Enhancing antenna performance and SAR reduction by a conductive composite loaded with carbon-silica hybrid filler

Al-Ghamdi, Ahmed A.; Al‐Hartomy, Omar A.; Al-Solamy, Falleh R.; Dishovsky, Nikolay; Atanasov, Nikolay; Atanasova, Gabriela

doi:10.1016/j.aeue.2016.12.013

Cited by 21 publications

(8 citation statements)

References 14 publications

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“…These antennas are light, can take the desired shape of the object, and can follow movements and change its shape . In all cases, the substrate and the insulating layers between the elements of these flexible antennas are filled elastomeric composites . However, the requirements for these composites are too serious: They must not change their characteristics under bending or pressure; they must have low relative permittivity to reduce signal propagation delay, low loss tangent to reduce signal attenuation along with better signal performance, mechanical flexibility, high dimensional stability, moisture absorption resistance, and high thermal conductivity to dissipate the heat generated .…”

Section: Resultsmentioning

confidence: 99%

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties

Al‐Sehemi

Al‐Ghamdi

Dishovsky

et al. 2019

Polymers for Advanced Techs

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Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properties of several metals and metal ions dopants used in the SiO 2 -CaO-P 2 O 5 system of bioglasses, such as Ag, Cu, Zn, and Fe. A number of authors have carried out research related to the influence of silver oxide on the properties of bioglasses.However, publications on the properties of elastomer-based composites containing bioactive glasses are relatively scarce. We have not found in the literature studies discussing how silver oxide concentration in bioglasses of the CaO-SiO 2 -P 2 O 5 -Ag 2 O system affects the significant properties of a natural rubber biocomposite. In this regard, the purpose of the present work is to investigate the aforementioned influence on the properties of this type of composites, namely, vulcanization, physicomechanical, thermal, dynamic, dielectric, electric, and thermoconductive characteristics. We have established those parameters of the composites to be impacted considerably by both degree of filling with bioglass and the silver oxide content in the latter. The improvement in the composites thermostability and some of their physicomechanical performance is the most significant. The volume resistance decreases, and the thermal conductivity coefficients increase. Results from scanning electron microscopy and energy-dispersive X-ray (EDX) analyses have confirmed the influence of silver oxide initially on the phase composition of the bioglass, hence on the properties of the biocomposites through changes in the bioglass used as filler. The dielectric characteristics of some of the biocomposites suggest that they can be used as substrates and insulating layers in flexible antennas for short-range wireless communications.

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Section: Resultsmentioning

confidence: 99%

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties

Al‐Sehemi

Al‐Ghamdi

Dishovsky

et al. 2019

Polymers for Advanced Techs

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“…Furthermore, wearable designs must comply with standards for specific absorption rates (SARs). Several planar structures, metamaterial (MTM) structures [ 6 ], ferrite sheets [ 7 ], soft surfaces, frequency selective surfaces (FSS), and large ground planes [ 8 ] have been used in body area network (BAN) applications as insulating layers to protect the human body from unwanted radiation [ 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Full Ground Ultra-Wideband Wearable Textile Antenna for Breast Cancer and Wireless Body Area Network Applications

et al. 2021

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Wireless body area network (WBAN) applications have broad utility in monitoring patient health and transmitting the data wirelessly. WBAN can greatly benefit from wearable antennas. Wearable antennas provide comfort and continuity of the monitoring of the patient. Therefore, they must be comfortable, flexible, and operate without excessive degradation near the body. Most wearable antennas use a truncated ground, which increases specific absorption rate (SAR) undesirably. A full ground ultra-wideband (UWB) antenna is proposed and utilized here to attain a broad bandwidth while keeping SAR in the acceptable range based on both 1 g and 10 g standards. It is designed on a denim substrate with a dielectric constant of 1.4 and thickness of 0.7 mm alongside the ShieldIt conductive textile. The antenna is fed using a ground coplanar waveguide (GCPW) through a substrate-integrated waveguide (SIW) transition. This transition creates a perfect match while reducing SAR. In addition, the proposed antenna has a bandwidth (BW) of 7–28 GHz, maximum directive gain of 10.5 dBi and maximum radiation efficiency of 96%, with small dimensions of 60 × 50 × 0.7 mm3. The good antenna’s performance while it is placed on the breast shows that it is a good candidate for both breast cancer imaging and WBAN.

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“…2 In all cases, the pad and the insulating layers between the elements of those flexible antennas are filled with elastomeric composites. 3 -6 However, the requirements for these composites are too serious: They should not change their flexural or pressure properties, they should have a low relative permittivity to reduce signal propagation delay, low loss tangent to reduce signal attenuation along with better signal performance, mechanical flexibility, high dimensional stability, moisture absorption resistance, and high thermal conductivity to dissipate the heat generated. 7 -10 Natural rubber (NR) has the potential to be used in such applications as it has a relatively low cost, is easy to process, has high elasticity and water resistance, has stable electrical properties, and what is particularly important—it is a product that comes from renewable sources and is environment-friendly.…”

Section: Introductionmentioning

confidence: 99%

Natural rubber composites containing low and high dielectric constant fillers and their application as substrates for compact flexible antennas

Al‐Sehemi

Al-Ghamdi

Dishovsky

et al. 2020

Polymers and Polymer Composites

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The vulcanization properties, physicochemical, dielectric, and electrical properties of natural rubber-based composites were investigated and compared. The composites contain 30–70 phr functional fillers having low (silicon dioxide (SiO2)) and high (titanium dioxide (TiO2)) dielectric constant values. The possibilities of using the composites as substrates in compact flexible antennas have been evaluated. Fillers are also characterized. It has been shown that they have a noticeable but different influence on all the properties of the composites studied. That is primarily due to the different structure and specific properties of SiO2 and TiO2, thereby determining the different “filler–filler” and “rubber–filler” interactions. The composite filled with TiO2 at 70 phr has a better capacity to act as a substrate in body area network antennas than the SiO2-filled composites. An antenna with such a substrate has features that meet all the requirements of the industrial, science, and medical spectrum. TiO2 composites do not change their resistance to pressure or deflection within certain limits, having a self-cleaning and antibacterial effect, which is also beneficial for their usage in antennas that are left on or near the human body.

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Enhancing antenna performance and SAR reduction by a conductive composite loaded with carbon-silica hybrid filler

Cited by 21 publications

References 14 publications

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties

Full Ground Ultra-Wideband Wearable Textile Antenna for Breast Cancer and Wireless Body Area Network Applications

Natural rubber composites containing low and high dielectric constant fillers and their application as substrates for compact flexible antennas

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Enhancing antenna performance and SAR reduction by a conductive composite loaded with carbon-silica hybrid filler

Cited by 21 publications

References 14 publications

Natural rubber–based composites filled with bioglasses from a CaO‐SiO2‐P2O5‐Ag2O system. Effect of Ag2O concentration in the filler on composite properties

Natural rubber–based composites filled with bioglasses from a CaO‐SiO2‐P2O5‐Ag2O system. Effect of Ag2O concentration in the filler on composite properties

Full Ground Ultra-Wideband Wearable Textile Antenna for Breast Cancer and Wireless Body Area Network Applications

Natural rubber composites containing low and high dielectric constant fillers and their application as substrates for compact flexible antennas

Contact Info

Product

Resources

About

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties

Natural rubber–based composites filled with bioglasses from a CaO‐SiO₂‐P₂O₅‐Ag₂O system. Effect of Ag₂O concentration in the filler on composite properties