Surface with high impedance

surfaces with high impedance (High-impedance surfaces or English HIS) are structures with periodic reason fixed or printed on a plan of mass. They have very interesting properties from an electromagnetic point of view, because they authorize the propagation of the electromagnetic waves along their surface only for certain wavebands. In other words, these structures exhibent one or of the forbidden bands in frequency, for which the wave propagation of surfaces is prohibited. Surfaces with high impedance belong to the class of the structures to photonic forbidden band (BIP) or photonic Cristaux.

The term of high impedance comes owing to the fact that in their forbidden bands, these materials of the composite type behave as homogeneous surfaces which would have a very high impedance.

Surfaces with high impedance were introduced by D. Sievenpiper and others with an aim of removing the waves of surface of antennas of the " type; patch" , and thus to increase their output. Indeed a " patch" is an aerial suppressed on a plan of mass, this antenna emits losses

Another propiété completely interesting, rising from the high impedance, is that an incidental wave arriving on such a surface would be seen completely considered (null coefficient of transmission: T = 0) with a coefficient of reflection R = 1. Thus contrary to a plan of traditional mass (for which R = -1), the considered electromagnetic wave would not be out of phase of 180° compared to the incidental wave.

Standard commodity

D. Sievenpiper, L. Zhang, R.F.J. Broas, N.G. Alexopolous, and E. Yablonovitch, “High-impedance electromagnetic surfaces with has forbidden frequency band,” IEEE Transactions one Microwave Theory and Techniques, vol. 47, No 11, pp. 2059-2074, Nov. 1999.

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