Microwave band gaps produced by varying numbers of mushroom metamaterial cells

Surface wave transmission at X-band frequencies through mushroom metamaterials was measured for different sizes of mushroom arrays fabricated on high-permittivity circuit boards. For arrays of width 1, 2, 3, and 26 cells, the band gap increased in frequency and depth as the number of cells increased. The maximum filtering effect was 22 dB. This study demonstrates the necessity of careful simulation or measurement to ensure that the desired band gap is achieved with finite band gap arrays.