A Leaky-Wave Analysis of the Phase Center in Fabry-Pérot Cavity Antennas

Phase centers are studied for Fabry-Pérot cavity antennas viewed as two-dimensional uniform leaky-wave antennas radiating pencil beams pointing at broadside. Alternative definitions for the phase center are considered and compared, as a function of the wavenumber of the relevant leaky waves and of the extension of the angular region of interest in the far field around the direction of maximum radiation amplitude. Analytical formulas are derived and numerical simulations of antennas constituted by planar grounded substrates covered with dielectric or metal partially-reflecting surfaces are provided to validate the analysis.