Modal analysis of leaky modes supported by planar metallic corrugations

Corrugated metal planar surfaces lend themselves to the realization of a wide range of guiding and radiating devices thanks to their compact and robust shape. In a homogenization regime corrugated metal surfaces can support a proper surface-wave mode. At higher frequencies, i.e., when the unit cell period and the free-space wavelength are comparable, they support proper and improper leaky-wave regimes. Here, we present an original dispersive study of a corrugated all- metal plane constituted by narrow grooves. A modal dispersive analysis is carried out using a method-of-moments approach. We investigate the proper and improper surface-wave regime across a relatively large spectrum. An interesting modal solution is achieved, showing large variations of the attenuation constant, an open stop band at the forward/backward transition and higher frequencies stop bands. A large region just after the open stop band is achieved where the phase constant is smaller than the attenuation constant, potentially offering wideband broadside radiation. The structure can support the design of an all-metal planar antenna.