Frequency selective surfaces exhibit an infinite number of alternating transmission and reflection bands. Generally, only the first pair can be used because of the presence of grating lobes due to the periodicity of the structure. In some applications, two reflection bands separated by a transmission band are required. This frequency responce can be obtained with a double grid Frequency Selective Surface (FSS). One grid, a perforated screen, yields the lower reflection band; the other one, an array of patches (crossed dipoles, tripoles, etc. ) yields the higher reflection band. However, in the intermediate frequency band, perfect transmission is obtained only if the grid separation goes to zero. Infact, in this case, the equivalent circuit of the fundamental mode reduces to a shunt susceptance, which presents alternating zeros and poles (Foster theorem). Hence, the desired frequency behaviour can be obtained by a perforated screen with metal patches inserted in its apertures. In other terms, this discontinuity can be seen as a perforated screen with double connected apertures.
A New Class of Frequency-Selective Surfaces / Orta, R.; Savi, P.; Tascone, R.. - STAMPA. - (1992), pp. 1767-1770. (Intervento presentato al convegno International Symposium on Antennas and Propagation (AP-S) tenutosi a Chicago, IL, USA nel July 18-25 1992) [10.1109/APS.1992.221508].
A New Class of Frequency-Selective Surfaces
Orta, R.;Savi, P.;
1992
Abstract
Frequency selective surfaces exhibit an infinite number of alternating transmission and reflection bands. Generally, only the first pair can be used because of the presence of grating lobes due to the periodicity of the structure. In some applications, two reflection bands separated by a transmission band are required. This frequency responce can be obtained with a double grid Frequency Selective Surface (FSS). One grid, a perforated screen, yields the lower reflection band; the other one, an array of patches (crossed dipoles, tripoles, etc. ) yields the higher reflection band. However, in the intermediate frequency band, perfect transmission is obtained only if the grid separation goes to zero. Infact, in this case, the equivalent circuit of the fundamental mode reduces to a shunt susceptance, which presents alternating zeros and poles (Foster theorem). Hence, the desired frequency behaviour can be obtained by a perforated screen with metal patches inserted in its apertures. In other terms, this discontinuity can be seen as a perforated screen with double connected apertures.File | Dimensione | Formato | |
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1992-Symp-APS-A NEW CLASS OF FREQUENCY SELECTIVE SURFACES.pdf
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https://hdl.handle.net/11583/1662035