Anisotropy of wood in the microwave region

Ziherl, Saša; Bajc, J.; Urankar, Bernarda; Čepič, Mojca

doi:10.1088/0143-0807/31/3/010

Cited by 9 publications

(8 citation statements)

References 9 publications

(17 reference statements)

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“…Microwave transmission has been used in testing wood for several years [1]. Timber is an anisotropic material and it is relatively transparent at microwave frequencies [2]. This opens an opportunity to study the anisotropic characteristics and dielectric properties of wooden beams at microwave frequencies using far-field measurements [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…Timber is an anisotropic material and it is relatively transparent at microwave frequencies [2]. This opens an opportunity to study the anisotropic characteristics and dielectric properties of wooden beams at microwave frequencies using far-field measurements [1][2][3][4]. Saeidi et al [5] applied near-field and far-field ultra-wideband (UWB) radio signals to image wood imperfections.…”

Section: Introductionmentioning

confidence: 99%

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A Cavity-Backed Slot Antenna on Timber

Radwan

Salchak

Albadri

et al. 2021

2021 IEEE Asia-Pacific Microwave Conference (APMC)

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Cavity-backed slot antennas can be used to detect anomalies and measure the dielectric properties of lossy media such as timber at microwave frequencies. An enhanced antenna design with the feed plate directly behind the rectangular slot allows maximum E-field coupling to the wood and provides more space for electronics inside the aluminum box. The E-field in a rectangular wood piece (100 mm × 70 mm × 70 mm) was calculated using CST simulations at the resonant frequency of 7.4 GHz. The wood material was modeled as isotropic with a relative permittivity of 2 and low conductivity (10 -6 S/m). A comparison between simulations and a spherical wave calculation showed significant change in E-field in the very nearfield region of the antenna at the distances smaller than 4 mm. The electrical field penetrated the 70 mm width, and reflection from the opposite wood-air interface was observed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Cavity-Backed Slot Antenna on Timber

Radwan

Salchak

Albadri

et al. 2021

2021 IEEE Asia-Pacific Microwave Conference (APMC)

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“…In the literature, several reports discuss the propagation of electromagnetic waves in anisotropic media, mostly light (see e.g. [4][5][6][7]), but also microwaves [8]. Reports that address mechanical systems, can be sorted into three groups.…”

Section: Introductionmentioning

confidence: 99%

Propagation of polarised mechanical waves in an anisotropic medium

Faletič

Čepič

2018

Eur. J. Phys.

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During the propagation in an anisotropic medium, linearly polarized light in general becomes elliptically polarized. One can detect the polarization state of the transmitted light, but not the evolution of the polarization state during the propagation inside the material. We present a mechanical model where this evolution can be observed. The anisotropic medium is modelled by a series of coupled anisotropic oscillators. An oscillator consists of a bead hanging on an elastic string, and is coupled to neighbouring oscillators with stronger springs. When the system is excited in the plane perpendicular to the springs, the trajectories of the oscillating beads indicate the polarization state of the excitation at their respective positions. We analyze the model analytically, numerically and experimentally.

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“…The authors considered simple hands-on experiments that allowed for an observation of conoscopic figures of transparencies [7][8][9] and simple arrangements for observing conoscopic figures of crystals [10][11][12][13][14]. More details were given for a theoretical analysis of conoscopic figures [9,13,15] and propagation of electromagnetic waves through other anisotropic media [16,17]. All references considering conoscopic pictures were focused on understanding its meaning.…”

Section: Introductionmentioning

confidence: 99%

Conoscopic figure: a complex consequence of a not so simple phenomenon

Pečar¹,

Čepič²

2014

Eur. J. Phys.

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Observation of conoscopic figures through a special microscope is widely used as an experimental method for determination of optical properties of anisotropic materials. The conoscopic figure appears when a divergent light passes through an anisotropic material sandwiched between crossed polarizers. The complex pattern of bright and dark areas appears due to different polarization states of light. The pattern gives information about optical axes and birefringence of the material and allows for deduction of microscopic structures at the origin of such properties. Due to the complexity of the figure, the method is often used following recipes. This contribution presents a series of experiments that provide students with experiences needed for construction and comprehension of optical phenomena that contribute to the complexity of the conoscopic figure.

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Anisotropy of wood in the microwave region

Cited by 9 publications

References 9 publications

A Cavity-Backed Slot Antenna on Timber

A Cavity-Backed Slot Antenna on Timber

Propagation of polarised mechanical waves in an anisotropic medium

Conoscopic figure: a complex consequence of a not so simple phenomenon

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