Permittivity Measurements in Millimeter Range of PTFE Foams

Standaert, Alexander; Rousstia, MW Mohadig; Sinaga, S.M.; Reynaert, Patrick

doi:10.1109/lmwc.2017.2724010

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…The reason is that in the final foam product the used blowing agent (CO 2 in this case) is replaced by air during the very slow process of diffusion. Because the relative permittivity of the air is lower than PE, this replacement helps to decrease the final relative permittivity of the produced foam compared to the solid polymer and according to Equation (8) decrease of the relative permittivity leads to decrease in the loss tangent of dielectric and consequently decrease of attenuation through the cable 11,13,14 …”

Section: Resultsmentioning

confidence: 99%

“…The results of Table 4 11,13,14 However, despite the results of former researches, it can be concluded that the foaming degree is not the only effective parameter. • Attenuation in a coaxial cable can be due to: (a) loss due to conductors, (b) loss due to dielectric tangent loss, and (c) loss due to the conductivity of dielectric.…”

Section: Loss Due To the Dielectric Conductionmentioning

confidence: 87%

“…It was also observed that the permittivity and dielectric loss were significantly lower in foams compared to solid PU elastomer. Standaert 13 tried to define a relationship between the porosity of poly tetra flour ethylene (PTFE) foams and their electrical permittivity. It was concluded that permittivity was linearly related to porosity of the dielectric material.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the effect of foam properties on the attenuation of coaxial cables with foamed polyethylene dielectric

Moradian

Azdast

Doniavi

2020

Polymers for Advanced Techs

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Polymeric foams are one of the new candidates for the insulation of signal cables due to their effect on decreasing the signal loss. Accordingly, the effect of using foamed polyethylene in the dielectric section of coaxial cables on their transmission properties is investigated in this study. The samples were coaxial cables with identical properties in all sections except the dielectric part which had different foam structures. The expansion ratio and structural properties including cell size and cell density of the foams were measured. In the next step, the attenuation along the cable was determined both experimentally and theoretically. Due to the results, attenuation showed up to 38.46% reduction by foaming the dielectric compared to the solid dielectric sample. The experimental results showed good accordance with theoretical data. However, in higher frequencies, difference between these two approaches rose. A comparison of experimental and theoretical data also revealed that the expansion ratio of the foam is not the only effective parameter on the attenuation of cable. There are two other major factors: cell density and open‐cell content. High cell density foams show a lower attenuation, while in foams with high open‐cell content, a major increase was observed in the attenuation.

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Section: Resultsmentioning

confidence: 99%

Section: Loss Due To the Dielectric Conductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Investigating the effect of foam properties on the attenuation of coaxial cables with foamed polyethylene dielectric

Moradian

Azdast

Doniavi

2020

Polymers for Advanced Techs

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“…Dielectric materials with a low dielectric constant and low dissipation factor at high frequencies, such as modified polyimide, liquid crystal polymers, , and polytetrafluoroethylene, , could effectively reduce the signal dissipation caused by the rising bandwidth in communication. Polyimides, , due to their high modulus, high strength, good temperature resistance, good film-forming properties, and high insulation performance, as one of the indispensable components in a flexible printed circuit, , are widely used in aerospace, , smartphones, new energy vehicles, and other fields.…”

Section: Introductionmentioning

confidence: 99%

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

Bei,

Chen,

Liu

et al. 2024

Macromolecules

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The development of polyimide (PI) films with both a low dielectric constant and low dissipation factor at high frequency is an urgent requirement in a new generation of mobile communication technology. Although some breakthroughs have been made in the study of low-dielectric constant polyimide, the main influencing factors and regulation of the high-frequency dissipation factors are still unclear, which severely limits its development and application, and they deserve further study. In this work, we prepared a series of low-dielectric constant polyimide films and measured their high-frequency dielectric properties at different humidity levels by using a homemade system. The free volume and water adsorption of these polyimide films were precisely evaluated by positron annihilation lifetime spectroscopy and the dynamic vapor sorption method, respectively. Our study shows that the main factor affecting the high-frequency dissipation factor of low-dielectric constant PI films is the water adsorption, and the influence of water adsorption capacity and water binding intensity on the increase of the high-frequency dissipation factor is analyzed in detail. The main factors affecting the water adsorption of these polyimide films are the free volume, molecular polarity index (MPI), and morphology. In the case of a similar structure, imide ring density, and morphology, the free volume of DP-BPDA, MDA-BPDA, TPM-BPDA, and FDA-BPDA gradually increases, resulting in an increase in water adsorption and high-frequency dissipation factors. HMDA-BPDA achieves a low water adsorption of 0.44% due to its appropriate free volume, low MPI, and partial crystallinity, thus achieving good comprehensive performance: low dielectric constant (2.84) and low dissipation factor (0.0029) at 50% RH. Therefore, for polymer materials, designing structures with low polarization, appropriate free volume, and low water adsorption will be an effective strategy to achieve both a low dielectric constant and low dissipation factor.

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“…The fabrication of the CSRR sensor is simple, and the cost is low. CSRR is very sensitive to dielectric properties [23,24], which has great potential for future water tree detection. However, there is little work about water tree detection by means of CSRR.…”

Section: Introductionmentioning

confidence: 99%

A novel characterization method for water trees based on the transmission characteristics of complementary split ring resonators

Xiao

Wang

et al. 2021

High Voltage

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In order to achieve rapid and simple non-destructive testing of water trees in materials, a novel water tree characterisation method based on the complementary split ring resonators (CSRR) was proposed. The characteristics of circular CSRR and rectangular CSRR were analysed in high-frequency electromagnetic simulation software. The resonant frequency of CSRR was found to be correlated to the dielectric constant of the materials. In addition, the lumped equivalent circuit parameters of CSRRs were also calculated and simulated. The results of electromagnetic simulations and circuit simulations achieved good consistency. In the experimental part, sensors based on the two kinds of CSRRs were fabricated and were used to detect the water tree defects in low-density polyethylene samples. The experiment results showed that the method of using CSRR sensors to detect water tree is feasible.

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Permittivity Measurements in Millimeter Range of PTFE Foams

Cited by 6 publications

References 9 publications

Investigating the effect of foam properties on the attenuation of coaxial cables with foamed polyethylene dielectric

Investigating the effect of foam properties on the attenuation of coaxial cables with foamed polyethylene dielectric

Relationship among the Water Adsorption, Polymer Structure, and High-Frequency Dissipation Factor: Precise Analysis of Water Adsorption of Low-Dielectric Constant Polyimide Films

A novel characterization method for water trees based on the transmission characteristics of complementary split ring resonators

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