Using subwavelength diffraction gratings to design open microwave cavities

We introduce an open microwave cavity that has a wall replaced by a sub-wavelength grating. Usually, sub-wavelength gratings show very low transmission. In our experiment, this phenomenon is compensated by the microwave cavity that finally allows all the energy to be transmitted. We study the far field emission of this system and show that coupling the cavity with a sub-wavelength grating gives rise to a zero order emission only at discrete angles and frequencies. We study the relations between angles of emissions and frequencies, the influence of geometric parameters such as the grating fill factor and the behavior of a chaotic cavity. We show that it allows us to make a configurable system that may have many applications in the fields of communications, detection and imaging, and may allow the study of open microwave cavities on a fundamental point of view.