EBG Cell Size Reduction by Elongating Surface Current Path

Electromagnetic band gap (EBG) cells are integrated among several applications due to their ability to suppress waves at a certain bandwidth. Moreover, some waveguides incorporate them in their structure, such as gap waveguide, which is suitable for millimeter-wave frequency applications due to its relatively low-loss, compactness, and simple fabrication. Here, a new EBG cell is presented to miniaturize the size to make it suitable for low-frequency applications. A spiral strip unit cell is introduced to shift the stop-band center frequency to half that of a conventional patch cell of the same cell size and parameters. Scaling the spiral to shift the stop-band lower frequency to that of the square patch offers 30% size reduction. However, the stop bandwidth is reduced.