To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Furthermore, numerical simulations of the proposed metamaterial electromagnetic properties and SAR reduction values were performed by adopting Computer Simulation Technology (CST) Microwave Studio 2019 software. active shimming. The SAR reduction calculation was successfully performed in this study by adopting a finite-different time-domain method. Furthermore, there are only a few analyses regarding 5G Mobile Network radiation reduction have been investigated in recent years. The SAR percentage values for all resonance frequencies were tabulated in Table 11. What MRI Sequences Produce the Highest Specific Absorption Rate - AJR Ikeuchi R, Hirata A. Dipole antenna above EBG substrate for local SAR reduction. Moreover, a metamaterial design that complies with this condition will obtain negative permittivity and/or permeability values. The second stage was the numerical analysis of electromagnetic absorption reduction to identify the effect of the metamaterial attachment inside the mobile phone. This dielectric substrate material with thickness, C=0.25mm as illustrated in Fig. CAS Novel Specific Absorption Rate measurement techniques Ramachandran, T., Faruque, M. R. I. Meanwhile, the SAR values averaged over 1g and 10g of tissue volumes, calculated using the CST software, with and without the metamaterial structure at all nine resonance frequencies which fall in the L-, S- and C-bands are tabulated in Tables Tables55 and and6.6. 3e indicates the impedance values computed using CST software. FOIA Broadband multi-layer terahertz metamaterials fabrication and characterization on flexible substrates. A challenging problem that arises in this domain is how to decrease the SAR values at the desired resonance frequencies that comply with these guidelines. In this paper, we present a fast technique for estimating the specific absorption rate (SAR) of multiple-antenna transmitting devices such as mobile phones, which utilize two or more. The lower band resonance frequencies are difficult to obtain in unit cell design as illustrated in Fig. All the frequency ranges of the left-handed characteristic are tabulated in Table Table3.3. A vital discovery arises that the permittivity values of both substrate material and copper structures contribute significant advantages to gain distinct results. Both analyses indicate that the variations in angle have a major influence on the outcomes and manifest dependent characteristics. MRI Module 2 Flashcards | Quizlet Ramachandran, T., Faruque, M. R. I., Ahamed, E. & Abdullah, S. Specific absorption rate reduction of multi split square ring metamaterial for L- and S-band application. Meanwhile, recently published absorption related research works3638 also mostly applied for frequency range more than 6GHz. 7b demonstrates the analysis of the few substrate materials that were utilized as a dielectric base material by adopting a similar MSM copper design structure. The famous Robust method was adopted for this calculation to find the superior characteristics of the metamaterial by utilising MATLAB 2021 software28,29,30. The fundamental assumption of this study is that the longer the distance, the greater the calculated SAR values. 48(6), 39393946. The substrate used is Rogers RT Duroid 5880(semi-flexible substrate) and it is specifically used due to its good dielectric constant. Finally, in C-band, the proposed metamaterial manifest two small frequency ranges from 4.002 to 4.080GHz and 5.898 to 6.000GHz with acceptable amplitude values. Cheng, Y., Li, Z. When a mobile phone is held in a talking mode by the user, then the head surface is often not in a flat position. The SAR exposure value of the mobile phone with and without the MSM attachment was calculated using a time-domain solver. For the frequency range from 2.028 to 2.178GHz and 2.376 to 2.670GHz, the proposed MSM design exhibits a negative characteristic with amplitude values from 5.434 to 1.828dB and 3.081 to 0.766dB, respectively. As some of the radiation energy emitted by wireless devices is absorbed by tissues in the human body, thus it should be taken into serious consideration. Furthermore, we discovered that the SAR values averaged over 1g and 10g of tissue volume reduced in a similar pattern and has a reduction percentage mean value of 88.931% and 88.828%, respectively. Waves Appl. The study11 focused on SAR computation in a muscle cube by utilising a square-shaped metamaterial with an adopted frequency range from 0 to 2.10GHz. Furthermore, Fig. Andreas J. Bartsch Combined Acquisition Technique (CAT) for Neuroimaging of Multiple Sclerosis at Low Specific Absorption Rates (SAR) Armin Biller, Morwan Choli, Martin Blaimer, Felix A. Breuer, Peter M. Jakob, Andreas J. Bartsch x Published: March 7, 2014 https://doi.org/10.1371/journal.pone.0091030 Article Authors Metrics Comments Media Coverage Phys. Specific Absorption Rate - an overview | ScienceDirect Topics The 10g cubic mass is used because heat diffusion evenly spreads the thermal energy to a much larger volume. Variable-Rate Selective Excitation (VERSE) Pulses for low SAR applications leave the pulse length unchanged, but modify the envelope of the RF pulse with a corresponding "dip" in gradient amplitude where at times where the RF pulse is highest. Faruque MRI, Islam MT, Misran N. Electromagnetic (EM) absorption reduction in a muscle cube with metamaterial attachment. Alam et al.14 proposed a double-negative semi-circular radiating patch antenna with a 34 hexagonal-shaped metamaterial for mobile wireless applications. How do radiofrequency fields affect biological tissues. A material that has an extraordinary and superior accomplishment, referred to as a metamaterial, is responsible for the debate topic of conversation in the telecommunications field. (2) refers to the thickness of the metamaterial slab. Computer Simulation Technology (CST) Microwave Studio. Pandey et al. The focus of this simulation was to calculate the scattering parameters of the proposed MSM design. Meanwhile, the least SAR value happened at the last resonance frequency of the C-band for both 5 and 10mm distances in 1g and 10g of tissue volumes. The comparisons between the SAR values with and without metamaterial reveal a few important details. Compact ultra-thin seven-band microwave metamaterial absorber based on a single resonator structure. M. T. I. provided necessary instructions for analytical and measurement purposes. The ICNIRP 2020 guidelines have mostly retained the similar restrictions that are set in 1998. gave significant involvement to design, analysis, characterization, fabrication, and application. Miniaturized Wearable Antenna with Reduced Specific Absorption Rate and This technique is based on a decomposition/superposition procedure with two different measurement scenarios. J. Electron. Specific absorption rate | Radiology Reference Article - Radiopaedia.org Generally, CST software is utilised in electromagnetic problem solving with accurate outcomes. Opt. Methods for Reducing SAR Avoid or minimize use of high SAR sequences (in the box above). Due to this limitation, we handle the metamaterial size miniaturization by providing reasonable interest when designing a unit cell metamaterial structure. According to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the IEEE C95.1-2019 standards, the SAR restriction is limited to 2W/kg averaged over 10g (g) of tissue volumes1,2. Few thicknesses of substrate material were adapted in this analysis, for example, 1.6mm, 1.575mm, and 1.524mm, respectively for stated substrate material. Fu P, Liu F, Ren GJ, Su F, Li D, Yao JQ. Meanwhile, for local exposure, the time interval is implemented as a six-minute average since it corresponds with the thermal time constant. To obtain On the other hand, we came across a famous query that linked with the detection of EFD and MFD on the Rogers RO3006 material. For example, the exposure areas for 1g of tissue volume at 1.458GHz are relatively illustrating a similar amount, however, the maximum SAR values (in yellow contour) reduce respectively when using metamaterial design. 3c. Al-badri, K. S. L. Electromagnetic broad band absorber based on metamaterial and lumped resistance. Furthermore, ranges from 2.718 to 2.916GHz and 2.988 to 3.996GHz, the MSM design manifested negative permittivity values with maximum amplitude values of 23.957dB and 86.048dB, accordingly. Figure7a illustrates the transmission coefficient result of the unit cell proposed MSM design. The two-layered homogenous metamaterial structure exhibit nine resonance frequencies which are similar to the proposed MSM design, but has lower magnitude values at certain peak points. 2b). Alam, T., Faruque, M. R. I. J. Figure3ae illustrate the plots of results that were obtained from the computer simulation such as S11, S21, permittivity (), permeability (), and refractive index (n). The specific absorption rate (SAR) of magnetic nanoparticles can be very high, of the order of 1 kW/g, in an alternating magnetic field of moderate strength and frequency [1, 2].This unique property can be successfully used both in magnetic nanoparticle hyperthermia [3, 4] and for remote sintering of a mixture of magnetic nanoparticles with a low-melting polymer material (S.A. Gudoshnikov et . Even though any dielectric substrate has a free-electron deficiency, the EFD and MFD still occurred. Absolute magnetic field distribution of the proposed MSM design at; (i) 1.2GHz, (ii) 1.458GHz, (iii) 1.56GHz, (iv) 1.896GHz, (v) 2.268GHz, (vi) 2.683GHz, (vii) 2.940GHz, (viii) 3.580GHz, (ix) 5.872GHz. We know that there are a lot of pieces that contribute to nonspecific absorption losses. IEEE Access 8, 214775214780 (2020). Fundamentally, in the deficiency of the ohmic loss condition, the antenna radiated power is corresponds to the reference power. The unique left-handed characteristic usually maximises the accomplishment of the material, for example, propagation in the backward wave, negative refraction index, and reversed Doppler shifts. High permittivity pads reduce specific absorption rate - PubMed Each band, namely L-, S-, and C-bands have 4:4:1 separated resonance frequencies precisely at 1.200, 1.458, 1.560, 1.896, 2.268, 2.683 2.940, 3.580 and 5.872GHz, respectively. 3 . The specific absorption rate is used as one of the main safety parameters in magnetic resonance imaging. Results Phys. Moreover, a metamaterial design that complies with this condition will obtain negative permittivity and/or permeability values. Characterization and analytical techniques, https://doi.org/10.1007/s11664-019-07156-z, https://doi.org/10.1016/j.optmat.2021.111129, https://doi.org/10.35848/1882-0786/ab9877, https://www.3ds.com/products-services/simulia/products/cst-studio-suite/, https://www.ansys.com/products/electronics/ansys-hfss, https://www.mathworks.com/products/matlab.html, http://creativecommons.org/licenses/by/4.0/. Article Open Access Published: 02 February 2022 Specific absorption rate reduction for sub-6 frequency range using polarization dependent metamaterial with high effective medium ratio. The simplified SAM phantom that is homogeneous to the real human head model based on the IEEE standard is composed of two components, namely an outer shell and fill with a tissue-stimulating liquid substance. It is clearly shown that the impedance frequencies were increased when compared to the resonance frequencies. The fabricated metamaterial manifest S21 results at 3.0667 and 4.986GHz with magnitude values of 18.433 and 25.080dB, respectively. Specific absorption rate - Wikipedia The performance of double-layer metamaterial structure was first investigated to identify whether the stacking affects the resonance frequencies. Therefore, the compact stack layered square-shaped metamaterial structure was introduced for SAR reduction application, precisely attributed to the fifth-generation technology. Figure3ae illustrate the plots of results that were obtained from the computer simulation such as S11, S21, permittivity (), permeability (), and refractive index (n). Jubaer Alam, M. R. I. F. et al. [2] introduced a new triangular-shaped metamaterial for electromagnetic (EM) absorption reduction. Lastly, the position as shown in Fig. The simulation results of the unit cell metamaterial were further validated by the equivalent circuit model. The FR1 applied for sub-6 bands whereas, FR2 was used for communication at the millimetre-wave frequencies above 24GHz. In addition, the introduced MSM structure manifests left-handed behaviour at all the resonance frequencies. Phys. We also describe the reflection and transmission coefficient outcomes obtained from the HFSS software in Fig. Therefore, fulfilling the conflicting goals of lightweight design, lower bands with multi-frequency band operation, and high EM absorption values is a challenging task, requiring a unique and compact metamaterial design structure. The absolute electric and magnetic field distributions created on the MSM metamaterial structure at nine resonance frequencies are displayed in Figs. Fundamentally, in the deficiency of the ohmic loss condition, the antenna radiated power is corresponds to the reference power. Besides that, when the dielectric constant values increase, it persuaded the capacitance value at the radiating element interval and the ground. 8ac exhibited similar patterns of SAR results. Generally, the typical design structure identifies the type of metamaterial and what kind of electromagnetic properties are possessed. The entire references stated here are successfully designed metamaterial structures exclusively for either SAR reduction or absorption applications. Furthermore, the lowest SAR value reported was higher than 50% at 5.872GHz for both average over 1g and 10g of tissue volumes. 7c possesses capacitive effects (C1 to C20) are denoted for the gaps between rings, while the inductive effect (L1 to L41) is for metallic strips. It is successfully demonstrated by simulations and experiments that, compared with conventional RF shield structure, the transmit efficiency can be enhanced by more than 32% and the peak . Nine maximum impedance values were manifested in this research work at all resonance bands. However, the numerically simulated S11 and S21 results also demonstrate contrasting outcomes. Meanwhile, the general array cell design approach for the EM absorption reduction also is limited by the size of the structure (number of columns and rows). IEEE Trans. 15, 110 (2019). Usually, most materials fall under two classifications, for instance, dispersive and lossy materials. In 2014, Mat et al.13 investigate the SAR values that were manifested in the human head with ear implantation. Although 5G is on its way, many countries are still using the 4G network. This type of metamaterial can manifest multiple resonance frequencies and be able to integrate with terahertz frequencies2023. The obtained reflection (S11) and transmission (S21) coefficient results were employed to compute the effective medium parameters of the MSM structure, i.e., permeability (), permittivity (), refractive index (n), and impedance (z) values. We also describe the reflection and transmission coefficient outcomes obtained from the HFSS software in Fig. A similar simulation method as in the CST software was adopted for this simulation process. Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed per unit mass by a human body when exposed to a radio frequency (RF) electromagnetic field.It can also refer to absorption of other forms of energy by tissue, including ultrasound. Numerous investigations have been performed to investigate the optimal electromagnetic absorption reduction values. Express 8, 133140 (2018). Meanwhile, the least SAR value exposure is shown in the blue colour contour. The amount of this energy that is absorbed by the human body tissues can be calculated using the SAR formula which is expressed as the power absorbed per unit mass. Correspondence to The adapted mobile phone was embedded with a keyboard, antenna, circuit, LCD components, and housing. The S-band has the highest number of frequency ranges that possess left-handed behaviour. Spin-echo MRI techniques use large radiofrequency pulses for the 90 and 180 manipulation of tissue magnetization. Meanwhile, another interesting topic of metamaterial absorbers is also widely investigated by many researchers around the world. This allows for the conclusion that the various SAR results were caused by the position of the metamaterial inside the mobile phone. Article Note: incurs a time or slice number penalty; not available on all scanners. CAS The unit cell design of the proposed metamaterial structure was simulated in CST software to compare with the S21 of the MSM design. Even though there are numerous research studies in the SAR reduction field with different Global Systems for Mobile Communications, studies continue restricted in terms of performance. Meanwhile, the maximum point reached 3.631, 5.865, 6.087, 2.943, and 6.323 at 2.178, 2.664, 2.904, 3.120, and 3.666GHz for the S-band frequency range. The MSM design possesses an optimised EMR value at 1.200GHz, which was decreased for the following resonance frequencies. 216, No. The authors declare no competing interests. Besides that, the MSM design is small, unintentional flaws might have happened when removing excess copper from the substrate material. Finally, the obtained data accomplished the aim of this investigation where the SAR values of the proposed metamaterial structure reduced extraordinarily and have superior characteristics. Meanwhile, the source of time-varying electric charges provides a high chance for magnetic field improvement and eventually generates time-variant electric fields. A. This unconventional material is unable to find in a natural state and possesses unique effective medium parameters which are also difficult to gain in conventional materials3. The outcomes of the proposed MSM structure reveals acceptable magnitude values with multi-bands nonuple resonance frequencies. For the electromagnetic absorption reduction application, the authors successfully introduced a shielding material to absorb radiation from the wireless device. Meanwhile, Ramachandran et al.18 investigate the SAR reduction values for just two resonance frequencies that fell in the L- and S-bands, respectively. 2017 Apr;88 (4):043701. doi: 10.1063/1.4979861. Open Phys. Moreover, fast-growing wireless communication technologies that support cellular data networks have also motivated this study. government site. Therefore, the calculation of SAR value for averaged over 1g and 10g of tissue volumes, the power-loss density was selected. Furthermore, we discovered that the SAR values averaged over 1g and 10g of tissue volume reduced in a similar pattern and has a reduction percentage mean value of 88.931% and 88.828%, respectively. PDF Specific Absorption Rate: How to explain, how to measure - ITU The fabricated metamaterial manifest S21 results at 3.0667 and 4.986GHz with magnitude values of 18.433 and 25.080dB, respectively. Note: increased susceptibility artifacts Reduce initial RF flip angle (). The MSM structure was placed at the middle of waveguide ports as displayed in Fig. Table 4 demonstrates the EMR values for all resonance frequencies. Faruque, M. R. I., Islam, M. T. & Misran, N. Electromagnetic (EM) absorption reduction in a muscle cube with metamaterial attachment. Int. Furthermore, the permittivity and permeability values were retrieved from the S11 and S21 data. The MSM design is placed near to mobile antenna for the proposed position, and it indicates optimised results compare to the other three positions. Xiong H, Hong J-S, Luo C-M, Zhong L-L. An ultrathin and broadband metamaterial absorber using multi-layer structures. The comparisons between the SAR values with and without metamaterial reveal a few important details. MATLAB. Generally, the typical design structure identifies the type of metamaterial and what kind of electromagnetic properties are possessed. 3e indicates the impedance values computed using CST software. Furthermore, the first resonance frequency at L-band has the second-highest SAR reduction values for 5mm distance and increased slightly for the next limit. Previous scientific works indicate that the unconventional material can control the SAR values that can be evaluated using respective computer software. 8d was selected because it manifested optimised SAR values. The polarization-dependent values exhibit 25% discrepancies when compared to the proposed metamaterial S21 result. SAR is a function of the electrical conductivity (, measured in Siemens/meter), the induced E-field from the radiated energy (measured in Volts/meter), and the mass density of the tissue (, in kg/cubic-meter). Propag. In addition, the introduced MSM structure manifests left-handed behaviour at all the resonance frequencies. Meanwhile, the analysis usage of multiple substrate materials was conducted by utilising FR-4, Rogers RT-5880 and Rogers RT-6002 with an of 4.3, 2.2, 2.94 respectively. Scattering (from CST & HFSS) and effective medium parameters of the MSM design (from MATLAB): (a) Numerically simulated S11 and S21 results, (b) Permittivity, (c) Permeability, (d) Refractive index, (e) Impedance value. Results Phys. Distances of 5 and 10mm were examined, and the results are demonstrated in Tables Tables99 and and10.10. Table Table1212 illustrates the existing SAR reduction comparison research works as well as the introduced MSM structure. The two-layered homogenous metamaterial structure exhibit nine resonance frequencies which are similar to the proposed MSM design, but has lower magnitude values at certain peak points. Due to specific reasons, the concern about minimizing radiofrequency exposure in humans tends to be an uphill climb for mobile manufacturing companies. Our findings on the permittivity values illustrated in Fig. The first stage was numerically carried out by using a frequency-domain solver and tetrahedral mesh. During the occurrence of the magnetic response, the magnetic field induced current in the rings when the wave propagates through the split ring resonator structure. Metamaterial based sucrose detection sensor using transmission spectroscopy. Hence, the unique MSM design can reduce 98% of the SAR value emitted from the mobile phone. High-Frequency Structure Simulator (HFSS). Pandey, S. & Singhal, P. K. Peak SAR reduction using metamaterial structure. J. Electromagn. At this frequency, the SAR reduction percentage value slightly increased in the 10mm distance. 1Space Science Center (ANGKASA), Universiti Kebangsaan Malaysia, UKM, 43600 Bangi, Selangor Malaysia, 2Dept. Careers, Unable to load your collection due to an error. As a library, NLM provides access to scientific literature. On the other hand, experimental validations were analysed for the fourth and fifth resonance frequencies of the unit cell metamaterial design (demonstrated in Fig. The SAR reduction calculation was successfully performed in this study by adopting a finite-different time-domain method. On the other hand, the following bands have two negative characteristics for each, respectively. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. ICNIRP. This investigation aims to construct an unconventional material with nonuple-resonance frequencies that possess left-handed behaviour. (5). Metamaterial techniques seem promising options to reduce the SAR in terms of low cost and ease-of implementation in mobile phones. Essentially, with a range difference of 0.996GHz, starting from 1.002GHz has amplitude values ranging from 69.246 to 37.961dB. Antenna Theory - Specific Absorption Rate (SAR) The unit cell MSM design exhibits only five resonance frequencies which start at 1.638GHz. The preliminary analysis of this research work indicates that the bigger substrate materials can manifest lower resonance bands for the square-shaped metamaterial design. Specific Anthropomorphic Mannequin (SAM) Phantom available in CST Microwave Studio was adopted for this objective. IEEE Trans. Hence, the focus of the research was to reduce the Specific Absorption Rate (SAR) for the Sub-6 frequency range by designing a multi-layered and compact, 1010mm2 sized metamaterial structure that can be attached inside a mobile phone by avowing any overlapping with existing parts. Med. Scientific Reports (Sci Rep) The third resonance frequency that falls in the L-band recorded the highest SAR values for both 5 and 10mm distance in 1g and 10g of tissue volumes. The last resonance frequency band, the proposed MSM design exhibits negative behaviour at the frequency range from 4.002 to 6.000GHz with acceptable magnitude values from 78.646 to 108.962. Faruque MRI, Islam MT. A further optimistic finding from these results is that the proposed MSM design possesses a left-handed behaviour for all three frequency bands. Although the unit cell metamaterial as well manifests optimised SAR reduction values, the authors focus to produce resonance frequencies of more than five in the selected frequency range. official website and that any information you provide is encrypted Federal government websites often end in .gov or .mil. The discrepancies between the two methods were occurred due to calibration error that has a great influence on the data produced. Mohammad Rashed Iqbal Faruque. Essentially, with a range difference of 0.996GHz, starting from 1.002GHz has amplitude values ranging from 69.246 to 37.961dB. Concurrently, the SAR analysis was carried out for only two resonance frequencies of 0.835GHz and 1.850GHz while employing a typical bar-type cellular phone. In brief, the high-intensity EFD recorded a maximum limit value of 4000V/m but MFD just reached a peak value of 150A/m. https://www.mathworks.com/products/matlab.html. Meanwhile, Lee et al.15 proposed a SAR analysis of four different ages of anatomical head models and compared them with numerically simulated values obtained through the SAM phantom model adapted from SEMCAD X software.
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