MULTIBAND FREQUENCY-SELECTIVE SURFACE WITH MULTIRING PATCH ELEMENTS

Theoretical discussions and experimental verifications are presented f or a multiband frequency selective surface (FSS) with perfectly conduc ting multiring patch elements. It is found that the narrow-ring approx imation is valid for a ring width less than 0.025 lambda with lambda b eing the wavelength of the FSS's resonant frequency. A single screen d ouble-ring element FSS is demonstrated for (1) a low-pass FSS that ref lects the Ka-band signal while passing the S-,X-, and Ku-band signals, and (2) a tri-band system that reflects the X-band signal while trans mitting through the S- and Ku-band signals. In addition, a double scre en four-band PSS with non-similar double-ring elements is developed by cascading the above mentioned two single screens. The good agreement obtained between the measured and the computed results verified the co mputer codes and the approaches of this paper.