Microwave absorption properties of Ag/NiFe2-xCexO4 characterized by an alternative procedure rather than the main stream method using “reflection loss”

Liu, Ying; Lin, Yuran; Zhao, Kun; Drew, Michael G. B.; Liu, Yue

doi:10.1016/j.matchemphys.2019.122615

Cited by 23 publications

(20 citation statements)

References 32 publications

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“…In history, wrong theories were always "supported" by experiments until the theories were proved wrong [22,23]. Although only a few sets of data from various compounds have been used to support our conclusions [6,7,13,21,24], their variety and the principles used for the analyses suggest that all experimental data published previously in the literature will support our conclusions. The experimental supports provided in this work are convincing and the theoretical arguments are easily accessible by experimentalists since the theoretical background is not beyond college physics.…”

Section: Introductionsupporting

confidence: 59%

“…They consider a block of material making up a film to have the same properties as the material in general. However, while permittivity ε r and permeability µ r can be properties of material [13], scattering parameters such as reflection loss RL are parameters for devices and not for material [7,8,11,13]. Film, which has thickness, is a device made of material but thickness obviously cannot be a general property of material.…”

Section: Introductionmentioning

confidence: 99%

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Microwave absorption of film explained accurately by wave cancellation theory

Liu

Yin

Drew

et al. 2023

Preprint

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It has been proved theoretically that in the field of microwave absorption, film and material are confused, and that the impedance matching theory (IM) which is usually applied to metal-backed film is inadequate. IM is defined by the difference between the absolute values of the input impedance of the film Zin and the characteristic impedance of open space Z0. Before the scientific community accepts any new theories, it is necessary to validate them with a variety of experimental data such as those obtained from films of different materials. By analysis of experimental data, it is shown here that the problems with IM cannot be solved even if different criteria such as the value of |Zin - Z0| or the phase difference between Zin and Z0 are used and therefore it needs to be replaced by wave cancellation theory. The analysis of published data in this work supports the following conclusions. The value of reflection loss RL is determined by energy conservation, specific to film since it is related to the amplitude of the resultant of the two beams reflected from the two interfaces in the film and the angular effect from the phase difference between the two beams is vital for understanding microwave absorption from film.

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Section: Introductionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Microwave absorption of film explained accurately by wave cancellation theory

Liu

Yin

Drew

et al. 2023

Preprint

Self Cite

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“…Additionally, achieving larger dipolar moment vibrations at low frequencies is difficult, increasing resistance compared to higher frequencies. [ 34 ] Applying the magnetic field to high permittivity magnetic materials induced eddy currents within the material. These eddy currents generate a magnetic field opposing the original magnetic field, which causes the energy to be dissipated as heat.…”

Section: Absorbing Materialsmentioning

confidence: 99%

Theory, Modeling, Measurement, and Testing of Electromagnetic Absorbers: A Review

Abu Sanad,

Mahmud,

Ain

et al. 2023

Physica Status Solidi (a)

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In the era of the fifth generation (5G) and the Internet of Things (IoT), electromagnetic interference (EMI) poses a significant challenge. The rapid growth of wireless communication applications leads to increased electromagnetic (EM) pollution, which can have adverse health effects. To address this issue, electromagnetic absorbers (EMAs) play a critical role in eliminating EMI and reducing EM pollution between electronic devices. The focus is now on developing diverse microwave absorbing materials (MAMs) with different structures to cover a wide range of frequencies while remaining cost‐effective and effective at high angles of incidence radiation. This article comprehensively reviews EMAs, highlighting their design parameters and importance in achieving high‐efficiency absorption. The review covers absorber theory, structure, materials for various frequency ranges, and the mechanisms responsible for dissipating electromagnetic waves (EMWs). Analytical and numerical methods for modeling and analyzing EMAs are discussed, along with performance indicators and testing methods. The role of absorbers in different applications is explored, and emerging research directions for enhancing microwave absorbers are also highlighted.

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“…The result is natural since Z M > Z 0 at high frequency and Z M < Z 0 at low frequency for magnetic material. 30 Because the data acquisition step is ∆ν = 170 MHz, the exact frequency at which Z M -Z 0 changes sign cannot be established.…”

Section: Rowmentioning

confidence: 99%

The problems in the quarter-wavelength model and impedance matching theory in analysising microwave absorption material

Liu

Drew

2021

Preprint

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It is shown here that many concepts in current mainstream microwave absorption theory are used inappropriately. Reflection loss RL has been used to characterize microwave absorption from material instead of film and the results have been rationalized by impedance matching theory. The quarter-wavelength model states that the reflection of microwaves with wavelength l from a film is minimized if the thickness of the film is m l /4 where m is an odd integer. But we show here that the model is wrong because the phase effects from interfaces have been overlooked. RL is an innate property only for metal-backed film. Impedance matching theory is developed from transmission-line theory for scattering parameter s 11 but cannot be generalized to RL.

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Microwave absorption properties of Ag/NiFe2-xCexO4 characterized by an alternative procedure rather than the main stream method using “reflection loss”

Cited by 23 publications

References 32 publications

Microwave absorption of film explained accurately by wave cancellation theory

Microwave absorption of film explained accurately by wave cancellation theory

Theory, Modeling, Measurement, and Testing of Electromagnetic Absorbers: A Review

The problems in the quarter-wavelength model and impedance matching theory in analysising microwave absorption material

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