Frequency Selective Surfaces for Extended Bandwidth Backing Reflector Functions

This paper deals with the use of frequency selective surfaces (FSS) to increase the efficiency times bandwidth product in ultra-wide band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be suitable as antenna ground plane only on a limited frequency range. In order to extend the higher frequency range of usability, an FSS can be sandwiched between the antenna and the ground plane. Ideally this FSS will not affect the behavior of the antenna at lower frequencies. The trade-offs that lead this type of designs will be discussed, having in mind a scenario with several antennas sharing the same platform or an unique UWB antenna array operating on the concept of connected arrays.