Phase Constant Measurement of Periodically Structured Surfaces-The Leaky-Wave Region

We address a practical approach to the dispersion measurement of the phase constant in the leaky-wave region of a periodically structured surface. If the structure is excited by a plane wave impinging from oblique directions, a coupling to the leaky mode supported by the structure can occur, leading to a reduction of the reflectance. Accordingly, by variation of the incident angle and the frequency of the plane wave, the leaky-wave region can be sampled. The dispersion characteristic of the phase constant of the leaky mode can therefore be extracted from the measurement of the reflection behavior at the surface. This method is applied to an example structure, where good agreement between simulation and experimental evaluation was found.