Frequency-selective surface (FSS) structures that may be used in a variety of different filtering capacities and applications. According to exemplary embodiments, there is disclosed: 1) a one-sided FSS structure that has a conductive grid and conductive loops located on the same side of a thin substrate and exhibits a single pole frequency response; 2) a multiple layer FSS structure that has several one-sided FSS layers and exhibits a multiple pole frequency response; 3) a loop/loop tunable FSS structure where the frequency response can be adjusted or tuned with a bias network; 4) a grid/grid tunable FSS structure where the frequency response can be adjusted or tuned without the use of bias network; and 5) an antenna arrangement that has a FSS structure placed over top of antenna array so that the need for separate components, like bulky filters in a transceiver chain, can be eliminated.