Microwave metamaterial absorber for sensing applications

Bakır, Mehmet; Karaaslan, Muharrem; Ünal, Emın; Akgöl, Oğuzhan; Sabah, Cumalı

doi:10.1016/j.opelre.2017.10.002

Cited by 117 publications

(66 citation statements)

References 36 publications

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“…Another reported technique to use MPA as a microwave sensor is adding an analyte layer to the MPA structure 28 – 30 . In this method, an air gap can be added between the substrate and metal layer 31 or between two substrates 32 , 33 . Like the previous method, the combination of the dielectric substrate and the sample provides an effective medium with a different permittivity ( ).…”

Section: Introductionmentioning

confidence: 99%

Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Amiri

Shariati

Lipman

2021

Sci Rep

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Continuous and accurate sensing of water content in soil is an essential and useful measure in the agriculture industry. Traditional sensors developed to perform this task suffer from limited lifetime and also need to be calibrated regularly. Further, maintenance, support, and deployment of these sensors in remote environments provide additional challenges to the use of conventional soil moisture sensors. In this paper, a metamaterial perfect absorber (MPA) based soil moisture sensor is introduced. The ability of MPAs to absorb electromagnetic signals with near 100% efficiency facilitates the design of highly accurate and low-profile radio frequency passive sensors. MPA based sensor can be fabricated from highly durable materials and can therefore be made more resilient than traditional sensors. High resolution sensing is achieved through the creation of physical channels in the substrate integrated waveguide (SIW) cavity. The proposed sensor does not require connection for both electromagnetic signals or for adding a testing sample. Importantly, an external power supply is not needed, making the MPA based sensor the perfect solution for remote and passive sensing in modern agriculture. The proposed MPA based sensor has three absorption bands due to the various resonance modes of the SIW cavity. By changing the soil moisture level, the absorption peak shifts by 10 MHz, 23.3 MHz, and 60 MHz, which is correlated with the water content percentage at the first, second and third absorption bands, respectively. Finally, a $$6 \times 6$$ 6 × 6 cell array with a total size of $$312 \,\hbox {mm} \times 312 \,\hbox {mm}$$ 312 mm × 312 mm has been fabricated and tested. A strong correlation between measurement and simulation results validates the design procedure.

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Section: Introductionmentioning

confidence: 99%

Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Amiri

Shariati

Lipman

2021

Sci Rep

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“…As a kind of special methodology, metamaterials have been widely used not only in the military field, for example, EM stealth [5][6][7], but also in the civil field, such as solar energy harvesting [8] and biological sensing [9]. Since Landy et al proposed a late-model perfect metamaterial absorber (MA) which can obtain an absorptivity rate of 99% at a specific frequency [10], MAs with the framework of metal-substrate-metal have been rapidly developed [11][12][13][14], which were generally based on electric or magnetic resonances and had the property of flexible adjustable absorption frequency by changing the geometrical parameters of the unit cell. Besides, traditional radar absorbing materials (RAMs) are generally comprised of magnetic metals or ferrite nanocrystalline particles dispersed in a polymer matrix, and always have a high thickness and heavy weight.…”

Section: Introductionmentioning

confidence: 99%

Wideband Absorption at Low Microwave Frequencies Assisted by Magnetic Squeezing in Metamaterials

Wang

Han

et al. 2020

Front. Phys.

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In this paper, the magnetic squeezing effect in metamaterials is explored and applied to achieve wideband absorption in low-frequency microwave bands. To this end, a metamaterial absorber (MA) is proposed, which consists of a square lattice of a split ring resonator (SRR) placed on top of a magnetic absorbing material (MAM) layer backed by a conducting ground. In the positive resonance region of SRRs, a strong magnetic squeezing effect occurs and more concentrated magnetic field lines are confined within SRRs. This results in significant magnetic field enhancement within the MAM layer, which provides a prerequisite for high-efficiency absorption enhancement at low frequencies. To verify this method, we fabricated a prototype using a 3.0 mm thick silicone MAM sheet. Both the simulation and experiment results show that with the assistance of magnetic squeezing in the SRR array, the absorption at lower frequencies is significantly enhanced and is above 90% in 1.25–2.31 GHz under normal incidence. Furthermore, the MA exhibits satisfactory stability for different polarization states and incident angles due to the square lattice of the SRR array. This design method may find potential applications in fields such as electromagnetic compatibility, wireless communication, and others.

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“…The reduction of this SAR value depends on reducing this backward energy. Meta‐surfaces due to their unique properties they proved useful in either absorbing energy in certain direction are reflecting back energy into certain direction to improve gain . Recent year's several attempts are being made to incorporate these metasurface (MS) based structures like artificial magnetic conductors, electromagnetic band gap structures, frequency selective surface (FSS), resonators, and some parasitic elements to redirect this backward energy to reduce the SAR for flexible antennas …”

Section: Introductionmentioning

confidence: 99%

Specific absorption rate reduction using metasurface unit cell for flexible polydimethylsiloxane antenna for 2.4 GHz wearable applications

Janapala

Nesasudha

Neebha

et al. 2019

Int J RF Microw Comput Aided Eng

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This article presents the design of a polydimethylsiloxane based flexible antenna for body worn applications. In order to reduce the specific absorption rate (SAR) metasurface (MS) based unit cell is proposed. Copper foil of thickness 3 mil considered for conducting layers. The proposed antenna is designed with leaf structure and covers the WLAN ISM band 2.4 GHz without metasurface (NMS) and with metasurface (WMS) unit cell. The MS unit cell at the backside of the antenna does not cover the entire antenna but only a portion of it where the backward energy is highly concentrated. This yields better result in reducing the SAR with a very compact sized MS unit cell. This MS structure improves the gain of an antenna and also reduces the SAR, by directing the radiating energy in opposite direction from the human user. The proposed antenna NMS has a simulated SAR value of 2.53 W/kg at 2.4 GHz over volume of 1 g of tissue, whereas WMS it is reduced to 1.53 W/kg. The comparative analysis of the proposed antenna presented with the help of performance matrices like reflection coefficient, SAR, gain, and radiation patterns.

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Microwave metamaterial absorber for sensing applications

Cited by 117 publications

References 36 publications

Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Wideband Absorption at Low Microwave Frequencies Assisted by Magnetic Squeezing in Metamaterials

Specific absorption rate reduction using metasurface unit cell for flexible polydimethylsiloxane antenna for 2.4 GHz wearable applications

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