Polarization-dependent electromagnetic band gap (PDEBG) structures: Designs and applications

EBG structures exhibit an in-phase reflection coefficient, which makes them desirable for low-profile antenna designs. However, a conventional EBG structure has an identical reflection phase for a normally incident plane wave in spite of its polarization sate. This paper presents novel polarization-dependent EBG (PDEBG) structures whose reflection phases are difference, depending upon the polarization state of the incident plane wave. This polarization-dependent reflection-phase feature is realized by changing the unit geometries, for example, by using a rectangular patch to replace the square patch, by cutting slots into the patch, or by offsetting the vias. By properly tailoring the phase difference between different polarizations, a useful EBG reflector is introduced, which can control the polarization state of the reflected wave. One attractive application of this reflector is that the reflected wave of a circularly polarized incident plane wave can maintain its polarization sense. (C) 2004 Wiley Periodicals, Inc.