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The Effect of Rotational Disorder on the Microwave Transmission of Checkerboard Metal Square Arrays.

Tremain B, Durrant CJ, Carter IE, Hibbins AP, Sambles JR - Sci Rep (2015)

Bottom Line: By applying rotational disorder to the elements comprising the arrays, with the lattice constant and element size unchanged, the electrical connectivity of the structure can be controlled whilst maintaining periodicity.When approximately half of the connections are broken, the resonant features are suppressed, with scattering loss shown to dramatically increase to as much as 40% of the incident power over a broad frequency range.The result is a thin, highly effective scatterer of microwaves.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL.

ABSTRACT
The effect of rotational disorder on the microwave transmission through thin metallic checkerboard arrays has been experimentally studied. Broad resonant features below the onset of diffraction, attributed to electromagnetic radiation coupling through the structure via the evanescent fields of bound surface waves, are found to be strongly dependent on the electrical connectivity of the surface. By applying rotational disorder to the elements comprising the arrays, with the lattice constant and element size unchanged, the electrical connectivity of the structure can be controlled whilst maintaining periodicity. The results show that rotational disorder can significantly affect transmission only when it changes the structure's connectivity. When the initial structure is just above the connectivity threshold (where the metallic occupancy is 50%), increasing disorder causes the resonant features in transmission to invert as the structure switches from a predominantly connected array to a disconnected array. When approximately half of the connections are broken, the resonant features are suppressed, with scattering loss shown to dramatically increase to as much as 40% of the incident power over a broad frequency range. The result is a thin, highly effective scatterer of microwaves.

No MeSH data available.


Related in: MedlinePlus

Illustration of square patches of side length L rotated at 45° to a square lattice of pitch λg = 5.95 mm.Orientation of the incident electric field vector E0 is also illustrated. (a) disconnected patches, X = 40% (b) threshold connection, X = 50% (c) connected patches, X = 60%.
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f1: Illustration of square patches of side length L rotated at 45° to a square lattice of pitch λg = 5.95 mm.Orientation of the incident electric field vector E0 is also illustrated. (a) disconnected patches, X = 40% (b) threshold connection, X = 50% (c) connected patches, X = 60%.

Mentions: In this study, we take a similar approach to Takano et al. by randomly perturbing the perfect checkerboard geometry. However in this case the square size is fixed and a Gaussian random rotation is applied to each element. This allows connections between the metallic squares to be broken (or made) whilst keeping the lattice spacing constant. As the system retains this underlying periodicity, diffractive effects such as the excitation of surface waves and the onset of diffracted orders above frequency are expected to remain. We explore how disorder in element rotation of the checkerboard patch and hole arrays affects the enhanced transmission phenomena below this onset of diffraction. We begin with a square array of square metallic patches of side length L rotated by 45° with respect to the square lattice vectors, as shown in Fig. 1. Varying the side length of the squares changes the metal occupancy (X) of the array and allows transmission both below and above the connectivity threshold (X = 50%) to be studied. As mentioned previously, for samples of metal occupancy X% the transmission TX of their inverse (or complementary) structures of metal occupancy (100 − X)% is 1 − TX, assuming that the only loss channels are specular reflection or transmission. This accords with the description of Babinet’s principle18.


The Effect of Rotational Disorder on the Microwave Transmission of Checkerboard Metal Square Arrays.

Tremain B, Durrant CJ, Carter IE, Hibbins AP, Sambles JR - Sci Rep (2015)

Illustration of square patches of side length L rotated at 45° to a square lattice of pitch λg = 5.95 mm.Orientation of the incident electric field vector E0 is also illustrated. (a) disconnected patches, X = 40% (b) threshold connection, X = 50% (c) connected patches, X = 60%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645165&req=5

f1: Illustration of square patches of side length L rotated at 45° to a square lattice of pitch λg = 5.95 mm.Orientation of the incident electric field vector E0 is also illustrated. (a) disconnected patches, X = 40% (b) threshold connection, X = 50% (c) connected patches, X = 60%.
Mentions: In this study, we take a similar approach to Takano et al. by randomly perturbing the perfect checkerboard geometry. However in this case the square size is fixed and a Gaussian random rotation is applied to each element. This allows connections between the metallic squares to be broken (or made) whilst keeping the lattice spacing constant. As the system retains this underlying periodicity, diffractive effects such as the excitation of surface waves and the onset of diffracted orders above frequency are expected to remain. We explore how disorder in element rotation of the checkerboard patch and hole arrays affects the enhanced transmission phenomena below this onset of diffraction. We begin with a square array of square metallic patches of side length L rotated by 45° with respect to the square lattice vectors, as shown in Fig. 1. Varying the side length of the squares changes the metal occupancy (X) of the array and allows transmission both below and above the connectivity threshold (X = 50%) to be studied. As mentioned previously, for samples of metal occupancy X% the transmission TX of their inverse (or complementary) structures of metal occupancy (100 − X)% is 1 − TX, assuming that the only loss channels are specular reflection or transmission. This accords with the description of Babinet’s principle18.

Bottom Line: By applying rotational disorder to the elements comprising the arrays, with the lattice constant and element size unchanged, the electrical connectivity of the structure can be controlled whilst maintaining periodicity.When approximately half of the connections are broken, the resonant features are suppressed, with scattering loss shown to dramatically increase to as much as 40% of the incident power over a broad frequency range.The result is a thin, highly effective scatterer of microwaves.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL.

ABSTRACT
The effect of rotational disorder on the microwave transmission through thin metallic checkerboard arrays has been experimentally studied. Broad resonant features below the onset of diffraction, attributed to electromagnetic radiation coupling through the structure via the evanescent fields of bound surface waves, are found to be strongly dependent on the electrical connectivity of the surface. By applying rotational disorder to the elements comprising the arrays, with the lattice constant and element size unchanged, the electrical connectivity of the structure can be controlled whilst maintaining periodicity. The results show that rotational disorder can significantly affect transmission only when it changes the structure's connectivity. When the initial structure is just above the connectivity threshold (where the metallic occupancy is 50%), increasing disorder causes the resonant features in transmission to invert as the structure switches from a predominantly connected array to a disconnected array. When approximately half of the connections are broken, the resonant features are suppressed, with scattering loss shown to dramatically increase to as much as 40% of the incident power over a broad frequency range. The result is a thin, highly effective scatterer of microwaves.

No MeSH data available.


Related in: MedlinePlus