Frequency-selective reflection and transmission by a periodic dielectric layer

The feasibility of using a periodic dielectric layer, composed of alternating bars having dielectric constants ε₁ and ε₂, as a dichroic surface at millimeter-wave frequencies is examined. For oblique incidence, it is found that total transmission and total reflection can be obtained at different frequencies for proper choices of ε₁ and ε₂ and the geometric parameters. The frequencies of total reflection and transmission can be estimated from wave phenomena occurring in a layer of uniform dielectric constant equal to the average value in the periodic layers. For some of the frequencies of total transmission, the bandwidth for 90% transmission is found to be 40%. The bandwidth for 90% reflection is always found to be much narrower, the greatest value obtained being 2.5%