Reconfigurable frequency selective surfaces

Frequency Selective Surfaces (FSSs) consist of two dimensional arrays of conductive elements mounted on a dielectric substrate. FSSs act as passive filters to microwave radiation. The frequency response of the filter is primarily controlled by the dimensions and shape of the elements. The frequency selective propeny of a conventional FSS cannot be altered once it is installed. By positioning two FSSs so they are parallel and closely coupled to each other a double layer FSS is created. If one FSS is moved across the plane of the other the frequency response of the double layer FSS alters. A method of moving the FSS using piezoelectric materials has been investigated. This allows the frequency response of the double layer FSS to be altered, or reconfigured, after it has been installed. Suitable piezoelectric materials were studied and methods of utilising them in a Reconfigurable FSS (RFSS) were considered. Computer models and frequency response measurements of conventional FSSs were used to establish the design criteria necessary to maximise the variation in frequency response of the RFSS. RFSSs were designed, modelled, and manufactured. Their frequency responses were then measured. The results of the computer models and measurements were compared and used along with knowledge of manufacturing problems to reiterate the design criteria and produce an RFSS with greater reconfigurability.