested by waveguide testing system. Influence of the hole on the SE of the samples is analyzed according to vertical or horizontal maximum size and polarization wave direction. Finally, the “Key Size theory” and “Secondary Size theory” are proposed to explain the influencing mechanism.

The hole influences on the SE are related to the vertical and the horizontal maximum size of the holes and the direction of the polarization wave. As the direction of the polarization wave is vertical (or horizontal), greater maximum size results in lower SE. As the maximum size is constant, greater maximum size causes lower SE. As the maximum size reaches to a certain value, a dividing point of the SE occurs. As the direction of the polarization wave is consistent with the direction of the maximum size, same hole area results in same SE.

The explored influences and mechanism provide an important guiding reference for the hole design of the EMS fabric, and can be applied to the holes design of the EMS garment, composite materials, and tents.

The purpose of this paper is to propose a new indicator-gray porosity that can objectively evaluate real porosities of electromagnetic shielding (EMS) fabric based on computer image analysis, which aims to address current porosity evaluation by tightness.

A method for the fabric image acquisition is determined and a gray digital model is established. The porosity membership region of true porosity is judged according to the total gray wave. A bi-directional judgment method based on horizontal and vertical single gray waves is proposed to automatically identify the gray porosity in the porosity membership region. After experiments, the differences between the gray porosity indicator and the tightness indicator are analyzed, the influence of the gray porosity on the shielding effectiveness (SE) is discussed, and the advantages of the gray porosity indicator are detailed.

Results show that the proposed indicator can accurately represent the real porosity size of the EMS fabric without pre-acquiring the structure parameters of the fabric, which provides a reference for the study of the electromagnetic characteristic of the EMS fabric.

The gray porosity presented in this paper is a new method to objectively evaluate real porosities of the EMS fabric, and can be applied to the research and evaluation of the electromagnetic characteristic for the EMS fabric.

No adequate study on scientific analysis of surface metal fiber (SMF) arrangement of electromagnetic shielding fabric (EMSF) and influence on shielding effectiveness (SE) is available at present.

This paper recognizes the SMF region and constructs a binary feature matrix according to edge condition, width condition and gray condition using the computer image analysis technique based on the construction of the surface digitized image of the EMSF. Three parameters of coverage, dispersion and uniformity are proposed to describe the SMF arrangement. Then experiments and testing samples are designed to analyze the relationship between the three parameters and the SE.

Results show that the proposed method can accurately recognize the SMF of the EMSF, the coverage, dispersion and uniformity can describe three aspects of the SMF arrangement of percentage content, porosity and orientation, and the three parameters are positively, negatively and positively correlated to the SE, respectively.

The research in this paper provides the basis for further description of the SMF arrangement of the EMSF, possesses the significance for the study of the shielding mechanism, transmission model, electromagnetic performance and rapid non-destructive evaluation of the EMSF and provide a new idea for the study on the shielding theory and application of the EMSF.

The purpose of this paper is to propose a new recognition algorithm on quadratic local extremum for fabric density recognition.

The density wave is established to correctly detect density by searching local extremes. The gray wave of each line in fabric image is extracted first. The derivation of gray wave is calculated, extreme waves including all true extreme values and false extreme values are obtained. And then the second derivative of extreme waves are calculated and the result makes local correction. The density wave, which can represent position and quantity of yarn and interstice, is established. According to the resolution and size parameters of image, the function of density with density wave statistics is given.

The experiment and analysis proved that the method proposed can detect fabric density simply and successfully with less calculation and no image preprocessing.

The algorithm provides practical guidelines for fabric density detection and provides a new thought for fabric characteristic identification. Future work could be focused on the development of methods for the automatic algorithm with color fabrics.

The algorithm based on quadratic local extremum presented in this paper is a new method to successfully detect fabric density and can be applied to the recognition for other categories of clothing fabrics and images.