Frequency-selective reflectors using periodic dielectric layers

The authors examine the feasibility of using periodically varying dielectric layers for implementing subreflectors that permit feed separation in large-aperture reflecting antenna systems. The specific periodic layers investigated are in the canonic form; they consist of alternating stripes in the form of rectangular bars having different dielectric constants. To illustrate their frequency-selection mechanism, the authors consider the simple case of a (TE) plane wave polarized along the y direction and incident at an angle theta in the xz plane perpendicular to the strips. The results reveal that the layer exhibits the desired frequency-selective properties, namely, total reflection at one frequency and total transmission at other well-separated frequencies. The approximate locations of the reflection and transmission bands can be predicted from the properties of an equivalent layer having a uniform dielectric constant equal to the average of that in the periodic layer.<>