On the Link Between Leaky-Wave Mechanism and Parasitic Resonances Observed in a Reflecting Periodic Surface Made of Phoenix Cells

This communication investigates a parasitic resonance with strong losses that is exhibited by a periodic structure composed of 4
^th
order Phoenix cells on top of a metal-backed dielectric slab. The physical origin of the phenomenon is examined through simulations. This study shows that this parasitic resonance is linked to a trapped wave propagating in the structure. It corresponds to a leaky-wave mechanism occurring under certain conditions. In order to avoid such undesired resonances, a design rule is derived which defines a new constraint on the cell periodicity.