Design for suppressing undesired reflections from frequency-selective surfaces employed in multiband sector antenna

This paper proposes a technique that uses the small-metal width of a frequency-selective surface (FSS) element to suppress the change in beamwidth due to the undesired reflection from other FSSs. FSSs reflect low-level electromagnetic waves that are expected to pass through essentially the FSSs outside of the desired reflection bands, and generate these low level reflections from other FSSs as undesired reflections. Electromagnetic field analysis based on a dual-band antenna structure shows the relationship between the metal width and the reflection coefficient of the FSS element, and the relationship between the metal width and the beamwidth in the desired band and the other band. This paper clarifies that the small-metal width of the FSS element can be used to reduce the change in beamwidth outside the desired band.